300D Rear Sag - PeachParts Mercedes-Benz Forum

rmmagow · #1 11-24-2006, 04:45 PM

The back end of my 83 is sagging pretty badly. How hard is the third member mount to replace? What should I watch out for and being a semi experienced wrench, how much time should I budget for the job? I want to try this before springs.

Thanks much.

Brian Carlton · #2 11-24-2006, 05:27 PM

You can replace the diff mount in one hour.

Naturally, you must support the diff on a hydraulic jack when you do this. If you have blocked the body up in the air, you've got the spring force driving the subframe downward.........with the jack bearing the load.

The one problem you'll probably run into is that you can't get to the upper cap screw that secures the diff to the mount because the stabilizer bar is in the way.

So, unscrew the four cap screws that hold the mount to the body and lower the diff........very slowly.........about 2" or so. Then the large cap screw is available for use with a socket.

Just remember, all the weight of the diff and the subframe is on the jack....and, you are working right behind it.

These instructions are based upon an earlier W126, which I'm making the assumption is similar.

sokoloff · #3 11-24-2006, 10:38 PM

Rich - if your differential mount needs to be replaced, your rear subframe bushings probably need it too.

Len

rmmagow · #4 11-25-2006, 10:35 AM

Quote:

Originally Posted by sokoloff

Rich - if your differential mount needs to be replaced, your rear subframe bushings probably need it too.

Len

Hi Len, Yup, looks like they are ready too. I'm not looking forward to the job. It's getting cold here and miserable. I'm going to have to move one of my cars out of the garage to try to do this a bit more comfortably. This should take care of any heavy maintenance on this car for a while.

Thanks much,

Rich M.

Brian Carlton · #5 11-25-2006, 10:38 AM

Quote:

Originally Posted by rmmagow

Hi Len, Yup, looks like they are ready too. I'm not looking forward to the job. It's getting cold here and miserable. I'm going to have to move one of my cars out of the garage to try to do this a bit more comfortably. This should take care of any heavy maintenance on this car for a while.

Thanks much,

Rich M.

The subframe bushings are miserable on a W123. Fraught with risk if the springs remain in the chassis.

Unless you're positive that they are toast, I'd do the diff mount (1 hour) and see how much improvement you get. The subframe bushings are not going to magically raise the back end 1" or so.......unless they are mashed flat.

The SDL got less than 1/2" from subframe bushings and diff mount. All that work for basically..........nothing........and those bushings were a piece of cake with the springs out of the vehicle.

rmmagow · #6 11-25-2006, 08:46 PM

I poked around the search and saw there are a few methods for doing the rear bushings. I'm going to do the diff mount first and see what happens. I'll have to unload some trunk crap too as I forgot about 250 lbs of concrete bags were back there from last winter. Didn't help anyway. It's not a snow and ice car even with snow tires. I've got a AWD Volvo to tackle this crap this year but it has turned out to be one of the worst car's I've ever owned. After the winter, it goes and will be replaced by a truck. The MB will become my daily driver again. I'll be looking at a cherry 300 TD this weekend and it will replace the 300D which'll become the kid's car in a couple of years. The TD is an 85 with 201K and ALL service records. I'd be the third owner.