Different gear ratios front and rear.
Gordon McKenzie
Been having a conversation in a rec.outdoors.rv-travel that got onto
4wd's. Anyone have a vehicle (or know of specific models) where the gear
ratios are different? Ie. 4.10's up front and 4.11's in the rear.
Someone is questioning that these exist and would like specific models
etc.
Thanks
--
Gord, Sue & Countess McKenzie
"Anyone with brains knows not to take anything
posted here too seriously, it's a sandbox for adults."
Bill A
> 4wd's. Anyone have a vehicle (or know of specific models) where the gear
> ratios are different? Ie. 4.10's up front and 4.11's in the rear.
> Someone is questioning that these exist and would like specific models
> etc.
My 95 Dodge Ram came with 4.09 rear, 4.10 front.
Bill
.
Grady Fields
Odd isn't it. My 97 Ram 1500 has a 3.54 rear and a 3.55 front (or vice
versa). I was puzzled at the difference as well.
--
NOSPAM...@ix.netcom.com
97 Ram 1500 SLT CC SB 4x4
Favorite quote "Doh"
wi...@epix.net
In Article<01bd25e6$cfffb730$a5e71fcc@gradynt>,
<gra...@ixDOTnetcom.com> writes:
> Odd isn't it. My 97 Ram 1500 has a 3.54 rear and a 3.55 front
>(or vice versa). I was puzzled at the difference as well.
Odd indeed. I just got off the phone with a close friend who was
a mechanic in a Jeep agency for many years, and he too had heard
rumors that some Suburbans might have had slightly different
gears front & rear, but thought it was accidental and never saw
one. No Jeeps, sez he, were ever shipped with mismatched gears
other than by mistake.
Now that we have a report of a specific unit with different
ratios, is there someone with a credible explanation for the
reason? I suppose it would make SOME sense for the factory to
foist off some nearly-matched gears in a chassis with a center
differential (i.e. in full time 4wd the customer would never
notice it), but otherwise I'm at a loss and wonder why anyone
would do this deliberately.
BTW the tale about the front end going farther on corners is NOT
a credible explanation IMO!
Will KD3XR
tjohnson
That's the reason most of the older model owners manual told you not to run
4 wheel drive locked up on the highway, because of the torque bind up.
--
tjoh...@XXXop9.com
To E-mail me you will have to take out the XXX
change SEND TO on any reply also spammers
Grady Fields <gra...@ixDOTnetcom.com> wrote in article
<01bd25e6$cfffb730$a5e71fcc@gradynt>...
> Odd isn't it. My 97 Ram 1500 has a 3.54 rear and a 3.55 front (or vice
> versa). I was puzzled at the difference as well.
>
Pete Prunskunas
While having my truck repaired a few years ago, I was talking with
the owner of the body shop. He had been in the business for many
years and had a lot of experience. He said that every 4WD he had
ever seen had one gear tooth difference between the front and rear
differentials. This would imply that a 3.54/3.55 type of situation is
entirely normal. FWIW.
Pete
> > Odd isn't it. My 97 Ram 1500 has a 3.54 rear and a 3.55 front
> >(or vice versa). I was puzzled at the difference as well.
>
Pete Prunskunas
An aquaintance (not a friend) once drove his Subaru 4WD a "while" on
smooth, dry pavement. The vehicle eventually came to a stop. You could
almost see the extra energy saved up in the driveshaft. :-)
Pete
Gordon McKenzie
tjohnson wrote:
>
> That's the reason most of the older model owners manual told you not to run
> 4 wheel drive locked up on the highway, because of the torque bind up.
No it isn't. Even with the same gearing, slight differences in tire size
will create the same binding. Just don't run in 4wd on dry pavement
(course *I* do it ALL THE TIME)
Matthew S. Whiting
A one tooth difference, would be much more than a .01 difference in the
ratio! The mismatch in ratio is typically due to having different sized
ring gears in the front end vs. the rear. I'm not a gear designer, but
I think there are certain parameters governing the size of the
individual gear teeth. If you go from say an 8" to a 9" ring gear and
have the same number of teeth on both, you will have different size
teeth. Typically, you will also have a different number of teeth on a
different sized ring gear. This then is matched with a pinion gear with
a tooth or two more of less and thus different ratios are obtained. If
you look at a chart of ratios for different size ring gears, you will
see that a different set of ratios are listed. Conventional wisdom says
that a 1% or less difference is not a problem. Since 1% of a typical
3.54 ratio is .035 and .01 is much less than that, you'll never know
that difference between say a 3.54 and a 3.55 ratio. Heck, you get more
difference than that simply by taking a curve in a truck with equal
ratios front and rear!
Matt
Jerry Bransford
wi...@epix.net wrote:
>
> In Article<01bd25e6$cfffb730$a5e71fcc@gradynt>,
> <gra...@ixDOTnetcom.com> writes:
>
> >(or vice versa). I was puzzled at the difference as well.
>
> Odd indeed. I just got off the phone with a close friend who was
> a mechanic in a Jeep agency for many years, and he too had heard
> rumors that some Suburbans might have had slightly different
> gears front & rear, but thought it was accidental and never saw
> one. No Jeeps, sez he, were ever shipped with mismatched gears
> other than by mistake.
>
> Now that we have a report of a specific unit with different
> ratios, is there someone with a credible explanation for the
> reason? I suppose it would make SOME sense for the factory to
> foist off some nearly-matched gears in a chassis with a center
> differential (i.e. in full time 4wd the customer would never
> notice it), but otherwise I'm at a loss and wonder why anyone
> would do this deliberately.
Heck, I can't remember ever seeing many 4x4s with *exactly* the same
front and rear ratio. It's very common... my brand new Jeep has a 3.54
and 3.55, my Blazer, Jimmy, and Cherokee had this same .01 difference
too.
Jerry
--
Jerry Bransford
To send me email, remove "junkmail" from my email address.
PP-ASEL, C.A.P., KC6TAY
The Zen hotdog... make me one with everything!
Chris Taylor Jr.
So why do it them Why not for simplicity ake in only have to make ONE kind
of differential make on instead of two ??
Chris
http://www.nerys.com/myjeep/
Matthew S. Whiting wrote in message <34C538...@epix.net>...
>Pete Prunskunas wrote:
>>
>> While having my truck repaired a few years ago, I was talking with
>> the owner of the body shop. He had been in the business for many
>> years and had a lot of experience. He said that every 4WD he had
>> ever seen had one gear tooth difference between the front and rear
>> differentials. This would imply that a 3.54/3.55 type of situation is
>> entirely normal. FWIW.
>>
>> Pete
>>
>> > > Odd isn't it. My 97 Ram 1500 has a 3.54 rear and a 3.55 front
>> > >(or vice versa). I was puzzled at the difference as well.
>> >
>> > Odd indeed. I just got off the phone with a close friend who was
>> > a mechanic in a Jeep agency for many years, and he too had heard
>> > rumors that some Suburbans might have had slightly different
>> > gears front & rear, but thought it was accidental and never saw
>> > one. No Jeeps, sez he, were ever shipped with mismatched gears
>> > other than by mistake.
>> >
>> > Now that we have a report of a specific unit with different
>> > ratios, is there someone with a credible explanation for the
>> > reason? I suppose it would make SOME sense for the factory to
>> > foist off some nearly-matched gears in a chassis with a center
>> > differential (i.e. in full time 4wd the customer would never
>> > notice it), but otherwise I'm at a loss and wonder why anyone
>> > would do this deliberately.
>
Mark Kovalsky
Chris Taylor Jr. wrote:
>
> So why do it them Why not for simplicity ake in only have to make ONE kind
> of differential make on instead of two ??
>
> Chris
Because the rear differential has to be able to live with a larger
torque
load than the front, and for a harder duty cycle.
The front only has torque when the rear is also taking torque. The rear
always
has torque, while the front does not always. This will allow a lighter
front
differential to be used without loss of function. It saves weight, which
means
better performance and better fuel economy. Of course better economy on
most
4x4 is a relative term...
--
Mark
----------------------------
'30 Ford Model "A" Tudor
'59 Edsel Corsair
'94 Ford Club Wagon 7.3L Diesel with Hypermax Turbo
'94 Sportsmen's 37' Travel Trailer
'97 Ford Taurus SHO
----------------------------------------------------------------------
The views expressed above are mine, and mine alone.
Greg Loxtercamp
I test drove a full size Bronco (~85) a few years ago. The sales guy (maybe
even the mechanic) said that's the way they set them up. The ratio up front
is one number smaller. Like the 4.10/4.11 example. He said so that the
back end doesn't come around. I think that if the two ratios were not
equal, they would rather have the front end pull against the back end.
Instead of the back end pushing the front. I'm not sure how much of that is
true...he was trying to explain why the truck made noise when I put it in
4wd.
For what it's worth...
Greg
Gordon McKenzie wrote:
> Been having a conversation in a rec.outdoors.rv-travel that got onto
> 4wd's. Anyone have a vehicle (or know of specific models) where the gear
> ratios are different? Ie. 4.10's up front and 4.11's in the rear. Someone
> is questioning that these exist and would like specific models etc.
>
> Thanks
wi...@epix.net
Gordon <m...@nowhere.com> writes:
> Even with the same gearing, slight differences in tire size
> will create the same binding. Just don't run in 4wd on dry
> pavement (course *I* do it ALL THE TIME)
Not only tire size differences, but loads and inflation
pressures will cause binding on hard surfaces. Binding does
occur naturally in any 4wd without a center differential (or
viscous coupling). BUT it's perectly OK to run in 4wd on dry
pavement IF your transfer case has either of these features.
I see we now have more than one report that certain vehicles do
have mismatched ratios. Which I admit is a big surprise to me!
Two questions:
1) Do these vehicles have a center differential ("full time"
feature)?
2) Why would the factory specify a different ratio - or permit
it - if it is actually insignificant?
Will KD3XR
Gordon McKenzie
Mark Kovalsky wrote:
>
> Chris Taylor Jr. wrote:
> >
> > So why do it them Why not for simplicity ake in only have to make ONE kind
> > of differential make on instead of two ??
> >
> > Chris
>
> Because the rear differential has to be able to live with a larger
> torque
> load than the front, and for a harder duty cycle.
>
> The front only has torque when the rear is also taking torque. The rear
> always
> has torque, while the front does not always. This will allow a lighter
> front
> differential to be used without loss of function. It saves weight, which
> means
> better performance and better fuel economy. Of course better economy on
> most
> 4x4 is a relative term...
>
Which is why I have a Dana 44 in front and an AMC20 in the rear ;-)
(I also have Full-time 4wd)
Gordon McKenzie
wi...@epix.net wrote:
>
> Gordon <m...@nowhere.com> writes:
>
> > Even with the same gearing, slight differences in tire size
> > will create the same binding. Just don't run in 4wd on dry
> > pavement (course *I* do it ALL THE TIME)
>
> Not only tire size differences, but loads and inflation
> pressures will cause binding on hard surfaces. Binding does
> occur naturally in any 4wd without a center differential (or
> viscous coupling). BUT it's perectly OK to run in 4wd on dry
> pavement IF your transfer case has either of these features.
>
> I see we now have more than one report that certain vehicles do
> have mismatched ratios. Which I admit is a big surprise to me!
Do I get a cupie doll for one-upping Will?
> Two questions:
>
> 1) Do these vehicles have a center differential ("full time"
> feature)?
Typically, no (as a matter of fact, my full-time truck has 3.31's at
both ends). This doesn't seem to be t/c related at all.
>
> 2) Why would the factory specify a different ratio - or permit
> it - if it is actually insignificant?
>
I think the best explanation I've seen here is that the different axles
just have different size gear sets and they are matched as close as
possible. These differences are minor and of no real consequence (so how
did the thread start anyway (not this thread, the one that prompted me
to start this thread (which the 4x4 group didn't see)))
Time to go home.
Matthew S. Whiting
Sandy A. Nicolaysen wrote:
>
> The way they do this has to do with the setup of the differential.
> Both front and read ring and pinion gears have the same number of
> teeth on each. The small difference in gear ratios is done this way.
This is good. Where, pray tell, did you come up with this
misconception?
> The pinion gear can be positioned against the ring gear +/- about 1/8
> inch. It is a matter of the number of shims between the pinion gear
> and the casing vs the number of shims between the ring gear and the
> carrier that determines the ratio. If you put the pinion gear closer
> to the axle, the ratio is lower, say 3.55->3.54. If the pinion gear
> is put further from the axle, ratio is higher. You haven't changed
> the number of teeth on the gears at all, but you change the ratio.
> You can get away with that with helical toothed gears.
Absolute horse pucky! I'll admit to having never heard this one
before...
Matt
wi...@epix.net
In Article<34c75058....@news.erols.com>,
<sand...@erols.com> writes:
> The way they do this has to do with the setup of the
>differential. Both front and read ring and pinion gears have
>the same number of teeth on each. The small difference in gear
>ratios is done this way.
>
> The pinion gear can be positioned against the ring gear +/-
>about 1/8 inch. It is a matter of the number of shims between
>the pinion gear and the casing vs the number of shims between
>the ring gear and the carrier that determines the ratio. If
>you put the pinion gear closer to the axle, the ratio is lower,
>say 3.55->3.54. If the pinion gear is put further from the
>axle, ratio is higher. You haven't changed the number of teeth
>on the gears at all, but you change the ratio. You can get away
>with that with helical toothed gears.
Sorry, but to put it as kindly as I can, you have been fed a
line of low-grade baloney. There is absolutely nothing that
affects the ratio of a gearset (of any kind) other than the
tooth count. What's more, there is a VERY small tolerance on
the correct mesh geometry, and changing gear mesh by 1/8 of an
inch in a rear end will definitely destroy the gears quickly.
Now if there is a REASON that makes sense to have a different
ration front/rear I have not yet read it. I can easily
understand why a maker would put a heavier rear end in a rig
designed for part-time 4wd (more wear) but a different ratio
still doesn't make any sense to me.
Will KD3XR
Jerry Bransford
Sandy A. Nicolaysen wrote:
>
> On Tue, 20 Jan 98 17:14:50 edt, wi...@epix.net wrote:
>
> >No Jeeps, sez he, were ever shipped with mismatched gears
> >other than by mistake.
Nope, not at all. For example, the 3.55 rear ratio option for the '97
Jeep Wrangler TJ comes with a 3.54 on the front differential. Same with
my old Cherokee. My old Blazer and Jimmy's front and rear differentials
were off by about the same amount too.
Chris Taylor Jr.
But that does not make sense HOW much of a difference is there between the
two different Differencials in so far as mass and dim specs go ??
Thanks
Chris
http://www.nerys.com/myjeep/
Gordon McKenzie wrote in message <34C54E...@direct.ca>...
>Mark Kovalsky wrote:
>>
>> Chris Taylor Jr. wrote:
>> >
>> > So why do it them Why not for simplicity ake in only have to make ONE
kind
>> > of differential make on instead of two ??
>> >
>> > Chris
>>
>> Because the rear differential has to be able to live with a larger
>> torque
>> load than the front, and for a harder duty cycle.
>>
>> The front only has torque when the rear is also taking torque. The rear
>> always
>> has torque, while the front does not always. This will allow a lighter
>> front
>> differential to be used without loss of function. It saves weight, which
>> means
>> better performance and better fuel economy. Of course better economy on
>> most
>> 4x4 is a relative term...
>>
>
>Which is why I have a Dana 44 in front and an AMC20 in the rear ;-)
>(I also have Full-time 4wd)
Eric
>
> >Now that we have a report of a specific unit with different
> >ratios, is there someone with a credible explanation for the
> >reason? I suppose it would make SOME sense for the factory to
> >foist off some nearly-matched gears in a chassis with a center
> >differential (i.e. in full time 4wd the customer would never
> >notice it), but otherwise I'm at a loss and wonder why anyone
> >would do this deliberately.
> Both front and read ring and pinion gears have the same number of
> teeth on each. The small difference in gear ratios is done this way.
>
> The pinion gear can be positioned against the ring gear +/- about 1/8
> inch. It is a matter of the number of shims between the pinion gear
> and the casing vs the number of shims between the ring gear and the
> carrier that determines the ratio. If you put the pinion gear closer
> to the axle, the ratio is lower, say 3.55->3.54. If the pinion gear
> is put further from the axle, ratio is higher. You haven't changed
> the number of teeth on the gears at all, but you change the ratio.
> You can get away with that with helical toothed gears.
>
The ratio is determined by dividing the number of teeth on the ring gear
by the number on the pinion. Moving the pinion deeper into the ring gear
changes the pattern, and noise, but can’t change the ratio!!
Eric
Master ASE Technician
Jon Kromer
The reason that this often happens is because they DON'T make matching
gear ratios. Other than Toyota, (Nissan too I guess) Most companies do
not make both there front and rear axel. A Dana front end and a Ford/GM
rear end for example.
The difference is minute as posted but most of these "it was built
that way cause the guys in R&D felt it to be prudent" Okay, if you say
so! The match them the best they can.
Jon
/\ /\
/ \ / \
/ \ / \
|| ||
-----------------------------------------------------------------------------
kro...@bigfoot.com PO BOX 1821 Corvallis, OR 97339
kro...@ucs.orst.edu
kro...@off-road.com
http://www.off-road.com/~kromerj
Sandy A. Nicolaysen
On Tue, 20 Jan 98 17:14:50 edt, wi...@epix.net wrote:
>No Jeeps, sez he, were ever shipped with mismatched gears
>other than by mistake.
I believe that is 100% correct.
>Now that we have a report of a specific unit with different
>ratios, is there someone with a credible explanation for the
>reason? I suppose it would make SOME sense for the factory to
>foist off some nearly-matched gears in a chassis with a center
>differential (i.e. in full time 4wd the customer would never
>notice it), but otherwise I'm at a loss and wonder why anyone
>would do this deliberately.
The way they do this has to do with the setup of the differential.
Both front and read ring and pinion gears have the same number of
teeth on each. The small difference in gear ratios is done this way.
The pinion gear can be positioned against the ring gear +/- about 1/8
inch. It is a matter of the number of shims between the pinion gear
and the casing vs the number of shims between the ring gear and the
carrier that determines the ratio. If you put the pinion gear closer
to the axle, the ratio is lower, say 3.55->3.54. If the pinion gear
is put further from the axle, ratio is higher. You haven't changed
the number of teeth on the gears at all, but you change the ratio.
You can get away with that with helical toothed gears.
>BTW the tale about the front end going farther on corners is NOT
>a credible explanation IMO!
Are you saying the front wheels don't travel further in a turn? I
think not, that's high school physics. I think what you are saying is
that the front vs rear axle ratio difference is for some other reason
than ease of turning. I, too, would like to know. - Sandy
Sandy A. Nicolaysen
>This is good. Where, pray tell, did you come up with this
>misconception?
GM shop manual.
>Absolute horse pucky! I'll admit to having never heard this one
>before...
You could be right about horse pucky. They tend to do that a lot.
I didn't write the manual.
>
>Matt
- Sandy
Sandy A. Nicolaysen
On Tue, 20 Jan 98 22:42:41 edt, wi...@epix.net wrote:
>Sorry, but to put it as kindly as I can, you have been fed a
>line of low-grade baloney. There is absolutely nothing that
>affects the ratio of a gearset (of any kind) other than the
>tooth count. What's more, there is a VERY small tolerance on
>the correct mesh geometry, and changing gear mesh by 1/8 of an
>inch in a rear end will definitely destroy the gears quickly.
depending upon how far the pinion gear rides toward the axle. We are
talking about very small ratio change here e.g. 3.73 -> 3.74.
>
>Now if there is a REASON that makes sense to have a different
>ration front/rear I have not yet read it. I can easily
>understand why a maker would put a heavier rear end in a rig
>designed for part-time 4wd (more wear) but a different ratio
>still doesn't make any sense to me.
>
>Will KD3XR
to get into a 'peeing contest' with people out there. I have enough
problems right now with the flames from 'towing in overdrive'. :-)
No hard feelings. - Sandy
T. Patrick Culp
I do not know about differentials but If the
diameter of a gear changes then the ratio will
change slightly even if the tooth count remains
the same. I am not sure how the teeth will mesh
with the same tooth count and a different diameter
BUT the ratio will change. i.e. a 10 tooth 2"
gear will turn different by a factor of 2 than a
10 tooth 4" gear. So if the gear is conical there
will be a very slight ratio shift the farther the
gear shaft is advanced if a different part of the
conical gear meets the ring. IMHO
> I don't know the 'official' reason either, but I don't have the time
> to get into a 'peeing contest' with people out there. I have enough
> problems right now with the flames from 'towing in overdrive'. :-)
> No hard feelings. - Sandy
--
********** T. Patrick Culp **********
http://www.campmor.com/
http://www.llbean.com/
http://www.rei.com/
http://www.expedition-leader.com/
http://home.pacbell.net/orbs/
T. Patrick Culp
T. Patrick Culp wrote:
>
> I do not know about differentials but If the
> diameter of a gear changes then the ratio will
> change slightly even if the tooth count remains
> the same. I am not sure how the teeth will mesh
> with the same tooth count and a different diameter
> BUT the ratio will change. i.e. a 10 tooth 2"
> gear will turn different by a factor of 2 than a
> 10 tooth 4" gear. So if the gear is conical there
> will be a very slight ratio shift the farther the
> gear shaft is advanced if a different part of the
> conical gear meets the ring. IMHO
The above refers to *speed* ratio not *gear*
ratio.
Will Rosenberry
How can moving the pinion closer to the ring gear make the ratio
change. even at 3/4" clearance the pinion is still going to go around
4.10 times for every 1 time the ring goes around! ( in a 4.10:1 rear)
I posted earlier that I have never heard of it in light trucks, But I
am not the most experienced one on this site by far. It is possible
what they are saying about different ratios. with a 40"
circumference tire with a 4.1 ratio, each time the motor goes around
one time the tire will cover 164" of ground and the 4.11 would cover
only .4" more
If you put the 4.11 in the front that would allow the front wheels to
turn slightly faster then the rear which would allow better steering
in the slop. (snow, mud, etc)
The older trucks that you had to backup to get out of 4wd that I
remember also had automatic hubs, backing up after switching the
transfer case from 2wd to 4wd would allow the "ratchet" in the hubs to
unlock.
Will
Squash
1977 chevy K-20
4.09 front
4.11 rear
I think that most 4x4s stock have a little difference.
--
Andy Quaas
wi...@epix.net
In Article<34C54F...@direct.ca>, <m...@nowhere.com> writes:
> Do I get a cupie doll for one-upping Will?
Nope. I am never too old or proud to learn a thing or two.
I thought Gail was mistaken and I was wrong.
So far I like the following explanation best:
>different axles just have different size gear sets and they are
>matched as close as possible. These differences are minor and
>of no real consequence
In other words, there's no *need* for them to be different.
This makes FAR more sense than the bafflegab about cornering and
handling. 4wd rigs without a center diff don't handle OR corner
smoothly in lock anyway, regardless of ratios and tires sizes
and phase of the moon!
Thanx, Gordon
Will KD3XR
Squash
I have 2 vehicles with 4.09/4.11 gears-both 77s (one chevy, one GMC).
They both have the factory gear-drive part time NP205 transfer case (in
other words, no differential in the t-case). I think that the extra
gearing in the front takes up the difference in load, and also makes the
front want to "pull out" from the rear, keeping the truck straighter (or
trying to). Professional mud-boggers will do this (more extreme
difference, tho) so the front claws faster than the rear to keep the
vehicle straight. Just some thoughts...
--
Andy Quaas
wi...@epix.net
In Article<34c96717....@news.erols.com>,
<sand...@erols.com> writes:
> Will: I was trying to point out that is the axle ratio would
>change depending upon how far the pinion gear rides toward the
>axle. We are talking about very small ratio change here e.g.
>3.73 -> 3.74.
Hey, Sandy, it is NOT a flame to say your IDEA is nonsense!
It simply does NOT work that way. As long as the two gears of a
set are in mesh, the ratio is determined by the tooth count.
Any manual that says otherwise is WRONG. Can you identify a text
that says that, or is that something someone SAID was in the
manual?
Will KD3XR
wi...@epix.net
In Article<34C5EB50...@pinnacleweb.com>,
<tpc...@pinnacleweb.com> writes:
> I do not know about differentials but If the
> diameter of a gear changes then the ratio will
> change slightly even if the tooth count remains
> the same. I am not sure how the teeth will mesh
> with the same tooth count and a different diameter
> BUT the ratio will change. i.e. a 10 tooth 2"
> gear will turn different by a factor of 2 than a
> 10 tooth 4" gear. So if the gear is conical there
> will be a very slight ratio shift the farther the
> gear shaft is advanced if a different part of the
> conical gear meets the ring. IMHO
Sorry, Pat, but this is NOT true. You can verify it yourself
with ANY set of gears. Changing the contact point to something
other than the design pitch line increases wear and noise but
does not and cannot change the ratio. A 41/10 tooth count is
ALWAYS 4.10:1.
Will KD3XR
wi...@epix.net
In Article<34C5EC88...@pinnacleweb.com>,
<tpc...@pinnacleweb.com> writes, quoting himself:
> > I do not know about differentials but If the
> > diameter of a gear changes then the ratio will
> > change slightly even if the tooth count remains
> > the same. I am not sure how the teeth will mesh
> > with the same tooth count and a different diameter
> > BUT the ratio will change. i.e. a 10 tooth 2"
> > gear will turn different by a factor of 2 than a
> > 10 tooth 4" gear. So if the gear is conical there
> > will be a very slight ratio shift the farther the
> > gear shaft is advanced if a different part of the
> > conical gear meets the ring. IMHO
>
> The above refers to *speed* ratio not *gear*
> ratio.
Not true. The "speed ratio" IS the gear ratio.
Will KD3XR
Donald J. Dickson
T. Patrick Culp wrote:
>
> T. Patrick Culp wrote:
> >
> > I do not know about differentials but If the
> > diameter of a gear changes then the ratio will
> > change slightly even if the tooth count remains
> > the same. I am not sure how the teeth will mesh
> > with the same tooth count and a different diameter
> > BUT the ratio will change. i.e. a 10 tooth 2"
> > gear will turn different by a factor of 2 than a
> > 10 tooth 4" gear. So if the gear is conical there
> > will be a very slight ratio shift the farther the
> > gear shaft is advanced if a different part of the
> > conical gear meets the ring. IMHO
>
> The above refers to *speed* ratio not *gear*
> ratio.
The people reporting the different front and rear ratios indicated that
the front ratio was lower(higher numerically) which would indicate that
the rear axle is always pushing the front. Is this difference present in
ALL 4WD or only those that are to be engaged where the surface is not
paved. Different tire wear patterns could probably have as much
significance as a 0.01 "speed" ratio. If there is NO centre differential
then the drive shafts are both turning at the same speed and if the
pinion has 10 teeth (for example) in one revolution it will engage 10
teeth on the ring gear regardless of whether or not it's effective
diameter is slightly different. If both the front and rear ring gear
have 40 teeth (ie a 4.00/1 ratio) when the drive shaft has revolved 4
times the pinion will be back to the same spot on the ring gear.
Different effective diameters work in belt driven CVT's (like
snowmobiles or ATV's) but teeth in a gear are constant.
Looking at it from the opposite direction, if both front and rear wheels
are turning at the same rate then for each revolution of the ring
gear(40 teeth), the drive shaft will turn 4 times(40/10=4).
The positioning of the pinion which causes a different "speed" ratio may
change how the teeth of the pinion engage the ring gear but I don't see
how that changes the "real" ratio.
Are we being "flim-flammed" by the manufacturer?
Don Dickson
--
When sign makers go on strike, who makes their picket signs?
B Funk
cx...@freenet.carleton.ca asks:
> Are we being "flim-flammed" by the manufacturer?
When are we not?
brian
Gordon McKenzie
Chris Taylor Jr. wrote:
>
> But that does not make sense HOW much of a difference is there between the
> two different Differencials in so far as mass and dim specs go ??
>
> Thanks
> Chris
> http://www.nerys.com/myjeep/
>
The two are very similar in size and strength. In prior and subsequent
model years (not immediately though) they had D44's front and rear. The
transfer cases in these beast are full-time 4wd so the two diffs see
more or less the same stresses, hence they are similar in strength.
Gordon McKenzie
wi...@epix.net wrote:
>
> In Article<34C54F...@direct.ca>, <m...@nowhere.com> writes:
>
> > Do I get a cupie doll for one-upping Will?
>
> Nope. I am never too old or proud to learn a thing or two.
> I thought Gail was mistaken and I was wrong.
>
> So far I like the following explanation best:
>
> >different axles just have different size gear sets and they are
> >matched as close as possible. These differences are minor and
> >of no real consequence
>
> In other words, there's no *need* for them to be different.
> This makes FAR more sense than the bafflegab about cornering and
> handling. 4wd rigs without a center diff don't handle OR corner
> smoothly in lock anyway, regardless of ratios and tires sizes
> and phase of the moon!
>
> Thanx, Gordon
Your welsome. I was interested in the topic and have learned a bit about
it as well.
John Banes
Matthew S. Whiting wrote in message <34C538...@epix.net>...
>Pete Prunskunas wrote:
>>
>> While having my truck repaired a few years ago, I was talking with
>> the owner of the body shop. He had been in the business for many
>> years and had a lot of experience. He said that every 4WD he had
>> ever seen had one gear tooth difference between the front and rear
>> differentials. This would imply that a 3.54/3.55 type of situation is
>> entirely normal. FWIW.
>>
>> Pete
>>
>> > > Odd isn't it. My 97 Ram 1500 has a 3.54 rear and a 3.55 front
>> > >(or vice versa). I was puzzled at the difference as well.
>> >
>> > Odd indeed. I just got off the phone with a close friend who was
>> > a mechanic in a Jeep agency for many years, and he too had heard
>> > rumors that some Suburbans might have had slightly different
>> > gears front & rear, but thought it was accidental and never saw
>> > one. No Jeeps, sez he, were ever shipped with mismatched gears
>> > other than by mistake.
>> >
>> > Now that we have a report of a specific unit with different
>> > ratios, is there someone with a credible explanation for the
>> > reason? I suppose it would make SOME sense for the factory to
>> > foist off some nearly-matched gears in a chassis with a center
>> > differential (i.e. in full time 4wd the customer would never
>> > notice it), but otherwise I'm at a loss and wonder why anyone
>> > would do this deliberately.
When I was four wheelin, about 20 years ago, it was common for the front
axle to have a higher ratio than the read axle. 3.55 front/3.54 rear etc.
The reasoning was that when in four wheel drive you wanted the front end and
steering wheels, pulling slightly harder than the rear wheels. This was
supposed to give better control. This difference in ratio was also why it
was recommended to never run in 4 wheel drive on dry pavement. It was
possible to get enough traction to break the teeth off the gears. On sand,
dirt, snow, ice etc. the tires would slip before a gear would break.
Kirk McGraw
"T. Patrick Culp" <tpc...@pinnacleweb.com> wrote:
>I do not know about differentials but If the
>diameter of a gear changes then the ratio will
>change slightly even if the tooth count remains
>the same. I am not sure how the teeth will mesh
>with the same tooth count and a different diameter
>BUT the ratio will change. i.e. a 10 tooth 2"
>gear will turn different by a factor of 2 than a
>10 tooth 4" gear. So if the gear is conical there
>will be a very slight ratio shift the farther the
>gear shaft is advanced if a different part of the
>conical gear meets the ring. IMHO
Well, as a mechanical engineer, I _do_ know
about differentials. There are power transmission
devices like Continuously Variable Transmissions
that behave as you suggest. Gearsets have fixed
ratios, even planetary gears have only a few fixed
ratios to choose from.
Tooth count determines the ratio between two
gears. Period. Moving the pinion gear in or
out will have no effect on the ratio.
Changing the diameter of the ring gear will change
tooth pitch (size) which will require a matching
tooth picth on the pinion, meaning it will have
a proportional diameter change.
Finally, the reason for the taller (lower numerical)
ratio on a front axle is that it provides directional
stability on slippery surfaces at speed. This is
very handy on washboard and gravel roads.
However, it is not compatible with AWD or the
currently popular shift on the fly, central disconnect
axles.
Kirk McGraw
Jerry Bransford
T. Patrick Culp wrote:
>
> I do not know about differentials but If the
> diameter of a gear changes then the ratio will
> change slightly even if the tooth count remains
> the same.
Not if the tooth count in the mating gears doesn't change. That's why
the same gear ratios can be used in the internal gearing of watches and
clocks of many different sizes since the gear diameter doesn't matter as
long as the ratios remain the same.
I am not sure how the teeth will mesh
> with the same tooth count and a different diameter
> BUT the ratio will change. i.e. a 10 tooth 2"
> gear will turn different by a factor of 2 than a
> 10 tooth 4" gear.
Nope, and again, see the above example. If the gear tooth count doesn't
change but the diameter of the gear ring does, the ratio will still
remain the same for a very basic reason... the ratio is the ratio of the
number of teeth on one gear vs the number of teeth on the meshing gear.
The ratio knows nothing about diameter, only the ratio between the
number of cogs or teeth between the meshing gears themselves. The
diameter of a gear (not a friction surface) is not part of a ratio
equation.
If the gear is larger in diameter but has the same number of teeth as a
smaller gear, the two gears will still rotate at the very same rpms.
The DIAMETER will rotate faster due to the increased circumference, but
the *ratio* of the rpms will remain the same. Hence a 4.11 ratio can
use different sizes of gears, but the ratio of teeth between the gears,
no matter what their size is, will (and must be) exactly 4.11 teeth on
one gear for every single tooth on the other meshing gear.
Steve Arrington
Sound like good logic to me, Believe this is what called stabil.
On Tue, 20 Jan 1998, Greg Loxtercamp wrote:
> I test drove a full size Bronco (~85) a few years ago. The sales guy (maybe
> even the mechanic) said that's the way they set them up. The ratio up front
> is one number smaller. Like the 4.10/4.11 example. He said so that the
> back end doesn't come around. I think that if the two ratios were not
> equal, they would rather have the front end pull against the back end.
> Instead of the back end pushing the front. I'm not sure how much of that is
> true...he was trying to explain why the truck made noise when I put it in
> 4wd.
>
> For what it's worth...
>
> Greg
>
>
> Gordon McKenzie wrote:
>
> > Been having a conversation in a rec.outdoors.rv-travel that got onto
> > 4wd's. Anyone have a vehicle (or know of specific models) where the gear
> > ratios are different? Ie. 4.10's up front and 4.11's in the rear. Someone
> > is questioning that these exist and would like specific models etc.
> >
> > Thanks
Jerry Bransford
wi...@epix.net wrote:
>
> In Article<34C5EC88...@pinnacleweb.com>,
> <tpc...@pinnacleweb.com> writes, quoting himself:
>
> > > diameter of a gear changes then the ratio will
> > > change slightly even if the tooth count remains
> > > with the same tooth count and a different diameter
> > > BUT the ratio will change. i.e. a 10 tooth 2"
> > > gear will turn different by a factor of 2 than a
> > > will be a very slight ratio shift the farther the
> > > gear shaft is advanced if a different part of the
> > > conical gear meets the ring. IMHO
> >
> > ratio.
>
>
> Will KD3XR
True, the speed ratio and gear ratio are identical. But the *ratio*
itself is a constant that only depends on the number of teeth on one
gear vs the other gear. A 10' diameter set of gears with 4110 teeth on
one gear and 1000 teeth on the meshing gear will rotate much *faster*
than another set of gears with a 1' diameter with 411 teeth on one gear
with 100 gear on the meshing gear, but the meshing gears are still going
to ROTATE at a 4.11 ratio to each other, no matter what their sizes
are.
Jerry Bransford
wi...@epix.net wrote:
>
> In Article<34c96717....@news.erols.com>,
> <sand...@erols.com> writes:
>
> > Will: I was trying to point out that is the axle ratio would
> >change depending upon how far the pinion gear rides toward the
> >axle. We are talking about very small ratio change here e.g.
> >3.73 -> 3.74.
>
> Hey, Sandy, it is NOT a flame to say your IDEA is nonsense!
> It simply does NOT work that way. As long as the two gears of a
> set are in mesh, the ratio is determined by the tooth count.
> Any manual that says otherwise is WRONG.
Will is exactly right. We're talking RATIOs here, not the overall speed
of a larger gear vs a smaller gear. The RATIO of the RPM count between
the gears is only dependent on the gear counts of the two meshing gears.
Paul Hovnanian
wi...@epix.net wrote:
>
[snip]
>
> Sorry, but to put it as kindly as I can, you have been fed a
> line of low-grade baloney. There is absolutely nothing that
> affects the ratio of a gearset (of any kind) other than the
> tooth count. What's more, there is a VERY small tolerance on
> the correct mesh geometry, and changing gear mesh by 1/8 of an
> inch in a rear end will definitely destroy the gears quickly.
Correct.
> Now if there is a REASON that makes sense to have a different
> ration front/rear I have not yet read it. I can easily
> understand why a maker would put a heavier rear end in a rig
> designed for part-time 4wd (more wear) but a different ratio
> still doesn't make any sense to me.
Other than a real bog-monster with a significant ratio difference,
I think that this may all be a figment of someone's imagination.
The point about a gear ratio being the ratio of tooth numbers
brings up an interesting point. A ratio of 4.11, for instance,
would be due to N1/N2 = 4.11. Since N1 and N2 must be integers,
what would be the change in N1 or N2 required to go from a
ratio of 4.11 to 4.10? It would require one gear set to have
a ratio of 411/100 and the other to be 410/100. So, how many
ring gears have 411 teeth? Not many. More like 41/10 or
something like that. The minumum difference would be 4.10 to 4.20
(or 4.00).
The numbers are different probably due to different manufacturers
rounding off ther specs differently.
--
Paul Hovnanian | spam to: Chairman Reed Hundt
hovn...@bcstec.ca.boeing.com | rhu...@fcc.gov
------------------------------+-----------------------------------
"Carpe diem" is NOT the "Fish of the day".
The Hepburn
In article <34C5FE...@genevaonline.com>, Squash <m...@genevaonline.com> writes:
> 1977 chevy K-20
>
> 4.09 front
> 4.11 rear
>
> I think that most 4x4s stock have a little difference.
I hate to say this, but ...
does this mean that there's a differential in the differentials?
Now back to the arguing!
--
Alan Hepburn | |
National Semiconductor | DON'T TREAD ON ME |
Santa Clara, Ca | |
al...@galaxy.nsc.com | |
Donald J. Dickson
Some interesting things appear when you work out pinion/gear
combinations:
GM
12/41=3.42
11/41=3.73
10/41=4.10
9/41=4.56
Same # ring teeth
Ford
11/39=3.55
11/41=3.73
11/45=4.09
same # pinion teeth
Dodge
Not sure because they just quote 3.5 and 3.9 could be
11/39=3.5
10/39=3.9
or
12/42=3.5
11/43=3.9
Calculations were done to 3 decimal places and rounded to either 1 or 2.
(eg 11/39 is 3.545 which could be 3.55 or 3.5)
It appears that there may be a bit different design philosophy between
manufacturers but doesn't answer why some have different front and rear
ratios.
Don Dickson
Donald J. Dickson
Grady Fields
[snip]
> I think that this may all be a figment of someone's imagination.
>
> The point about a gear ratio being the ratio of tooth numbers
> brings up an interesting point. A ratio of 4.11, for instance,
> would be due to N1/N2 = 4.11. Since N1 and N2 must be integers,
> what would be the change in N1 or N2 required to go from a
> ratio of 4.11 to 4.10? It would require one gear set to have
> a ratio of 411/100 and the other to be 410/100. So, how many
> ring gears have 411 teeth? Not many. More like 41/10 or
> something like that. The minumum difference would be 4.10 to 4.20
> (or 4.00).
>
> The numbers are different probably due to different manufacturers
> rounding off ther specs differently.
> --
> Paul Hovnanian | spam to: Chairman Reed Hundt
> hovn...@bcstec.ca.boeing.com | rhu...@fcc.gov
> ------------------------------+-----------------------------------
> "Carpe diem" is NOT the "Fish of the day".
>
here's a table giving a reasonable range of pinion teeth (horiz axis) and
ring teeth (vert axis)...
8 9 10 11 12 13 14 15
30 3.750 3.333 3.000 2.727 2.500 2.308 2.143 2.000
31 3.875 3.444 3.100 2.818 2.583 2.385 2.214 2.067
32 4.000 3.556 3.200 2.909 2.667 2.462 2.286 2.133
33 4.125 3.667 3.300 3.000 2.750 2.538 2.357 2.200
34 4.250 3.778 3.400 3.091 2.833 2.615 2.429 2.267
35 4.375 3.889 3.500 3.182 2.917 2.692 2.500 2.333
36 4.500 4.000 3.600 3.273 3.000 2.769 2.571 2.400
37 4.625 4.111 3.700 3.364 3.083 2.846 2.643 2.467
38 4.750 4.222 3.800 3.455 3.167 2.923 2.714 2.533
39 4.875 4.333 3.900 3.545 3.250 3.000 2.786 2.600
40 5.000 4.444 4.000 3.636 3.333 3.077 2.857 2.667
41 5.125 4.556 4.100 3.727 3.417 3.154 2.929 2.733
42 5.250 4.667 4.200 3.818 3.500 3.231 3.000 2.800
43 5.375 4.778 4.300 3.909 3.583 3.308 3.071 2.867
44 5.500 4.889 4.400 4.000 3.667 3.385 3.143 2.933
45 5.625 5.000 4.500 4.091 3.750 3.462 3.214 3.000
46 5.750 5.111 4.600 4.182 3.833 3.538 3.286 3.067
47 5.875 5.222 4.700 4.273 3.917 3.615 3.357 3.133
48 6.000 5.333 4.800 4.364 4.000 3.692 3.429 3.200
49 6.125 5.444 4.900 4.455 4.083 3.769 3.500 3.267
50 6.250 5.556 5.000 4.545 4.167 3.846 3.571 3.333
so for my 97 Ram 1500 with a Dana 44 front 3.54, i'd guess that the config
is 39:11 (ring to pinion teeth) or 3.54:1 (normalized) and the CC 9 1/4
3.55 most likely occurs from a 32:9 or 3.55:1.
if anybody else out there is a "coder", the table above was produced by the
following code ...
#include <stdio.h>
main()
{
int r, p;
printf("%5s ","");
for(p=8; p<=15; p++)
printf("%5d ",p);
printf("\n");
for(r=30; r<=50; r++)
{
printf("%5d ",r);
for(p=8; p<=15; p++)
printf("%5.3f ",(float)r/p);
printf("\n");
}
}
--
NOSPAM...@ix.netcom.com
97 Ram 1500 SLT CC SB 4x4
Favorite quote "Doh"
wi...@epix.net
In Article<34C64DEB...@bcstec.ca.boeing.com>,
<hovn...@bcstec.ca.boeing.com> writes:
> The point about a gear ratio being the ratio of tooth numbers
> brings up an interesting point. A ratio of 4.11, for instance,
> would be due to N1/N2 = 4.11. Since N1 and N2 must be
>integers,
> what would be the change in N1 or N2 required to go from a
> ratio of 4.11 to 4.10? It would require one gear set to have
> a ratio of 411/100 and the other to be 410/100. So, how many
> ring gears have 411 teeth? Not many. More like 41/10 or
> something like that. The minumum difference would be 4.10 to
4.20
> (or 4.00).
Not quite. 37/9=4.11111. So there is some rounding but not
in the manner you suggested. It appears, once all the smoke
settles, that the RIGHT answer is simply that 41/10 and 37/9
gearsets are close enough.
BTW 40/10, 44/11 and EVEN numbers like that are NOT commonly
used in gears because the same teeth would always meet each
other, increasing the risk that a microscopic defect could grow
into a failure.
Will KD3XR
Gordon McKenzie
The Hepburn wrote:
>
> In article <34C5FE...@genevaonline.com>, Squash <m...@genevaonline.com> writes:
> > 1977 chevy K-20
> >
> > 4.09 front
> > 4.11 rear
> >
> > I think that most 4x4s stock have a little difference.
>
> I hate to say this, but ...
>
> does this mean that there's a differential in the differentials?
>
> Now back to the arguing!
>
Matthew Dilligan
The position of the ring and pinion will have _no_
affect on gear ratio, it is determined by the ratio of the
number of teeth and nothing else. I would bet this whole
debate is the result of someone screwing up rounding off the
last digit of the axle ratio.
Matt
'72 Chevy Blazer
In article <34c85e71....@news.erols.com>,
Sandy A. Nicolaysen <sand...@erols.com> wrote:
>On Tue, 20 Jan 1998 21:22:14 -0500, "Matthew S. Whiting"
><whi...@epix.net> wrote:
>
>>This is good. Where, pray tell, did you come up with this
>>misconception?
>GM shop manual.
>>Absolute horse pucky! I'll admit to having never heard this one
>>before...
>You could be right about horse pucky. They tend to do that a lot.
>I didn't write the manual.
>>
>>Matt
>- Sandy
Grady Fields
[snip]
> Finally, the reason for the taller (lower numerical)
> ratio on a front axle is that it provides directional
> stability on slippery surfaces at speed. This is
> very handy on washboard and gravel roads.
> However, it is not compatible with AWD or the
> currently popular shift on the fly, central disconnect
> axles.
>
> Kirk McGraw
>
>
Hey my 97 Ram 1500 Dana 44 fron is a Center Axle Disconnect and my rear is
a CC 9 1/4 3.55! Might have to retract the bit about "not for CAD"..
Grady Fields
Donald J. Dickson <cx...@freenet.carleton.ca> wrote in article
<34C660...@freenet.carleton.ca>...
here's a table giving a reasonable range of pinion teeth (horiz axis) and
ring teeth (vert axis)...
Now to answer the main question. Different axles produced by different
manufacturers for different applications and constraints. I do not know all
there is to know about design. For example in the above chart, there are
many ways to get the same or nearly the same ratios. For example:
32:8 = 36:9 = 40:10 = 44:11 = 48:12 = 4.00:1
Why as an engineer you'd choose 36:9 vs 48:12 is beyond me. Might have to
do with distributing stresses more evenly with more teeth. Who knows. For
all I know, there are actually pinions out there which dont fall within 8
<= teeth <= 15 and ring gears that dont fall within 30 <= teeth <= 50.
I think the answer to the burning question "Why are front/rear ratios
different?" is probably, two-fold
1. It may be easier to just buy somebody else's axle (e.g. as dodge does
for front axles Dana 44, 60, 80 on 1500, 2500, 3500 Rams). And if their
ration is within some design limit, fine.
2. Yet to be determined is whether or not is is preferable to have the
front axle/wheels travle at a slightly faster rate (e.g. via a slightly
lower numerical ratio like 3.54 on my fron and 3.55 on the rear) since it
"may" help pull the vehicle thru as opposed to equal ratios which "may"
have a tendency for the back end to "walk" around. I cannot prove it, but
I'd suspect that the rear wheels tarvel a shorter distance than the front
wheels in a turn.
John Hascall
Paul Hovnanian <hovn...@bcstec.ca.boeing.com> wrote:
}The point about a gear ratio being the ratio of tooth numbers
}brings up an interesting point. A ratio of 4.11, for instance,
}would be due to N1/N2 = 4.11. Since N1 and N2 must be integers,
}what would be the change in N1 or N2 required to go from a
}ratio of 4.11 to 4.10? It would require one gear set to have
}a ratio of 411/100 and the other to be 410/100. So, how many
}ring gears have 411 teeth? Not many. More like 41/10 or
}something like that. The minumum difference would be 4.10 to 4.20
}(or 4.00).
Not so, you can vary both gears to get closer:
41/10 = 4.10
45/11 = 4.09
for example.
John
--
John Hascall, Software Engr. Shut up, be happy. The conveniences you
ISU Computation Center demanded are now mandatory. -Jello Biafra
mailto:jo...@iastate.edu
http://www.cc.iastate.edu/staff/systems/john/welcome.html <-- the usual crud
Erich Coiner
Paul Hovnanian wrote:
>
> The point about a gear ratio being the ratio of tooth numbers
> brings up an interesting point. A ratio of 4.11, for instance,
> would be due to N1/N2 = 4.11. Since N1 and N2 must be integers,
> what would be the change in N1 or N2 required to go from a
> ratio of 4.11 to 4.10? It would require one gear set to have
> a ratio of 411/100 and the other to be 410/100. So, how many
> ring gears have 411 teeth? Not many. More like 41/10 or
> something like that. The minumum difference would be 4.10 to 4.20
> (or 4.00).
Try 37/9=4.1111
Erich
Matthew S. Whiting
Sandy A. Nicolaysen wrote:
>
> On Tue, 20 Jan 1998 21:22:14 -0500, "Matthew S. Whiting"
> <whi...@epix.net> wrote:
>
> >This is good. Where, pray tell, did you come up with this
> >misconception?
> GM shop manual.
> >Absolute horse pucky! I'll admit to having never heard this one
> >before...
> You could be right about horse pucky. They tend to do that a lot.
> I didn't write the manual.
> >
> >Matt
> - Sandy
What manual? You actually saw something this erroneous in print!?
Matt
Matthew S. Whiting
Sandy A. Nicolaysen wrote:
>
> On Tue, 20 Jan 98 22:42:41 edt, wi...@epix.net wrote:
> >Sorry, but to put it as kindly as I can, you have been fed a
> >line of low-grade baloney. There is absolutely nothing that
> >affects the ratio of a gearset (of any kind) other than the
> >tooth count. What's more, there is a VERY small tolerance on
> >the correct mesh geometry, and changing gear mesh by 1/8 of an
> >inch in a rear end will definitely destroy the gears quickly.
> depending upon how far the pinion gear rides toward the axle. We are
> talking about very small ratio change here e.g. 3.73 -> 3.74.
Sandy, the ratio won't change. Do some research to prove it to yourself
as you seem unwilling to believe the folks here that know.
> >Now if there is a REASON that makes sense to have a different
> >ration front/rear I have not yet read it. I can easily
> >understand why a maker would put a heavier rear end in a rig
> >designed for part-time 4wd (more wear) but a different ratio
> >still doesn't make any sense to me.
> >
> >Will KD3XR
> I don't know the 'official' reason either, but I don't have the time
> to get into a 'peeing contest' with people out there. I have enough
> problems right now with the flames from 'towing in overdrive'. :-)
> No hard feelings. - Sandy
Sandy, there is no official reason because what you are saying is simply
wrong. If you think that people trying to correct a gross misconception
of yours constitutes a "peeing" contest, then I understand why you
refuse to accept this. Simply a case of "don't confuse me with the
facts."
Matt
Nicholas Leiterman
Paul Hovnanian wrote:
---------SNIP-----------
>
> Other than a real bog-monster with a significant ratio difference,
> I think that this may all be a figment of someone's imagination.
>
> rounding off ther specs differently.
> --
> Paul Hovnanian | spam to: Chairman Reed Hundt
> hovn...@bcstec.ca.boeing.com | rhu...@fcc.gov
> ------------------------------+-----------------------------------
> "Carpe diem" is NOT the "Fish of the day".
You can change the tooth count on both gears. for example:
41/10 = 4.10 and 37/9 = 4.11 or 45/11 = 4.09
As for the diameter or the amount of mesh changing the ratio, Its been a
long time since I laughed so hard!
Nick Leiterman
Kent, WA
ni...@gte.net
Matthew S. Whiting
T. Patrick Culp wrote:
>
> I do not know about differentials but If the
> diameter of a gear changes then the ratio will
> change slightly even if the tooth count remains
> the same. I am not sure how the teeth will mesh
> with the same tooth count and a different diameter
> BUT the ratio will change. i.e. a 10 tooth 2"
> gear will turn different by a factor of 2 than a
> 10 tooth 4" gear. So if the gear is conical there
> will be a very slight ratio shift the farther the
> gear shaft is advanced if a different part of the
> conical gear meets the ring. IMHO
>
Let me try an example to try to convince you, and Sandy, that you are
simply incorrect on this. Let's assume we have identical ratios of say
4.00 for the sake of argument. Let us rotate the pinion gear 400
revolutions. Do you agree that the ring gear will rotate 100
revolutions? OK, having established that: Let's assume that moving the
ring gear 1/8" away from the pinion gear changes the ratio to 4.01. Now
let's rotate the pinion 401 times. This should result once again in the
ring gear making 100 revolutions. Right? Now please explain to me how
the pinion gear can now make one additional rotation as compared to the
first case without jumping teeth? Keep in mind that 1/8" of an inch
will still keep the teeth well engaged. This same set of gears simply
can't satisfy the above two conditions.
Matt
Vogt Family
Gordon McKenzie wrote:
>
> Been having a conversation in a rec.outdoors.rv-travel that got onto
> 4wd's. Anyone have a vehicle (or know of specific models) where the gear
> ratios are different? Ie. 4.10's up front and 4.11's in the rear.
> Someone is questioning that these exist and would like specific models
My '61 F-100 has 3.92 gears in front (Dana 44) and 3.89 in back (Ford
9"). This is from the factory.
Birken T. Vogt - KE6DLT
Vogt Family
wi...@epix.net wrote:
> Now if there is a REASON that makes sense to have a different
> ration front/rear I have not yet read it. I can easily
> understand why a maker would put a heavier rear end in a rig
> designed for part-time 4wd (more wear) but a different ratio
> still doesn't make any sense to me.
That is because of there are only certain ratios available for any given
differential make. i.e. Dana make diff in front, Ford make diff in
back.
cheyenne
Differences in front to rear gear ratios on 4x4 vehicles are
negligible and are driven by performance design constraints, not, as
some have suggested (such as the front differential needs to be loaded
[in torque] more than the rear, or visa versa). Rear differentials
are larger and stronger than front differentials for reasons that are
obvious. Thus, front differentials are designed to occupy less space
(smaller size, less weight). So, a front differential could have a 37
tooth ring gear with a 9 tooth pinion gear for a ratio of 4.11 and a
rear differential have a 41 tooth ring gear with a 10 tooth pinion
gear for a ratio of 4.10. In that case, the overall difference
(delta) is of no consequence when the vehicle is driven in 4-wheel
drive in design conditions, ie, conditions where tire-to-contact
surface allow some rotational difference. Notice that the 37 tooth
ring gear in the front can be designed at a smaller diameter (again,
smaller size, less weight).
Another example would be 37/10 front for 3.70 ratio and 41/11 rear for
a 3.73 ratio. Both ratios (3.70 and 3.73) are within design
parameters and would not cause so-called driveline windup (torque
delta) when the vehicle is driven in design conditions.
Still further, 34/10=3.40 ratio and 41/12=3.42 ratio. If you have
paid attention so far, you will notice that the ratios mentioned in
the 3 examples are all Chevrolet/GMC light truck ratios: 4.10 3.73
and 3.42. Also, note the commonality of parts: for the 3 examples (6
differentials), the 34-tooth ring gear is used once, 37-tooth is used
twice, 41-tooth is used 3 times, and the 10-tooth pinion gear is used
3 times. And parts commonality is a design goal at the auto
companies.
Jerry Bransford
Zilbandy wrote:
> >>
> >> >No Jeeps, sez he, were ever shipped with mismatched gears
> >> >other than by mistake.
> >
> >Nope, not at all. For example, the 3.55 rear ratio option for the '97
> >Jeep Wrangler TJ comes with a 3.54 on the front differential. Same with
> >my old Cherokee. My old Blazer and Jimmy's front and rear differentials
> >were off by about the same amount too.
> >
> >Jerry
>
> If the ring gear has 39 teeth, and the pinion has 11 teeth,
> the resulting ratio is 3.545. This might be called either
> one. I don't know what the actual tooth count is, but there
> aren't a lot of combinations that give you a 3.54 / 3.55
> result.
That very well could be, I'm just going by what the ratio tags say on
the diffs. But even in the ring and pinion gear catalogs I have been
pouring through, they also say I have a 3.55 and 3.54 on my two Dana (30
and 35) axles.
Regards,
T. Patrick Culp
Kirk McGraw wrote:
> Well, as a mechanical engineer, I _do_ know
> about differentials. There are power transmission
> devices like Continuously Variable Transmissions
> that behave as you suggest. Gearsets have fixed
> ratios, even planetary gears have only a few fixed
> ratios to choose from.
>
> Tooth count determines the ratio between two
> gears. Period. Moving the pinion gear in or
> out will have no effect on the ratio.
>
> Changing the diameter of the ring gear will change
> tooth pitch (size) which will require a matching
> tooth picth on the pinion, meaning it will have
> a proportional diameter change.
So, what mosy of you are saying is that there is
no such thing as a variable pitch Ring and Pinion
gear? This is very interesting as we use a pair
of them on a wheelchair drive assembly. They are
used to time the right wheel speed with the left
wheel so that the chair will track straight. It
is a conical pinion that, as it is advanced into
the conical ring, changes speed. As you said, the
tooth pitch of the conical pinion does change as
the diameter increases so as to mesh with the
ring, which does not change. The tooth pitch
changes and becomes sharper as the diameter gets
larger. The gear ratio is the same but not the
speed. Again, I say that I am not talking about
automobile differentials but I was explaining what
Sandy was talking about. I am not a mechanical
engineer but that has not hampered the fact that
they have been using these for years. I must say
I have enjoyed all of the proof given that they
are not possible though. Hahaha :)
********** T. Patrick Culp **********
Jerry Bransford
What so many people are not realizing is we're talking about ratios
here, not speed of rotation. There *is* a difference.
If the tooth-count doesn't change, the ratio doesn't change even though
the overall rotational speed will change with larger or smaller
diameters. But again, the RATIO does not change with only diameter
changes, the tooth to tooth numerical ratio must change for there to be
an actual change to the *ratio* itself.
If the pinion gear is turning at 4,110 rpms with a 4.11 differential,
the ring gear will turn at 1000 rpms, no matter WHAT the ring and pinion
gear diameters are. The 4.11 ratio is maintained, no matter what the
gear diameters are.
JErry
Eric
T. Patrick Culp wrote:
>
> T. Patrick Culp wrote:
> >
> > I do not know about differentials but If the
> > diameter of a gear changes then the ratio will
> > change slightly even if the tooth count remains
> > the same. I am not sure how the teeth will mesh
> > with the same tooth count and a different diameter
> > BUT the ratio will change. i.e. a 10 tooth 2"
> > gear will turn different by a factor of 2 than a
> > 10 tooth 4" gear. So if the gear is conical there
> > will be a very slight ratio shift the farther the
> > gear shaft is advanced if a different part of the
> > conical gear meets the ring. IMHO
>
> ratio.
>
>
Try again. These transmisions use a hypoid gear set, which requires an
oil rated for hypoid use. in short, this means that the gears SLIP when
engaged. the only ratio that counts is tooth count.
10 teeth on the pinion and 42 on the ring gear is a 4.20 ratoio. This is
true on a ten inch ring gear or a twenty inch truck part!
Eric
Zilbandy
Jerry Bransford <jer...@junkmailcts.com> wrote:
>Sandy A. Nicolaysen wrote:
>>
>> On Tue, 20 Jan 98 17:14:50 edt, wi...@epix.net wrote:
>>
>> >No Jeeps, sez he, were ever shipped with mismatched gears
>> >other than by mistake.
>> I believe that is 100% correct.
>
>Nope, not at all. For example, the 3.55 rear ratio option for the '97
>Jeep Wrangler TJ comes with a 3.54 on the front differential. Same with
>my old Cherokee. My old Blazer and Jimmy's front and rear differentials
>were off by about the same amount too.
>
>Jerry
If the ring gear has 39 teeth, and the pinion has 11 teeth,
the resulting ratio is 3.545. This might be called either
one. I don't know what the actual tooth count is, but there
aren't a lot of combinations that give you a 3.54 / 3.55
result.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Barry Burnett (Zilbandy) z...@azstarnet.com
Tucson, Arizona USA
The Dead Suburban's Home Page
http://www.azstarnet.com/~zil/suburb/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Zilbandy
Gordon McKenzie <m...@nowhere.com> wrote:
>Been having a conversation in a rec.outdoors.rv-travel that got onto
>4wd's. Anyone have a vehicle (or know of specific models) where the gear
>ratios are different? Ie. 4.10's up front and 4.11's in the rear.
>Someone is questioning that these exist and would like specific models
>etc.
>
I was curious about the numbers, 4.10 vs 4.11, 3.54 vs 3.55,
etc., so I made a little chart in Excel that shows various
ring and pinion combinations and the resulting ratios. If
you know how many teeth are on your ring gear and your
pinion gear, you can look up the ratio on the chart, or if
you know your ratio, you can browse the chart and look for
various combinations of ring and pinion sets that get you
close to your ratio.
If you're interested in looking this over, browse to this
url:
http://www.azstarnet.com/~zil/suburb/rearend.gif
It's a very plain and simple chart, so don't expect a lot. I
don't know what the actual range of ring gear teeth or
pinion gear teeth is. I think this chart will cover most of
the combinations out there. If anyone knows more about the
numbers, let me know and I'll modify my chart. I believe the
Chevy 12 bolt common ratios are 4.10, 3.73, 3.42 which use a
ring gear with 41 teeth and pinions of 10, 11, and 12 teeth.
Zilbandy
Paul Hovnanian <hovn...@bcstec.ca.boeing.com> wrote:
>The point about a gear ratio being the ratio of tooth numbers
>brings up an interesting point. A ratio of 4.11, for instance,
>would be due to N1/N2 = 4.11. Since N1 and N2 must be integers,
>what would be the change in N1 or N2 required to go from a
>ratio of 4.11 to 4.10? It would require one gear set to have
>a ratio of 411/100 and the other to be 410/100. So, how many
>ring gears have 411 teeth? Not many. More like 41/10 or
>something like that. The minumum difference would be 4.10 to 4.20
>(or 4.00).
37/9 gives you a 4.111 ratio. 45/11 would give you a 4.091.
That and 41/10 are about all the practical choices there are
in the 4.1 range. See the chart at
http://www.azstarnet.com/~zil/suburb/rearend.gif
M & R
One tooth more or less will not affect anything the 4X4's are supposed to
do. You are not supposed to use 4wheel drive on dry pavement, so when you
are playing in the dirt do you think that your front and rear will give
sacrifice to slippage. It won't make any difference. The front and rear
will be turning at different speeds. And for the idea of ratio's being
able to change by moving the pinion in or out is ludicris. The amount of
teeth on pinion and ring gear is the only thing that can change ratio.
Moving the pinion in or out may indeed change the speed but not the ratio.
Mark S.
--
"My Opinions"
"Constructive Opinions Boast Character, Negetive Promotes Disillusions"
Will Rosenberry
>
>>
>> If the ring gear has 39 teeth, and the pinion has 11 teeth,
>> the resulting ratio is 3.545. This might be called either
>> one. I don't know what the actual tooth count is, but there
>> aren't a lot of combinations that give you a 3.54 / 3.55
>> result.
>
>That very well could be, I'm just going by what the ratio tags say on
>the diffs. But even in the ring and pinion gear catalogs I have been
>pouring through, they also say I have a 3.55 and 3.54 on my two Dana (30
>and 35) axles.
>
>Regards,
>Jerry
If 11X39 teeth = 3.545 what teeth combo would you need to go up to
.01 in ratio. I don't think that little change is possible
Will Rosenberry
>If 11X39 teeth = 3.545 what teeth combo would you need to go up to
>.01 in ratio. I don't think that little change is possible
I'm sorry, I found the answer on the next post I read. it is
possible.
note: This is the longest thread I have seen on this news group that
stuck to the same subject with out "linching" someone!
Will Rosenberry
wi...@epix.net
In Article<34C6D9FA...@pinnacleweb.com>,
<tpc...@pinnacleweb.com> writes:
> So, what mosy of you are saying is that there is
> no such thing as a variable pitch Ring and Pinion
> gear? This is very interesting as we use a pair
> of them on a wheelchair drive assembly. They are
> used to time the right wheel speed with the left
> wheel so that the chair will track straight. It
> is a conical pinion that, as it is advanced into
> the conical ring, changes speed. As you said, the
> tooth pitch of the conical pinion does change as
> the diameter increases so as to mesh with the
> ring, which does not change. The tooth pitch
> changes and becomes sharper as the diameter gets
> larger. The gear ratio is the same but not the
> speed. Again, I say that I am not talking about
> automobile differentials but I was explaining what
> Sandy was talking about. I am not a mechanical
> engineer but that has not hampered the fact that
> they have been using these for years. I must say
> I have enjoyed all of the proof given that they
> are not possible though. Hahaha :)
Patrick, the system you describe is not a true "gear"
system. I am not familiar with it, but it sounds like a
continuously variable *friction* drive. More details
would be useful.
It is in fact impossible to vary the ratio (speed and gear
ratios are synonymous). There really is no such animal as a
hypoid gear set with a 10/41 tooth ratio producing anything
other than exactly 4.10:1 output.
Will KD3XR
Gordon McKenzie
Same goes for the 4x4 group (snipped from some previous response). Still
wish we had a definitive answer as to why, although I do lean towards
the different differential and gearset opinion.
M & R
Why don't you guy's think of ratios in another method. For exampl: 1 man
2 skinny women. 2 to 1! 1 man to Fat woman. 2 to 1 !!!! The amount of
women did not chage just physical appearance. Changing the size of pinion
or ring gear will not change anything but physical appearance. Also moving
the ring gear closer or farther away from the pinion will result in self
destruction of a match assembly. There is a thing called run in or tooth
pattern. They are lapped at the gear factory for optimum pattern. Also I
agree that most companies don't use there own front axles so the axle
manufacture had to come up with ratio's that would accomodate with the
corporates. also the higher ratio in front was designed to pull the front
end straighter in 4 wheel drive. I know you might not like what I have to
say but people get a f........ grip!!!!!!
John J. Stafford
In article <NEWTNews.88533...@epix.net>, wi...@epix.net wrote:
> Odd indeed. I just got off the phone with a close friend who was
> a mechanic in a Jeep agency for many years, and he too had heard
> rumors that some Suburbans might have had slightly different
> gears front & rear, but thought it was accidental and never saw
> one. No Jeeps, sez he, were ever shipped with mismatched gears
> other than by mistake.
It's been my understanding that the front is _supposed_ to
run a bit faster than the rear wheels (for part-time 4WD)
and it's been the practice for decades.
Tom Christian
> Finally, the reason for the taller (lower numerical)
> ratio on a front axle is that it provides directional
> stability on slippery surfaces at speed.
A Goodyear Wrangler AT LT245/75R16 Load Range E tire, when new, has
an overall diameter of 30.7" (circumference = 96.45") and a tread depth
of 16/32". Simplifying things slightly with ideal rigid tires, one full
revolution of the drive shaft will produce the following travel
distances:
3.54 axle ratio => 27.24" of travel
3.55 axle ratio => 27.17" of travel
A tread wear differential of only 3/32" from new, not uncommon
between front and rear tires because of the increased tire wear caused
by steering, will overshadow the difference between the two axle ratios.
The new diameter is 30.7" - 3/32" = 30.61" (circumference = 96.15"). One
full revolution of the drive shaft now produces the following travel
distances:
3.54 axle ratio => 27.16" of travel
3.55 axle ratio => 27.09" of travel
Back to our hypothetical ratio offset: If the rear differential has
a ratio of 3.55 and the front differential is offset with a ratio of
3.54 to help keep the front end in front, then a tread wear difference
of only 3/32" will reverse the effect of the ratio offset. To tire wear
you can add differences in tire pressure, road irregularities and such.
I suspect that any casual attitude by automobile manufacturers toward
intermix of 3.54/3.55 axle ratios is more because it's inconsequential
than anything else.
Tom
============================
Tom Christian
External Technology Program
Hewlett-Packard Laboratories
3404 East Harmony Road
Fort Collins, CO 80528-9599
E-Mail: t...@fc.hp.com
Phone: (970) 898-3531
FAX: (970) 898-6198
RickStapls
Wi...@epix.net wrote.....
> There is absolutely nothing that
>affects the ratio of a gearset (of any kind) other than the
>tooth count. What's more, there is a VERY small tolerance on
As is so often the case, Will is correct.
Rick Staples,
ASE Certified Master Technician, Certified Master Truck Technician, etc.
Just east of Boulder, just west of reality.
'And it is also said,..Go not to the Elves for counsel, for they will say
both no and yes.' 'Is it indeed?.. Elves seldom give unguarded advice, for
advice is a dangerous gift, even from the wise to the wise, and all courses may
run ill.' - Tolkien
Matthew S. Whiting
cheyenne wrote:
>
> Differences in front to rear gear ratios on 4x4 vehicles are
> negligible and are driven by performance design constraints, not, as
> some have suggested (such as the front differential needs to be loaded
> [in torque] more than the rear, or visa versa). Rear differentials
> are larger and stronger than front differentials for reasons that are
> obvious. Thus, front differentials are designed to occupy less space
> (smaller size, less weight).
Not always. The front axle in my 1994 Chevy K1500 has a 200 lb. greater
GAWR than does the rear axle...
Matt
Stephen Green
Great Debate .. Best ever!
Ok, from the posts we have now established that ratios are determined from
the number of teeth on a wheel, we have also determined that there are in
fact some vehicles which may have different ratio's front to rear, We all
know that when turning a most 4x4 vehicles in a circle, some resistance
front to rear occurs. We also know that some vehicles, notably jeeps have a
lesser problem than the others.
My question: What ratio's should one have in the front and in the rear.
Waht is the difference between partial full time 4x4 vs full time 4x4 vs AWD
in the drive trains realative to axle ratios?
--
==================================
Stephen D. Green
North Saanich, British Columbia, CANADA
sdg...@msn.com
EMAIL: sdg...@msn.com
================================
RickStapls wrote in message
<19980122223...@ladder02.news.aol.com>...
-Brad D-
Dodge has been putting different gears up front then on back for years. I
was talking with a local Ford dealer about changing my gears on my
F250HDCrewCab 4WD and he mentioned that Ford, although lists the ratios the
same they can be off by a tenth of point due to machining difference, axle
diameters etc. So maybe Dodge is just being a bit more honest.
-Brad D-
Gordon McKenzie <m...@nowhere.com> wrote in article
<34C4E8...@direct.ca>...
> Been having a conversation in a rec.outdoors.rv-travel that got onto
> 4wd's. Anyone have a vehicle (or know of specific models) where the gear
> ratios are different? Ie. 4.10's up front and 4.11's in the rear.
> Someone is questioning that these exist and would like specific models
> etc.
>
> Thanks
Will Rosenberry
On Thu, 22 Jan 1998 15:22:38 -0700, Tom Christian <t...@fc.hp.com>
wrote:
I checked with Mr. Goodwrench last night and he says GM has been doing
this .01 difference for years and still does. The higher numerical
ratio goes in the rear which allows the front to turn faster thus
allowing traction to steer.
Will Rosenberry
wi...@epix.net
In Article<01bd27b4$1171a920$LocalHost@bwd200>,
<bra...@aracnet.com> writes
> Dodge has been putting different gears up front then on back
>for years. I was talking with a local Ford dealer about
>changing my gears on my F250HDCrewCab 4WD and he mentioned that
>Ford, although lists the ratios the same they can be off by a
>tenth of point due to machining difference, axle diameters etc.
Brad, Brad, Brad -- the idiot that told you that stuff is the
kind of practical joker that sends a kid after a left-handed
crescent wrench or a bucket of compressed air - and then guffaws
for the benefit of onlookers.
Machining differences and axle diameters do NOT affect gear
ratios. ONLY the tooth count determines the ratio. It is
forever fixed until the teeth fall off.
Will KD3XR
Jerry Bransford
Will is 100% correct.
Erich Coiner
Stephen Green wrote:
>
> Great Debate .. Best ever!
>
> Ok, from the posts we have now established that ratios are determined from
> the number of teeth on a wheel, we have also determined that there are in
> fact some vehicles which may have different ratio's front to rear, We all
> know that when turning a most 4x4 vehicles in a circle, some resistance
> front to rear occurs. We also know that some vehicles, notably jeeps have a
> lesser problem than the others.
>
> My question: What ratio's should one have in the front and in the rear.
> Waht is the difference between partial full time 4x4 vs full time 4x4 vs AWD
> in the drive trains realative to axle ratios?
>
> --
> ==================================
> Stephen D. Green
The same.
Full time 4wd has a differential in the transfer case so the drive train
does not bind up on high traction surfaces (read paved roads).
AWD is full time 4WD. It is a marketing name designed not to scare
people away from buying it on minivans and station wagons.
As Tom Christian noted, small variations in the exact tire diameter are
as large or larger of an effect than the difference in differential
ratios noted.
The bottom line is this: A part time 4wd with no center differential is
meant to be used in poor traction conditions only. When the traction is
poor the wheels can slip and scrub and it does not have a noticable
effect on steering control or driveline longevity. It doesn't take much,
all you need is a dirt road instead of concrete or asphalt.
Erich remove NOSPAM to reply
Gordon McKenzie
Erich Coiner wrote:
>
>
> The same.
> Full time 4wd has a differential in the transfer case so the drive train
> does not bind up on high traction surfaces (read paved roads).
> AWD is full time 4WD. It is a marketing name designed not to scare
> people away from buying it on minivans and station wagons.
Most makers seem to differentiate full-time 4wd as having a transfer
case with a differential and AWD being a more sophisticated system with
traction sensing, automatically put power to non-slipping wheels etc.
Most AWD don't have low range while most full-time 4wd do. Think of the
difference between an Olds Bravada (AWD) and a Jeep Quadratrac
(full-time 4wd).
Squash
ok- i think that i have figured it out, too.
My truck has a 10.5" ring gear in the rear, 8.5" in the front. The
number of teeth used to make the ratio on the front axle would be
smaller than the number of teeth on the rear (both pinion and ring).
And since they are different diameters, the ratio of ring:pinion can
remain the same (as the front) with a greater number of teeth. So a 1
or 2 tooth difference in the rear will make the difference. Most
trucks, new and old, have a different size ring and pinion gear for the
front an rear. I think that the old dodges that had dana 60s front and
rear had identical gear-ratios.
--
Andy Quaas
Erich Coiner
Not necessarily, The 10 inch gear may have the same number of teeth as
the 8.5 inch they would just be BIGGER Teeth.
Erich
Grady Fields
OK, so It's well establish that different ratios can occur on front/rear.
Now for the next question. Does anybody have knowledge of a setup in which
the front axle is numerically higher than the rear axle (e.g. a 4.10 front
and a 4.09 rear)? The question applies to factory equipped vehicles only.
Don't wanna hear about somebody doing it just for fun.
All I've seen so far is equal ratios or lower ratios in the front than in
the rear.
Gordon McKenzie <m...@nowhere.com> wrote in article
<34C4E8...@direct.ca>...
> Been having a conversation in a rec.outdoors.rv-travel that got onto
> 4wd's. Anyone have a vehicle (or know of specific models) where the gear
> ratios are different? Ie. 4.10's up front and 4.11's in the rear.
> Someone is questioning that these exist and would like specific models
> etc.
>
> Thanks
Jerry Bransford
Stephen Shoihet wrote:
>
> wi...@epix.net wrote:
>
> >Brad, Brad, Brad -- the idiot that told you that stuff is the
> >kind of practical joker that sends a kid after a left-handed
> >crescent wrench or a bucket of compressed air - and then guffaws
> >for the benefit of onlookers.
>
Pilots and Air Force types love to send their wet-behind-the-ears types
off for these non-existant items.... ten feet of flightline or a gallon
bucket of prop-wash <g>!
Vogt Family
Grady Fields wrote:
>
> OK, so It's well establish that different ratios can occur on front/rear.
>
> Now for the next question. Does anybody have knowledge of a setup in which
> the front axle is numerically higher than the rear axle (e.g. a 4.10 front
> and a 4.09 rear)? The question applies to factory equipped vehicles only.
> Don't wanna hear about somebody doing it just for fun.
>
> All I've seen so far is equal ratios or lower ratios in the front than in
> the rear.
Yes, that would be me. I own a '61 Ford F-100 (not exactly cutting edge
technology) with a 3.92 open Dana 44 up front and a 3.89 limited slip
Ford 9" in back. This is factory. It handles just fine. I still
maintain that it is due to the availability of manufacturers ratios.
3.89 is not listed as a ratio available for the Dana 44. In addition,
may I re-state the assertion that tire pressures may make more of a gear
ratio difference than this, and certainly turning radius.
Birken T. Vogt - KE6DLT
Carl Byrns
Grady Fields wrote:
>
> Now for the next question. Does anybody have knowledge of a setup in which
> the front axle is numerically higher than the rear axle (e.g. a 4.10 front
> and a 4.09 rear)? The question applies to factory equipped vehicles only.
PMFJI-
Assuming a part time transfer case, such a setup would produce a vehicle
that could not be controlled in 4wd, because the rear axle would tend
push the rear end around. That's why the front axle runs at same speed
or a little faster- to pull the front end (positive steering).
Stephen Shoihet
wi...@epix.net wrote:
>Brad, Brad, Brad -- the idiot that told you that stuff is the
>kind of practical joker that sends a kid after a left-handed
>crescent wrench or a bucket of compressed air - and then guffaws
>for the benefit of onlookers.
We sent a new prep guy to the store for a gallon of striped paint :-)
-Steve
Kelowna, B.C., Canada
Squash
Big Jim wrote:
> In case you didn't catch one of my other posts, one of my old dodges
> ("63 PowerWagon) had Dana 44s front and rear - 4.09 front and 4.10
> rear.
In case you missed my line of thinking, you CAN'T have a .01 gear ratio
difference with the same diameter ring gear! If you can, explain to me
how.
--
Andy Quaas
Bill A
Big Jim wrote:
> >front an rear. I think that the old dodges that had dana 60s front and
> >rear had identical gear-ratios.
>
> In case you didn't catch one of my other posts, one of my old dodges
> ("63 PowerWagon) had Dana 44s front and rear - 4.09 front and 4.10
> rear.
My 95 Dodge has Dana 60s front and rear- and its 4.09, 4.10. Maybe the
reverse cut front gears have different # of teeth?
I wish this thread came up a couple weeks back when I had the covers off
for the gear oil change-I suspect the different ratios are just a matter
of how many teeth fit in how much space.
Bill
Squash
i agree. The new dodges really have a reverse dana 60 in front? Wow
that is really cool. I am a chevy nut, but the new dodges have the best
drivetrain you can get!
--
Andy Quaas
wi...@epix.net
In Article<34CDEB...@genevaonline.com>,
<m...@genevaonline.com> writes:
> In case you missed my line of thinking, you CAN'T have a .01
>gear ratio difference with the same diameter ring gear! If you
>can, explain to me how.
Since tooth counts are not directly affected by diameters, you
can have 37/9 and a 41/10 gearsets with the same nominal ring
gear diameter and a ratio difference of .01. (4.11 vs 4.10)
Will KD3XR
Will Rosenberry
My friend who rebuilds rears for a business says they just add 1 tooth
to the pinion and remove one from the ring. The difference is .01
Will Rosenberry
Jerry Bransford
Absolutely correct. The diameter itself has *nothing* to do with a gear
ratio, it's *entirely* dependent on the number of teeth on each gear.