[OdlandMB]

Hello, I have a 1978 450 SL W107. I had bought this car recently and when I bought it the person pointed out a clunking in the back end that occurs when you accelerate rather fast from a stopped position. It is both right and left as well as straight forward. He had a used transmission put in a few years ago and it has happened since. The transmission shifts well otherwise and if you slowly accelerate it does not clunk. When I go over bumps, there is no clunking. It clunks about 10 times and then is done. Feels/sounds like the wheels of an airplane as they are being lowered before landing. I have had the car 2 weeks and otherwise love it. Thanks in advance for any advise.

 

[jaymaynard]

I can't offer any advice, sadly; it doesn't sound like a suspension clunk, and that pretty much rules out any suggestion I have.

Edit: Thinking some more about it, it also doesn't sound like anything aft of the transmission in the driveline: I can't think of anything that would cause the noise and then go away once the car has been driven for a while.

Does it do it every time you start driving? How long does the car have to sit for the behavior to return? Does it do it more if it's sat for a long time than if it's sat for a shorter time?

Which end of SD are you in? I'm about two hours east of Sioux Falls. The one trip I took over there in my 560SL, there was just enough of I-90 that wasn't under construction east of Brandon to actually have an 80 MPH speed limit that I could get up to. I was jealous.

 

[OdlandMB]

Thanks for the response. The clunking can happen every time that I stop and go to accelerate. It is very reproducible. Planning to have it looked at by local MB service shop. Just curious what others say so I know if I am getting snowballed or not when the service shop tells me their thoughts. We are In Sioux Falls.

 

[Anovak]

First thing I would check are the flex discs......my 280SL had a similar issue that was resolved by replacing them. I did not see the extent of the degradation until we pulled them off. Then, it was very clear both front and rear flex discs had problems. This is a serious issue and I would not want to be driving the car as if one should fail completely you are looking at major damage at the very least and injury to life/limb at worst! Suggest proceeding with extreme caution until you have had the problem diagnosed and repaired.

 

[jaymaynard]

I had thought that flex discs might be the culprit, but why would it stop making the noise after being driven a bit?

Regardless, that should definitely be checked out.

OdlandMB, what shop are you planning to use?

 

[Weather Man]

When I had a clunk back there it turned out to be a flange hitting a sway-bar link. Happened when I went over a bump. Check your links back there, and the bushings on the sway bar itself.

 

[JN74SL]

I have a clunk back there too, it is the spare tire as I don't have the hold down bolt. Check that before you go nuts