• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Odd Clunk and Grinding sound

O

oldmantompkins

NAXJA Forum User
Location
Denver
So when I am at or above 40 mph every time I let off the gas or get back on it I hear and feel a clunk from the mid/rear of the jeep. Also if I get the throttle in the perfect position it will make a horrible grinding sound (only very very little throttle does it do this).

Have an 01
100k miles
231 t-case
8.25 rear
and about a 3" lift.

I have checked u-joints and they are fine. When I put the rear on jack stands and rotated the drive shaft there was some play in the t-case while the car was in neutral and 2wd.
Also when at higher speeds 50+ I get a load groan. Figured wheel bearings but it changes with throttle position not speed.
When spinning the rear tires they acted as expected except when I spun the drivers side tire forward the other side acted like it wanted to move but didnt. When I spun it backwards it rotated opposite like I expected it to. This something to worry about?

So to sum it up.
Thud when on and off the gas.
Grinding sound when very lightly on throttle at speed.
Load groan at highway speeds that changes with throttle not speed.
The play in the T-case could not be a problem at all but im not sure what is acceptable and whats not.

Thanks in advance. I have a trip to moab soon and I need to figure this out.
 
Open the diff and look inside. Inspect the drained oil for metal shavings. Replace the u-joints, "looking" at u-joints tells you little to nothing. Worn u-joints can clunk and vibrate/drone. Check the exhaust for the clunk and groan/vibe. It it touching anything or able to move enough to touch ? Some differential clunking is normal.
 
Checked rear diff and it seemed fine with little to no metal shavings.

Ill replace the u joints then. Figured I would be able to get some play from them moving drive shaft etc.

Exhaust is plenty clear of anything and everything.
 
I've been getting a wierd grinding/vibrating noise when I push the clutch In when I'm on the freeway or when I let off the gas to the point where I'm not accelerating or decelerating. Sounds like it's coming from my tranny area. I'll be following this to see what you find out
 
I had the grinding sound when I let off the gas and or feathered it. Mine mostly went away after a t_case drop..
Do you have an sye installed?
 
Not the U-joints. Installed fresh set of spicers and still have the thunk and grind. Seems to be internal to the transfer case. Im crossing my fingers it holds up to the next week in moab.
 
Have you checked the drums/rotors for excess heat signs? Check the brake pads, and clips....Also the flex plate bolts, and tranny mount, maybe even the engine mounts to be extra thourough?

My 89 had me scratching my head with similar noises, turned out the gas pump wanted the gas tank at least 1/2 full!!! LOL, that one came and went with the gas tank fill ups!

Might jack up the rear end, and run it, no load at speeds, and track down a hot spot, or noises with a stethoscope.
 
Mine did that before I got a sye. I helped eliminate it a little bit by adjusting my pinion angle and doing a transfer case drop but it didn't go completly away untill I did the sye. I believe it was caused by play in the slip yoke on the back of the transfer case.

It made the noise whenever I would either get on the gas lightly or let off the gas. It sounded like it was going to bind and blow out the back half of the Jeep but I drove with it for a few hundred miles before I got the sye and when I did the sye it didn't have any bad wear on the output shaft of the transfercase or the slip yoke so I probably could have driven on it for longer.
 
oldmantompkins said:
So when I am at or above 40 mph every time I let off the gas or get back on it I hear and feel a clunk from the mid/rear of the jeep. Also if I get the throttle in the perfect position it will make a horrible grinding sound (only very very little throttle does it do this).

Have an 01
100k miles
231 t-case
8.25 rear
and about a 3" lift.

I have checked u-joints and they are fine. When I put the rear on jack stands and rotated the drive shaft there was some play in the t-case while the car was in neutral and 2wd.
Also when at higher speeds 50+ I get a load groan. Figured wheel bearings but it changes with throttle position not speed.
When spinning the rear tires they acted as expected except when I spun the drivers side tire forward the other side acted like it wanted to move but didnt. When I spun it backwards it rotated opposite like I expected it to. This something to worry about?

So to sum it up.
Thud when on and off the gas.
Grinding sound when very lightly on throttle at speed.
Load groan at highway speeds that changes with throttle not speed.
The play in the T-case could not be a problem at all but im not sure what is acceptable and whats not.

Thanks in advance. I have a trip to moab soon and I need to figure this out.
Click to expand...

Thread REVIVAL! Any update or cures to this problem because I am experiencing EXACTLY the same problem as the OP.
 
I had these issues, exactly - the u-joint at the rear axle was bad. I had just replaced it but the driveline angles were horrible and caused it to grind and clunk. SYE cured the problem. To make it worse my rear axle wasn't square thanks to a bent spring eye...
 
I wasted more time and money trying to fix that same issue. Spent about $200 on a SYE and junkyard front DS. Haven't looked back since
 
Had the same issue and symptoms after lifting my old jeep. I added some degree shims under the rear leafs to correct the angle of the rear driveshaft to the t-case and issue went away.
 
Reviving the old post Sorry. But I have the same exact issue and mechanic said it's the transfer case. There is a play on both drive shaft t case side.
 
The front output shaft will have a bit of slop in it. It's just the way they are. It's hard to keep up with all your threads. If you've just lifted it, haven't adjusted the front pinion angle, or haven't put in a SYE then you need to start looking at driveline angles first. If a lift was just installed, u-joints are now operating at in a different rotational pattern and can make some noise. As an example, when I replaced the rear springs on my XJ, I had some u-joint noise for a few weeks. That wasn't a lift, it was just getting rid of sagging rear leafs & putting it back to stock... but with a lift, you need to measure and accommodate for driveline angle changes. In the front, explore adjustable lower control arms & in the rear, explore SYE and shims under the leafs at the axle...
 
Last edited:
i had this same issue after putting on a 3in lift. ended up putting hockey pucks under the transmission cross-member to fix the angle.
 
You must log in or register to reply here.

Similar threads

Z
Whirring sound only heard from inside
Replies
7
Views
118
Z.m4v
Z
G
Deep, Bassy Rumble Only at Very Low Speed
Replies
0
Views
1K
GraniteCow
G
WGxj
1997 XJ 4.0L AW4 Long Crank Problem
Replies
5
Views
96
Tim_MN
Tim_MN
B
Diagnosing this sound - rear wheel bearing?
Replies
1
Views
2K
Tim_MN
Tim_MN
M
NP 231 input shaft
Replies
3
Views
2K
RCP Phx
R
Back
Top