"thud" noise in rear suspension

[boardsnow]

When driving, my entire rear suspension makes a loud thud noise during casual driving; when actually driving over road obstructions and other minor road bumps.

The front suspension smoothly passes over the bumps, yet when my rear suspension overcomes half of the bump, when dropping; you know when you drop as there is a loud thud.

- my best description.
Now, In no way am I a mechanic, but I noticed that the front shocks have their boots on the top, and the gas chamber on the bottom.
however, my rear suspension has the boots on the bottom and the gas chamber on the top.

Logically, I understand the front; yet the rear I don't.
I'm no scientist but I can make a few hypothesis' as to why I would assume that thud noise can be on account of the reversed installation of the rear shocks.

On the other hand, a mechanic I brought the vehicle said I might have chipped a tooth in my differential.
A performance center specialist countered that diagnosis as there is no "grinding" noise evident. So as there are no other ideas, I am going out on a limb to try and prove my idea wrong(and i fail to do so) yet I have no mechanical experience/knowledge.

Does a reversed installation sound right, as to the root cause of a "thud" noise when driving casually over small road obstructions?

[TJ54]

TJ, XJ, YJ, ZJ,  :?:

[boardsnow]

97 tj.
shocks are procomp es3000.
4" suspension.

thud is only located in the rear. the shocks were purchased as a complete set, where all 4 where sold together in a sealed box.

no problems present with the front suspension.

[OffroadChef]

If you lost some teeth, i would suspect your speed would be sluggish. you could always open up the diff and check it out.

[fug]

It's likely the upper part of your rear shocks.   With the standard bar pin/rubber bushing setup its possible for the shock to walk sideways and either hit the body or the bar pin its self... results in annoying thump when you go over bumps and is hard to diagnose.

Check out this write up here

[02TJSport]

when I took my stock shocks off and put on my skyjacker I believe the chamber is at the bottom and the boot at the top for both the new ones and the stock ones.  Not sure if it would cause that noise but you never know.  If nothing else it could rule it out.

[boardsnow]

If I can hit 60 easy would that then be plausable to rule out the loss of any teath?
That and the factor which a loss of teeth would also be accompanied by a grinding noise?

Never the less; I've heard so far that facots which could contribute to the "Thud" are either the placement of the shocks or tightening of the rear track bar.

I don't know, as I am not a mechanic, but I believe it would have something to do with the placement of the shocks.

[Bnine]

You're shocks are designed to run "Can up", they are not installed wrong.

Most common causes

Track bar clearence to the gas tank

Loose shock hardware

Shock contact on the rear axle due to pinion rotation

Bad or loose control arm bushing/mount

Seized gas shock

Easiest way to diagnose is to have someone jump up and down on the rear bumper while you check clearences and listen for the sound.

If the rear bounces, you will find your problem.

The the rear wont bounce, the shocks are seized.

To tell the difference, bounce the front.

[BlackYJ]

Boardsnow, listen to the people on these boards, both ECO and CJA, they are ALL telling you to jump on the back and have a look around.  Without being there, all we can do is speculate.