Originally Posted by envoy_to_the_Stars
I have a 1972 280SEL. It has AccuAir air-ride suspension, and sits about 1.5" lower than factory ride height when driving. It has recently started making a rather alarming noise from the rear end on hard acceleration, and occasionally when shifting into Drive.
When I hit the gas hard, I hear one loud "Clunk" from the rear end, as if the differential is hitting the underbody of the car. Same clunk is heard when shifting into drive. It seems to me like it's happening when a sudden amount of torque is delivered to the rear end.
It is not noticeable under light acceleration, or in reverse. This makes me think it could be a differential bushing, or something of that nature. I can't see any evidence of anything actually hitting the underbody, but something has to be making an abrupt motion under there to make that kind of noise.
If anyone can offer ways to test and find the source of the noise, or a diagnosis, I would appreciate it! Thanks in advance for the help!
First off: a warm welcome to the benzworld forum.
At least you put : TX and what car you have, that's a great start.
Now I have seen some of these as of late w108 or W114 cars that are lowered , with the rear wheel so crooked, that one think a catastrophic rear axle failure had occurred.
Well, that is probably what you got.
The axles were not designed for these lowered angles.
And even though Mercedes , even 40 year old (or should I say especially those from that age ?) do NOT take any and all abuse.
Now to make a proper long distance diagnosis of your problem, and avoid a 30+ post, ping-pong rally about what it could be, it would probably be wise for you to make a video of the noises (and when they occur) and what kind of strange angles in the suspension (front and back, I guess) we are talking about.
If you're willing to do that much, I am willing to help.
Otherwise it is just too many different possibilities, added to the usual list .
Hope to hear back.