Transmission-repair or replace? - PeachParts Mercedes-Benz Forum

smittyinnola · #1 10-21-2009, 08:52 AM

Hi Guys,

I am clueless on this topic...on a 123 car what would be the easier or better thing to do, rebuild the tranny or swap out? Why?

Also, are the trannys on the 123/126 turbos compatible? Thanks!

pawoSD · #2 10-21-2009, 09:30 AM

That is up to you, swapping saves $$, but a rebuild will likely last longer. If I had the $$ I'd do a rebuild.

The transmissions between the W126 and W123 are compatible, but you need to change the rear tail pieces between the cars for it to work, as the W123 has a mechanical speedometer/output for it. And the W126 has an electronic pickup for the speedometer. Its a fairly easy swap and I have done it before with no issues.

Graplr · #3 10-21-2009, 09:42 AM

Ditto. If you can find a good used tranny for cheap I'd swap...but that is pretty much gambling.

I guess it depends on how much you want to spend and how long you are going to keep the car. When mine went I ordered a supposedly low miles one from a boneyard and had it shipped. It has worked for 20k but will probably have the old one rebuilt (sitting in the garage) at some point as I don't know how many more miles I will get out of the used one.

There are some subtle differences on the tranny's. Your best bet is to find the same year/model for a swap. I swapped an 83SD into my 84SD and the tach doesn't work anymore since the pickup on the 84 is in the tranny but on the 83 it is still at the front of the engine.