Front end problem. Whats your diagnosis?

[Tim Smith]

Been driving around in front wheel drive for a few days now while I'm waiting for the new U-joints on the rear shaft to arrive. As things are, the rear drive shaft is out and I've been driving in four wheel high.

For background, normally I get around in two wheel high with the front hubs unlocked. I have noticed a problem with four wheel in the past where it feels like the front diff is not at the same gear ratio as the rear. Never really was sure what the problem was but I think I've just gotten a little closer to figuring it out. ;)

A couple of things I've noticed while in FWD:


If I accelerate in a turn, the steering pulls from left to right as if it were releasing the build up in different wheel speeds. I liken this to turning on tarmac when in four wheel.
Driving along at around 45, every once in a while there is a skip and the truck sort of feels like it just missed a tooth in the gear. This doesn't happen reliably such that you can time it or anticipate it.
I turned the wheel to full lock in a gravel driveway to test the front diff. If I do not accelerate then the steering wheel doesn't pull much at all like it does in the first bullet but if you give it any throttle, the truck starts bucking and hopping about uncontrollably.
I accelerated from one stop sign and in the middle of the intersection (just at my shift point from 1st into 2nd) I went through a divot/hole in the road. Again the truck started bucking and bouncing. It was almost uncontrollable until I let off the throttle. As if the power to the wheels was feeding the reaction.

My guess is the spider gears in the front diff have ceased. Whats your guess?

[KevinNY]

It does sort of sound like the front diff is acting like a locker.

[Andrew IIA]

It does sort of sound like the front diff is acting like a locker.
That's my read on it too. Add more pixie dust to the diff.
A

[LaneRover]

Have you tried to hit the gas on gravel or dirt to see if you get both wheels spinning? (with the wheels straight ahead)

Brent

[KevinNY]

Tim, if you just jack up a front wheel and give it a spin it should give you your answer, with one wheel off the ground you should be able to turn that wheel and see the front prop shaft turn. If it won't spin jack the entire front end in the air and see if both front wheels only turn in unison and the same direction to confirm that the diff is Gefuct!

[scott]

get the front up on blocks, get the wheels running shift to 3rd and let it idle (this way if it falls off the blocks it should just stalh).

what are the wheels doing? what happens to the one when you put your boot (foot cover not trunk lid) against the other and stop it?

[Tim Smith]

Okay, so I jacked up one wheel and gave it a turn. As expected the drive shaft turned and there didn't seem to be any skips like a busted spider gear might show. Did the same on the other wheel with the same results. There does seem to be a bit extra play between turning either wheel and the prop-shaft engaging but not knowing what that should be, I'm just guessing.

Then I jacked up the front and put it in 3rd as suggested. With the motor idling along, I was able to put my foot on one wheel and it came to a nice smooth stop while the other side sped up. Same thing on the other side.

This test looked good until I put the steering in full lock while the wheels were spinning. Every once in a while you could hear something jam up and release. Same thing if you turn left or right to full lock.

Now I'm thinking it's a bad U-joint in one of the steering knuckles. Does that sound about right?

[scott]

yep bad u-joint

[Tim Smith]

I almost wish it was the diff. :(

Do I have to pull the whole steering swivel to get at the front u-joints? Is there a way to get at them without pulling the whole joint like through the hubs?

[scott]

go here

http://www.landrovernet.com/forum/showthread.php?t=34539

looks like you can pull half shafts with swivel ball inplace

[Tim Smith]

Superb link Scott!

I guess this means I'll probably get around to fixing those leaky swivels too *since I'm in there*. ;)