my 89 truck with SAS has a problem with the front axle. ill put it in 4 and ill be able to move but when i let off the gas its like im putting on the brakes and the truck comes to a complete stop.. but in 2 its fine..,

I'm thinking because my axle seal leaks where it the wheels turn on the axle. IS it possible for all the axle fluid to leak out and my axle gears be running dry? causing my truck to come to a stop?'

yes the gear ratio is the same in the front and rear.

 

i would check the front drive shaft, jack up th front, lock the hubs and spin the tires, if it stopping the truck its going to have to be obvious.

axle gears???????

 

He OBVIOUSLY means the ring and pinion gears....





Fred

 

Is it not making any noise? Is it doing it in 2wd also? Is it doing in 4 with the hubs unlocked?

 

no noise except for i can hear the drive shaft in the front spinning but its spinning smoothly. its always made noise cause its a custom square drive shaft.

ok so i test drove it. and this is how it went:

2wd/hubs unlocked = OK
2wd/hubs locked = OK
4wd/hubs unlocked = OK after i unlocked them from being locked, and after i drive about 5 feet.
4wd/hubs locked = problem

and could it be my transfer case? because once i put it in 4H or 4L its a sob to get it back into 2wd. the only way for me to get it back in 2wd is if i unlock my hubs and then drive about 5 feet, then i can get it back into 2wd.

 

If it does fine in 4wd with the hubs locked, it ain't the transfer case - the case is spinning whether the hubs are locked or not.

Does it CLUNK when you drop it from 4wd to 2wd?

It's been working fine before this?

How do you know the gear ratios are the same?

If you're worried about running dry of gear oil, have you checked the level? If so, is it good?

 

its like i cant even force it into 2wd after i put it in 4wd. its like i have to unlock the hubs and drive to free the gears, to put it in 2wd.

yea its been working fine until recently. and the only thing ive done since i wheeled it last is replace the clutch but i doubt the clutch has anything to do with any of this.

they are both stock axle, never been opened. both are 4:10s.

i havent checked the fluid yet cause i dont have the right size socket.

 

okay, I'm going out on a limb, do you have the custom square tube front driveshaft... are the ujoint's on the shaft timed properly?

 

timed properly??? what does that mean?

the front drive shaft is fine. its been on the truck since ive owned it and ive never had a problem with it.

 

well, if you haven't had a problem with it til now, it's probably timed right. but basically, if you were to let the truck sit exactly as it is now, you should be able to undo the u-joint cross, leaving the u-joint X on the axle and transfer case, and spin the drive shaft around 180 degrees and be able to bolt it back up without moving the axle/pinion or transfer case output shafts.
Don't know if that makes sense, but at the moment, that's the quickest way I can describe it.
If the u-joints aren't timed properly, you will bind the joints.

 

jack up the wheels and see if its hard to spin the wheels by hand locked, unlocked, and each wheel individually. basically to check the wheel hubs (bearings)

 

Go buy the socket you need. Its like 2 dollars at the autoparts store...

 

Very strange, it's not the driveshaft if you have no issues with the hubs locked. If it was the driveshaft, it would bind as soon as it tried to turn, whether being driven by the hubs or t-case so you would still have a problem even if it wasn't in 4wd with the hubs locked or in 4wd with the hubs unlocked. I'm assuming that the front diff is open and you are testing in a straight line on level ground. You can eliminate front wheel bearings and brakes if it coasts fine in neutral and the hubs are unlocked. The only thing that it can be is something binding when everything is locked together. If it were anything solely in the front axle assembly, you would have issues with the hubs unlocked and in 4wd as the driveshaft would be turning the ring and pinion the same speed as the rear. So this leaves only 2 possibilities the way I see it... either your diffs are in fact 2 different gear ratios and you just didn't notice it before, or you have different diameter tires between the front and rear of the truck. Perhaps you have one tire that is low or something easy to overlook??? Maybe somebody swapped one of your diffs while you weren't looking???? Stranger things have happened. One last check you could do to completely eliminate the front end would be to only lock one hub at a time and test it again. Jack up the front and lock one side at a time, spin the wheel on that side and check for free movement of the driveshaft or unusual noises. The opposite wheel should not turn, obviously. If it does, then you have a problem with one of the hubs. Hope this gives a bit more insight...

 

are you absilutely sure the gear ratio is right?? Have you pulled the front diff to see if everything is where is should be up their?

 

x2...start with the obvious things first

 

tires are all the same size, and the gears are all the same. the axles are 100% stock. ive been wheeling plenty of times and never had a problem till now.

ill check the fluid today.. anybody know what size socket it is for the diff bolt?

 

27 mm...it should be one of the first tools to buy for a yota

 

Should be 24mm on the drain and fill bolts for the front diff, unless you have the socket head bolts, then 10mm allen key. Where are you doing the 4WD/locked hubs test? I.e. what sort of surface? If you are on a high traction surface, it sounds like normal part time 4WD driveline binding.

 

sorry yea i meant 24.....typo

 

Aint it 24 mm?Mine are.