Bad thump from rear suspension

I Have replaced the upper bushings of the rear suspensions (normal not auto levelling) the metal clunks i heard on every pothole have disappeared but now i hear thumps from the rear suspension. My mechanic told me that the shock absorbers have to be changed because they don’t absorb anything :slight_smile:

how can i check the shock absorbers to validate his assumption?

Andrea …

The old fashion way to check a shock absorber is to keep pushing down and releasing on that corner (3 or 4 times) as hard as you can until you kind of get it rocking. Now stop and the corner shouldn’t bounce more than one more time before it returns to normal. If it keeps bouncing the shock is malfunctioning.

While you’re doing this listen for the “thump” noise you’re hearing. If you don’t hear the noise and the car passes the bounce test I’m pretty sure the problem isn’t your shock.

When you say you now here “thumps” is it in the same driving situations that you heard the “Clunks” ?

Hello the weird thing is that before replacing the upper bushing o could not ear the thumps , I ear thumps only when I pass over big disconnection of the road and if I guess right in the extension of the sospension. The only thing the mechanic has done is replacing the upper bushing of the shock absorber that where in very bad shape, and yes, I ear the thump in similar situation of the metal metal clunking noise that now is gone?.

Andrea …

What I found out years ago was that there is a difference in the “Top hat” on the self leveling system and the normal system. Although they are both virtually identical, the hole in the top on the SLS system is slightly larger than the hole in the normal system.

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#7 in diagram named “spring/damper housing” but often referred to as the “top hat”.

Screenshot 2023-05-24 at 6.05.36 PM

Why this matters is that if you don’t change the top hats (or modify the old SLS ones) it allows the upper rod on the shock absorber to move around eventually eating up the bushings and then bang against the top hat which produces the clunking noise.

Either way, bad bushings or bad shocks you’re forced to remove and take apart the assembly. When you do, check the hole in the top of the “top hat” to see if there are signs of metal on metal and perhaps the hole is now slightly elongated.

are you doing an evil knievel trick, getting airborne…good info from others…do the bounce test as suggested, if good - raise the rear end - wheels off so you can see the suspension full dropped - then you can inspect everything, suspension will be noisy when fully extended then when fully compressed after landing

Along with the good advice already provided about checking the function of the shocks and also inspecting the suspension with the car raised, you should also check the condition of the ‘A’ frame bushes, they are probably as old as the rest of the suspension bushes and will cause a thump if they are breaking up. They are number 14 in the diagram.

Also make sure the jack, spare and whatever else you keep in the trunk is “battened down” …many a suspension replaced due to a spare clunking … :wink:

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My experience with running these cars for many years is that it is almost never the actual shock in the rear. It is MUCH more likely that instead it is bad bushings on a good shock.

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Gentleman …

I certainly agree with Steven.

The only way I can think of to possibly check the rear shock assembly for noise (clunk or bump :grinning:) while still on the car would be to jack up the rear end and remove the tire. But because the spring and shock will be fully extended you would also need to jack up the rear wheel hub a bit to unload the shock within the spring. Now it might be possible to reach in and wiggle the shock and see if you hear rattling at the top.

Mind you I’ve never done this but it might work.

My money is still on the upper shock mount and bushings being the culprit.

Tha parts that actually have been replaced, are 12,13,14,15… I see a big bushing number five, maybe it needs to be replaced too. Anyway I bought a couple of Monroe shock absorbers because the rear makes a couple of bounce after pushing…

Andrea …

Since you’ll have to remove and disassemble the two rear shock assemblies to replace the shock absorbers an inspection of the soft parts will tell you what needs to be replaced.

I’d also discuss with your mechanic the difference in the two (normal and SLS) top hats and see what he (or she) thinks about it.

I nearly got caught out like that. I had a grating noise followed by a small thump almost every time I braked, after a few hours checking all the rear suspension components I discovered the clamp holding the spare wheel was loose !

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