Diagnosing front-end wobble on '89 300SEL - PeachParts Mercedes-Benz Forum

Brett24 · #1 03-07-2011, 01:04 PM

I'm having a spot of trouble diagnosing the cause of a front-end wobble on my '89 300 SEL.

It started as a mild wobble, but has progressed (over about 3-5 thousand miles) to the point where the car is essentially undriveable. The wobble hits around 50-55 MPH, then doesn't go away again until I slow down to about 30-35 MPH. As I live in a rural area, and exit my driveway onto a highway, I need highway speeds every time I leave the house.

So far I've replaced wheel bearings, tie rods, and (very worn) guide rod bushings. I have six mounted tires for that car, so I've tried all combinations of tires on the front. Nothing, so far, has seemed to help. (Taking it to a front-end shop is very much an admission of defeat for me, so I'm not ready to do that yet.)

The boots on lower control arm ball joints are in bad shape and the ball joints are visible and rusty. But doing a test I found (while searching the archives) that checks for ball joint play, the ball joints appeared to be without play/slop.

Any thoughts, pointers, ideas?

Also, I have a 12-ton shop press, and spring compressors. Is there anything else I would need to be able to replace the ball joints? (I've never done that job before.)

Thanks.
Brett

Hit Man X · #2 03-07-2011, 04:52 PM

Check your driveshaft and flex discs.

Brett24 · #3 03-07-2011, 05:33 PM

Quote:

Originally Posted by Hit Man X

Check your driveshaft and flex discs.

Thanks. I'm not following how a drive shaft issue would cause a front-end wobble. (Might also be described as a violent "shimmy".)

Brett

Hit Man X · #4 03-07-2011, 08:30 PM

Because one of my cars did it and the entire front end shook... the two pieces of the driveshaft were not in relation to one another when I had it removed to be balanced (I love PO's

)

francotirador · #5 03-07-2011, 08:43 PM

"It started as a mild wobble, but has progressed (over about 3-5 thousand miles) to the point where the car is essentially undriveable. The wobble hits around 50-55 MPH, then doesn't go away again until I slow down to about 30-35 MPH."

I had those exact symptoms in my 1990 300SE. I had new Michelins mounted and balanced and the problem disappeared.

Hirnbeiss · #6 03-08-2011, 07:09 AM

ditto on the wheel balance.

S-Class Guru · #7 03-08-2011, 08:22 PM

Idler arm kit?

DG

mak · #8 03-10-2011, 12:24 PM

if it is not the drive shaft flex couplings or the center mount then as mentioned may be the idler arm or the front suspension bushing requiring a thorough checking.

Brett24 · #9 03-12-2011, 12:55 PM

Thanks guys.

It turned out to be the simplest of the possibilities suggested. I had the wheels balanced and the problem disappeared.

I didn't realize my wheels were so out of balance (perhaps I threw a weight or two). And I didn't realize that being out of balance could cause that level of handling difficulty.

Brett

Randy · #10 03-21-2011, 08:39 AM

The W126 has a damper on the steering linkage, and it needs to be effective, or this is the result: a violent wobble which will appear out of nowhere and scare you. Not particularly expensive to replace as I recall. I hope this helps you.