Bad Sway Bar Link
 

Just thought I would show a bad sway bar link vs a new one. My 85D was clunking at the rear whenever I hit bumps. At first i thought my 2-year old Bilsteins were bad. Turned out to be worn sway bar links. Each side was worn pretty much the same. Replaced them and no more clunks.

What was bad about them? The ball joint?

Once the rubber boot is damaged they get all loose and sloppy at the ball joint. The boots on mine were split, not completely off like tobybul's, and they made the rear clunk. The new ones were very stiff compared to the old ones.

exactomundo, compadre!! Thats right... as you can see the boots are gone. Kinda similar to a worn out tie rod end. They were all broken up as I removed the old link. A good way to tell if the link is bad is to rock the car sideways. That action affects the sway bar which in turn moves the link. If the link ball is loose, it will make a creeky-clunky sound.

Its easy to replace the link. Hardest part is that the rear wheel has to come off to get easy access. The top end is held by a 17mm bolt. You will need 2 17mm box end wrenches. One to turn the nut and the other to hold down link bolt on the opposite side. The bottom end will also require a 17mm wrench to loosen the link bolt that is bolted directly to the back of the hub. I sprayed both ends with Knocker Loose (Liquid wrench or WD-40 will work) a day before. I think it made loosening the nuts easier.

I replaced those several years ago on my SD and the rear end "plunk" sound was instantly gone. Mine were beyond shot, I was amazed they hadn't broken apart!

Ditto.....
 

I did mine on the 300D last month.......I think it made a difference in handling, and I had an odd clunk and rattle that I had been searching for for quite some time......found out what that was by accident when I changed these.....

I changed them only because they were cheap (compared to most MB parts) and I was working on suspension......

SB

Yeah, I was getting a loud clunk from the rear end when I made a sharp turn, like pulling onto a street. Turns out one of my sway bars links was broken off completely!!, and the other was old and loose. Easy DIY repair, cheap (like $12 for each) and well worth the time and effort. Makes a huge improvement.:)

Thanks for the heads up. I had assumed they were good if still in one piece. Looked at them when installed new shocks last year. Changed them today and got rid of noise plus improved ride and handling. Feels like a different car. Even my wife thinks so!