Clunks and bumps over rough road

I apologize in advance for the rookie question, and I promise I searched, but I really don't know what to search for, but I have an issue that I would like some advice on tracking down.

I have a 97 Cherokee, 4.0, auto, 8.25 rear end, all stock suspension, and when I go over bumps/potholes, the whole chassis feels "loose" Part of my problem is that I can't do a great job of describing this feeling, it kind of clunks over bumps more than I think it should, and definitely more than my other cars, and just general doesn't feel as solid as I think it should, and as a previous Cherokee did.

Also, when I shut it off, there is kind of a clunk that comes from the rear of the vehicle, similar to a clunk I hear when I hit potholes. I drove around without anything in the back, and it didn't change anything.

One other thing that I haven't been able to replicate again is a clunk from the front end when I locked up the front wheels during a snow storm. I was in 4hi coming up to a stop sign, and as soon as the wheels locked up, the front end clunked pretty good, and I got it to do it several more times each time when I locked up the wheels. Now, on dry pavement, it doesn't make the clunk, even under heavy braking, but I don't want to go locking up my brakes trying to find this noise again.

I know this is all kind of vague, and I know that makes it harder to help with, but I was wondering if there were any common spots to check (mounts, bushings that typically go bad) before I dig deeper than I need to. Also, this truck has 300k on it, so part of me is just wondering if this is something I am stuck dealing with, but I am thinking that I should be able to make it feel more solid than it is, even though I'm sure it won't be as good as the day it rolled off the assembly line, but I can accept that.

Thanks!

Your first problem sounds like the exhaust is contacting the transmission cross member. Usually a combination of things, the exhaust hanger from the trans mount is soft or worn out and/or the exhaust has settled or relaxed over the years.

If your rear trans mount is covered in oil that would be a good place to look, the oil reacts with the rubber eventually, the rubber softens and deteriorates.

I loosen off the down pipe to header bolts enough to get a little movement in the connection and the cross over to CAT clamp and stick a 3/4" thick piece of wood in between the exhaust and the cross member and re-tighten. Not a cure but it does sometimes last awhile before the clunk returns.

You may also want to take a close look at your right motor mount.

X2 on the above, also look at the exhaust in the rear. the tailpipe or muffler might be banging on the trailer hitch or floor.
also look at your front control arm mounts for something loose, maybe a loose shoch absorber?

I guess I should add that it technically isn't all stock, but has a muffler and turndown before the rear axle. I can still check around the tranny mount, but there is no chance of it contacting the trailer hitch or anything rear of about the back of the rear doors

Motor mounts are cheap n easy. I doubt they've been replaced as most ignore them till their radiator gets chewed up.. Also trans mount and the above mentioned ideas.
You may want to have someone turn the wheel while you look underneath for play in joints. Maybe rock it back and forth in N with the brakes on and see what moves underneath. Troubleshooting is fun lol.

If things like the exhaust and motor are rattling around that could be motor and exhaust mounts. The fact that this occurs when shutting off the engine is key.

When the chassis itself feels disjoint from the road, it's a suspension problem. If you have warn parts like ball joints the whole vehicle may move around over potholes, manhole covers, etc...

solomon7 said:

Motor mounts are cheap n easy. I doubt they've been replaced as most ignore them till their radiator gets chewed up.. Also trans mount and the above mentioned ideas.
You may want to have someone turn the wheel while you look underneath for play in joints. Maybe rock it back and forth in N with the brakes on and see what moves underneath. Troubleshooting is fun lol.

Click to expand...

For motor mounts, should I go brown dog or just napa/autozone/ etc.

There is a bit of a price difference, but the brown dog ones look bulletproof, and I have read good things about them. Also, is there any performance upgrade available for the tranny mount? I am the type to upgrade rather than replace if it isn't a crazy amount of money.

I Periodically grab onto the front corner of the valve cover and give the whole motor a couple of hefty shoves to the side (both directions). If it moves at all inside the engine bay, you likely have motor mount issues. The motor mounts cook on the drivers side, engine torque and I'd guess the design, stresses the motor mounts enough on the passengers side to snap the bolts in the block on occasion.

The engine is constantly flexing the exhaust, the exhaust is hung by only a few hangers and those are stiff. Over the years the joints can relax a bit and the exhaust can sag. It doesn't take much, there really isn't much room for the exhaust between the floorboards and the tranny cross member. If you can't stick your finger between the exhaust and the transmission cross member, at least until the first finger joint, the chances of the exhaust contacting the cross member are pretty high.

When I replace parts I ask myself about intended usage, or just how hard I'm likely to be on the vehicle. And ask myself how long the part that is in there has lasted and how long a stock replacement is likely to last (it may outlast the rest of the vehicle). My Renix is 26 years old and still has many original parts.

Brown Dog motor mounts may be a good idea. I recently had to remove the broken off motor mount bolts from the block on the passengers side of my 96. The motor mount was still in good shape the bolts holding the mount to the side of the block, not so good. It was a pain to get those broken bolts back out of there, two were rusted in there pretty good. Not much room to work down there, I had to move a bunch of stuff to get to those bolts.

Brown Dog hands down over NAPA..

Stock XJ?? Napa or any OEM style mounts will be fine... You don't need mounts that cost 10x more. You are NOT going to get 10x more life from them unless you keep the rig for about 50 years.

Loose feeling is suspension. Could be anything bad shocks, alignment, tires, and just plain worn out suspension parts

A super easy way to check if its your motor mounts, you need two people, open hood start it up hold break shift to reverse and forward and have you or your friend look at motor to see if there is movement.

Grab your shocks and give them a good hard shake. The bar pins in the bottom of the front and top of the rear shocks tend to come loose. The squeaking and banging had me chasing 2 different noises until I grabbed the shock to slide under my junk and... Presto! Found both noises.