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Discussion Starter · #1 ·
This is a new trooper for me, so I haven't really taken it anywhere yet. When shifting into 4 (hi or low) it will roll a few feet and then start to bind--feels almost like a spring is winding up. I have manual hubs, and with EITHER the hubs locked OR the transmission in 4h/l it is smooth. ONLY with both engaged, ie load placed on system, is it noticeable. I had in on a lift, all wheels off the ground and engaged, and there was no apparent binding then either.
On the ground it will keep binding, when shifted to 2h, until I back up...

It acted the same before I put the manual hubs on...

Differential, transfer case, or transmission? I don't see how it could be the hubs or wheel bearings. I could stretch my brain to CV joints that only bind with real load--maybe I'll go lock one side at a time.

None of these parts are just really fun to replace, so I'd like to do just one and not just fish around. Any ideas?
 

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If you are turning any at all on a hard surface binding is normal. If your front and rear tires aren't the same diameter or the differentials aren't the same ratio also normal, straight or turned. Odd size tires or different gears won't bind with the wheels in the air.
 

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yea ether your turning on pavment in 4WD, have diffrent tire sizes, or some one swaped one of your diffs.

in high gear at 60 mph what is your RPMs?

for comparison i have the same auto, 86 T\D trooper.
with, 31" tires and the very common 4.55 gears 14.5% O\D = 2,600 rpms at 60.
with 235/75/15 tires it goes to about 2,750 rpms at 60 with the 4.55 gears.
http://www.rocky-road.com/calculator.html
one exsampal
if you have 31" tires and are turning about 2,300~ rpms at 60mph in high gear, you have a 4.11 rear diff.

the only gears that fit your auto "that are in the USA and where made in matched pars" are 4.11s and 4.55s there are also 3.42s and 3.73s that will fit your rear diff out of 1981/1987 2WD isuzu pups. "but (none) of these gears will fit the frunt 4WD diff"

one other possabilety thats VERY OUT OF THE ORDANARY
is diesel troopers in 87 have 4.11 stock "there very rare, only 200~ of them" no other trops got them in the USA. thus some one could have assumed it had 4.55s and put a 4.55 in it :roll:
 

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Discussion Starter · #4 ·
Thanks, guys.

Going straight on pavement should not give noticeable binding (if everything works right). I'm talking about dragging to a full stop in half a block on pavement, and almost as bad on dirt. Going straight. This is my fourth Trooper, and I've driven a bunch of similar other ROW 4WDs--Cruisers, Nissan Patrols, Samys/Sidekick varieties, I know this is way outside the normal tight&slip of driving on pavement.

Engaging either hub alone (3wd?) does nothing noticeable. Only bloth together, so I'm thinking front differential.

HOWEVER, went and looked at POS tires the PO left on--the front tires are at least matching brand 235/70R15s, but back has unmatched 235/75R15s (and the spare is yet different). Would that almost one inch make that much difference? Well, it needs new tires anyway...
(MATH: using tire calculator for diameter
27.95275590551181 v.
28.87795275590551)

BTW, I don't think its turning as low as 2300 at 60, have to get on the freeway to check later).
 

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Discussion Starter · #5 ·
Without tearing it open, how to check gears? Jack it up and turn the drive shaft while measuring wheel rotation?
 

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That's 3" difference in circumference, 12 revolutions is three feet farther that the tread of the larger tire has traveled than the smaller. And different tire brands are not necessarily the same size even if labelled the same, and wear reduces the diameter, so a badly worn smaller tire and a near new larger one could be even more different in diameter.
Check for different gearing first like this: Jack up one side, tires off the ground, other two on the ground, lock both hubs, t-case in 4h, tranny in neutral. Mark each tire tread at the same place, say straight down towards the ground. Now turn one wheel with your hands one revolution. If both diffy's have the same gearing the marks will both return to the same place with each revolution no matter what the tire size is. If different gears they won't & the more revolutions the more obvious the difference will be, since one wheel will turn faster than the other.
I'm betting the gears are fine, you need a matching set of tires.
 
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