PDA

View Full Version : TCase Headscratcher


AHorseThief
04-01-2012, 07:53 PM
I recently redid the parking brake on my 40. I also fixed the speedometer (knowing how fast I'm going is pretty cool).

I got the parking brake adjusted, and took it for a test drive. Everything was fine at first, but then it started bucking and pulsing. It kinda felt like the parking brake was intermittently catching. I took everything apart and poked around, but didn't really find anything out of place. I did re-tighten the (non) castle nut and applied some blue Loctite so that I could stop worrying about the nut coming loose.

I finally got the tcase refilled today and took it out for another test drive. At first the bucking continued, and I was ready to give up and park it until I got a better idea. As I was about to get out of the truck, I noticed that the tcase shift lever was closer to 4wd than 2wd than it usually sits. I've been using low range to pull into the garage because it's a tight fit.

I rather forcefully moved the lever up into 2wd and went for another drive. No bucking or pulsing or scary noises coming from the drivetrain.

So after that wall of text, a couple questions. My tcase is "difficult" to shift into and out of low range. It appears it might need extra convincing to come out of 4wd as well. Are there any duct tape fixes for this?

Could not quite being in 2wd explain the bucking/dragging/pulsing action?

Subzali rode in it while it was acting up, so maybe he has a better explanation of what it was doing.

subzali
04-01-2012, 08:33 PM
Well that's interesting. I guess it could explain it, but if I remember right you had your front hubs unlocked the whole time we were doing the testing. So there shouldn't be anything that's binding...

AHorseThief
04-01-2012, 09:52 PM
I'm pretty sure we unlocked them before we went joyriding. Didn't we?

farnhamstj
04-08-2012, 10:08 AM
Are you certain front and rear diffs have the same ratio?

treerootCO
04-08-2012, 11:37 AM
Moab 2010 I drive the 40 to town and left the parking break on. It did exactly what you describe but only after I drove for 30min at highway speeds. Probably gets hot and makes the pads work better.

AHorseThief
04-09-2012, 02:08 PM
Are you certain front and rear diffs have the same ratio?

This rig has been thoroughly "improved" by the various PO's that have owned it. Short answer is no.

AHorseThief
04-09-2012, 02:12 PM
Moab 2010 I drive the 40 to town and left the parking break on. It did exactly what you describe but only after I drove for 30min at highway speeds. Probably gets hot and makes the pads work better.

I originally thought this was what was going on, but I've taken it apart, put it back together and had the problem come and go. :dunno:

Air Randy
04-09-2012, 08:39 PM
Do you have some type of locker in the rear diff? Those can cause similar symptoms especially if they are starting to go bad. Or you could have some busted spider gears in the rear diff.

AHorseThief
04-10-2012, 01:41 PM
No locker.

Wouldn't busted spider gears be a consistent kind of problem? I've got to learn how to break stuff all the way. Then I won't be wondering what's wrong. :hill:

60wag
04-10-2012, 03:23 PM
I'd jack up the truck, wheels off the ground and confirm:
1. both front hubs lock and unlock as expected
2. the 2wd/4wd lever actually connects/disconnects the front drive shaft from the tcase
3. both front and rear diffs feel correct when one wheel is turned by hand. If the drive shaft doesn't turn, the wheel on the opposite side of the axle turns the other direction with minimal noise. Backlash is mostly ok.

Air Randy
04-10-2012, 03:27 PM
Usually, yes, it could come & go though if broken pieces were moving in and out of the gears. Thats probably not it anyways.

From re-reading your original post, it probably was partially between the gears in the tcase and it may have been popping in and out of gear, that was the bucking you were feeling. Have you checked your tcase shift linkage? See if it has any slop or wear in it. Sometimes it can be adjusted or something may just be loose.

farnhamstj
04-10-2012, 05:23 PM
Drain fluids in both diffs and see if there is metal in the gear oil. Could be a ring and pinion, could be broken spider gear. Could also be a lose pinion nut (involves removing the drive shafts (14mm bolts PITA) from the diffs, There is a torque spec) I'd check those things too, and count the driveshaft turns per revolution of tire.

I would never presume to know more than Randy or Mike, or anyone else really. I'm just sharing some of my experiences. I too have had pop out of gear that was related to worn linkages.