W124 rear end thud on bad surface/low speed

[OM606]

Hi everyone, this is one of the annoying, quite hard to diagnose noise. There's a thud noise at the back of the car. At first i thought it was a bag of tools left in the boot. It's bad when driving over pavement or a rough surface with gravel or some of the very patched roads we have here, particularly when driving slow. It almost sounds like i have a trailer behind the car. Dampers where shot, i replaced them, the car drives smoother but the noise is still there.

I've asked someone to shift the transmission between R, N and D while i was under the car and out of four subframe bushings, i was able to see a slight movement in one of the front ones. The differential mounts aren't cracked or squished but it was tilting a bit either way between R and D, is this normal? Inner control arm bushings are thin but it seems like they are perished, the bolt going through is quite rusty as well. Other bushings look fine. The car drives fine, accelerates straight, brakes straight. However, i think that it doesn't feel as smooth as is should.

If you have experience with the kind of issue with the W124, please chime in!

 

[GP801]

Did you get a really good look at the rear subframe mounts? The usual problem is rust/rot rather a failed bush. Can be quite hard to see but if the dampers are ok the next likely cause is the subframe mounts.

 

[OM606]

Did you get a really good look at the rear subframe mounts? The usual problem is rust/rot rather a failed bush. Can be quite hard to see but if the dampers are ok the next likely cause is the subframe mounts.

Hard to tell, are you talking about rust forming on the metal part inside the rubber mount or the chassis? The chassis has little rust where the subframe mounts to it. I caught that in time when the factory coating was slowly starting to peel off, i sanded it off and it's all solid metal.

 

[ChipChop]

If your car is an estate, an S124, is the self levelling suspension working? Broken SLS spheres and low hydraulic fluid levels caused by leaks can make the rear ends thud over poor road surfaces.

 

[OM606]

If your car is an estate, an S124, is the self levelling suspension working? Broken SLS spheres and low hydraulic fluid levels caused by leaks can make the rear ends thud over poor road surfaces.

Forgot to mention that it is the 93 220E, not the estate.

 

[grober]

My money would be on front subframe mounts of the rear subframe-mounts or body attachments bolt mounts-other suspects would be differential mounts [soften thro oil saturation]----if these are OK that leaves rear anti rollbar mounts/drop links or the central propshaft mounting??