R129 500SL knock from front end - help

[Deleted member 11979]

My 1991 R129 500SL has developed a clonk noise which can be felt through the steering when under certain conditions. The noise is coming from the front passenger side of the car.

When the car "twists" it happens, i.e when reveresing down our drop kerb with a bit of lock on for example. It doesn't happen at speed, or when both wheels are up and down, i.e speed tables. It doesn't appear to happen on potholes.

You can hear it happening from inside and outside the car.

I have had 2 garages look at it now, both have checked all the bushes, springs, top mounts, shocks and ball joints, all is fine.

The first one replaced the anti roll bar end bushes but this did not help. The steering damper is fine, the wheel nuts are done up etc.

Does anyone have any ideas what it could be?

Any thoughts would be greatly appreciated as it is getting annoying, thanks a lot in advance

 

[bolide]

On a W124 it's the inner ARB bushes that wear out and I'd expect the R129 to be the same

The rubber of the bushes tends to wear away the powder coating on the ARB so bushes can be a loose fit & that's what makes them clonk

Nick Froome
www.w124.co.uk

 

[Deleted member 11979]

On a W124 it's the inner ARB bushes that wear out and I'd expect the R129 to be the same

The rubber of the bushes tends to wear away the powder coating on the ARB so bushes can be a loose fit & that's what makes them clonk

Nick Froome
www.w124.co.uk

thanks nick,

these were tested with the trusty steel bar and there was no movement found apparently, could they be worn and not move?

 

[bolide]

At £4 each it's cheaper to replace them that to test them. At least then you'll know

Also check that the ARB hangers haven't come loose or snapped - I imagine it's the same setup as the W124

Nick Froome
www.w124.co.uk

 

[Dieselman]

It sounds like the steering idler bush is gone.

Either waggle the steering violently from side to side with a helper watching the steering gear on the passenger side, or draw out of a right turn junction with some lock on and violently pull the wheel back to straight. If it clonks it's probably the idler.

To test ARB joints grab the car from the side as high as possible and violently rock it. This will show any weakness.

 

[Deleted member 11979]

Thanks for your help chaps, as it turned out it was one of the diagonal bars that "hold" the car and stop it from flexing, one of the bolts was loose!!