Well first of all I'd like to say hello to everyone and that I'm new to this forum and jeeps. I have recently bought a 1991 xj 2 door sport 4wd. I have so far replaced the starter, the oil pressure sender, rear driveshaft and u-joints, and am in the process of putting in a cable system to replace the front vacuum actuator for the 4wd. I love this cherokee and cant wait to sink a few dollars into it but heres my issue:

While shifting gears it will make a clunk sound from what sounds like the rear end. It goes away if I shift VERY carefully (let off gas, push in clutch, shift gear, let off clutch, and then give it gas, all extremely slow) I've just recently replaced the u-joints and had it on the hoist to check play but everything seems okay. The noise has been there since I bought the old beast, and is still there after replacing the driveshaft (broke the first one being an idiot)

The clunk is also there sometimes if im coasting down a road and then apply the gas (all while in gear) The noise is frustrating the s**t out of me and im scared im wrecking something! Anyways does anyone have any ideas on what this might be?

Thanks!

 

Sounds like differential. Could be too much play in the gears or something if it does that when you hit the gas.

By the way, that's some major sag you have in the back. Could the springs be so badly sagged that when you apply power to the rear axle, it's twisting causing a clunk? I'm not sure if you can do this with your year, but you could remove the rear shaft and drive in 4wd (front wheel drive) to see if it still does that. This eliminates some other possibilities.


How are your tranny mounts? How are the motor mounts? They can clunk when going bad.

 

Hi, and welcome from the Bay Area, CA.
I'm thinking that your problem could be any of the following:

1) Bad driveshaft u-joints. ...First thing I'd check....
(Check the cheapest things first!)
Check them all.
Put it on a lift, get under it and with the Jeep in gear, try to turn the DS.
Put a prybar in the u-joints and gently, but firmly, see if you can find any play.

2) Rear end problem. While it's on the lift and in gear, grab a rear tire and turn it both ways....there shouldn't be much movement. Hear a clunk?

3) See if you can move your driveshaft forward or backwards...Possible loose yoke where the driveshaft connects to the input shaft of the diff, or possible diff input shaft bearing problem.

4) Possible bad transmission output shaft thrust bearing(s).

That's where I'd start...hopefully others will suggest additional things to check, too.
Hope this helps!
Good luck!

 

Good catch on the sag, Mud! Good suggestions!

 

Haha yeah I know the sag is pretty bad. The leaf springs are so bad in the back that they actually look like they are upside down, haha. I just bought the thing for a winter beater, I actually drive a 1995 honda prelude but I've definitely fallen in love with the jeep! Im hoping for just a tranny mount but it could be the rearend too. Hoping its not something too pricey! Anyways ill check it out over the next few days when I have a sec. Thanks everyone

p.s. if anyone has had a similar problem let me know what helped!

 

The salvage yard is your friend. i went to one near my house, they had about 20 xj's there.

 

Hell, call me crazy, but I'd check the trans mount first...

 

Good call for sure. Now if I could only find the motivation to check it after work in this cold weather I am so "fortunate" to have here up in B.C.

 

I am having a very simular problem.

Its an auto 2000 with a 231

I get a clunk when going from reverse right to drive, but I don't get the clunk if I pause in netural for a second. I also get it on hard stops but only when I release the brake after a harder then normal stop. Kinda like something sets. Then some times on accelration the it is again.

Odd thing is this is a 34K mile cherokee. I am worried because the past owner was a moron so I have been fixing his mistakes for about a month now and now this happens.

I am going to do the ujoints so hopefully that will take care of it.

 

Yep. definately check the trans mount. its really cheap and really easy to do. dont just "check" it. spend 20.00 at napa and change that joker

 

That could be the slip yoke needing greased. One way to tell is to take off the rear shaft, put it in 4wd and see if it still does it. The slip yoke on the rear driveshaft goes dry and clunks when suspension settles after a stop and on acceleration. It also could be the trans mount.

 

Right from the factory service manual:

DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted into gear (or the clutch engaged), can be caused by:

• high engine idle speed;
• loose engine/transmission/transfer case mounts;
• worn U-joints;
• loose spring shackles or U-bolts;
• loose pinion gear nut and yoke;
• excessive ring gear backlash; and
• excessive differential side gear-to-case clearance.