Rear suspension knock/clunk from pushing on bumper
 

Trying to diagnose a rear suspension clunk that I'm getting when going over bumps... I had some suggestions on another post but since the other post was regarding all sorts of noises/issues, I thought i'd start this thread in case it helps someone out with this specific item.


Basically I noticed the clunk when driving, but when the car is in the driveway and I push down on the rear quarter panel or bumper, it knocks on the upward swing of the suspension. Previously it was suggested that the shocks might be gone or I might have deteriorated bump stops...but this noise is coming when the car is at the upper most location (farthest away from the bump stop).


Should I be looking at subframe bushings, or is there any particular area that is common on the vehicle? Just noticing this on the right side at the moment...


Pete

Hi Pete,

The most common cause of knocking sounds in the rear suspension, especially if it sounds as though they are coming from the back seat, is deterioration of the upper rear shock bushings. The primary culprit is the rubber "tophat" guide bush, Part 14 in the diagram below, which is supposed to isolate the shock rod from the steel upper mounting plate, Part 7 in the diagram. When that little rubber bush deteriorates, it allows the shock rod to knock against the inside hole of the mounting plate, and the metal-to-metal contact is clearly audible.

http://www.jaguarclassicparts.com/il...es/mh4585b.jpg

Here's the link to the diagram with part identifications and part numbers:

Damper and Spring-Rear - Parts For XJ6 (2.9, 3.2, 3.6, 4.0) from (V)500001 to (V)667828 | Jaguar Classic Parts UK

Since you have to remove the shock/spring assemblies and compress the spring in order to replace the guide bush, you should replace the other bushes as well since they also deteriorate: Parts 13 & 15, plus the large foam "donut" spring isolator bush, Part 5. If your shocks are no longer damping well, they're still available, often at reasonable prices if you shop around (don't forget ebay).

The photos at the links below will give you an idea of what's involved:

Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page

Cheers,

Don

Don,


Thanks for your help on this - pulled my strut out today and the three orange spongy bushings were virtually nonexistent.. just a big crumbling mess.


Something I noticed... I think the order of assembly is incorrect ont he last photo over at jag lovers link. If you look at photos 10 and 11 and compare it with 12, the order of the orange bushings changes. I verified 10 and 11 are ok, when compared with the part numbers/illustration in the parts manual.... but the orange bushing with the bigger hole should be on *top* of the upper spring mounting plate...and the one with the smaller hole (Which has that strange convex/concave contour to it) should be on the bottom. Photo #12 seems to indicate it's the reverse. I was looking closely at these as I was trying to figure out which way the convex bushing (CBC225455) should be pointing, with the concave end pointing up, or down...as it basically sits between a flat guide bush (CBC2933) and a flat washer (CBC5431) that came with my shock.


The photos have been a big help, but I just wanted to point this out in case it confused anyone else..


Pete

Hi Pete,

You're right! The new bushings shown at the top of the photos are not in the correct order. I believe the order of the old bushings is correct in photos 9, 10 and 11. I don't recall even considering the importance of laying out the new bushings in the correct order - I was just trying to show what they looked like in comparison to the old bushes. Oh well!

Thanks for noticing this and posting the correct info, and I'm glad you got your rear end sorted!

Cheers,

Don

Just installed a rebuilt differential and Bilstein shocks in my 88!

Hi R-Rocks,

Welcome to the forum! Congratulations on installing the rebuilt diff and new shocks on your '88. What were the symptoms that prompted you to replace the diff?

Cheers,

Don

I could hear it getting worse as time went by, it got to the point if I grabbed the base of the seat belt I could fill the vibration. A friend blocked the car up on his lift, we ran it, you could hear it with the stethoscope. I checked and greased all Ujoints, carrier bearing, checked the fluid in the diff. I thought maybe wheel bearings but in the turns the noise did not change.