My 1996 XJR6 suffers from a banging/knocking sound when presented with an uneven road surface. The sound seems to come from the rear N/S area: it sounds like something is loose or rattling around!

My mechanic has taken a very careful look at the rear end and has reported nothing that's loose or requiring attention. Our suspicion is the central exhaust mount (with bushes) and that this is loose and causing the exhaust to twist and rattle at the rear.

Does anyone have any experience of this? Any words of wisdom gratefully received.

 

upper rear shock bushes?

 

+1

The classic symptom and issue, worn upper shock bushings.

Could be other things, but once you suspect the upper shock mounts, you can zero in on it and I bet that's the issue. Very common wear item given the car's age.

A recent thread on the topic:

https://www.jaguarforums.com/forum/x...ut-had-146849/


And a "how to":

https://www.jaguarforums.com/forum/x...ent-how-62143/


If you replace the rear shocks, you should also look at replacing the upper spring bushings and any other worn rubber spacers, pads, etc while the springs are out.

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Many thanks guys - good food for thought.

Just one question: my rear shocks don't seem to showing any wear in their operation (the usual bouncing after being compressed) so don't need replacing in their own right. Would you suggest replacing them as a matter of course if the bushes need doing?

 

That's what I did, but to each his own. Think I was beyond 100k miles at the time.... figured it was due.

 

If the sound is most apparent going over cobbles or high frequency bumps, and sounds like a squash ball rattling around inside a tin, I would suggest LOWER rear shock absorber bushes.
These can be replaced without replacing the shocks, and your decision really depends on how confident you are your shocks are still fit for purpose. These cars really respond to shocks and bushes in good condition, and given you will need to remove the shocks to attend to lower and upper bushes, and given it isnt a 5 minute job, you might be wise to replace the lot while you are at it.

 

It really is the upper shock bushings. Take them out, and you will see. They look like they were made of tough styrofoam. Weak at best.

 

Hi I own xj308sport I had the same noise rattle at rear it was rear shocker drivers side had it changed made all the difference lovely smooth drive now ...tony

 

Hi I had a similar knocking noise at the L/R suspension on a customers 95xj and after replacing rear shock bushes top and bottom it was still there' Checked exhaust and hangers but still there. It was finaly diagnosed as the lower rear hub pivot pin or bolt that goes thru the bottom suspension arm. The one with the off centre head or washer to adjust rear wheel camber' It was actually the hole in the bottom arm where the bolt goes thru had worn bigger than the bolt and on uneven surface was causing a metalic rattle. Very annoying and hard to find.
Cheers Ray.

 

Would be best if you can post pictures to show the members what you are referring to

 

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Hi I have arrowed the hole where the bolt that has the eccentric head which enables you to adjust toe in. This bolt goes thru the wish bone and hub carrier. It is this hole that is arrowed that seems to wear and when going over any rough patches of road and sometimes even small undulations causes the clunky or metalic rattle as the bolt that goes thru both the wishbone and hub carrier is now smaller than the hole. Hope this helps
Cheers Ray.

 

Usually the cost and effort to get the rear springs and shocks out make it worthwhile to consider replacing the shocks at the same time as the spring and shock bushings. By the time the upper shock and spring bushings deteriorate, the shocks are often high mileage or a decade or more old, so even if the shocks are in good operating condition it often makes sense to take care of them due to the cost/complexity of the whole operation.

Also, while the bushings aren't terribly expensive, as I recall you'll spend enough on them that it blunts the cost of new shocks notably as the shock bushings are included with the new shocks.

I can say that I am very glad I went ahead and replaced my shocks with the bushings as I don't want to have to remove them again for a loooong time. It was a real PITA job. And if I had paid someone, it would have been very expensive. So I did it all at once. After all, the shocks were nearly 20yrs old even though they still seemed OK. And I still sold the used shocks for about $100 since they were rebuildable Bilsteins.

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