What the heck is klunking?

Have a 98XJ. On bumps or a bumpy road there is a klunking heard from the rear area. Of course on the highway, it is silent. I have checked all of the customary things that [ususlly] clunk... spare tire, rear hatch, undercarriage structure/shocks/torsion bars/hitch, and about everything I can think of.
It has to be something I am missing. Thinking it has to be something behind the tank I cannot see or something like that. Nothing seems to be loose... ideas or past experience with this problem ?!?!?

shock absorber bushings? I know you said you already checked the shocks, but so did I and it turned out this was my issue. Also, is there any sign of wear on the rears of the shackles or on the frame crossmember where they would strike if pushed back?

EDIT: exhaust too, see if your exhaust hangars are all still present (one at the tranny crossmember, one after the muffler, one right near the shackle) and see if it's bouncing off the side of the diff housing, the top of the axle tube, the gas tank heat shield, the shackle, or (if equipped) the tow hitch.

Could be the rear shocks' bar pins loading up and then releasing.

kastein: think I have checked all of that, however will do it again.
joe_peters: if you speak of a bar that goes through the shock bushing and bolts to a member with 2 bolts.... wouldn't the bushing be visibly egg-shaped?
thanks

u bolts? crumbled degree shim?

bcmaxx said:

u bolts? crumbled degree shim?

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What the devil is a "crumbled degree shim"? Is it under the muffler bearing?

I had my Ebrake cables banging against the exhaust making some loud noise. Took me a while to track that one down.

idahjo said:

kastein: think I have checked all of that, however will do it again.
joe_peters: if you speak of a bar that goes through the shock bushing and bolts to a member with 2 bolts.... wouldn't the bushing be visibly egg-shaped?
thanks

Click to expand...

No. Bar Pin shocks are known for this issue.

Try pulling the shocks from the axle and drive it over a few bumps--noise gone, it is the shocks. Just be ready for a fun ride.

idahjo said:

What the devil is a "crumbled degree shim"? Is it under the muffler bearing?

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Crumbled is in the dictionary, and a crumbled degree shim would seem to be a degree shim that has crumbled into little bits. :doh:

i agree with joe peters. this occured on two of my xjs. one time it was because of a defective bushing on a new shock partially disintegrated at the bar pin. the other was because stock the bar pin actually broke on one side and was actually somewhat hard to see due to rust buildup

I suspect it's a stock XJ, thus idahjo has no need for degree shims and hasn't read up on them.

idahjo - mine looked fine on inspection, I didn't notice they were bad till I grabbed them and yanked pretty hard back and forth. Turned out one of my lower bushings was so shot that the metal ring on the end of the shock absorber was about 50% through a very nice polishing/burnishing job on the mounting stud. Another thing this noise could be caused by is a bowling ball in the trunk.

... speaking of which, have you checked to see if the tire jack is clipped down under the rear seat? Complete shot in the dark, but maybe that could be making the noise... I imagine it'd be fairly quiet though.

kastein said:

I suspect it's a stock XJ, thus idahjo has no need for degree shims and hasn't read up on them.

idahjo - mine looked fine on inspection, I didn't notice they were bad till I grabbed them and yanked pretty hard back and forth. Turned out one of my lower bushings was so shot that the metal ring on the end of the shock absorber was about 50% through a very nice polishing/burnishing job on the mounting stud. Another thing this noise could be caused by is a bowling ball in the trunk.

... speaking of which, have you checked to see if the tire jack is clipped down under the rear seat? Complete shot in the dark, but maybe that could be making the noise... I imagine it'd be fairly quiet though.

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YEP! Checked all the 'stuff' stored under the rear seat (Jack & stuff).
This is a stock XJ and "degree shims" are nothing I have ever heard of prior.
I am still not clear on just what a "bar-pin" shock is. Is it a type of shock, or is it something to do with its mounting? (I will do an internet search for some enlightenment)
OK.. THE NAME REFERS TO THE TOP CROSS PIN MOUNTING WHERE THE SHOCK ATTACHES TO THE BODY WITH TWO BOLTS...MY HUNCH WAS CORRECT ;^) http://4x4icon.com/offroad/bar_pin_eliminator/index.htm
thanks

P.S.; this old guy is not going outside to check things out until tomorrow (to stiff from cutting firewood the last two days)!

SOLVED!

Curiosity got the better of me so I went out to take a 'look-see'. The top mounting pins were OK on the rear shocks, BUT the R/R lower rubber bushing eluded my initial inspection.. it was worn to the point it was allowing the lower mount to KLUNK.

'Want to thank you guys for the help. I come in here whenever I have a problem or a question and usually get some straight-poop. The strangest solution was the member who suggested the remedy for an 'air-bag ON indicator; "To smack the center of the dash firmly and repeat it every several thousand miles" [it worked]!!
Thanks again, Idahjo

Glad to help!

Good luck on those shocks, assuming you are replacing them (I've never had a shock bushing go bad without the shock being nearly worthless) you'll want to get a mapp gas + oxygen torch (or if on a budget, a propane torch should help a bit) and/or an air chisel. Rear shocks on an XJ are famous for being annoying to remove; the bolts at each end of the bar pins tend to snap off when twisted. Heat the suckers up with the torch and they might come out though, if they start feeling like they are binding up, twist them back in a quarter turn or so to unjam the rust in the threads, then continue backing them out till they bind up again. If you do end up breaking them off, use either a hand chisel/punch and a BFH or an air chisel to knock the weld nuts off the inside of the crossmember, then use scotch tape to hold new nuts into a wrench and pass them up in or tie thread/thin wire around the end of a bolt and pull them through so the nuts end up on the bottom.

None of this matters I guess if you don't need to replace the shocks - if you don't, I am jealous and you get it easy and (obviously) only need to replace the lower bushings.