1979 450SL "clunk" from rear end when turning right

[mwalsh]

Anyone know what this might be before I break down and take it to the shop:

Loud clunk, which sounds like the whole back end of the car is going to come apart. Happens with sharp right hand turns (or swerves in that direction), plus when backing out from the driveway.

Tried getting the back wheels up off the floor and putting it into reverse, sound is not duplicated this way. Nor when jumping up and down on the back bumper. Nor when pushing on the car's rear to get the suspension to move laterally. It's quite literally only when the drive train is under load and with the aforementioned movements.

Nothing is obviously loose or worn out back there when I look underneath the car.

I see two (what look to me like) CV joint type axles out back instead of a banjo type. If this type of noise was on the front end of a FWD car, I'd immediately start thinking in terms of a CV problem, or perhaps wheel bearings. Do you think I might be on the right track here?

[Emmerich]

I had something similar in my 6.9 except it was turning left. Only did it after running at high speed, and then slowing down and turning tightly.

My turned out to be a failure in the differential, a pin had worked its way out and was being ground down by the gears slowly, under certain load conditions.

Not a common thing.

[woolf]

Originally Posted by mwalsh

Anyone know what this might be before I break down and take it to the shop:

Loud clunk, which sounds like the whole back end of the car is going to come apart. Happens with sharp right hand turns (or swerves in that direction), plus when backing out from the driveway.

Tried getting the back wheels up off the floor and putting it into reverse, sound is not duplicated this way. Nor when jumping up and down on the back bumper. Nor when pushing on the car's rear to get the suspension to move laterally. It's quite literally only when the drive train is under load and with the aforementioned movements.

Nothing is obviously loose or worn out back there when I look underneath the car.

I see two (what look to me like) CV joint type axles out back instead of a banjo type. If this type of noise was on the front end of a FWD car, I'd immediately start thinking in terms of a CV problem, or perhaps wheel bearings. Do you think I might be on the right track here?

Sounds very much like a drop-link from the rear sway bar has broken - quite a common problem and easy + cheap to repair. the link conects the end of the rear sway bar to the wheel hub and when it fails the sway bar can touch the wheel - makes a horrible noise!!!

Remove the wheel (probably the right hand one) and you'll see the problem staring at you.

[pwogaman]

Try rocking the car from side to side. That is one way to assist you in diagnosing the drop link (part number 115 320 15 89). It connects the sway bar to the trailing arms at the inner hub. The sway bar is pictured as the item you see closest to you in the bottom picture leaning over the edge of the pallet. You will only need two 17mm open end wrenches to replace it. While you have to remove the wheel to get to it, you don't have to compress the spring or anything like that. Use caution when jacking the car because you will need to stick you head in the wheel well to see what you are doing. In other words, don't just use the trunk jack without any other support to keep the body from dropping if the trunk jack should give way.

Here is a link to the part if you find that it is the problem: http://catalog.peachparts.com/ShopByVehicle.epc?q=1979-Mercedes--benz-450sl-Suspension&yearid=1979%40%401979&makeid=63%40%40MERCEDES-BENZ%40%4063%40%40MERCEDES-BENZ%40%40X&modelid=6280%3AMBC|1537%3AED|10000065%40%40450SL&catid=241464%40%40Suspension&subcatid=241475@@Sway+Bar+Link&mode=PA

[mwalsh]

Thanks guys. I'll check into the drop links first, since that seems like an easy and cheap fix. Are there any recommended torque settings for the replacements?

Also. there are rubber bushings on that sway bar, held in by a U shaped bracket. My experience with the same bushings on the front sway bar is that they hold up pretty well. But is there a part number for the replacements on the rear, just in case I do some "might as well" repairs?

[pwogaman]

Rubber bushings are unlikely your problem.

[mwalsh]

Pleased to say that you were right. Passenger side one had broken away at the hub end.