1986-560sl: Rear pounding / like there's no suspension
 

It sounds and feels like a total loss of rear suspension yet I am sure it is not shocks or springs. Could it be inside the rear end or have something to do with some type of arm? It seems to disappear for days at a time then suddenly reappear. I took it to an official Mercedes dealer but their mechanics don't have enough experience with older cars. At 160 dollars per hour they would love to have me there for days at a time. They claimed the problem is a rear wheel bearing but it makes no sense to me. Anyone been through this before? Suggestions?

Bouncing rear ends on those cars are due to dead accumulators in the self leveling rear suspension. The lack of nitrogen in the cells prevents the fluid in the struts from moving, so the suspension is locked. Only the tires have any flex, and it will ride HARD.

To check, shove down hard on the bumper with your foot. The car must move up and down on the suspension. If the only thing that happens is that the tires bugle out some, the accumulators are shot and must be replaced -- about $100 each, I think, plus a couple hours labor. Not cheap, but if you don't replace them, the seals in the struts will blow, and those are more like $650 each!

Check the level in the hydraulic reservoir under the hood, too -- if it is low, you might get rear sag and a rough ride, too. Use ONLY approved hydraulid fluid, ATF or power steering fluid will cause trouble.

Peter

I don't think that these cars have hydropneumatic suspension, just the usual shocks, coil springs and rubber mounts.

The mount points are a triangular shaped part above the differential and rubber doughnuts alongside the sides of the car, behind the jack hole (but under the car). If these are bad, I suppose that the rear end could wander. I replaced mine before they did.

I'm almost sure that it is a hydraulic problem. I faced this problem when I over raised the car using the connecting rod (I don't know its name) that are located near the difference. Try to make ur car at a lower level.

All the best : ))..

The 560SL doesnt have Hydraulic suspension. Only the 560SEL has that standard.

well, that and the SEC, 190 16valve and wagons during this gen, but yes, no SL'ing on SL's.

I'd wager some bushing or another is Completely worn out. I would start w/ the shock bushings/buffers. Get it to a reputable indy..they can check out the lower bushing on the rack quite easily. The uppers will be a bit more difficult (Removing some interior trim) but worth it. If this is hitting as hard as you say I would hold off driving the car until it is fixed..


Jonathan