My 84 300 SD had some clunks in the front end and was a little drifty so I decided to rebuild the suspension. Since I intend to keep the car for a long time and it is not much harder to do it right, I decided to do the complete job. I called up my buddies in the local Mercedes Benz Club and got access to all the tools I needed to do the job.
Everything was taken out and all parts have been replaced with top quality stuff (lemfoder, febi, bilstein)...Ball joints, track rod mounts, subframe bushings, upper control arms, drag link, idler arm kit, tie rods, lower control arm bushings, shocks, etc. While I had the car up on stands, I also replaced both rear subframe mounts and the differential carrier using the Stu Ritter/Richard Easley method. When I finished, I took it to the dealer and got a 4 wheel alignment done by the guy who does Mercedes Benz alignments all day.
When I picked up the car, I was surprised to hear that it "barely came into alignment". The problem in the front end is that he was only able to get 8.1 degrees of castor on each side ( the range is 9.5 to 10.5) before the the track rod ran out of threads. (toe and camber are OK) The old track rods were bottomed out too, but a printout from an alignment I had done a couple of years ago shows readings of 10.6 and 10.8 for left and right castor. I can see no evidence that the car has ever been in any sort of major collision.
The car rides much better now but my goal was to get the car to ride like a new car and I am not there yet because the wheel doesn't return the way it should which makes it harder to drive. In the last couple of days, I have been looking at 126s I see to determine if it is normal for track rods to be adjusted down all of the way. The two I have seen so far have both been adjusted to the point that threads are not visible.
My question is...should I pull the track rods and mounts out on both sides and grind a quarter inch or so off the rods so that I have some adjustment room? It wouldnt be too tough to do now that I have already been there and have access to a klann spring compressor. Maybe 3 or 4 hours total time and no out of pocket expense except for another alignment.
My other alignment issue is with the rear end. The new subframe mounts and differential mount make it ride better but my total toe reading is -.12 degrees which is outside of the specified range of .25 to .75. Does that mean that I need to replace the trailing arm bushings and if so should I use the regular ones or the eccentric ones? What is the best way to replace the trailing arm bushings? It looks like I could take out the shock, squeeze down the spring but not remove it, unbolt the trailing arms, pop out the bushings and then jack them back into place and bolt them back in. Is that right or do I need to remove the entire trailing arm which would be a much tougher job?
Has anybody out there been through this? Let me know if you have any ideas

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Tom Hughes
St. Louis
84 300SD
92 300D
86 300SDL

Tom:

FWIW. I just finished a complete front end replacement identical to yours. My track rods were also adjusted to the point of no threads showing bothy before the new parts were installed and after. However, the car was and is within the alignment specs. (1990 300SE)

I am just about to tackle the rear suspension, inlcuding the trailing arm bushings, so I will be watching your thread here for good tips.

Jon

I had forgotten about this thread. When I did not get any responses I figured that I was on my own.

My trailing arm bushings looked pretty good and it looked like the only way to replace them was to drop the rear suspension (which is a lot of work) so I did a little more investigating. I did not have a reading of rear wheel toe in before replacing the the subframe and differential mounts (because the 4 wheel alignment from the tire store really wasn't a 4 wheel alignment...you have to go to the dealer for that) so I am not sure what effect the new rear subframe mounts and differential mount had. To see, I put a floor jack under each side, raised the car a couple of inches, measured the toe of the wheels with a tape measure and discovered that the rear wheels toe in as the car is raised. My plan now is to remove the springs and install thicker pads and also to replace the rear shocks. I think that will solve my rear toe in problem.

The front end castor is only 2 degrees short so I am living with it. Every time I see a 126 in a parking lot I peek underneath to see if there are any threads left. 60% of the cars I have observed do not.

The car rides and handles like a new car now so the job was worth the effort!

__________________
Tom Hughes
St. Louis
84 300SD
92 300D
86 300SDL