450 SLC Suspension Drag Link???

I have had my mercedes in several times for a "clunking noise" in the rear end on acceleration. It has been diagnose as a faulty "drag Link" by more than 1 repair facility. I have had the work done on several occasions. The noise will dissapear for approximately 6 months and resurface. I seem to be in a "fix the symptom not the problem situation" My question consists of this. #1 what is a drag link? Where is it located?? And what could cause it to.....
Also, what is the clunking noise - I see no rub marks on the drive shaft - I have replaced universal joints - rear differential and axles have all been gone through with no damage found. rear coil springs and shocks have been replaced. Help!
I am sick of paying for the same repair. Three times now, and I still dont know what a drag link is......

[Michael]

Make them show you what it is!! As I understand it, a drag link attaches to the rear diff. from the rear frame/subframe, and is responsible for keeping the diff from rotating. If it's clunking, there's play in there somewhere and the drag link replacement seems to quell it.

Perhaps you need to go a bit deeper and determine why the drag link is being stressed so much? Perhaps there are some other bushings that are past their prime?

[This message has been edited by Michael (edited 09-13-2000).]

[79450sl]

I had the same type of sound that you are describing. While under the car doing some unrelated things, I noticed that the rear sway bar was not sitting evenly. What it ended up being was a broken sway bar link. The sway bar would bang into the inside of the rear rim.

Might want to check that your sway bar links are still intact.

Just my .02

-Rich
'79 450 SL 185K

[Gilly]

The drag link is a front steering component, it connects the Pitman arm (on the steering gear box) to the idler arm.

Gilly

[dmorrison]

As Gilly pointed out there is no drag link in the rear suspension. It is a front suspension item. Lets figure out what your having replaced and why its not solving your problem.

The picture below is your rear suspension. which unit are they replacing?

Items that could cause the "clunk".

Item nummber 1. Your rear shock absorber may have failed internally and is causing the noise. When was the last time they were replaced or tested? Check the mounting bolts.

Item number 18. Your rear differential mount. Its rubber and may be worn.

Item Number 2. The sway bar links do wear and break. Check these and the sway bar mounts.

Item number 17. Rear axels. they do wear and can cause noise. Usually a grinding noise. Are the rubber boots on the axels leaking or torn?

Item number 4. these are the trailing arm bushings, 4 in all. they do wear and cause the suspension to not move correctly.

Item number 9. Your subframe mounts. Do wear but not familiar with a "clunk" with the subframe bushings.

Item 12. Flex disks. Can and do wear. A very hard rubber laminate. A visual inspection will tell you if they have come apart.

Item number 14. This is your drive shaft center support. This can cause a clunk. It is a large rubber donut that holds the drive shaft in the center of the bearing assembly. It does wear and can be replaced. Usually the sound is a multiple clunking sound as the driveshaft is moving out of center as you accelerate. Again a multiple clunking sound while accelerating.

Other things that can cause the clunk would be the differential internals. This means taking the differential apart and looking for wear in the gears.

One additional item. At the tip of the coil spring is a piece of rubber hose. My 300Td had these. I'm not 100% sure about the 107. I figures they were put on the spring to prevent any noise from the spring hitting the spring perch in the trailing arm. Have your coil springs ever been removed? If so and the rubber hose not replaced it could be this. If they have never been removed then I would not worry about this.

Dave

[dmorrison]

Item number 3 is the front drag link. Unless you have steering in the rear suspension, you will not have a drag link back there

Dave

[Gilly]

As Gilly pointed out there is no drag link in the rear suspension. It is a front suspension item.

As I pointed out, it is a STEERING component, nothing to do with the suspension at all.

Gilly

[zeggate]

There is a sway bar link in the rear and it can cause noise if it is broken.See Sl forum (107 Sway bar fix)

[britojr]

Hello from Brazil
I am trying to find a rear suspension part but I was unable to find it nowhere
also diagrams and papers do not show it.
The papers above also do not show it too
It looks like a modified stabilizer with big 2 bushings.
Does anyone knows this part??
450SLC YM 74 euro

tks a lot