I've got a mystery clunk in the front end of my XJ-S that my mechanic and I have been trying to track down in the front end for awhile and I think we're both stumped.

It only happens intermittently and usually when the car is making a right turn under load, usually from a stop. Slowing into a turn seems less likely to cause the sound.

I've had:

• the sway bar reattached,
• new endlinks/bushes installed,
• all 6 shocks refreshed (within 2000 miles),
• the springs removed and reseated with the rubber bushing things refreshed as well.
• The steering rack is less than 10k miles old.

At this point, my '88.5 XJ-S is quieter going over our crappy surface-of-the-mood roads than my 1995 X300... except when I take a right turn, even on smooth pavement.

The car doesn't exhibit any other handling symptoms.

Any idea what else I might check?

Thanks in advance,
Rhett

 

if the engine mounts are worn , the exhaust can bang against the bodywork

on reving the engine, it should move, but not excessively , same goes for the gearbox mount

its strange how sometimes the clunk isn't coming from where you hear it


at least another two to tick from the list.......

BB

 

Motor mounts are good. I had them checked when we replaced the subframe mounts and double-checked when trying to troubleshoot this problem just a few weeks ago.

Gear box mount was replaced a year ago.

Someone on Jag-Lovers suggested ball joints. Thoughts?

 

A few ideas in addition to the others above:

Have you tightened up the lower shock absorber mounting bolts on the bottom wishbone and renewed their bushes?

Have the anti roll bar mounting rubbers on the chassis frame been renewed (a sod of a job). Are the ARB drop-link rubbers 100% and the bolts tightened up and the washers in place?

Have you removed the hubs and bearings and inspected the stub axles? If these have the commonly-found wear groove in them from the bearing inner races, this can also cause clonks. As can a stub axle not being 100% tight in the upright.

Top and particularly bottom wishbone bushes if worn will make this noise, how old are they?

Are the rack bushes good and their mounting bolts tight? on full lock the rack is under quite a bit of lateral pressure.

Also the subframe itself can move and clonk. Check the big round 6 shot bushes at the front are Ok and the huge bolt through them is tight. The rear of the front subframe is mounted to the chassis frame on a special rubber V mount each side. This incorporates an anti-falling out bolt-type bit that goes through the rubber. It is just possible that if these mounts are really worn, this mechanism is clonking.

So nothing a full rebuild of the entire front will not cure!

Greg

 

i did a full front end rebuild and not a thump in sight

apart from the wife when she needs to get out of the boot ( trunk )


BB