W126 cracked trailing arm. Can it be safely welded? - Page 2 - PeachParts Mercedes-Benz Forum

300D85 · #16 07-17-2010, 07:10 AM

W123 1984 300TD wagon rear trailing arm bushings R&R

Quote:

From what I remember the later W123 chassis used the same 126xxx part number rear trailing arm as the 1st gen W126 chassis. At some point in time (79???) there was a change in rear toe spec for the W123. The early W123 chassis also used the 115xxx part. So, I assume only the toe spec was changed. I doubt it will offer any more negative camber. I guess one could make encentric bolts/washers for the bushing holes.

bolomiester · #17 09-06-2010, 11:53 AM

I was able to locate a used right side trailing arm, and installed it along with new bushing for both sides. We also replaced the original coil spring shims with new ones that are 14mm thick v. the 9.5mm originals, and new Bilstein comfort shocks. The last step was to have a wheel alignment done.

The rear whels now have the same amount of negative camber. I'm not sure it's the correct amount, but it does look right, and the car no longer has a pull to the right.

I took the car on a 600 mile trip a few days after it was finished and, interestingly enough, the car's mileage improved by 1.5 mpg.

Thanks to everyone that offered advice. Welding was clearly not the way to go. As bad as the rust on the trailing arm looked on the bottom, it was far worst on top. Almost like swiss cheese.

The rust thing is a real mystery. It was only this part and the bracket that holds the fuel pump, fuel acumulator and fuel filter that show any sign of rust, and they were both very badly rusted, the car is otherwise rust-free. ????

JamesDean · #18 09-06-2010, 03:32 PM

not to threadjack, but here is a picture of the trailing arm on my on 82 SD, I think its weldable for a repair, theres two small holes developing on the bottom of it. I figure one can spray something up in there, then weld over?

http://i.imgur.com/E9ksf.jpg

Stretch · #19 09-06-2010, 03:47 PM

Quote:

Originally Posted by JamesDean

not to threadjack, but here is a picture of the trailing arm on my on 82 SD, I think its weldable for a repair, theres two small holes developing on the bottom of it. I figure one can spray something up in there, then weld over?

http://i.imgur.com/E9ksf.jpg

This probably isn't what you want to hear but you'd probably have to take it off to repair it anyway. If you decide to do so don't be super careful with it:- take an angle grinder with a wire brush attachment to it and see if the holes get any bigger... there may be more welding needed than you think (but I hope not)

bolomiester · #20 09-07-2010, 07:57 AM

Quote:

Originally Posted by JamesDean

not to threadjack, but here is a picture of the trailing arm on my on 82 SD, I think its weldable for a repair, theres two small holes developing on the bottom of it. I figure one can spray something up in there, then weld over?

http://i.imgur.com/E9ksf.jpg

When we got mine out the rust was far worst on the top than the bottom. I can weld fairly well, but I wasn't confident my work would be good enough so I got a quote from a local guy with a great reputation. As it turned out his price to fix up the bottom was almost as high as replacing it was. Which is why I decided not to weld. Of course, as it turned out welding would only have fixed half the problem, so it's a good thing I went with a replacement.