MB's current rear suspension is a five link design -- spring link on the bottom perpendicular to the centerline holds the wheel carrier (hub with bearing and brakes) on a bushing. The spring sits here, top end is on the subframe. Camber link is the same on the top. In the center of the wheel carrier, front edge, there is a tie rod with normal tie rod end and an eccentric bolt on the other. Front edge top to middle of the subframe is the torque link, from the bottom edge of the wheel carrier to the front of the subframe at about 25 degrees is the thrust link.

These five links allow the wheel to move nearly straight up and down but not side to side or to turn in or out. There is some camber change with height to compensate for body roll in turns.


The torque link prevents the wheel carrier from laying over at the top toward the inside under torque loads (acceleration), and when the rubber bushing in it goes bad, the wheel carrier DOES move. This causes torque steer -- car pulls to the right under acceleration, and the wheel carrier will flop over the other way (tilted out at the top front) when yoyu lift your foot of the pedal. When the bushing gets pretty bad, the thumps when you do this. It will get fairly dramatic, with the body shifting on the suspension eventually.

No way the tire shop did anything. Probably the rubber finally tore while the car was on the lift with the suspension hanging down for a while. You will see shreds of rubber from the bushing hanging around the bolt and nut if they are bad.

While not exactly difficult, replacement is a PITA due to limited room -- you have to screw a nut off about a quarter inch of fine thread one flat at a time, and it's a locker nut, won't spin freely until it's nearly off. You also must have a floor jack and substanital jack stands.

Also, as I said, if one is bad, the rest aren't far behind, I'm fairly sure part of the thump (if not all of it, for that matter) is bad differential mounts (do you have loud shifts, with a bump in the read on gear changes?) and the subframe mounts are probably going. You can check the diff mounts by watching the bolt while you jack up the rear of the car by using a floor jack under the diff -- if the bolts move very much in the hole, they are shot. Diff mounts are on the rear of the diff, about centerline, plus one vertical one in the front.

I've got all this work scheduled on the 87 myself later this fall, plan to remove the subframe to get better access since I need to do all four mounts, the rest of the links, and diff mounts.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!