Rear shock & nitrogen pressure
HardWorkingDog
at the shock exposed since I removed the subframe and thinking it's
probably time for a rebuild. I've had the bike almost 8 years and
never done anything for it, other than replace the mounting bearings.
Hmmm, a schrader valve... Figured I'd test it to see if there was any
pressure in there. Got out the tire gauge we use for road bike tires,
it read 82 psi. I'd done a little research, seems that 135-165 psi is
the going pressure. Aha, low! Definitely time for service.
I look over at the 2 other, newer, YZ's sitting in the stable, quietly
minding their own business. Hmmm, I wonder, what pressure THEIR shocks
have???
So I checked, with my handy dandy bicycle pressure gauge. This one:
http://ecx.images-amazon.com/images/I/41mVMEvHOxL._SS500_.jpg
They were both at 105 psi.
I did a little more reading. I think I've probably released a
significant amount of nitrogen by simply checking it with a tire
pressure gauge. Anyone have direct experience with nitrogen pressures,
and the best practice for checking, on a dirt bike shock?
I'm thinking I'm going to need to top up the N on both shocks while I
have my '99's shock serviced.
--
Charles
'99 YZ250
Mike Baxter
wrote:
I was reading this and saying no,no, no, NO,NO! out loud. At least
you found out prior to going riding. :-)
I just dropped the FZ1 shock off at Phil's house.
Mike Baxter
HardWorkingDog
Mike Baxter <mgb***@comcast.net> wrote:
>
> I was reading this and saying no,no, no, NO,NO! out loud. At least
> you found out prior to going riding. :-)
Well, at least my foreshadowing worked <g> I can use rmd to hone my
writing skills...
Too bad my memory is so bad. google found a discussion about this very
topic almost exactly 2 years ago.
> I just dropped the FZ1 shock off at Phil's house.
I gotta talk to you about Mr. Douglas.
--
Charles
'99 YZ250
john
news:harvey-067DAE....@news.individual.net...
I hear some kid from phoenix tried topping his shock
off with the oxy acetylene tank in his dad's garage....
blew up faster than a Obama's deficit
I am Tosk
joh...@g-male.comm says...
I was gonna' ask, what state did he land in?
Rowdy Mouse Racing, ugh, gym work for the winter...
bajacornman
So you are saying he dumped like 1500-2500 psi into it or introduce o2
or fuel?
john
>So you are saying he dumped like 1500-2500 psi into it or introduce o2
>or fuel?
took a valuable comodity and crammed it up the wrong
orifice and blew it all to hell...
HardWorkingDog
<4c2b8dfb-631b-49a4...@m35g2000prh.googlegroups.com>,
bajacornman <bajac...@adelphia.net> wrote:
> > > I did a little more reading. I think I've probably released a
> > > significant amount of nitrogen by simply checking it with a tire
> > > pressure gauge. Anyone have direct experience with nitrogen pressures,
> > > and the best practice for checking, on a dirt bike shock?
> >
> > > I'm thinking I'm going to need to top up the N on both shocks while I
> > > have my '99's shock serviced.
And I did some MORE reading. Found this gem:
http://groups.google.com/group/rec.motorcycles.dirt/browse_thread/threa
d/4ab3599432bb89cb/2c792684770ae388?hl=en&q=nitrogen&lnk=ol&
A classic, from the days when rmd smoked cigars, and pulled out nails
with it's teeth.
Featuring:
JayC apologizing, sincerely.
Hellsickle posting differential equations.
Buckley being pleasant.
Levy being dlevy.
Me and dirtcrashr talking about Bay Area nouvelle cuisine.
Tuner and Jeff Howe (where'd he go?) and Deeney contributing some real
info on what makes shocks work and how to do what needs to be done.
Definitely worthwhile to read all 161 posts.
I don't think I made the shocks unusable by sticking my tire gauge on
the N bladder schrader valve. Buried in there is a test that Jeff Howe
did to determine how much pressure bled off when he applied a gauge to
the shock. He came up with an average 6 psi loss. This is definitely a
significant loss but I think I'm safe to say my attempt was no worse
than that, so if I read 105 psi the shock was already far too low to
begin with. I think I'm going to put together a nitrogen filling
system. Just what the garage needs.
I'm guessing that the shock with 85 psi is probably beat to hell
inside.
--
Charles
'99 YZ250
XR650L_Dave
If you pumped in O2 at any kind of significant pressure, the oil would
combust vigorously.
Dave
Whelan - '02 200exc (x2) & '04 MTD 38
pressure, screw out the compression adjuster, pump out the old oil,
put in new fluid, work it until after it sits for 20 minutes you can't
get any bubbles by stroking the shock (this can take a lot of
iterations), screw the adjuster back in, pump in the required psi. I
use a pump that looks very similar to this:
http://www.amazon.com/Cane-Creek-Bicycle-Shock-Pump/dp/B000ZMUV7U
My experience has been the extra care I take working out 99.9% of the
bubbles yields a better result than those wonderful caring
professional mechanics at the local honda shop.
-my two cents
-Joe
HardWorkingDog
<a65c4041-f80f-4b2b...@a5g2000prg.googlegroups.com>,
Sounds like you use plain ol' garage air to re-pressurize the shock? I
think I'll stick with Nitrogen. I think I've let the thing go so long
it's way beyond just replacing the oil. It's got to be taken apart.
But thanks.
--
Charles
'99 YZ250
JayC
> with it's teeth.
Man - those were some good 'ole days, alright.
I still don't know how I was able to get ANY work done back then.
I miss everybody.
JayC
HardWorkingDog
<7b27e2ed-42ac-41a0...@l26g2000yqd.googlegroups.com>,
JayC <j...@sysmatrix.net> wrote:
Have any idea what happened to Jeff Howe and his TrakControl
suspension business? He seems to have disappeared from google-izing
after about 2004 or so. He WAS a little touchy...but seemed to be
doing some good work with suspension.
--
Charles
'99 YZ250
Tim H
> > A classic, from the days when rmd smoked cigars, and pulled out nails
> > with it's teeth.
>
> Man - those were some good 'ole days, alright.
Yep, rmd was a much more vibrant place back then. I'm glad I found it
before it's untimely demise.
> I still don't know how I was able to get ANY work done back then.
>
> I miss everybody.
I miss people reading and responding to my posts.
Tim H
T.I.M. - The Invisible Man
Tiago
> Tim H
> T.I.M. - The Invisible Man
ok, you're The Invisible Man, I'm the thread killer.
we could form a duo!
LOL!
-- T
-> pestering rmd since 1999
HardWorkingDog
<7c33ff46-0dc3-4b12...@t34g2000prm.googlegroups.com>,
Tim H <tntha...@msn.com> wrote:
> On Feb 3, 9:28�am, JayC <j...@sysmatrix.net> wrote:
> > > A classic, from the days when rmd smoked cigars, and pulled out nails
> > > with it's teeth.
> >
> > Man - those were some good 'ole days, alright.
>
> Yep, rmd was a much more vibrant place back then. I'm glad I found it
> before it's untimely demise.
I don't know about untimely. Everything has a season...
Anyway, it's still stumbling along, albeit a shadow, but I still find
it worthwhile. It's what we put into it.
> > I still don't know how I was able to get ANY work done back then.
> >
> > I miss everybody.
>
> I miss people reading and responding to my posts.
>
> Tim H
> T.I.M. - The Invisible Man
I know you've mentioned this before, I still think I've got a higher
killthread score than you but really I think everyone, except maybe MW
Inc, feels like they're somehow ignored at one point or another.
I read everything that comes along. I've disliked my tendency to try
to get a one-liner in on every thread. I'd rather contribute something
meaningful or that advances the discussion in a thoughtful way, so if
I've got nothing to add I'll often just lurk.
There is a value to encouraging words, but I guess I generally think
of you as one of the rocks of rmd, and how can you encourage a rock?
btw, how did your cylinder issue work out? I can't remember if your
went new or replate.
--
Charles
'99 YZ250
john
john
I am Homer of Borg. Prepare to be.....ooooh donuts...
"Tim H" <tntha...@msn.com> wrote in message
news:7c33ff46-0dc3-4b12...@t34g2000prm.googlegroups.com...
XR650L_Dave
> In article
> <7b27e2ed-42ac-41a0-93c7-e225b2784...@l26g2000yqd.googlegroups.com>,
If that was spelled geoff, he's not one of the howe and howe howe's is
he?
Dave
HardWorkingDog
<f3018208-9b2f-4864...@x9g2000vbo.googlegroups.com>,
XR650L_Dave <spamT...@yahoo.com> wrote:
Don't think so--his sig was always "Jeff".
--
Charles
'99 YZ250
I am Tosk
har...@mush.man says...
>
> In article
> <7c33ff46-0dc3-4b12...@t34g2000prm.googlegroups.com>,
> Tim H <tntha...@msn.com> wrote:
>
I have always found great information and thinking here. For me the
place has been a lifesaver in many ways... Probably wouldn't have made
it through a whole season of racing without you folks, seriously.
Rowdy Mouse Racing, Thanks RMD!
dsc-ky
> In article
>
> - Show quoted text -
I think several other people have said that air works... maybe not as
well as pure nitrogen. How would pure argon or pure co2, pure helium,
etc work? How bout Argon/co2 mix? :) Is there anything really magical
about the choice or nitrogen?
Of course the argon, co2 and co2/argon mix are commonly found in many
a garage including mine. :)
HardWorkingDog
<733c1431-c3f5-4c7e...@z26g2000yqm.googlegroups.com>,
dsc-ky <Dudley....@eku.edu> wrote:
> I think several other people have said that air works... maybe not as
> well as pure nitrogen. How would pure argon or pure co2, pure helium,
> etc work? How bout Argon/co2 mix? :) Is there anything really magical
> about the choice or nitrogen?
That's been hashed about pretty well in the thread from 2002 I
referred to earlier. From my poor memory, it is stable, dry, safe and
cheap. Other gases don't have all those advantages. Don't know that
I'd call that magical, but good enough for me. That and it's what
Kayaba/Ohlins/WP/Showa recommends, and as far as I know it's what
every top level off-roader dirt bike racer uses as well.
> Of course the argon, co2 and co2/argon mix are commonly found in many
> a garage including mine. :)
Yes, well...I caught the smiley, but the easy way is usually not the
right way :)
--
Charles
'99 YZ250
dsc-ky
> In article
Don't some other inert gasses share those qualities?
WoodsChick
> On Feb 3, 9:28 am, JayC <j...@sysmatrix.net> wrote:
>
> > > A classic, from the days when rmd smoked cigars, and pulled out nails
> > > with it's teeth.
>
> > Man - those were some good 'ole days, alright.
>
> Yep, rmd was a much more vibrant place back then. I'm glad I found it
> before it's untimely demise.
>
> > I still don't know how I was able to get ANY work done back then.
>
> > I miss everybody.
I do, too.
>
> I miss people reading and responding to my posts.
Hi, Tim! Just wanted to say "hi" and respond to your post <G>
>
> Tim H
> T.I.M. - The Invisible Man
Tami-
Whelan - '02 200exc (x2) & '04 MTD 38
There's nothing plain about my garage.
Yeppers - it's free and works fine.
> I
> think I'll stick with Nitrogen.
Maybe, just maybe an RC or JS could detect the small difference
between a nitrogen- versus an air-charged shock the 10th or 12th time
through a long section of stadium whoops (when the shock's so hot you
could cook with it). Or maybe not.
If you have a free source for nitrogen, great, but if you're spending
$ to have someone charge it with nitrogen, in my not-so-humble opinion
that's wasted $.
> I think I've let the thing go so long
> it's way beyond just replacing the oil. It's got to be taken apart.
In the legendary words of Sherman T. Potter, "Horse Apples!!"
If it's not leaking all it probably needs is a fluid change.
When it's been a while since you've serviced your forks, and they're
not leaking, do you replace all the bushings, seals and wipers? Of
course not, you dis-assemble them, inspect everything, maybe replace a
bushing here and there, clean it all up real good and put fresh fluid
in (or maybe just dump out the fluid, flush some solvent through them
a few times to clean, let the solvent evaporate then put in fluid).
Geez, the first time I tore into the KTM's forks (because of seal
leakage), I didn't replace anything, I just shortened the springs in
the seals, cleaned everything up, put in fresh fluid, put on seal
savers and ignored them for six months.
If your shock is not leaking oil and the bladder isn't burst (if fluid
doesn't come out when venting the pressure) then all you're REALLY
getting paying someone to "rebuild" it is fresh oil (and probably a
poor job of working the air bubbles out) and recharged with nitrogen
(or air, who knows unless you watch them charge it?).
While I'm at this, I'll go into full rant mode:
The last time I worked on the XR's (KYB) shock, I changed the fluid
and spent probably 45 minutes working out the bubbles (first
iteration), let it sit for maybe an hour, then maybe 20 minutes
working out the bubbles (2nd iteration) and so forth for probably 8-10
iterations until I could let it sit for maybe an hour and not get
bubbles when stroking the shock.
I then took it to the local shop to have it charged with nitrogen
where they expected me to pay $30 (min shop charge) for the 10 seconds
of work and $0.02 nitrogen needed. Uh, no. I pressurized it with the
air pump mentioned earlier.
The VERY interesting part about this, at least for me, was the
resulting action was NOTICABLY better than ANY of the prior "rebuilds"
shops had done.
In retrospect, the reason seems clear. No shop (other than a "real"
shop like PC) would spend the time working out all the air bubbles
yielding such consistent action.
Lesson = you want something done right, do it yourself. You want a
quickie, hire someone paid piece rate.
> But thanks.
No sweat dude.
You gonna try and make Idaho this summer?
> Charles
> '99 YZ250
HardWorkingDog
<791437c0-ee94-44e0...@b36g2000pri.googlegroups.com>,
dsc-ky <Dudley....@eku.edu> wrote:
> On Feb 3, 4:33�pm, HardWorkingDog <har...@mush.man> wrote:
> > In article
> > <733c1431-c3f5-4c7e-ab18-6d28396f1...@z26g2000yqm.googlegroups.com>,
> >
> > �dsc-ky <Dudley.Corn...@eku.edu> wrote:
> > > I think several other people have said that air works... maybe not as
> > > well as pure nitrogen. How would pure argon or pure co2, pure helium,
> > > etc work? How bout Argon/co2 mix? :) Is there anything really magical
> > > about the choice or nitrogen?
> >
> > That's been hashed about pretty well in the thread from 2002 I
> > referred to earlier. From my poor memory, it is stable, dry, safe and
> > cheap. Other gases don't have all those advantages. Don't know that
> > I'd call that magical, but good enough for me. That and it's what
> > Kayaba/Ohlins/WP/Showa recommends, and as far as I know it's what
> > every top level off-roader dirt bike racer uses as well.
> >
> > > Of course the argon, co2 and co2/argon mix are commonly found in many
> > > a garage including mine. :)
> >
>
> Don't some other inert gasses share those qualities?
I think the idea is that nitrogen IS inert--nonreactive--in the case
of a shock bladder/body. Argon could be a close second, but I suspect
it is quite a bit more expensive. The fact that there is no water
vapor is key, at least Deeney seemed to think so.
Interesting that Fox is making a big push to return to their roots by
building dirt bike shocks again. They're pretty impressive looking,
and being ridden by Brock Tickle pretty successfully (from scrape's
neck of the woods). Anyway, they still make air shocks for bicycles,
but their dirt bike shocks are pressurized with nitrogen.
--
Charles
'99 YZ250
Mike Baxter
wrote:
I have a couple N2 tanks and a regulator in need of a bout a $15 part.
It cost $8 to swap to a full tank when empty. With todays energy
cost, it's cheap compared to running my compressor.
Mike Baxter
HardWorkingDog
<a9fc797b-b890-4155...@s36g2000prh.googlegroups.com>,
"Whelan - '02 200exc (x2) & '04 MTD 38" <yo...@sisna.com> wrote:
> > Sounds like you use plain ol' garage air to re-pressurize the shock?
>
> There's nothing plain about my garage.
Woo-hoo! <g> I think pictures are in order here. Normally the air in
my garage is rarefied as well, especially after eating at Taqueria. My
wife stays away--she's learned. :)
> Yeppers - it's free and works fine.
>
> > I
> > think I'll stick with Nitrogen.
>
> Maybe, just maybe an RC or JS could detect the small difference
> between a nitrogen- versus an air-charged shock the 10th or 12th time
> through a long section of stadium whoops (when the shock's so hot you
> could cook with it). Or maybe not.
That would be a good test.
> If you have a free source for nitrogen, great, but if you're spending
> $ to have someone charge it with nitrogen, in my not-so-humble opinion
> that's wasted $.
but, but, that's what dirt biking is all about isn't it? turning money
into noise. Most people consider it all a waste anyway.
I've got a connection in the HVAC business, so I'm going to spend
money on a regulator/gauges/hose/chuck and a bottle of nitrogen so's I
can do it myself.
> > I think I've let the thing go so long
> > it's way beyond just replacing the oil. It's got to be taken apart.
>
> In the legendary words of Sherman T. Potter, "Horse Apples!!"
>
> If it's not leaking all it probably needs is a fluid change.
In the words of Harry Potter, "Expelliarmus!"
No, I really want the shock opened up and gone through, piece by
piece. I don't want to put myself through shock school right now, so
I'm having Phil Douglas do it, along with some of his valving
expertise. I spent about 30 minutes today talking with him. What a
cool guy. He lives breathes eats sleeps suspension and I can't think
of a better way to waste some money.
> When it's been a while since you've serviced your forks, and they're
> not leaking, do you replace all the bushings, seals and wipers?
Uhhh, yeah, I do. You don't? Maybe not the wipers if they look
undamaged. I always replace the bushings and seals when I replace the
oil. Phil Douglas machines the edges of the bushings so they don't get
an almost imperceptible mushroom edge as they're inserted...and he
machines the axle to make sure the fork clamps are able to smoothly
slide over the axle, allowing me to precisely align the forks parallel
and even when I install the wheel. I learned these two things just
from talking to him this afternoon. He's one of those guys that loves
what he does, and just can't help being excited to share it with
someone who asks questions.
> Of
> course not, you dis-assemble them, inspect everything, maybe replace a
> bushing here and there, clean it all up real good and put fresh fluid
> in (or maybe just dump out the fluid, flush some solvent through them
> a few times to clean, let the solvent evaporate then put in fluid).
> Geez, the first time I tore into the KTM's forks (because of seal
> leakage), I didn't replace anything, I just shortened the springs in
> the seals, cleaned everything up, put in fresh fluid, put on seal
> savers and ignored them for six months.
That's cool. Sounds like you get a charge out of mcgyvering stuff. I
do too, when there's no other option, but I also get a charge out of
putting in new seals when the old ones are worn. (I have also used old
35mm film stock to remove bits of grit that cured a leaking seal
without even taking the forks off. And I also take a toothbrush and
water to the wipers to clean all the dirt off after every ride.)
> If your shock is not leaking oil and the bladder isn't burst (if fluid
> doesn't come out when venting the pressure) then all you're REALLY
> getting paying someone to "rebuild" it is fresh oil (and probably a
> poor job of working the air bubbles out) and recharged with nitrogen
> (or air, who knows unless you watch them charge it?).
>
> While I'm at this, I'll go into full rant mode:
>
> The last time I worked on the XR's (KYB) shock, I changed the fluid
> and spent probably 45 minutes working out the bubbles (first
> iteration), let it sit for maybe an hour, then maybe 20 minutes
> working out the bubbles (2nd iteration) and so forth for probably 8-10
> iterations until I could let it sit for maybe an hour and not get
> bubbles when stroking the shock.
>
> I then took it to the local shop to have it charged with nitrogen
> where they expected me to pay $30 (min shop charge) for the 10 seconds
> of work and $0.02 nitrogen needed. Uh, no. I pressurized it with the
> air pump mentioned earlier.
>
> The VERY interesting part about this, at least for me, was the
> resulting action was NOTICABLY better than ANY of the prior "rebuilds"
> shops had done.
>
> In retrospect, the reason seems clear. No shop (other than a "real"
> shop like PC) would spend the time working out all the air bubbles
> yielding such consistent action.
>
> Lesson = you want something done right, do it yourself. You want a
> quickie, hire someone paid piece rate.
That's why I'm having Phil do it. I suspect he's as close to a "real"
shop that I'm ever going to get--don't think Team Green is interested
in me. I've never paid anyone to do any work on my bikes. Other than
this. And Pacific Crest Pipe Repair. And Myler's Radiator Repair. And
the cylinder replaters.
> > But thanks.
>
> No sweat dude.
>
> You gonna try and make Idaho this summer?
Yes. Don't know if it's gonna work though, already have a schedule
conflict. We're talking first week of August, right?
--
Charles
'99 YZ250
john
> I've got a connection in the HVAC business, so I'm going to spend
> money on a regulator/gauges/hose/chuck and a bottle of nitrogen so's I
> can do it myself.
>
> Charles
> '99 YZ250
I send my shocks out, but I do have a
few hundred gallons of nitrogen at the shop
if I ever get nutty and find free time
okay now you're hooked on nitro....
what to do with the rest of the bottle??
clean nitrogen is good for storing food.
if you find rice cheep or some other
dry commodity you would like to eat....
take can/pail/drum, line with food grade plastic
bag, fill with rice, insert tube connected
to nitrogen, fill bag from bottom slowly
hold bag loosely closed around tube while
filling, hold match over exhausting air.
when the air snuffs the lit match then you
have purged the oxygen from the bag.
heat seal or twist fold & seal the bag,
put lid on container & store in cool dark place.
rice wheat barley oats... ect will keep
a long time this way... smaller families 1 gallon pails
larger go for the 2-5 gallon pails.
JayC
>
> I miss people reading and responding to my posts.
I love you man!
But you're not getting my Bud Light...
JayC
JayC
> well as pure nitrogen. How would pure argon or pure co2, pure helium,
> etc work? How bout Argon/co2 mix? :) Is there anything really magical
> about the choice or nitrogen?
No - nitrogen is cheap and dry. The problem with "shop air" is not
the O2 - the gas charge is held in a rubber bladder after all (except
on some of those crappy KTMs). The issue is moisture - gas with water
in it reacts very differently than a dry gas.
OTOH, the last shock I charged (my XR400) was done with plain ole'
shop air to as close to the ~135PSI that my little compressor can do
(142# is spec) with as fast a pull-off of the fill check as I could
manage. Close enough. I planned on getting it re-done properly with
nitrogen whenever I got a round tuit, but haven't ridden the bike
since so who cares.
JayC
HardWorkingDog
"john" <joh...@g-male.comm> wrote:
Nice. I don't keep rice for emergency supplies (yet) but I think it
would be very useful in my emergency coffee bean supply. Priorities...
--
Charles
'99 YZ250
Whelan - '02 200exc (x2) & '04 MTD 38
Before pressurizing the shock, the air bladder is already full of room
air.
All the added nitrogen does is increase the pressure.
Applying Boyle's Law, at constant temperature, I'd need to squeeze 1.0
volume to 0.5 volume to increase 10 atmospheres of pressure. So, if a
shock bladder is 5 cubic inches, I need to cram 10 cubic inches of gas
in that 5 cubic inches of volume to get ~150 psi [change from 1
atmosphere (~15psi) to 10 atmospheres (~150psi)].
Therefore, after charging a shock with nitrogen, the result is a
bladder filled with half regular old air and half added nitrogen
(ignoring compression of the hydraulic fluid and any bubbles remaining
in the fluid).
So, all we're really debating is what to fill HALF the bladder with.
Disclaimer - I'm trusting all you engineers out there (Tim?) to check
my work.
Wudsracer
***********************************************
**************************************************
I don't post as much, because I don't always see where I could assist
the discussion. If that's the case, I just read and lurk.
However, I check in almost every day that I have internet connection
and see what my friends are doing. (and what they are talking about.)
I don't pay lots of attention to some threads, and none at all to
flames, but I read EVERYTHING that Tim Harrell posts, whether I
respond or not.
If I make it to Idaho this summer, You better be there. :-)
Jim/Aged Wudsracer
PS. John Aiton's facebook page has some great Sawtooth NF riding
pictures. I saw Murray and DJ in them.
Wudsracer/Jim Cook
Smackover Racing
'06 Gas Gas DE300
'82 Husqvarna XC250
Team LAGNAF
john
dude... now I have to add another wing to the see-mint bunker... dang
how could i have forgot the #1 commodity for trading with geeks , i'm
guessing
a month or two after the crunch i could trade 1lbs of beans for a prius
<grin>
side note... post hurricane cleanups i participated in
you would not believe how much a cold beer is worth.....
i've flown in supplies & provided free labor on several occasions,
but it's the beer that won me celebrity status....<grin>
john
Krap, digging another hole
HardWorkingDog
<3f19f42b-4893-49be...@x10g2000prk.googlegroups.com>,
"Whelan - '02 200exc (x2) & '04 MTD 38" <yo...@sisna.com> wrote:
> Therefore, after charging a shock with nitrogen, the result is a
> bladder filled with half regular old air and half added nitrogen
> (ignoring compression of the hydraulic fluid and any bubbles remaining
> in the fluid).
>
> So, all we're really debating is what to fill HALF the bladder with.
That's why you pull a vacuum on the bladder BEFORE you charge it with
nitrogen.
> Just to keep beating a dead horse long after it's a faded stain:
What stain?
<g>
--
Charles
'99 YZ250
Whelan - '02 200exc (x2) & '04 MTD 38
>
> That's why you pull a vacuum on the bladder BEFORE you charge it with
> nitrogen.
While the one bladder I worked with was pretty thick, it was still
rather delicate rubber. I'd think putting enough vacuum on it to
significantly change the garage air-to-added nitrogen ratio would rip
the bladder.
Here's a scenario - I take my shock to Dufus Bike Shop where Bubba
Doofus pulls an air hose off a compressor, hooks it to the N2
regulator, then pressurizes my shock with the rust-and-water-filled
compressor air in the hose.
I have so little faith in "service" anymore, I'm just sick and tired
of paying good money for incredibly inept service. It's now to the
point when I get what I paid for I rejoice.
On a different hobby, I wanted a Stratocaster with good action. How
naive.
Visiting Guitar Center I discovered the process is 1) spend hundreds,
maybe thousands, on a guitar, 2) take it to a luthier/tech for "setup"
where maybe, just maybe, I'd get what I want but probably end up
paying hundreds of dollars until I give up and settle for what he
gives me.
I was lucky - I bought this very guitar (I'm the customer they
mention):
http://www.youtube.com/watch?v=Q0N28Eo5EYY
This is how George leveled the frets:
http://www.youtube.com/watch?v=rZrC67fdYlw
The result is incredible. No buzz ANYWHERE on the freboard,
incredibly low action. Perfect guitar to learn on. Instead of
getting disgusted with the screeching from my sloppy fingerings, as
long as I hit it anywhere between the frets it sounds right. Truly a
beginner's guitar.
Here's the point (yea, I know, FINALLY) - after getting the strat, I
wanted to get my acoustic similarly setup but Georg's shop is in
Florida. So I call ALL the techs/luthiers in the local area. None
could do the same job as George and many laughed at me when I
described what George does for $60. In essence the message was "Pay
me $200 to do a sloppy job of ruining your frets."
This is so typical of today's "service." You trust you're buying
quality, qualified, competent work and what you're really getting is
nowhere near what you could do yourself.
Well, now that I've worked myself up to a full lather. Here's this
week's example:
My septic system (ATU) has an air pump. The first time the pump
failed, it took the local highly-respected compressor experts months
to get the rebuild kit and repair it during which the outside airlines
froze & burst, the system failed, called out the pumper, extra fees,
tore up the deck to get to the burst air lines, showering at work,
laundry at the coin-op, on an on--money, backed up system, doom,
gloom.
So I spent $300+ for a spare pump so I'd have an extra when one
fails. I've gone through a few swaps and usually pay ~$200 for the
rebuild which takes 6-8 weeks.
Last Friday, the pump fails. No big deal. I pull the spare off the
shelf, swap it for the failed unit, then box up the failed unit to
take in for repair. The spare dies after an hour.
What appears to have happened is when I'd taken the unit in for repair
~3.5 years ago, the tech couldn't figure out why it wasn't getting
power so he spent an hour replacing the pump's AC cord. When it still
didn't get power, he discovered the thermal overload was tripped which
he reset. The unit then made noise and pushed out a very small amount
of air. I pick it up and was very pleased with the quick turnaround
and $100 bill. Like the trusting idiot I am, I didn't test it. It
appears one diaphragm was completely torn and the second had an hour's
use left before it tore enough to lose all ability to push air.
Now I'm the first to admit mistakes happen. Live and let live I say.
So I took the unit in and explained this pump they're repaired 3.5
years ago had failed after an hour's use. As it was well beyond the
90-day warranty, they refused to even open it up unless I paid for it.
I had the kit for $109.95 in hand on Monday and replaced the wasted
diaphragms in about 20 minutes. Again, I learned if I want something
done right do it myself. In doing so I get better, cheaper, faster
results.
Tim H
A few comments and corrections, Professor Dowd.
First, Boyle's Law only deals with the effect of varying the pressure
and/or volume a fixed volume of gas, pV=k. The ideal gas law, pV=nRT,
tells us wht happens when you add more gas (increase "n"). If
temperature and volume remain unchanged (R is already a constant),
then you can see that the pressure is directly proportional to the
volume, i.e. twice the pressure takes twice the volume, 10 times the
pressure takes 10 times the volume. Now your bladder is only holding
about 10% room air. If you pressurize/depressurize/pressurize a couple
of times, that percentage gets REALLY low.
That was fun. I don't get to correct you on math related stuff very
often.
On the subject of air vs nitrogen in general, I only see 2 downsides
to air. First, due to the presence of some quantity of water vapor,
i.e. humidity, air will result in more pressure increase from
temperature increases than nitrogen would, simply because water vapor
expands more than dry nitrogen (less than ideal gas behavior). The
second drawback, and considerably less important in my view, is the
higher risk of corrosion from the oxygen and H2O present. I don't see
this as a huge corrosion risk in a rubber bladder with only one end
exposed to and anodized aluminum cap. I believe that the changes in
reservoir pressure from heating are going to be a lot less severe for
someone that rides like you do in the places you go to than if you
were a desert rat or moto boy and hammered whoops all day; then you
might notice the difference as the shock gets hot, but I'd think
that'd depend to a large extent on how humid the air you put in was to
start with. I doubt that you would ever heat yours up enough to notice
the changes in the compression resistance (more gas spring effect,
slows flow through the compression valving since flow is proportional
to pressure differential, and higher reservoir pressure decreases the
differential across the compression valve). I suspect that you would
be stopping to let yourself cool down before the shock would need it
as badly. Someone like Kurt Casselli, on the other hand, could
probably keep that sucker hot enough, and be sensitive enough, to tell
the difference. Again, depending on the amount of water vapor in there
to begin with. Anyway, I don't see a problem with your use of shop air
as long as it's working for you. Scott might notice the difference,
Mike Lafferty almost certainly would.
At least that's how I see it.
Tim H
HardWorkingDog
<538dee37-2c4c-4d95...@v20g2000prb.googlegroups.com>,
"Whelan - '02 200exc (x2) & '04 MTD 38" <yo...@sisna.com> wrote:
> I was lucky - I bought this very guitar (I'm the customer they
> mention):
>
> http://www.youtube.com/watch?v=Q0N28Eo5EYY
>
> This is how George leveled the frets:
>
> http://www.youtube.com/watch?v=rZrC67fdYlw
>
> The result is incredible. No buzz ANYWHERE on the freboard,
> incredibly low action. Perfect guitar to learn on. Instead of
> getting disgusted with the screeching from my sloppy fingerings, as
> long as I hit it anywhere between the frets it sounds right. Truly a
> beginner's guitar.
Good stuff. I wish they'd shown how they crown and polish the frets.
I'm trying to picture the technology, I imagine something like a
laminate trimmer...
--
Charles
'99 YZ250
john
> Now I'm the first to admit mistakes happen. Live and let live I say.
> So I took the unit in and explained this pump they're repaired 3.5
> years ago had failed after an hour's use. As it was well beyond the
> 90-day warranty, they refused to even open it up unless I paid for it.
>
> I had the kit for $109.95 in hand on Monday and replaced the wasted
> diaphragms in about 20 minutes. Again, I learned if I want something
> done right do it myself. In doing so I get better, cheaper, faster
> results.
local yoke-al takes a air suspension bag from a truck airbag...
http://www.4x4offroads.com/image-files/custom-sport-trac-rear-four-link-setup-front-air-bag.jpg
looks kind of like that rubber thing in the link above...
then hooks a wind mill up to a fly wheel with a arm off of it
similar to the old school steam locomotives drive wheels....
the arm pumps a leaver to squish the air bag which has
a one way check valve making it simple air compressor...
this he uses to aerate his lake.... I wonder if a similar setup
(minus the windmill) could provide a cheep dependable
solution to pump failure... really you only need what 10-20 psi
to pump air?? what is the conversion ~ 1/2 psi per foot of water??
guessing sludge in septic is denser than water so to percolate the
tank you should be able to get away with a low psi air pump.
HardWorkingDog
<7c85256b-17d0-480b...@k36g2000prb.googlegroups.com>,
Tim H <tntha...@msn.com> wrote:
> Anyway, I don't see a problem with your use of shop air
> as long as it's working for you.
And I meant to add earlier, that if I needed to pressurize my shock in
the middle of Baumgartner, and Joe offered me his bike pump, I'd use
it.
--
Charles
'99 YZ250
JayC
>
> Disclaimer - I'm trusting all you engineers out there (Tim?) to check
> my work.
Er, uh....
For 10x pressure, you'll need 10x gas by volume. IOW, if you take a 10
cups of air and squish it down to a cup, you'll end up with 10x
pressure. P1*V1 = P2*V2.
So, if you fill w/ nitrogen to 10 atmospheres, then let it out and
refill again, you end up ~99% pure. Nifty.
Also, it is important to consider the bubbles left in the oil. Once
you pressurize the bladder, the bubbles are squeezed to 1/10 their
original size, so their effects are reduced an order of magnitude
(which is why you charge a shock in the first place).
JayC
Whelan - '02 200exc (x2) & '04 MTD 38
> looks kind of like that rubber thing in the link above...
> then hooks a wind mill up to a fly wheel with a arm off of it
> similar to the old school steam locomotives drive wheels....
> the arm pumps a leaver to squish the air bag which has
> a one way check valve making it simple air compressor...
> this he uses to aerate his lake.... I wonder if a similar setup
> (minus the windmill) could provide a cheep dependable
> solution to pump failure... really you only need what 10-20 psi
> to pump air?? what is the conversion ~ 1/2 psi per foot of water??
> guessing sludge in septic is denser than water so to percolate the
> tank you should be able to get away with a low psi air pump.
Wow!!! That is genius. Let me noodle on this...
I think 5psi is good. While waiting for the rebuild kit, I turned the
shop's compressor down so far I could just barely feel the air out of
an air gun and that worked fine. The compressor has a 20gal tank &
cycled every 20 minutes. I was wondering if I could adjust where the
compressor kicks on from 80psi down to maybe 10psi and get maybe close
to an hour between cycles. That's fine for emergencies but, geez, if
I could figure out something like you're describing that'd be both so
cool and free :)
Whelan - '02 200exc (x2) & '04 MTD 38
> First, Boyle's Law only deals with the effect of varying the pressure
> and/or volume a fixed volume of gas, pV=k. The ideal gas law, pV=nRT,
> tells us wht happens when you add more gas (increase "n"). If
> temperature and volume remain unchanged (R is already a constant),
> then you can see that the pressure is directly proportional to the
> volume, i.e. twice the pressure takes twice the volume, 10 times the
> pressure takes 10 times the volume.
d'Oh!!!! The equation Jay posted was the one I was using (P1xV1=P2xV1
@constant temp) & I just can't do simple algebra. Good thing I don't
work with numbers for a living.
I'm really glad my students don't visit this group.
> Now your bladder is only holding
> about 10% room air.
Yea, well, hmmm. (sound of joe's bubble bursting)
> That was fun. I don't get to correct you on math related stuff very
> often.
Did you (&Jay) do that off the top of your head? Mighty impressive.
> On the subject of air vs nitrogen in general, I only see 2 downsides
> to air. First, due to the presence of some quantity of water vapor,
> i.e. humidity, air will result in more pressure increase from
> temperature increases than nitrogen would, simply because water vapor
> expands more than dry nitrogen (less than ideal gas behavior).
yeppers, I would expect water vapor would indeed expand more quickly
than nitrogen. I wonder how much?
Am I reading this graph correctly that at 50C & 50%rh there's ~50g of
water in 1kg of air or approximately 5%? If so, and I start with 50
cubic inches of air that I then compress to 1/10 its volume to yield
10x its pressure, then I'm taking 5% x 50 = 2.5cubic inches of water
and pushing it into the 5 cubic inch bladder? Is that correct?
http://en.wikipedia.org/wiki/Relative_humidity
I observe the compressor tank quickly accumulates a surprising amount
of water. Is that due to the above effect?
-Joe
WoodsChick
Hi, Tim! Just letting you know I read this post. I think I might be
smarter now. Either that or it's just a headache... Thanks, anyway!
Tami-
Whelan - '02 200exc (x2) & '04 MTD 38
>
> > There's nothing plain about my garage.
>
> Woo-hoo! <g> I think pictures are in order here. Normally the air in
> my garage is rarefied as well, especially after eating at Taqueria. My
> wife stays away--she's learned. :)
Two words - "litter boxes"
> No, I really want the shock opened up and gone through, piece by
> piece. I don't want to put myself through shock school right now, so
> I'm having Phil Douglas do it, along with some of his valving
> expertise. I spent about 30 minutes today talking with him. What a
> cool guy. He lives breathes eats sleeps suspension and I can't think
> of a better way to waste some money.
Who's Phil Douglas?
> Uhhh, yeah, I do. You don't? Maybe not the wipers if they look
> undamaged. I always replace the bushings and seals when I replace the
> oil. Phil Douglas machines the edges of the bushings so they don't get
> an almost imperceptible mushroom edge as they're inserted
really?
>...and he
> machines the axle to make sure the fork clamps are able to smoothly
> slide over the axle, allowing me to precisely align the forks parallel
> and even when I install the wheel.
I just leave the axle loose, bounce the front end a few times to let
it settle in and (hopefully remember then to) tighten it up. That's
not good enough?
> That's cool. Sounds like you get a charge out of mcgyvering stuff. I
I like doing things myself to know they're done right or, if done
wrong, I'm at fault.
I think KTM's dealt with the fork seal issue, but my '02's came with
incredibly loose seals & the trick fix, rather than endlessly replace
seals, was shorten the springs to tighten them up. It actually took
me two tries, the first time I only clipped off about 5 coils--that
was about 1/4 of what was needed :)
> without even taking the forks off. And I also take a toothbrush and
> water to the wipers to clean all the dirt off after every ride.)
I'm way too lazy. I use those neoprene fork savers.
> > You gonna try and make Idaho this summer?
>
> Yes. Don't know if it's gonna work though, already have a schedule
> conflict. We're talking first week of August, right?
No clue. I kinda out of the loop...
IdaSpode
'04 MTD 38" <yo...@sisna.com> wrote:
>>...and he
>> machines the axle to make sure the fork clamps are able to smoothly
>> slide over the axle, allowing me to precisely align the forks parallel
>> and even when I install the wheel.
>
>I just leave the axle loose, bounce the front end a few times to let
>it settle in and (hopefully remember then to) tighten it up. That's
>not good enough?
My "version" of the correct way to install the front axle on a modern
KTM:
Install axle through forks/wheel
Hand tighten axle nut
Tighten R side pinch bolts (mostly to hold axle for next step)
Fully tighten axle nut
Fully tighten L side pinch bolts
Loosen R side pinch bolts
Take bike off stand, cycle the forks up and down a few times
Fully tighten R side pinch bolts
Recheck L side pinch bolts
*Go riding
*If you have spread the brake pads to aid in installing the wheel
(front or rear) be sure to remember to cycle the brake lever to get
the pads back out next to the rotor _before_ you go riding... (BTDT,
braaaap, braaaap, braaaap, corner coming up, holy crap no rear brake)
IdaOnKTM200#11
(ordered, paid for and waiting for #12 to arrive)
HardWorkingDog
<ea57ce22-f170-4f01...@a17g2000pre.googlegroups.com>,
"Whelan - '02 200exc (x2) & '04 MTD 38" <yo...@sisna.com> wrote:
> I just leave the axle loose, bounce the front end a few times to let
> it settle in and (hopefully remember then to) tighten it up. That's
> not good enough?
It is if the axle is perfectly free to slide between the loosened
clamp. Have you checked to see if it slides easily before you bounce
it?
--
Charles
'99 YZ250
Whelan - '02 200exc (x2) & '04 MTD 38
> > it settle in and (hopefully remember then to) tighten it up. That's
> > not good enough?
>
> It is if the axle is perfectly free to slide between the loosened
> clamp. Have you checked to see if it slides easily before you bounce
> it?
I don't know about perfectly free, but I can pretty easily slide the
fork leg with the loose pinch bolts out and in on the big part of the
axle. When I finish, right before tightening the pinch bolts I DO NOT
put it back on the stand. I leave it on the ground with the
suspension compressed the little bit with the bike's weight (race
sag?) - I'm concerned if I put the front wheel back in the air and the
fork bottoms weren't perfectly aligned, e.g., by having one higher in
triple clamp, that would defeat the purpose of the exercise.
I've been doing it this way forever and I don't think I get any mis-
alignment-induced stiction. I remember once leaping then landing on
the face of the stump and watching the front end very smoothly and
completely compress before I flew over the stump and the bike
followed. Tim, you remember that? You and Tom were right behind me.
HardWorkingDog
<7f309b1c-ef84-4cee...@k36g2000prb.googlegroups.com>,
"Whelan - '02 200exc (x2) & '04 MTD 38" <yo...@sisna.com> wrote:
> I don't know about perfectly free, but I can pretty easily slide the
> fork leg with the loose pinch bolts out and in on the big part of the
> axle. When I finish, right before tightening the pinch bolts I DO NOT
> put it back on the stand. I leave it on the ground with the
> suspension compressed the little bit with the bike's weight (race
> sag?) - I'm concerned if I put the front wheel back in the air and the
> fork bottoms weren't perfectly aligned, e.g., by having one higher in
> triple clamp, that would defeat the purpose of the exercise.
OK.
Good ridin' to ya!
--
Charles
'99 YZ250
john
lernt dat from a steam turbine guy...
back when i was fiddling with hyper
hot metals & other freaky engineers
anyhow as water in your shock turns to
vapor from the friction the internal pressure
will go wacky stacky and the whoops will
dump you like a toddler mutton busting
http://video.google.com/videoplay?docid=497282319128675460&ei=73trS7GSH5qoqwKb2vnLAg&q=mutton+busting&hl=en#
"Whelan - '02 200exc (x2) & '04 MTD 38" <yo...@sisna.com> wrote in message
news:cc9851dc-3c5b-479c...@a5g2000prg.googlegroups.com...
HardWorkingDog
<ea57ce22-f170-4f01...@a17g2000pre.googlegroups.com>,
"Whelan - '02 200exc (x2) & '04 MTD 38" <yo...@sisna.com> wrote:
> Who's Phil Douglas?
http://query.nytimes.com/mem/archive-free/pdf?_r=1&res=9E0DE6D81339EF3A
BC4F52DFBE668389639EDE
--
Charles
'99 YZ250
Tim H
You talking about your big crash just after the start of the second
loop of the Sparkplug? That was a classic. I was just back around the
corner and missed the crash, but the aftermath was pretty impressive.
Tim H
Whelan - '02 200exc (x2) & '04 MTD 38
>
> http://query.nytimes.com/mem/archive-free/pdf?_r=1&res=9E0DE6D81339EF3A
> BC4F52DFBE668389639EDE
I'm having trouble getting that link to work.
Whelan - '02 200exc (x2) & '04 MTD 38
> > alignment-induced stiction. I remember once leaping then landing on
> > the face of the stump and watching the front end very smoothly and
> > completely compress before I flew over the stump and the bike
> > followed. Tim, you remember that? You and Tom were right behind me.
>
> You talking about your big crash just after the start of the second
> loop of the Sparkplug? That was a classic. I was just back around the
> corner and missed the crash, but the aftermath was pretty impressive.
I think Tom saw the whole thing. His comments, as I recall, after the
race:
1. "Joe, why did you do that?"
2. "I swear your arms and legs were moving before you hit the
ground. It was like you KNEW your bike was seeking revenge on you."
I'm sure that was my most spectacular crash. I sure am glad Tom saw
it. It'd been a real shame if nobody'd seen it.
I think my most public crash was when I tossed the same poor bike away
entering Tahuya River campground...
HardWorkingDog
<b5d679ce-7f03-4da1...@b1g2000prc.googlegroups.com>,
"Whelan - '02 200exc (x2) & '04 MTD 38" <yo...@sisna.com> wrote:
That's just as well--it is a poor joke. (Long url's that wrap often
show up with a line break character in the middle of the url, and you
have to manually copy/paste/remove the line break character to get it
to work.)
Anyways, he's a racer (ISDT silver medalist) who has developed a
hands-on business of tuning suspensions, local to the SF Bay area.
Does the work himself. No flunkies involved. Very enjoyable to talk
with. Doesn't mind spending half an hour chatting with a nobody like
me who pesters him with the same questions he's been getting for 20
years.
I've wanted a chance to try this--here's a real(non-joke) link, in a
roundabout way:
http://lmgtfy.com/?q=Phil+Douglas+suspension
--
Charles
'99 YZ250
Whelan - '02 200exc (x2) & '04 MTD 38
>
> That's just as well--it is a poor joke. (Long url's that wrap often
> show up with a line break character in the middle of the url, and you
> have to manually copy/paste/remove the line break character to get it
> to work.)
That's what I thought. I tried pasting the pieces together but it
kept redirecting me to a "member's" page I couldn't access.
When I post long links, I use
> Anyways, he's a racer (ISDT silver medalist) who has developed a
> hands-on business of tuning suspensions, local to the SF Bay area.
> Does the work himself. No flunkies involved. Very enjoyable to talk
> with. Doesn't mind spending half an hour chatting with a nobody like
> me who pesters him with the same questions he's been getting for 20
> years.
It sure is wonderful when you find someone like that.
Congratulations.
Les Tinius in Port Orchard, WA is the same way.
HardWorkingDog
<b01f9555-4d13-494d...@p13g2000pre.googlegroups.com>,
"Whelan - '02 200exc (x2) & '04 MTD 38" <yo...@sisna.com> wrote:
>
> When I post long links, I use
>
> http://tinyurl.com/
Yeah, used to use this. I didn't want you to think it was leading you
to a certain KX for sale...I have an embargo against url shorteners
because they've been used for nefarious purposes.
Alright, I'll try again. Found this page when I originally did a
google search for phil douglas
http://query.nytimes.com/gst/abstract.html?res=9E0DE6D81339EF3ABC4F52DF
BE668389639EDE
Just above the bank of google ads is a link to "view full article"
that gives you a pdf of the original page from 1922. Somehow I found
it entertaining. Sorry to waste your bandwidth...
> > Anyways, he's a racer (ISDT silver medalist) who has developed a
> > hands-on business of tuning suspensions, local to the SF Bay area.
> > Does the work himself. No flunkies involved. Very enjoyable to talk
> > with. Doesn't mind spending half an hour chatting with a nobody like
> > me who pesters him with the same questions he's been getting for 20
> > years.
>
> It sure is wonderful when you find someone like that.
> Congratulations.
>
> Les Tinius in Port Orchard, WA is the same way.
Well, I'll have to wait until I get it all back together to see if
it's going to help my sorry riding skills. (Oh yeah, and thanks Baxter
for reminding me that I'm not up to riding Moab with my current
skills. Being honest still sucks sometimes.)
--
Charles
'99 YZ250
Tim H
> @constant temp) & I just can't do simple algebra. Good thing I don't
> work with numbers for a living.
Yeah, good thing.
> I'm really glad my students don't visit this group.
That could make for an intersting classroom conversation.
> > Now your bladder is only holding
> > about 10% room air.
>
> Yea, well, hmmm. (sound of joe's bubble bursting)
Well, from over here it was a very faint "Pop!".
> > That was fun. I don't get to correct you on math related stuff very
> > often.
>
> Did you (&Jay) do that off the top of your head? Mighty impressive.
It's weird the information that crawls out of the recesses of my head
sometimes. It's sort of comforting to find that all of that time spent
learning stuff wasn't completely wasted, you just need to find a
reason to remember.
> > On the subject of air vs nitrogen in general, I only see 2 downsides
> > to air. First, due to the presence of some quantity of water vapor,
> > i.e. humidity, air will result in more pressure increase from
> > temperature increases than nitrogen would, simply because water vapor
> > expands more than dry nitrogen (less than ideal gas behavior).
>
> yeppers, I would expect water vapor would indeed expand more quickly
> than nitrogen. I wonder how much?
Not sure off the top of my head (hasn't crawled to the surface
yet...). I'll see if I can get a chance to look into that. The really
huge danger is that you have any condensation inside the reservoir,
because in going from liquid (water droplets) to vapor (steam), the
volume and pressure change would be huge.
>
> Am I reading this graph correctly that at 50C & 50%rh there's ~50g of
> water in 1kg of air or approximately 5%? If so, and I start with 50
> cubic inches of air that I then compress to 1/10 its volume to yield
> 10x its pressure, then I'm taking 5% x 50 = 2.5cubic inches of water
> and pushing it into the 5 cubic inch bladder? Is that correct?
Not exactly. You can't switch back and forth from percent by mass to
percent by volume like that.You'd need to determine the mass of the
air your putting in the bladder, the corresponding mass of water, then
translate that into volume. It'll be a lot less that what you
predicted (mass of water is much, much higher than the same volume of
air).
> http://en.wikipedia.org/wiki/Relative_humidity
>
> I observe the compressor tank quickly accumulates a surprising amount
> of water. Is that due to the above effect?
Yeah, pretty much. At any given temperature, water will only vaporize
up to the point of it's vapor pressure at that temp. Since you're
squeezing more air into the compressor that will eventually wind up at
the same temperature it went in at (room), some of it (the part in
excess of what will develop vapor pressure at that temperature) will
condense. This COULD happen in a reservoir too, and it would be bad
because a few drops of liquid water can generate a lot of water vapor
and significantly raise the pressure in the vessel when it flashes to
a gas.
Tim H
>
> -Joe
Tim H
Now THAT was a classic. Looped out and thrown away wheelying over a 6
inch log. In full view of most of the club. The crash itself wasn't
even in the same league, but it sure was funny.
Tim H
HellSickle
you change it. The volume in a shock is so low, that the act of
measuring it will reduce the pressure by at least 30psi.
When charging a shock with a schraeder valve, I set the line pressure
about 10psi than where I want to the shock, to account for the small
loss when you pull the chuck off the valve.
If you've never changed the oil in your shock, it's long overdue.
Shock oil gets worked about 4x harder than fork oil. Feel how hot
your shock gets after an extended charge through a rock garden.
-Jeff-
On Feb 1, 12:25 pm, HardWorkingDog <har...@mush.man> wrote:
> I've got my '99 YZ torn down to the bare bones right now. I'm staring
> at the shock exposed since I removed the subframe and thinking it's
> probably time for a rebuild. I've had the bike almost 8 years and
> never done anything for it, other than replace the mounting bearings.
>
> Hmmm, a schrader valve... Figured I'd test it to see if there was any
> pressure in there. Got out the tire gauge we use for road bike tires,
> it read 82 psi. I'd done a little research, seems that 135-165 psi is
> the going pressure. Aha, low! Definitely time for service.
>
> I look over at the 2 other, newer, YZ's sitting in the stable, quietly
> minding their own business. Hmmm, I wonder, what pressure THEIR shocks
> have???
>
> So I checked, with my handy dandy bicycle pressure gauge. This one:http://ecx.images-amazon.com/images/I/41mVMEvHOxL._SS500_.jpg
>
> They were both at 105 psi.
>
> I did a little more reading. I think I've probably released a
> significant amount of nitrogen by simply checking it with a tire
> pressure gauge. Anyone have direct experience with nitrogen pressures,
> and the best practice for checking, on a dirt bike shock?
>
> I'm thinking I'm going to need to top up the N on both shocks while I
> have my '99's shock serviced.
>
> --
> Charles
> '99 YZ250
Mike Baxter
wrote:
Hey, hey hey! I was talking about 5MOH. That trail appears to test
all riders. You can ride all over Moab no problem.
Mike Baxter
WoodsChick
> On Fri, 05 Feb 2010 10:13:02 -0800, HardWorkingDog <har...@mush.man>
> wrote:
>
>
>
>
>
> >In article
That's what I was thinking. There's a ton of stuff that can be ridden
out there on a friggin' streetbike by anyone with Charles's skills.
Tami-
HardWorkingDog
Mike Baxter <mgb***@comcast.net> wrote:
> Hey, hey hey! I was talking about 5MOH. That trail appears to test
> all riders. You can ride all over Moab no problem.
<g>
Yeah, I saw the look on your face when I mentioned "Moab." One bad
liar to another. I can either quit or get better, 'sup to me.
--
Charles
'99 YZ250
Whelan - '02 200exc (x2) & '04 MTD 38
> huge danger is that you have any condensation inside the reservoir,
> because in going from liquid (water droplets) to vapor (steam), the
> volume and pressure change would be huge.
Other than the danger of blowing the main seal or bursting the
bladder, what's the huge danger with the pressure in the bladder
increasing from spec? There's no pressure differential on either side
of any damping valving that I can visualize, i.e., how would higher
pressure affect how quickly the shock's piston can push/pull fluid
through orifices?
> > Am I reading this graph correctly that at 50C & 50%rh there's ~50g of
> > water in 1kg of air or approximately 5%? If so, and I start with 50
> > cubic inches of air that I then compress to 1/10 its volume to yield
> > 10x its pressure, then I'm taking 5% x 50 = 2.5cubic inches of water
> > and pushing it into the 5 cubic inch bladder? Is that correct?
>
> Not exactly. You can't switch back and forth from percent by mass to
> percent by volume like that.
So if 1 liter of air, at 25C, has 1.19 grams of mass, then 1kg of mass
of air (with its 50g of water) takes up ~840 liters of volume. 50
cubic inches is ~0.82 liters which is about 1/1000 of 840 liters so 50
cubic inches of air has about 1/1000 of the 50g of water found in the
kg (mass) of air. So we could expect we're putting 50mg of water into
the shock bladder.
Since, for water, 1g of mass = 1cc (& 1ml) of volume, then 50mg is
50/1000 of a cc (or a ml) which is about 1/1000 of a teaspoon.which is
about 0.007 drops (1/150th of a drop).
Does that sound approximately correct?
> > I observe the compressor tank quickly accumulates a surprising amount
> > of water. Is that due to the above effect?
>
> Yeah, pretty much. At any given temperature, water will only vaporize
> up to the point of it's vapor pressure at that temp. Since you're
> squeezing more air into the compressor that will eventually wind up at
> the same temperature it went in at (room), some of it (the part in
> excess of what will develop vapor pressure at that temperature) will
> condense.
I tried to figure out what you said here and failed, but I did
undestand that water changes from vapor to liquid ("condenses") for
two reasons, encountering temp < dew point and increased pressure. I
tried to get a handle on how much pressure was needed to squeeze how
much water out of a given level of humidity and thus far have failed.
-Joe
Mike Baxter
wrote:
Seriously. When I think Moab, I think 5 miles of hell. That's what
pops into my head. That and trials bikes. There is tons of stuff
that doesn't require you to be a hero. I need to work on my
communication skills.
Mike Baxter
HardWorkingDog
Mike Baxter <mgb***@comcast.net> wrote:
> On Fri, 05 Feb 2010 15:03:32 -0800, HardWorkingDog <har...@mush.man>
> wrote:
>
> >In article <997pm55im7pe837gq...@4ax.com>,
> > Mike Baxter <mgb***@comcast.net> wrote:
> >
> >> Hey, hey hey! I was talking about 5MOH. That trail appears to test
> >> all riders. You can ride all over Moab no problem.
> >
> ><g>
> >
> >Yeah, I saw the look on your face when I mentioned "Moab." One bad
> >liar to another. I can either quit or get better, 'sup to me.
>
>
> Seriously. When I think Moab, I think 5 miles of hell. That's what
> pops into my head. That and trials bikes. There is tons of stuff
> that doesn't require you to be a hero. I need to work on my
> communication skills.
Honestly, 5MOH *isn't* what I think of--I've never been there--just
seeing the photos of that amazing landscape has had me fascinated. I
think the only thing I'd regret is not going...but yeah, I'm no hero.
--
Charles
'99 YZ250
Wudsracer
Jim
***************************************
>On Thu, 4 Feb 2010 11:20:43 -0800 (PST), "Whelan - '02 200exc
>
>I have so little faith in "service" anymore, I'm just sick and tired
>of paying good money for incredibly inept service. It's now to the
>point when I get what I paid for I rejoice.
>
>On a different hobby, I wanted a Stratocaster with good action. How
>naive.
>
>Visiting Guitar Center I discovered the process is 1) spend hundreds,
>maybe thousands, on a guitar, 2) take it to a luthier/tech for "setup"
>where maybe, just maybe, I'd get what I want but probably end up
>paying hundreds of dollars until I give up and settle for what he
>gives me.
>
>I was lucky - I bought this very guitar (I'm the customer they
>mention):
>
>http://www.youtube.com/watch?v=Q0N28Eo5EYY
>
>This is how George leveled the frets:
>
>http://www.youtube.com/watch?v=rZrC67fdYlw
>
>The result is incredible. No buzz ANYWHERE on the freboard,
>incredibly low action. Perfect guitar to learn on. Instead of
>getting disgusted with the screeching from my sloppy fingerings, as
>long as I hit it anywhere between the frets it sounds right. Truly a
>beginner's guitar.
>
*****************************************************
Wudsracer/Jim Cook
Smackover Racing
'06 Gas Gas DE300
'82 Husqvarna XC250
Team LAGNAF
Whelan - '02 200exc (x2) & '04 MTD 38
> >mention):
>
> >http://www.youtube.com/watch?v=Q0N28Eo5EYY
>
> >This is how George leveled the frets:
>
> >http://www.youtube.com/watch?v=rZrC67fdYlw
>
> >The result is incredible. No buzz ANYWHERE on the freboard,
> >incredibly low action. Perfect guitar to learn on. Instead of
> >getting disgusted with the screeching from my sloppy fingerings, as
> >long as I hit it anywhere between the frets it sounds right. Truly a
> >beginner's guitar.
>
> Nice guitar!
>
> Jim
Yes, yes indeed.
I was wondering if anyone noticed the "beginner's guitar" comment.
As a beginning guitar player, I'm horrified at what is routinely
called a "beginner's guitar."
If a guitar has high action, uneven frets, etc. it's called a
"beginner's guitar" when it should be called an "experts-only guitar"
because only an expert could possibly get decent sounds out of it.
Instructors complain guitar students don't practice enough, while
telling them to buy cheap "beginner's guitars." Many/most students
who buy "beginner guitars" get frustrated trying to do the impossible
(get decent tones out of such a POS) with predictable results (shorter
and shorter practice times until finally giving up).
A neighbor of a riding buddy wanted to learn to play guitar, paid
almost $3K for a brand-new Gibson (at the local store of a national
guitar chain) with high action & that buzzed all over the fretboard.
His instructor never suggested getting the guitar setup and the
student gave up, saying "I guess I don't have any talent for playing
the guitar."
I first discovered this nonsense Spring 2008 when I took my first
guitar course. I was using a Takamine acoustic with high action and
uneven frets so even after developing calluses, my fingertips were
still mush after 20 minutes of practice & couldn't get the strings
down past the frets enough.
I recall an episode at the Guitar Center, ~playing a Martin acoustic
that buzzed anytime I didn't place my fingers perfectly just behind
the frets & having the salesmen say that as a beginner that's what I
need to learn to properly position my fingers. What bull. It's more
important for a beginner to be able to play & make progress than to
get fed up with poor action and give up.
So I bought one of Denny Zager's "EZ Play" guitars:
which was MUCH better. Not realizing I could easily change my own
strings, I took the Zager to a luthier/tech to do so. He raved about
how spoiled I was as a beginner with such an easy-to-play guitar.
Little did I know...
When I decided to buy a strat with the best action I could get I was
so fearful of spending $ and getting a guitar that didn't play as
easily as the Zager. Little did I know...
When first played George's strat, I couldn't believe it. The buzz-
free action is so low (0.015" and 0.0425 for the 1st and 6th strings,
respectively, at the 21st fret) (*) that I play it all day long
without my fingertips turning to mush. As a matter of fact, spending
months exclusively playing the strat have led to my calluses nearly
disappearing.
Playing the Zager now is like a wrestling match, i.e., I'm so used to
using such a light touch that it's a real physical exercise getting
the Zager's strings down. Frank Trowbridge (of BTO fame) is now
leveling the Zager's frets and working on the nut and bridge in an
attempt to get the action down - I sure hope it turns out close to the
strat's action:
So anyways, the moral of the story is if anyone needs a guitar with
very low buzz-free action it's a beginner who would be well-advised to
avoid anything with a "beginner's" label and find a craftsman like
George at Acme or Frank Trowbridge to work on their guitar.
Little I still know...
-Joe
(*) If you order a guitar from George and want low action & pay the
extra $60 for his fret level, crown & polish, he guarantees a minimum
string height of 4/64" (0.0625) at the last fret - I think mine came
out extra well so he could get the strings down much farther. I asked
him to set it up with extra light strings (0.009" to 0.042").
john
>called a "beginner's guitar."
>
>If a guitar has high action, uneven frets, etc. it's called a
>"beginner's guitar" when it should be called an "experts-only guitar"
>because only an expert could possibly get decent sounds out of it.
>
>-Joe
hmm this has me thinking kids guitar might
need some fine tuning to make it easier to play
i could chuck it up on the surface grinder <grin>
john
Mike Baxter
it sports a Aplinestars decal on the front so it's not 100% off topic.
Mike Baxter
On Sat, 06 Feb 2010 01:43:24 -0600, Wudsracer <babb...@Lucy.com>
wrote:
Whelan - '02 200exc (x2) & '04 MTD 38
> It's definitely nicer than my guitar. I have a Schecter Omen 6, but
> it sports a Aplinestars decal on the front so it's not 100% off topic.
Aren't humbucker's fun? I had to have a humbucker-equipped guitar so
I got this:
http://www.rondomusic.com/al-3000csbplain.html
I don't think the above does it justice:
http://www.the-dowds.com/guitar/al3000_1.jpg
http://www.the-dowds.com/guitar/al3000_2.jpg
I got the 3000 model as they at least make an attempt at leveling the
frets, but I still had to adjust the truss rod (it was WAY loose) and
set the string height. They did a fine job on the nut.
I see your Schecter has a tune-o-matic bridge. I'm kinda disappointed
with the ToM as I can't set individual string heights without
replacing and/or filing the saddles. I've been lusting after this:
http://www.youtube.com/watch?v=L3qY0Xl_6NY
I'm so happy with the buckers in the AL3000, I just had to fiddle with
the strat so I put the Fralin bridge single coil in the neck position
and put this in the bridge (the 15K Ohm version):
http://store.guitarfetish.com/lilkiwhhuhus.html
I chose this because it's cheap, hot, noise-free - the reviews seems
pretty accurate:
I tell you, it sure was easy swapping the pups. With the toneshaper,
there's no soldering involved. I should have taken a picture of
George's wiring before I messed it up. The wire routing was beautiful
before I got my hands on it.
-Joe
Mike Baxter
guitar (made in China). The Kona is pretty to look at and it will
likely just become wall art. I found it new on E-bay for $99 with free
shipping, so I just thought I try it out. Made in China.
http://www.guitarsandmore.com/?sec=product_details&product_id=226
Mike Baxter
I am Tosk
babb...@Lucy.com says...
Hummm. I have a custom one off guitar with aluminum fretboard and frets
I need to have set up. I am probably going with Lakland and the Plek
system they have developed here:
http://www.lakland.com/plek.htm
My friend lives out that way and is a avid bass player. He has known
several folks who have used them for setup and raved about it.
Rowdy Mouse Racing, plek me doc, just plek me...
I am Tosk
@m24g2000prn.googlegroups.com>, yo...@sisna.com says...
>
> > >I was lucky - I bought this very guitar (I'm the customer they
> > >mention):
> >
> > >http://www.youtube.com/watch?v=Q0N28Eo5EYY
> >
> > >This is how George leveled the frets:
> >
> > >http://www.youtube.com/watch?v=rZrC67fdYlw
> >
> > >The result is incredible. No buzz ANYWHERE on the freboard,
> > >incredibly low action. Perfect guitar to learn on. Instead of
> > >getting disgusted with the screeching from my sloppy fingerings, as
> > >long as I hit it anywhere between the frets it sounds right. Truly a
> > >beginner's guitar.
> >
I have worked a bit on some of my guitars. The first thing I did when I
got my Martin Backpacker was to lower the bridge in my shop. I built a
nut for my one off too, but I am not sure if I like it any better than
the stock nut, which was bone too;) I like them real low too and my
first strat was actually a great setup for a mid level Strat. I played a
lot of guitars before I bought it and didn't go to the store with any
particular guitar in mind. I just play a bunch until one feels right.
My 12 string Takamine is a wonderful guitar. My friend who worked at the
shop where we bought it couldn't believe it sat there so long. It has a
beautiful sound for a $300 guitar. We decided that folks who buy 12
strings are usually more accomplished guitarists, and just decided
somehow that they didn't want a "cheap" 12.
I have really got to start playing more again, but I really need the one
off to be set up right first.
RMR aka Sikstrings on another group, in another galaxy, far, far away!
Whelan - '02 200exc (x2) & '04 MTD 38
> I need to have set up. I am probably going with Lakland and the Plek
> system they have developed here:
>
> http://www.lakland.com/plek.htm
That sure looks like the way to do it. Gosh, I wish there was a shop
in the Spokane area that did that.
Tim H
> In article <f8rpm5132i7lkl5d74eppp1eskop8em...@4ax.com>,
> Mike Baxter <mgb...@comcast.net> wrote:
>
>
>
>
>
> > On Fri, 05 Feb 2010 15:03:32 -0800, HardWorkingDog <har...@mush.man>
> > wrote:
>
> > > Mike Baxter <mgb...@comcast.net> wrote:
>
> > >> Hey, hey hey! I was talking about 5MOH. That trail appears to test
> > >> all riders. You can ride all over Moab no problem.
>
> > ><g>
>
> > >Yeah, I saw the look on your face when I mentioned "Moab." One bad
> > >liar to another. I can either quit or get better, 'sup to me.
>
> > Seriously. When I think Moab, I think 5 miles of hell. That's what
> > pops into my head. That and trials bikes. There is tons of stuff
> > that doesn't require you to be a hero. I need to work on my
> > communication skills.
>
> Honestly, 5MOH *isn't* what I think of--I've never been there--just
> seeing the photos of that amazing landscape has had me fascinated. I
> think the only thing I'd regret is not going...but yeah, I'm no hero.
>
> --
> Charles
>
> - Show quoted text -
Charles,
The riding at Moab is relatively easy, though sometimes breathtaking,
and you could ride it with little or no problems (and you'd be forever
glad you did).
From my limited experience in the San Rafael Swell, the riding is
tougher, but still mostly do-able for a competent rider such as
yourself.
5MOH might be a little out of your league, but I still think you ought
to try it. There are bailouts if you find it overwhelming.
I can't wait for the opportunity to go back.
Tim H
HardWorkingDog
<03bec58a-226b-4639...@o16g2000prh.googlegroups.com>,
Tim H <tntha...@msn.com> wrote:
> The riding at Moab is relatively easy, though sometimes breathtaking,
> and you could ride it with little or no problems (and you'd be forever
> glad you did).
> From my limited experience in the San Rafael Swell, the riding is
> tougher, but still mostly do-able for a competent rider such as
> yourself.
> 5MOH might be a little out of your league, but I still think you ought
> to try it. There are bailouts if you find it overwhelming.
> I can't wait for the opportunity to go back.
Thanks, Tim. I guess that's why they call it (5 miles of) Hell.
Bailouts are good.
--
Charles
'99 YZ250
I am Tosk
3c08f2...@b1g2000prc.googlegroups.com>, yo...@sisna.com says...
>
> On Feb 6, 11:02ï¿œam, Mike Baxter <mgb...@comcast.net> wrote:
> > It's definitely nicer than my guitar. ï¿œI have a Schecter Omen 6, but
I love the SD Pearly Gates pickups and the dual position pods give me a
lot of room to work with the sound. Mine had the Shaller roller bridge
for string adjustment. It is adjustable on three axis.
RMR, I can play Smoke on the Water;) Uh, no I can't;)
Whelan - '02 200exc (x2) & '04 MTD 38
> > is that you have any condensation inside the reservoir,
> > because in going from liquid (water droplets) to vapor
> > (steam), the
> > volume and pressure change would be huge.
>
> Other than the danger of blowing the main seal
> or bursting the
> bladder, what's the huge danger with
> the pressure in the bladder
> increasing from spec? There's no pressure differential
> on either side
> of any damping valving that I can visualize,
> i.e., how would higher
> pressure affect how quickly the shock's piston
> can push/pull fluid
> through orifices?
So, we're all happy with ending this thread this way?
I.e., with the question "how could pressure increases affect damping?"
just hanging there, unaddressed.
I am Tosk
@g28g2000prb.googlegroups.com>, yo...@sisna.com says...
>
> > > The really huge danger
> > > is that you have any condensation inside the reservoir,
> > > because in going from liquid (water droplets) to vapor
> > > (steam), the
> > > volume and pressure change would be huge.
> >
> > Other than the danger of blowing the main seal
> > or bursting the
> > bladder, what's the huge danger with
> > the pressure in the bladder
> > on either side
> > of any damping valving that I can visualize,
> > i.e., how would higher
> > pressure affect how quickly the shock's piston
> > can push/pull fluid
> > through orifices?
>
> So, we're all happy with ending this thread this way?
>
> I.e., with the question "how could pressure increases affect damping?"
> just hanging there, unaddressed.
Well, I would imagine it could make the fluid move faster from side to
side of a valve. This could be caused by the higher differential created
when pressure is applied to one side of the valve. I am just guessing, I
don't know for sure.
Rowdy Mouse Racing, my shocks are shot;)
john
that would randomly toss his thru the woops
I wonder if he had a bit of condensation issue
, nahh it was an evil bike with a hex on it.
john
"There are three ways a man can be ruined:
women, gambling, and farming. My father
chose the most boring."
Pope John XXIII. 1881-1963
"Whelan - '02 200exc (x2) & '04 MTD 38" <yo...@sisna.com> wrote in message
news:2d86bef0-f2cf-40f4...@g28g2000prb.googlegroups.com...
Tim H
>
> - Show quoted text -
Nah, that's probably why I haven't been sleeping worth a damn this
week.
Let's try another shot at this.
In order for a fluid to move, well, anywhere, there has to be a
pressure differential between where it is and where it goes. When the
shock is just sitting there statically, i.e. no movement, the pressure
from the bladder is felt equally everywhere inside the shock body.
What some folks on this thread have forgotten or don't understand, is
that the pressure from the reservoir is NOT felt equally under dynamic
conditions. When the shock is trying to compress, high pressure is
generated on top of the shock piston (given current shock orientation
in modern bikes), which begins pushing the fluid towards a lower
pressure area, of which there are 2 in this situation: the other
(lower) side of the shock piston, and into the reservoir through the
compression adjuster valve. Flow rate is dependent on the pressure
differential, and the high pressure generated above the piston is a
function of the piston compression stack, the speed at which the shock
is trying to compress, resistance to flow through the compression
adjuster, and the viscosity of the fluid. Pressure in the reservoir is
only what the bladder is putting on it plus the pressure from the
incoming fluid. As the shock fluid squeezes through the valve into the
reservoir, there is a pressure drop so that as long as the piston is
moving up (shock collapsing), there will always be lower pressure in
the reservoir than in the shock body, so the fluid will always flow
that direction. If the reservoir pressure is increased significantly,
as it likely would be if a few water droplets vaporized as the shock
heats up, then the pressure differential is reduced, so fluid flow is
reduced, thus increasing the resistance to compression. If the
reservoir pressure equals the shock body pressure, then fluid will not
flow, and the shock would be essentially hydraulically locked. That'd
take a shitload of reservoir pressure though, given the mechanical
advantage of modern rear suspension and the fact that the fluid HAS to
flow for the shock to collapse (fluid displacement to offset the shaft
volume being pushed into the fluid in the shock body), which will
generate some very, very high pressures over the piston.
Clear as mud now?
Tim H
I am Tosk
@t17g2000prg.googlegroups.com>, tntha...@msn.com says...
>
> On Feb 11, 7:57ï¿œpm, "Whelan - '02 200exc (x2) & '04 MTD 38"
> <yo...@sisna.com> wrote:
> > > > The really huge danger
> > > > is that you have any condensation inside the reservoir,
> > > > because in going from liquid (water droplets) to vapor
> > > > (steam), the
> > > > volume and pressure change would be huge.
> >
> > > Other than the danger of blowing the main seal
> > > or bursting the
> > > bladder, what's the huge danger with
> > > the pressure in the bladder
Yes actually, it's about what I was thinking I just have to read it
again later and make sure it adds up to me, I may have had it backwards
in my head but the idea was there;)
Rowdy Mouse Racing, dumb as a box of old pistons sometimes;)
JayC
>
> I.e., with the question "how could pressure increases affect damping?"
> just hanging there, unaddressed.
I would expect that the effect of increased pressure would be felt
with increases in shaft speed. Highest-speed damping would likely be
affected most, so I guess the best setup would be to run the lowest
pressure possible that would assure no foaming or cavitation.
JayC
john
>On Feb 11, 7:57 pm, "Whelan - '02 200exc (x2) & '04 MTD 38"
<clear as wd40>
fluid flows in relation to viscosity &
orifice size, pushed by pressure differentials....
when mechanical lever action, or H2O
phase changes,,,, great pressure differentials occur..
well, they do until a seal is blown........
say now, that reminds me of a joke <grin>
john
Whelan - '02 200exc (x2) & '04 MTD 38
> pressure differential between where it is and where it goes. When the
> shock is just sitting there statically, i.e. no movement, the pressure
> from the bladder is felt equally everywhere inside the shock body.
> What some folks on this thread have forgotten or don't understand,
me!! me me me
> is
> that the pressure from the reservoir is NOT felt equally under dynamic
> conditions. When the shock is trying to compress, high pressure is
> generated on top of the shock piston (given current shock orientation
> in modern bikes), which begins pushing the fluid towards a lower
> pressure area, of which there are 2 in this situation: the other
> (lower) side of the shock piston, and into the reservoir through the
> compression adjuster valve.
Ahhh, and since the ~5ci bladder of pressurized gas is presumably
easier to squeeze than fluid, that's where the fluid heads.
> Flow rate is dependent on the pressure
> differential, and the high pressure generated above the piston is a
> function of the piston compression stack, the speed at which the shock
> is trying to compress, resistance to flow through the compression
> adjuster, and the viscosity of the fluid. Pressure in the reservoir is
> only what the bladder is putting on it plus the pressure from the
> incoming fluid. As the shock fluid squeezes through the valve into the
> reservoir, there is a pressure drop so that as long as the piston is
> moving up (shock collapsing), there will always be lower pressure in
> the reservoir than in the shock body, so the fluid will always flow
> that direction. If the reservoir pressure is increased significantly,
That is a great description of the pressure differential during shock
piston movement. Thanks Tim. but...
I still can't see what the effect of `1/150th of a drop of water would
have on the bladder pressure, i.e., for all I know it could be 10psi
(or 0.001psi) at 200F?
I mean, I'm obviously clueless, but if the 1/150th of a drop of water
would increase the bladder 10psi and the pressure differential you're
describing above is 150psi (say 300 psi is initially generated from
sitting on the bike). Then, in that situation, the 1/150th of a drop
of water's effect on shock action may not be significant, i.e., the
difference in fluid flow during a 140psi or 150psi differential
(300psi above shock piston) between scenario A=bladder at 150psi and
scenario B-bladder at 160psi may not be felt by the rider.
> Clear as mud now?
Thanks Tim!!! I can see what you're saying, but I'm still stuck on
(a) what's the effect of the 1/150th of a drop of water on the
pressure in the bladder, and (b) is the resulting change in bladder
pressure and its corresponding effect on fluid flow enough to be
detectable by a rider (which has to be the definition of significant)?
So, from what I can see, we still don't know if charging a shock with
N2 instead of air makes a detectable difference in damping.
BUT!!! I can see how more or less pressure in the bladder would
affect damping.
Thanks again!!!
-Joe
Tim H
<yo...@sisna.com> wrote:
>
>
> I still can't see what the effect of `1/150th of a drop of water would
> have on the bladder pressure, i.e., for all I know it could be 10psi
> (or 0.001psi) at 200F?
>
> I mean, I'm obviously clueless, but if the 1/150th of a drop of water
> would increase the bladder 10psi and the pressure differential you're
> describing above is 150psi (say 300 psi is initially generated from
> sitting on the bike). Then, in that situation, the 1/150th of a drop
> of water's effect on shock action may not be significant, i.e., the
> difference in fluid flow during a 140psi or 150psi differential
> (300psi above shock piston) between scenario A=bladder at 150psi and
> scenario B-bladder at 160psi may not be felt by the rider.
Just did a quick Google search on the expansion rate of water to
steam. The expansion ratio is about 1:1700, so if you have a 0.5cc
drop of water that turns to steam, it wants to take up about 950cc
(about a quart). Since the reservoir volume remains basically
unchanged, that's going to result in a pretty high pressure increase,
but calculation it might be a bit more time consuming than I ought to
spend on it right now.
> > Clear as mud now?
>
> Thanks Tim!!! I can see what you're saying, but I'm still stuck on
> (a) what's the effect of the 1/150th of a drop of water on the
> pressure in the bladder, and (b) is the resulting change in bladder
> pressure and its corresponding effect on fluid flow enough to be
> detectable by a rider (which has to be the definition of significant)?
Pressure increase will vary widely depending on how much water was in
there to begin with.
> So, from what I can see, we still don't know if charging a shock with
> N2 instead of air makes a detectable difference in damping.
Depends on how dry the air was to begin with. If you fill it on a
relatively dry day and run the air through a water seperator like
you'd use for a spray gun air supply, the difference would be pretty
minor I would think. I think your results speak for themselves...if
you can't detect a problem, what else really matters? I'm pretty sure
you'll never get Dungey and Villopoto to switch to compressed air, but
they use their suspension to a slightly different level than most of
us.
> BUT!!! I can see how more or less pressure in the bladder would
> affect damping.
>
> Thanks again!!!
You're welcome, of course.
TIm H
Whelan - '02 200exc (x2) & '04 MTD 38
> steam. The expansion ratio is about 1:1700, so if you have a
> 0.5cc drop of water
Was there something wrong with my calculations to obtain 50/1000 of a
cc (or of a ml) of water in a bladder?
> that turns to steam, it wants to take up about 950cc
50/1000 x 1700 = 85cc which, for water, is 85ml which is ~5.2ci
> (about a quart). Since the reservoir volume remains basically
> unchanged, that's going to result in a pretty high pressure increase,
Instead of compressing 50ci into a 5ci volume, 55ci would be
compressed into a 5ci volume so the effect of the 50mg of water
expanding into steam would be to raise the pressure in the bladder an
extra atmosphere (~15psi).
Thus, on a day with 50% relative humidity, the expected effect of
filling a shock bladder with regular old air is that if/when the shock
gets so hot it boils the water in the air, it will boost the pressure
by approximately 15psi which is ~10% of the recommended pressure.
Note that the boiling point of water increases with pressure.
According the this graph:
http://www.engineeringtoolbox.com/boiling-point-water-d_926.html
at 150psi, the boiling point of water is 359 degrees Fahrenheit.
Since the bladder pressure is set with the shock fully extended, the
359F represents the "floor" temp at which the water in the bladder
would vaporize and boost the pressure 15psi.
So, the "BOTTOM LINE" is:
1. Unless the shock gets hotter than a skillet frying a burger does,
there's no effect.
2. IF the shock gets up near 400 degrees Fahrenheit, then the water
may vaporize and boost the bladder pressure 15psi.
See any errors?
-Joe
Wudsracer
will affect the condition of the oil.
Jim
Mike Baxter
wrote:
You need some Ambien!
Mike Baxter
JayC
> My thoughts on this pertain to the moisture from the air, and how it
> will affect the condition of the oil.
The air is completely isolated from the oil, so there will be no
interaction. Moisture will simply cause a greater performance
difference due to temperature.
JayC