most likely rear bushing - thrust arms in particular, but you might as well replace them all if your car has 100k miles or more. Just replaced the thrust arms on my 16v and the bushings were GONE. resulted in considerable caster and toe-in changes under acceleration and deceleration. MASSIVE amounts of rear-end steering and a handful to drive in the wet.

whenever you have one end of some thing fixed, the free end will move in an arc. This is counter productive to the goal of allowing suspension articulation while not affecting caster, camber or toe because allowing lateral movement of the wheel as the suspension compresses and rebounds would induce rear-end steering. one way to fix the problem would be to allow the component which connects the fixed point and the free end to tlelscop, thereby eliminating the arc. since this is usually an axleshaft, telescoping is out of the question. mercedes-benz decided to go another route and designed the 5-link suspension.

in very basic terms, the mercedes-benz 5-link suspension uses a modified double wishbone design: 2 a-arms are located - one on top and the other below. these a-arms are then cut apart to provide 2 links each. the arms are all of different lengths and control the caster, camber, and toe.

the 5th link is the thrust arm which eliminates the lateral movement of the wheel to about 1/16th or 1/32 of an inch. the issue of lateral movement which occurs is dealt with by using the rubber bushings.

the bushings in the 5-link suspension are what allows the required play to occur in the system while keeping the track (the distance from the centerline of one tire to the other) the same.

This is why the car is so predictable in handling and why the bushings wear out quickly. this is also why the bushings are sold as a unit with the control arm AND this is why the heim-jointed control arms aren't the greatest idea on a street bound MB. all the stresses generated are no longer absorbed by the bushings and wind up being transferred to the subframe and chassis.

you can expect to find metal fatigue on cars with the aftermarket suspension links in a few years.

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'94 W124.036 249/040 leder; 8.25x17 EvoIIs
'93 W124.036 199/040 leder; 8.25x17 EvoIIs, up in flames...LITERALLY!
'93 W124.036 481/040 leder; euro delivery; 8.25x17 EvoIIs
'88 R107.048 441/409 leder; Euro lights
'87 W201.034 199/040 leder; Euro lights; EvoII brakes; 8x16 EvoIs - soon: 500E rear brakes
'70 R113.044 050/526; factory alloys; Euro lights