when i pass over a pothole i ear a clunk from the rear of my XJ40, i think it comes from the passenger side. the rear shock absorbers have been recently hoverhauled, maybe its a bushing… which are the most common issues of this kind? i would like to diagnose the problem before going to te mechanic, so i can bring the spares to him .
andreal1967 …
A solid clunk (not a rattle or clink) from the rear of the car going over a bump or pothole is almost always caused by bad upper bushings in one or both of the rear shock absorber assemblies. I know you say that they’ve been “recently” overhauled but these cars are notorious for this problem.
The trouble is you can’t reproduce the sound of bad shock bushings by pushing down on the rear of the car and you can’t see the damage unless you remove the shock absorber assembly and take it apart.
The two isolators #15 and #5 or the hard rubber guide bushing #14 are almost assuredly your problem. When these start to deteriorate it allows the metal sleeve to bang against the side of the hole in the top of the spring/damper mounting (top hat) when the spring is compressed and then abruptly unloaded. One of the most (if not the most) problem with these cars … right up there with broken door handles.
Almost guaranteed that all 3 of those bushings weren’t replaced or they were assembled incorrectly.
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Thanks a lot, so what should i order? is there a kit that can buy somewhere complete of what my mechanic should replace?
Unless you remove the assembly first and check, you will have to find out what parts were replaced then order the remaining pieces. There are several possible parts that could have failed, one that could involve welding if damaged, part #7 in the illustration above.
andreal1967 …
Is your car converted from the rear hydraulic self-leveling system to standard shock absorbers ?
The three “perishable” parts #5,14 and 15 are readily available and aren’t that expensive. So considering the time and effort required to remove and take apart the shock assemblies I think it’s false economy not to always replace them whenever you have everything apart. But that’s just my opinon.
There was actually a different “spring/damper mounting” (top hat) #7 used on the self leveling system
than used on the standard shocks, two different part numbers The ONLY difference is the size of the hole at the top. The SLS hole is slightly larger than the standard one. The trouble is that very few people change this part when doing the conversion and this allows the top stem of the new shock absorber to move around a little bit and over time enlarging the hole which then eats up part #14. And this metal on metal causes the loud CLUNK when going over a bump.
looking up into the top hat part #7
Part #14.
While it is true that most metallic clunks from the rear of the car usually come from worn shock bushings it is not always the case, and considering you have recently had both shock absorbers overhauled it would make sense before you begin ordering parts to check the fulcrum pivot bearings for play, and also both ‘A’ frame bushes, both can cause a noticeable clunk or knock when driving over a rough road or pothole if they are worn and are much easier to check and therefore rule out.