I'm the second owner of this 420SEL with 88K on the odometer. I live ij Billings, MT and unfortunately have only one Benz mechanic that I have any faith in! Even then, he makes me wonder how well he follows actual Benz repair procedures! I just replaced the upper control arm and track rod bushings as well as front and rear shocks. Had the rotors turned and pads replaced also. With all this, I still hear and feel a clunking sound from the area under the drivers feet during certain turning and small bump situations. Question is this: Do I finish the front end job by replacing the lower control arm bushings and possibly the steering knuckle? I dread the cost and hassle of removing the front springs!!
Appreciate any and all of your expertise!
respectfully,
Michael

The 126 and the 123 use the same lower balljoints. Both have to extricated with quite some force, and the new ones must be put in with a special tool to press them back in. Figure about 2- 2 1/2 hours. The only mechanic that you have faith in ought to do this job.
hope this helps -Larry

Btw, never turn Benz rotors, always replace!! They aren't that expensive for the 126.
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03/83 300D 184k
07/73 280 160k

[This message has been edited by Larry Delor (edited 05-16-2000).]

Larry,
Thanks for the quick reply!
As for the rotors, is there not a small amount that you are able to turn and still stay within tolerances? Haven't had a chance to reference my service manual for the exact amount.......but I have heard both sides of the arguement, i.e., to turn or not to turn!
As for the clunking sound.are you recommending that I do point a finger at the lower ball joint?
respectfully,
Michael

Harpman,

I have been told that the rotors are manufactured with only about 40 thousandths of excess material. Several years of use and one turning would bring you right at, or under minimum thickness. Once you get that thin, heat build-up can quickly warp the rotors, giving you vibration and shake when stopping.

Once under the minimum thickness you also stand the chance of a catastrophic failure of the rotor. Example: I knew a mechanic back in Texas, who was short on funds, he needed brakes and the front rotors needed to be turned. He almost got the grooves out, but the rotors were already under minimum. Being short on cash, he used them anyways "until next payday". We had a good rain storm, he'd been driving to work, hit a Houston puddle, and the cold water making contact with the thin rotors caused a catastrophic separation of the rotor at the hub. The front tire continued down the road, while his bumper ate pavement.

Now I'll admit, I had no idea MB rotors were built to such close tolerences, but thanks to this board I do now.

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Mike Tangas
73 280 SEL 4.5

[This message has been edited by MikeTangas (edited 05-18-2000).]

Mike,

Was this an MB that lost the front wheel upon rotor failure. I can't understand how this could happen. The rotor is sandwiched between the wheel and the hub.

Larry

Have you check your brake support joint at front axle usually joint loosed will cause problem just like your's. hope this help
part number is 126 330 11 35.

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MB STARS Master Guild Technician,12 years MB tech
6 years independent shop owner

Larry,

No the disc separation was not from a MB, but it was a real life incident with a mechanic I knew. The car was a 71-72 El Dorado or a Tornado, can't remember which. It was about 75 when he turned them down to far. There may have been more to it that caused the wheel to come off, but the separation of the rotor started the chain of events.


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Mike Tangas
73 280 SEL 4.5