350SDL Transmission Woes - Page 9 - PeachParts Mercedes-Benz Forum

400Eric · #**121** 12-07-2016, 03:16 AM

Quote:

Originally Posted by ROLLGUY

That is so close to the earlier 2.88 in the '85 300D's, I wonder if those diffs would be an upgrade in a 123, or even if the diff would bolt in. I have sold every 2.88 diff I have had, they seem to be in demand.......Rich

I am pretty sure that the 2.88s are all 185 mm cases. There is also a 2.87 ratio that is also a 185 mm case! Weird! (My 92 300E has one!)

Quote:

Originally Posted by MongooseGA

I couldn't tell you any of this info. It is a little nice to know that maybe someday, down the road, I can upgrade my W123 with the W126 diff though! LOL! (The W123 might be my favorite car I've ever owned, I really don't intend to ever sell it. If I move abroad, I'll find a way to bring it)

I know of threads where folks upgraded from 185 cases to 210 cases, but only in platforms (like W124s and W126s) that came with 210 cases in some models. I don't know if there was ever any W123 that ever came with a 210 case. Without supporting donor car parts such an upgrade would be a pain and expensive too. But don't let that stop you!

Remember though that not all W126s have 210 mm diffs! I know for a fact that all of the M103 powered W126s had the 185 diffs, who knows what others may have them!

Frank Reiner · #**122** 12-07-2016, 10:07 AM

Quote:

Originally Posted by ROLLGUY

That is so close to the earlier 2.88 in the '85 300D's, I wonder if those diffs would be an upgrade in a 123, or even if the diff would bolt in. I have sold every 2.88 diff I have had, they seem to be in demand.......Rich

Roller:

Thru model year 1985 (USA) the mounting for the 185mm and 210mm center piece (diff) is the same, and the two can be interchanged.
Starting 1986 the R107 and W126 chassis' received a new mounting for the center piece, which precludes a direct bolt-in in the W123. However, the 1986-91 210mm internals can be installed in the earlier cases.

400Eric · #**123** 12-07-2016, 06:12 PM

Frank, was there ever a W123 that came stock with a 210 mm diff? If not there are several issues (besides the diff mounts themselves) that will need to be addressed before one could swap a 210 case into a W123. Please see these links below that I culled from a very long thread.
http://www.peachparts.com/shopforum/2852442-post108.html
http://www.peachparts.com/shopforum/2853882-post111.html

In this case (no pun intended) the OP was able to overcome all of the issues only because he was swapping his 210 case into a W126, which, as we all know, had the 210 case installed stock in many of it's models. So he was able to just swap in the additional readily available factory parts that can be found just about anywhere used, as needed. I don't think this is the case (no pun intended) with the W123. (Barring some rare AMG hybrid of some sort.)

Does the R107 have the same basic rear sub-frame as the W123? I seem to remember that the R107 was actually based on the W115/114. That is clearly evident in the front suspension.

ROLLGUY · #**124** 12-07-2016, 08:11 PM

Quote:

Originally Posted by Frank Reiner

Roller:

Thru model year 1985 (USA) the mounting for the 185mm and 210mm center piece (diff) is the same, and the two can be interchanged.
Starting 1986 the R107 and W126 chassis' received a new mounting for the center piece, which precludes a direct bolt-in in the W123. However, the 1986-91 210mm internals can be installed in the earlier cases.

That begs the question, could the entire rear suspension from a 126 bolt into a 123? I have heard there is even aluminum control arms in some 126's, and that would be a pretty cool upgrade for a 123.

spock505 · #**125** 01-27-2017, 05:02 PM

Going through the above vac diagram removing, cleaning and checking components seems to have helped no end.

Removed the vacuum control modulator attached to IP, cleaned and refitted.

Overall these small improvements made a noticeable difference when backing off the bowden cable. Previously good shifts would have resulted in a sluggish response, now you have sensitive kick down together with upper range shifts when needed - perfect!

The car is very usable without the worry of 'wallop' it';s going to shift, hard to put down to a single component though.

400Eric · #**126** 01-29-2017, 10:20 PM

Thanks for the update!

Regards,
Eric