Drivetrain Slop and Noise

Joined
Oct 20, 2010
Messages
13
Location
Hollis, NH
I've been trying to nail down a drivetrain issue for about 6 months now - some of you may have seen me ask about this on FJNortheasters or ExploringNH - and I'm getting close but I still am not quite there yet..

The slop (play) has slowly gotten worse over time- this is driving me INSANE because there is probably 2x more slop than my maxima with 225k miles and broken/rusted off motor tranny mounts. I mean, I could probably pull the engine out of that car without loosening a bolt. I've GOT to find this problem so I'm going to list out everything I know so far.

6mt 59K miles only had 33" tires and extra weight on it for 10k miles, only been offroad since 36k miles.

Symptoms:
*In all gears at all speeds, there is noticeable play in the drivetrain when applying the throttle and then releasing it. There is a LOT in 1st gear especially.

*The front driveshaft can rotate much more than the rear if the vehicle is stationary and all 4 wheels on the ground. This is the same if the center diff is locked or open.

*when you rotate the front driveshaft by hand, you can hear some clunking from the transfer case, but also the front diff.

*The play was only noticeable in 4h meaning 4HL and 4LL would make it go away, but now I can notice it to a lesser effect in 4hl and 4LL

*The transfer case was VERY noisy until I changed the oil to Lucas at 57K. That fixed the noise and dampened some of the slop for a while, but it has started coming back now.

*When I first get in the car, the level of noise and harshness of the slop is pretty low, as I drive (especially loaded down or wheeling) it gets worse and worse. The shifting also degrades as distance increases (built up heat increases).


Other Information
*I've been through a fair amount of water

*I've had to replace a front axle seal

*The driveshafts had probably not been greased at all until 32000 miles when I got the FJ.

*I have (1) rebuilt CV shaft

*The inboard part of the CV shafts rotate with the front driveshaft-there is a little play there not as much as I'm feeling while driving it

I've got a Y-pipe and hi-tuck Buds

Things I've checked/done:

*Greased the crap out of the driveshafts
*checked for play in the rear pinion bearing (as best I can w/out pulling the driveshaft)
*Checked for play in the driveshaft splines/u-joints (can't find any)
*Checked all the motor mounts and tranny mounts, seems good no signs of play there****Need to re-check the underside of the motor mounts****
*Checked all the propeller shaft bolts-Tight as can be
*Rear Lower Links are tight w/ no play
*Front Diff mounts tightened and checked
*Just got it inspected very thoroughly so I don't think any wheel bearings are bad
*Checked the outboard bearings in the front diff assy
*Changed Front diff oil 2x (1 for CV swap) - Looks Normal
*Changed Rear diff oil - Looked normal
*Changed Transmission oil - Looked Great
*Changed Transfer Case oil - BLACK and smelled very burnt. Some paste on the magnet but no chunks in the oil.

So all signs seem to point to the transfer case here... But why does it get worse with use(heat)? My guess is because the oil is getting too hot and thinning out.... But why? Why do I have so much play? Short of pulling the case and opening it up, how do I proceed with diagnosing this?

My plan so far has been to just deal with it, but the noise got REALLY bad after a loaded down road trip through the mountains of NH last weekend.

I've got 800 miles left on my powertrain warranty :D


Any thoughts?
 
Joined
Oct 20, 2010
Messages
13
Location
Hollis, NH
I also jacked up one front wheel and did a test to see how far I could rotate the wheel in different configurations. The transmission was in 1st gear for all of these:

4H: approx 10* (degrees) rotation free play.

4HL: approx 3* rotation free play

4LL: Same as 4HL

There is a tiny bit of play in the front diff, but it appears to be the same or not much more than is in the rear.

From the way I understand the transfer case, this rules out the TC chain as the cause, because the amount of play in the front output shaft should be the same whether the center diff is locked or open... right?

Might this mean that all the slop is coming from the center diff?
 

Mtbcoach

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Joined
Jun 29, 2006
Messages
4,372
Location
Carolina Beach NC
Sorry to hear of your troubles. I just went through troubleshooting drivetrain noise and might offer some guidance.

It does sound like your t-case has been abused. Any idea how much oil you drained when you changed it?

I'd suggest getting all 4 wheels safely off the ground so you can start it, put it in gear and crawl around underneath. By using a stethescope (few have) or a long screwdriver (place handle against your ear, drive end against part listening to), look, listen and feel as many things as you can safely. I wish I had done this, I only used my eyes and wound up chasing around another problem.

I'll bet it will be clear once you do this. Other than pulling the t-case and splitting it open, I don't know of another way to really tell where the fault is.

You could pull one driveshaft, drive it, replace and pull the other, drive it again to isolate front from back but it still won't tell you if its the t-case or not.

Obviously, be safe about getting it off the ground. I have a nice set of jack stands and didn't need to rev the engine at all, just idling in gear made it clear where the problem was.

Good luck, hope this helped some...
 
Joined
Oct 20, 2010
Messages
13
Location
Hollis, NH
The Tcase had the correct amount of oil in it when it was drained, I drained it into a measuring cup so I could inspect it as well as measure.

Good idea - I'll try putting it up on stands when I can get some time.

Thanks for the help! I'll post any updates.
 
Joined
Oct 20, 2010
Messages
13
Location
Hollis, NH
I did try getting the vehicle up and listening around but nothing jumped out at me. I think the next step is pulling the case.

It did however seem that the engine moved back and forth a lot if I got on the clutch and let go real quick (wheels in the air)... wondering if my motor mounts are loose/bad? Fan doesn't hit the shroud though.
 
Joined
Oct 20, 2010
Messages
13
Location
Hollis, NH
I've been living with this for a while now, and haven't noticed any new noises, or bad noises. I've noticed when driving with the center console off (was doing some wiring) that the transmission does seem to rock back and forth a lot whenever I get driveline play.

I'm going to seriously check out the motor mounts now. Every time I go wheeling and put a lot of load on the drivetrain, the problem gets a bit worse.
 
Joined
Oct 20, 2010
Messages
13
Location
Hollis, NH
Well, I checked the motor mounts and they look fine where they are welded to the frame. I had someone watch them with a flashlight while I loaded and unloaded the engine with the brakes on, and the engine rotates a LOT in the bay.
Watching the engine move while driving (in a parking lot) with the hood up, I was able to determine that the cause of the drivetrain lash is excessive engine movement.

Anyone know if there is a way to stiffen those rubber mounts up a bit?
 

Mtbcoach

Moderator
Joined
Jun 29, 2006
Messages
4,372
Location
Carolina Beach NC
You can't "stiffen" the mounts. If you have excessive movement, something is wrong. You need to have some perspective on what is "normal" engine movement. Sitting in the driver's seat, trying to evaluate proper engine movement while driving with the hood up is not the most effective way to troubleshoot this issue...
 
Joined
Oct 20, 2010
Messages
13
Location
Hollis, NH
I did have a second person watching the engine and mounts.

I agree the right way to do this would be to compare with another MT FJC. I'm planning to do it ASAP.

I did check carefully to make sure I don't have the frame crack issue where the motor mounts are welded on - everything looks fine.
 

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