The inside part of my W126's rear tires are wearing out to the point that there is an oval-like hole about 2cm long and 0.5cm wide. Could this be bad shocks? I also left the tires a little over pressured at 33 psi. At this point I'm reluctant to drive my car, but am looking forward to replacing the shocks myself...

1. If the shocks are the case, do I have to jack up the car? Jack stands? Any precautions that I need to take? Special tools? Extra Adjustments?

2. If NOT the shocks, could it be anything else? Just normal wear on tires?

I doubt the idea of bad shocks. When I had similar problems, it was due to worn trailing arm bushings. There are two on each arm and it is difficult to see how worn they are until you remove the bolt and lower the subframe. In order to do this, you will need the MB spring compressor and I used 3/4 dr. sockets with a length of 5/16" all-thread, washers and nuts to press the old bushings out and reinstall the new. I used KY to lube the bushings for reinsertion as it is water soluble.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

how is your rear camber and ride height?

if its low, the inside of the tires will wear out. the diff mount usually wears out and can cause the saggy rear end condition. of course there are many factors that contribute like shocks, springs, trailing arm bushing, subframe bushings, but the diff mount is definitely one of them, and is very easy to R and R.

ddd

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

So in this case, it looks like I have to jack up the car? Possibly remove the wheel? KY? MB spring compressor? I looked up the bushings and they are less harsh on my already thin wallet...but buying is the easy part.

Sorry to be newb, just wanna get it right.

You actually pointed out a good one because the W126 DOES sit quite low in the rear.

In this case, what's the DIY for the diff. mount? Special tools? Jack? Jack stand?

Again sorry to be newb...

For the differential mount, rear squatting when placing the transmission in drive and rear lift when placing in reverse were the symptoms. Yes, it will give you maybe an inch or so. It's four bolts holding it to the chassis and two into the back of the differential. (Be sure and support the differential when removing.)

For the subframe bushings, do a search as there are good posts with photos. Especially, check for posts in the DIY section as Will Hunter has sorted many good posts that help in these areas. It requires unbolting the leading end of the trailing arm from the subframe (no tire or wheel removal). Not difficult techwise but buy some epsom salts for a tub soak if you have seen a few years as it is a lot of "up-n-down". Specialty tools, such as the MB spring compressor, are available in "Tool Rental" from other forum members.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

Check for toe-out also. Excessive toe in/out can cause the tires to wear on the edges.

Front toe-in will actually make the front rise up and ride on the outside of the tires, toe-out will make it ride low and eat the inside edge of the tires. Not sure which way the rear works.

__________________

Gone to the dark side

- Jeff

The Search button is your friend.

__________________
91 350SD
14 F150 Eco
19 Fusion Hybrid
11 GT500

what are epsom salts ?

Ask a pharmacist.

__________________
83 SD

84 CD

Without this special spring compressioner tool, is it still possible to replace the trailer arm bushings?

I'll take some pictures and I hope some people can tell me if it's normal or not to have the rear be at it's current level.

Yes, it's possible but if you are working with jackstands, instead of a lift, you are looking at a lesson in self-abuse. It is well worth the ~$35 tool rental for the MB spring compressor (note: don't use any other type). Also, the reason for mentioning a search is more helpful to you. There have been many excellent write-ups including photos that help describe these jobs in a way that a quick reply cannot.

BTW, Epsom Salts is a brand of magnesium salts which, combined with warm bath, is excellent for sore muscles. Most folks over 40 y.o. have discovered its benefits.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

Here is the height of the rear of the 300SDL. Please tell me what you think!

Attached Thumbnails

     

That height appears to be pretty close to normal from what I've seen. Unless you are getting the squat/rise symptoms that I mentioned, I doubt the differential mount is a problem.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )