Drivetrain binding -- IN AWD

[Gizmo McGee]

Just had an adventure out in George Washington National Forest, but now I'm having an issue.

TL;DR, the truck doesnt want to turn when in AWD.

Truck is a 2002 Limited -- very mildly lifted (1" Moog '99 springs in the front, 2" of OME springs in the back) but otherwise bone stock.

Took the family camping out on Meadow Knob in Virginia at the beginning of the month, and exploded my passenger-side CV axle trying to get up over a rock ledge on the way to Flagpole Knob in 4L with the center diff locked (I bit off a bit more than I could chew).

Got the truck back down the mountain in 2WD, and the only part I could find on a holiday weekend was a Duralast Gold (autozone house brand) CV axle.

Didn't have the tools on me to do the job myself, so I brought it to a local shop that swapped in the axle quickly for me.

At the urging of my better half, the next few days of camping and exploring were all on tamer forest service roads, so I kept the truck in 4H with the center diff unlocked.

Whenever I did that, though, the truck would bind up when turning -- even relatively mild turns, like 70-90* turns. Truck turns absolutely fine in 2WD.

I've pulled the 4WD Actuator cap and all seems normal -- I don't think I'm somehow actually driving with a locked center diff.

I suspect the cheap CV axle, so I ordered a used OEM axle on eBay, but that's been delayed and not getting here for a while.

I'm fine to drive in 2WD for the next few weeks, but it's bugging me to not know for certain what's up. Anything else I should check while waiting for the new (old) axle?

 

[phattyduck]

Is there a chance of damage to the front diff? Pull the front prop shaft, put it in 4WD, lift the front end and see if the front diff is locked in some way. You can also lift all 4 wheels and see what else is locked when it shouldn't be - t-case would be the other option. Both can be checked with all 4 off the ground and the t-case in 4-Hi-U

-Charlie

 

[Gizmo McGee]

Thank you, that's a good call. I'll check the front diff for any binding or lockup.

The inner end of the axle stayed in the diff, so I'm hoping that kept any debris from getting in there -- and there's no groaning or other sounds coming from straight motion in 4WD like I'd expect if I somehow damaged the axle bearings on the diff side. But it'd be good to rule out any of that. And check the fluid for glitter, of course.

 

[Gizmo McGee]

Ok, got to work on it today. Front diff fluid was low, but the diff is in good shape. Felt the teeth through the drain plug as my father spun the driveshaft by hand, and everything felt intact. No chunks or much else in the old fluid.

Up in the air, turning one wheel spun the other in the opposite direction and did not spin the driveshaft.

Transfer case was overfilled and had a few small metal flakes in the old fluid, but nothing out of the ordinary.

Up on jackstands I started the truck and let all four wheels spin, front wheels near full droop. Turned gently from lock to lock and I could not get the binding to happen.

So whatever is going on happens with the truck weighted, again leading me to suspect a bad CV. Fingers crossed. But at least I’ve got fresh fluid in the front differential and the TC now?

 

[Gizmo McGee]

Well I think I figured it out, and it’s not great. It’s the transfer case. Specifically I think I’m skipping teeth on the chain. Hence the metal flakes.

Got it out on a gravel road and it did the weird jump-bind while turning. Felt like it was in the center, not the CV, so on a lark I locked the center diff. Nothing. No bind, no jumps.

So I guess I’m out a multi-mode T-case. Sucks. But at least I’ve got 4wd.

I’m guessing this isn’t a rebuildable situation? What’s a good source for another transfer case?

 

[jgue467]

I would start looking at local wrecker shops - TC on Runners do not fail very often and when they do its just gaskets needing replacing so you should be able to find a good one for not much since there are so many out there. Luck and enjoy the Runner.

 

[jgue467]

I would start looking at local wrecker shops - TCs on Runners do not fail very often and when they do its just gaskets needing replacing so you should be able to find a good one for not much since there are so many out there. Luck and enjoy the Runner.

 

[3bears]

Well I think I figured it out, and it’s not great. It’s the transfer case. Specifically I think I’m skipping teeth on the chain. Hence the metal flakes.

Got it out on a gravel road and it did the weird jump-bind while turning. Felt like it was in the center, not the CV, so on a lark I locked the center diff. Nothing. No bind, no jumps.

So I guess I’m out a multi-mode T-case. Sucks. But at least I’ve got 4wd.

I’m guessing this isn’t a rebuildable situation? What’s a good source for another transfer case?

thats too bad about transfer case

you can post up in the for sale forum, they have a section for "want to buy"

 

[turbo8]

Are you sure you are unlocking and locking the center diff properly? When it is locked, turning will do what you are describing; binding and jumping. Unlocked would be smooth.

 

[Gizmo McGee]

Are you sure you are unlocking and locking the center diff properly? When it is locked, turning will do what you are describing; binding and jumping. Unlocked would be smooth.

It was still binding in center-locked, it was just happening at the tires, kicking up gravel.

I do want to go in and just make sure the actuator is clocked properly. Is it possible to have it clocked wrong and not set off the flashing dash indicator?

TCs on Runners do not fail very often and when they do its just gaskets needing replacing

... and frankly, that's the thing. I'm kind of amazed, if I truly managed to damage the transfer case. I think I need a second opinion.

What I tried to do -- climb a stone step that was just about at bumper height -- shouldn't be enough to kill a TC, especially with some of that energy going into killing the axle.

Anything I can do to definitively test it without dropping it and splitting the case?

 

[phattyduck]

Well I think I figured it out, and it’s not great. It’s the transfer case. Specifically I think I’m skipping teeth on the chain. Hence the metal flakes.

Got it out on a gravel road and it did the weird jump-bind while turning. Felt like it was in the center, not the CV, so on a lark I locked the center diff. Nothing. No bind, no jumps.

So I guess I’m out a multi-mode T-case. Sucks. But at least I’ve got 4wd.

I’m guessing this isn’t a rebuildable situation? What’s a good source for another transfer case?

The chain is always "active" whether the center diff is locked or unlocked. You have a bad center diff - which is bypassed/locked when the center diff is locked.

Either way, the easiest/cheapest will be a used transfer case...

-Charlie

 

[Gizmo McGee]

The chain is always "active" whether the center diff is locked or unlocked. You have a bad center diff - which is bypassed/locked when the center diff is locked.

Either way, the easiest/cheapest will be a used transfer case...

-Charlie

Thanks.

Yeah, the more I read and look at diagrams I think I understand what happened better.

My remaining question (mostly so I learn how to not do this again): If I had the center diff locked, doesn't that mean the mode shift sleeve was keeping it from seeing any torque? How did I break the center diff if it was locked?

And, in general, how should I be climbing an obstacle in 4lo to avoid this in the future?

 

[phattyduck]

And, in general, how should I be climbing an obstacle in 4lo to avoid this in the future?

It sounds like you were doing everything right. Who knows - there may be a primary issue in the transfer case that caused the diff to fail after the fact.

-Charlie

 

[Gizmo McGee]

Just to wrap this up -- I found a low mileage transfer case and am making arrangements to get my hands on it.

Interested to get the old case apart and see the extent of the damage (and maybe salvage some repair parts for a next time.)