Cracked Control Arm--Not much time - Page 2 - PeachParts Mercedes-Benz Forum

engatwork · #16 09-13-2006, 09:47 PM

Totally remove the control arm to get it out of the way. The area will have to be cleaned, prepped and then welded. You want someone that can give you what is called a "full penetration" weld

. Let the welder tell you how he wants to weld it. Done right it will be as strong as it was prior to cracking.

pwogaman · #17 09-13-2006, 11:30 PM

Agreed - you need a good clean full penetration weld. Clean - without impurities or inclusions. Full penetration - welded throughout the crack. Add in good for lack of porosity. Structural welding should be done by a trained / certified professional with the right kind of equipment using a shielding gas, such as a MIG welder. Don't let some around the corner amature welder attempt it. Bit the bullet and pay to get it done correctly. If done right it will be stronger than it was coming out of the factory.

Each clunk you've been hearing since February is a fatigue cycle which will eventually lead to overload and sudden failure.

Another option for you is to replace the subframe from some place like this:

http://www.mercedesdismantlers.com//Photos.html

http://www.mercedesdismantlers.com//prod.html

http://www.mercedesdismantlers.com//mercedes,wholeyard.html

http://www.mercedesdismantlers.com//mailform.html

I've dealt with them before for various trim parts and have been to their yard and have found them to be quite reasonable.

TwitchKitty · #18 09-14-2006, 11:44 AM

You can find a cheap replacement. If it cracked due to stress I would be concerned that it is "tweaked" in other ways as well. It failed once and didn't kill anyone. Why give it a second chance? On the other hand I could weld it myself and be confident that it would not break in the same place a second time.