My 126 ('91 300SE) kinda chewed up my new rubber doughnuts that hold the end of the front swaybar to the upper control arm.
I noticed the sway bar shaft was pretty rough under the old doughnuts I removed. I really didn't clean up the bar, I assumed the new doughnuts would stick to it. However, it seems the new ones are chaffing on the rough bar, and getting reamed out.
They look pretty rough and have a lot of powder, and groan loud after 4k miles.

So, should one clean and sand the bar to make it smooth, or was it intended to be rough so the rubber would adhere rather than slide on it? It looks like rust build up, but maybe it was always intentionally rough. I assume I should not use lube of any kind, except maybe the rubber slide lubricant that dries up after an hour or so?

oh, everything else is in good shape - ball joints, control arm inner bearings, etc.

Tks,
S=Class

The sway bar should be clean. A problem comes in removing the paint. The bar should be covered (protected) as much as possible to prevent surface cracks that ultimately mean a broken bar. It is my understanding that the bars are covered in a durable epoxy paint.

When I replaced the front bushings on a 300SD I had to clean the bar quite a bit around the bushing contact area. I used a tough plastic scrubbie and worked at it quite a bit.

I did lube the bushings with a light coat of silicone spray. They never groaned. I believe the bushings, when installed at the factory, if they are the older style, did have some silicone on them.

The bar should not be "gripped" by the two big rubber bushings but instead securely locate the bar and allow movement.

I noticed in replacing the 124 front bar bushings that they had a new almost corrugated type of inner material running in parallel to the bar to facilitate movement.

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Thanks. I'll clean it up and try again.

These MB bars are very unusual in the way they slide through the bushings, instead of the traditional 'bolt type' endlink setup. This design sets the bushings up for a short lifespan, but at least they are cheap and easy to replace. Seems like greasable polyurethane bushings would be ideal here.

Had the same situation on my 124.

Very rough surface on bar and lots of wear on the rubber.
Figured the new bushings would not last long like that.

Cleaned the bar up as best as I could with emery cloth, and applied a silicone grease, which is compatible with the rubber.
Recently examined, and found bushings are still in good shape after 15k.

__________________
1986 300E 5-Speed 240k mi.

Thanks for the info, guys.
But the plot thickens.......
The reason I checked the bushings was due to a loud groan coming from that area when I bounced the car. I could feel the vibration in the control arm as I pushed the car up and down,
So when I removed the control arm and found the somewhat worn bushings, I figured I had the culprit. Well, I slicked up the sway bar and greased the old bushings with silicon grease and put it back together (until i could get new bushings) and it still groaned! I even backed off the bolt in the end of the swaybar and sprayed silicon on the bushings, still groaned.
While i had the control arm off, I checked the almost new inner bearings, they look great. The ball joint is 13 years old, but was very tight - almost can't move it by hand. That's why i left it on when I rebuilt the system last year. But now I'm wondering if the ball joint is the bad guy????
And of course, it's the one that is part of the entire control arm, and costs $100!

Think I'll pull the ball joint /arm back out and move the joint around a lot, and shoot some grease under the boot (perfect boot) and see if that makes a difference. I should be the expert on upper arm removal after this weekend.

Grrrrrrrrr.
S-Class Guru

Could it be a shock? Try not to end having to replace the sway bar. As you know for the 126 it passes between the real and false firewall. I had to replace mine and it was a horror movie.

If it's the ball joint, it will also groan when you turn the wheel. If it only groans on up and down motion, it's the bushings or the guide rod bushing on the firewall.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I just bought my silver C230, with 39,000 kms.

I am hearing a wierd noise in the front end whenever the car takes a slight up or downward slope. The dealer said it is the ball joint and just has to replaced. Is this possible for a car with this mileage?

Please enlighten me so I will not get screwed again by this dealer.

Thanks