Wednesday, December 23, 2015

W123: Center Support Bearing Replacement

While I was doing the entire trans swap/trans reseal I noticed the center support was a bit weak upon my good ole fashion wiggle test. So, yanked it out and found it had a huge tear in half of the rubber. The support is most likely the original, the shaft didn't look like it was ever separated to do the replacement work. Though, unlike most others, I noticed mine didn't have any sort of provision for a cir-clip. Seems in 85 Mercedes moved towards a better, press fit style bearing over the somewhat loose clipped one.

If you're going to do this job, you're going to have to figure out a way to compress the drive shaft enough to remove it. It's locked in place by a large (41 / 46mm) lock nut, if the splines are a bit rusty, hit them with some penetrating oil and let it sit for a bit. Smack the area with a hammer a few times and it should free it up enough that you'll be able to compress it with some elbow grease. You'll notice my shaft has a bit of grease on the splines - I did this to allow me to slide the shaft easily. Wipe off excess as it will cause balancing problems.

My new support / Old

The dirt shields are still in place, which is a good sign. If a car like this is anywhere near salt, these shields get rust welded in place, or totally disintegrate. I'm happy to say this one is solid. 

Now, the bad bearing wasn't my only problem. When I removed the old bearing, I noticed it was burnt and slightly scrored - seemingly from a frozen bearing. I hit it with a bit of steel wool to polish it up a bit. Then smeared a bit of grease for the upcoming bearing install.

No install pics - I wish I had 6 arms to do it all. But here's the newly installed bearing/center support ready to go back into the car.

I'm pulling the trans I just put in as I found it has a front torque converter seal leak. Go figure - I had a new seal and forgot to put it on.


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