NP203 Transfer Case Help
sbest
><SNIP> I am having problems with my
>NP203 transfer case (clunking, rattling) and would like some advice from
>someone with experience. The transfer case demonstrates the classic
>"clunk" while moving from foward to reverse or reverse to foward.
>However, there is also a dull, clunk-clunk as the truck drives along under
>power. It is most noticeable from a dead stop as the truck accerlates to
>cruising speed. The clunk-clunk increases in frequency with speed. Also,
>the clunk-clunk is very noticeable as the truck coasts to a stop.
>Furthermore, the transfer case whines and emits a "spinning", "grinding"
>sound under full throttle, either at speed or from a stop.
Hmmm, hard to diagnose from here but it sounds worse than the typical
wornout chain. To check the chain, put the front wheels up against an
obstacle (big log etc) and try to climb it in low range. If it makes a
loud "CLUNK-CLUNK-CLUNK" noise the chain is jumping over the sprocket
teeth. It it is a thumping or grinding noise that increases with road
speed, it is likely driveshaft ("U"joints) or bearing noises.
Isolate whether it is driveshaft or t-case. If it is t-case, get a
manual and delve into it. Except for the weight, this is a very easy and
cheap t-case to work on. A new chain is about $100 and you can use
silicone RTV for gaskets. As you take it apart there is one way that the
bearing rollers stay in and there is one way the rollers all fall out.
Study this part carefully and it is a 2 hr job to replace a chain.
>Do you have any experience with these symptoms? I suspect a loose chain
>or differential unit going bad. I would like to know if I should pursue a
>rebuild or find a new (or at least used) transfer case.
This case is easily home rebuildable and all the bearings and seals are
available at the dealers or slightly cheaper at an industrial bearing
supply house. You can pick up another NP203 for about $50 and they rarely
wear anything but the chain, so don't spend too much on internal parts if
your diff or sprockets are chewed up (which is rare).
>Where can I obtain parts for the best price? I would like to convert to
>part-time if possible.
What! Part-time kit? Heresy!
Since you likely have the "big nut" front hubs I don't think you can get
freewheeling hubs, so it really would be a waste to put a part-time kit
(from Milemarker) in it. Use either synthetic gear oil or even better 0w50
synthetic motor oil (10w30 was factory recommended) to make her run smooth
and drag free. Some synthetic gear lube in both diffs and she'll roll as
free as anything.
>Jeff Webster
>1979 Dodge Power Wagon 150
>360, A727
Mine was a 78, 360, 4speed NP435. My brother-in-law blew my 360 up so I
dropped a 4bbl 360 from a Caravel police car. Best thing I ever did.
Better fuel mileage and great gobs of power. Most of the "poor
fuelmileage" rumours came from those sucky stock motors I am sure!
I really liked that truck.
Steve Best, Nova Scotia, Canada
4x4 van website:
http://www.glinx.com/users/sbest
Sign up for the 4x4van newslist:
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sbest
>Hello Steve,
>
>Nice to see a fan of the NP203. I love mine and would never consider going
>part-time. I love full time in winter when the our roads can be
>intermittently bare concrete or solid ice. I guess this is the result of the
>plows sometimes going down to concrete and at other times riding on top of
>an inch of black ice.
Hear, hear! I love the fulltime for the same reason. With 5 months that
could possibly have snow and ice on the highway this is the ultimate
all-weather intercepter. Total traction, all the time.
>A couple of questions for you.
>
>The previous owner told me he had installed a chain saver in my 203 yet when
>I rotate the yoke at the front driveshaft I feel some free play. Did he bs
>me about the chain saver or is this still possible with it installed?
Hmmm, I have actually never seen one of those chainsavers (friction
tensioner strip) except for advertizements back in the 80s. I have found
that trying to feel backlash is not a very reliable indicator of chain
wear in these gearboxes. There are a bunch of spline connections and the
chain itself is more prone to stretch than slack, as the oil around each
pin kind of takes up the slack until real torque is put on it.
The theory on the chainsaver (correct me if I am wrong) is to eliminate
slack and chain "slap".
>I use synth in mine but was wondering how often I should change the fluid?
Once every couple of years is probably plenty.
It gets no contaminates other than water so long life is the rule.
Mine got changed if I dunked it but never otherwise. The oil in my van
NP203 is 4 years old and is just getting changed because I am installing a
new chain this year.
>O.K. one bonus question. I usually change from HIGH to LOW or vice versa
>while in neutral with a bit of a roll. Is this the best way or is there a
>better method?
That is pretty much the way I do it, but also with every variation
thereof. I have to be careful with the automatic transmission. If it is in
gear (DRIVE or REVERSE) it can easily overspeed the NP203 input shaft so
it won't engage, just grind. My shifter is greased up so it shifts well.
The van's t-case will usually shift at a stop in PARK, while rolling in
gear if the road and engine speed are close or rolling in neutral. It will
also shift to high when rev'ed out in low if you match the road speed. It
takes a little skill to avoid grinding but it works.
Of course it pops in and out of LOCK in its respective range anytime.
I am no real expert in these T-cases Jorg, I just like them a lot.
I first discovered them in army truck I had to drive. My old Dodge was
more akin to a sportscar with its ample power, this present Ford van is
more akin to a sure footed mountain goat. Either way, I like the NP203.
My present van has locking hubs and a few years ago I did some trial
runs with the hubs unlocked and the front driveshaft off. I saw a
negligable, almost imperceptable improvement in fuel mileage. Certainly
not worth installing a part-time kit or removing the front driveshaft on
long trips.
Jeff Webster
at least point me in the right direction). I am having problems with my
NP203 transfer case (clunking, rattling) and would like some advice from
someone with experience. The transfer case demonstrates the classic
"clunk" while moving from foward to reverse or reverse to foward.
However, there is also a dull, clunk-clunk as the truck drives along under
power. It is most noticeable from a dead stop as the truck accerlates to
cruising speed. The clunk-clunk increases in frequency with speed. Also,
the clunk-clunk is very noticeable as the truck coasts to a stop.
Furthermore, the transfer case whines and emits a "spinning", "grinding"
sound under full throttle, either at speed or from a stop.
Do you have any experience with these symptoms? I suspect a loose chain
or differential unit going bad. I would like to know if I should pursue a
rebuild or find a new (or at least used) transfer case.
Where can I obtain parts for the best price? I would like to convert to
part-time if possible.
Thanks for the help,
Rob Owens
ujoint (on the axle, not the driveshaft).
if it is the t-case, steve best may be able to help you. he knows a
lot about the np203 and is on this newsgroup once in a while.
-rob
In article <Pine.OSF.4.21.00100...@wpi.WPI.EDU>,
Sent via Deja.com http://www.deja.com/
Before you buy.
me here
bearings replaced this weekend so i may ask them to look at those
then....
me
On Tue, 03 Oct 2000 16:55:27 GMT, Rob Owens <hic...@my-deja.com>
wrote:
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sbest
>>It will
>> also shift to high when rev'ed out in low if you match the road speed. It
>> takes a little skill to avoid grinding but it works.
>
>Hmm, haven't had the guts to try that yet. A friend used to run one behind
>a mild BBC in a Blazer and did this for fun to annoy all the performance
>car drivers out there. This guy was nuts and if it survived his idea of fun
>then its tough enough for me.
Yup! That's the trick. A good working 360 with fulltime 4WD traction and
low range will TOAST most performance cars in a short dragrace.
I would run through the gears in low range then shift to 3rd/Hi and do 3rd
and 4th on the HIGH side. The acceleration from stop is neck snapping and
yet the torque is spit between front and back axles. I did break things,
but not the NP203. Sounds like your friend and I have shared maturity
phases at one time or another?
With my big diesel/auto van the acceleration is lethargic at the best of
times, but if you are loaded up for camping and start dragging a 21'
travel trailer behind you there is a total weight of over 7 tons to move
with only 165hp. Getting up steep hills in towns and pulling out into
traffic is a nightmare. I drop it in lowrange to master these situations.
The shifts are a little harsh with the auto-trans in lowrange (I'd never
consider a shift kit) but it takes me to 30mph with ease, I back of the
throttle and with a gentle pressure feel the transfercase shifter into
HIGH range. Sometimes a little grunt from the gears if I don't get it
perfect but you get good at it after a while.
These are a sophisticated and versatile transfercase.
I feel limited when driving a part-time unit.
>> Of course it pops in and out of LOCK in its respective range anytime.
>
>Haven't noticed this myself. Lucky I guess.
No, what I meant is that you can jump into or out of "LOCK" anytime you
wish, at 70mph or a crawl, with ease. Some of the NP203s will jump out of
"LOCK" by themselves if the shifter is not adjusted properly or worn, but
this is not hard to cure.
>> My present van has locking hubs and a few years ago I did some trial
>> runs with the hubs unlocked and the front driveshaft off. I saw a
>> negligable, almost imperceptable improvement in fuel mileage. Certainly
>> not worth installing a part-time kit or removing the front driveshaft on
>> long trips.
>
> Ah, I thought of giving that a try on a trans-continental type trip. Guess
>it's not worth the bother though my driveshaft is real easy to get to.
That was the reason I was going to do it. I was heading to Florida in
the spring. By my figures at the time I would save $50 worth of diesel.
Not worth the chance of getting stuck in a sudden snowstorm or stuck if I
had to cross a muddy median to avoid and accident on the Interstate.
>One more question. Is the NP203 available in aluminum?
>
> Jorg
No, and more is the pity. That would probably take 100 lbs off of its
rather hefty weight. Cast iron does not make up for a good skid plate but
it will take far more abuse than aluminum. If you have to carry extra
weight, your lowest center point is not a bad spot to have it.
Jorg
sbest <sb...@TAKEOUTglinx.com> wrote in message
news:39d8b511....@news.glinx.com...
> On Tue, 3 Oct 2000 10:55:08 -0400, Jeff Webster <jweb...@wpi.edu> wrote:
Hello Steve,
Nice to see a fan of the NP203. I love mine and would never consider going
part-time. I love full time in winter when the our roads can be
intermittently bare concrete or solid ice. I guess this is the result of the
plows sometimes going down to concrete and at other times riding on top of
an inch of black ice.
A couple of questions for you.
The previous owner told me he had installed a chain saver in my 203 yet when
I rotate the yoke at the front driveshaft I feel some free play. Did he bs
me about the chain saver or is this still possible with it installed?
I use synth in mine but was wondering how often I should change the fluid?
O.K. one bonus question. I usually change from HIGH to LOW or vice versa
while in neutral with a bit of a roll. Is this the best way or is there a
better method?
Thanks
Jorg
Jorg
sbest <sb...@TAKEOUTglinx.com> wrote in message
> On Wed, 4 Oct 2000 09:21:34 -0500, "Jorg" <ye...@your.uncle.com> wrote:
>
> The theory on the chainsaver (correct me if I am wrong) is to eliminate
> slack and chain "slap".
Chain slap I believe, something like a chain tensioner on a bikes cam
chain.
Oh well, it works ok so its probably best to let sleeping dogs lie.
>It will
> also shift to high when rev'ed out in low if you match the road speed. It
> takes a little skill to avoid grinding but it works.
Hmm, haven't had the guts to try that yet. A friend used to run one behind
a mild BBC in a Blazer and did this for fun to annoy all the performance
car drivers out there. This guy was nuts and if it survived his idea of fun
then its tough enough for me.
> Of course it pops in and out of LOCK in its respective range anytime.
Haven't noticed this myself. Lucky I guess.
> My present van has locking hubs and a few years ago I did some trial
> runs with the hubs unlocked and the front driveshaft off. I saw a
> negligable, almost imperceptable improvement in fuel mileage. Certainly
> not worth installing a part-time kit or removing the front driveshaft on
> long trips.
Ah, I thought of giving that a try on a trans-continental type trip. Guess
it's not worth the bother though my driveshaft is real easy to get to.
One more question. Is the NP203 available in aluminum?
Jorg