coverting electrical speedo to mechanical? - PeachParts Mercedes-Benz Forum

westkill · #1 03-21-2003, 07:36 AM

Hi, I am using motor/tranny out of a 83 SD and its been installed in a 4x4 truck. It has the electronic speedo connection in the tailshaft. Does anyone know if I can simply swap the speedo piece out to one from a MB that had a mechanical speedo(cable driven)? Also what type/year MB would I need to look at?
Also on the side of the tranny where the shift lever attaches is a wiring harness. I figure some wires must be a neutral start switch and reverse lights. Am I on the right track? Any help would be appreciated. Mike

sixto · #2 03-21-2003, 02:00 PM

Mike,

Try the tail housing from a 722.315 (123 300t) or 722.309 (123 280). It should fit the SD transmission and give you a gear drive. I don't know if you can move the gear drive parts over. The tail housing has to come off to get to the parts.

You got it right on the adjustable electronics box on the side.

Sixto
91 300SE
87 300SDL
83 300SD

#3 03-23-2003, 08:13 PM

I made the mistake of buying the wrong trans for
my 300sd. I got the one for the 123 chassis that
has a cable for the speedo (722.315) but the Sd
has the electric signal setup. I got it on ebay and
the seller said it would fit. (my fault, he gave the id
number correctly)The mechanic who put in my trans said he would be able to take the parts from my origanal trans and put them in the new one so the speedo will work. This involved dropping the driveshaft and removed the tail portion
of the trans. He may be giving me a deal by saying it
will cost $150. He has not had time to do this operation
so I can't say it is a sure thing. The trans I bought was
for a 82-85 300d, cd, td.

SYRacing · #4 03-14-2005, 12:52 PM

Any updates?
The trans is installed in mine, and it has the electronic sender for the speedo, while my W123 has the mechanical..I still have the tailhousing from the one I removed....Has anybody done this swap with any success?

#5 03-15-2005, 10:39 AM

Yes-the swap was done with success. I'm pretty sure there was no extra modification required, just fitting and bolting it. The mechanic used my old tailhousing. A good question would be what sealing agent to use when joining the tailhousing to the trans. I did not ask what was used, it was white, never leaked when the car was sold 1.5 years later. You should find out what the best sealing agent is to avoid leaks.

boneheaddoctor · #6 03-15-2005, 11:14 AM

Quote:

Originally Posted by Mark Tamburrino

Yes-the swap was done with success. I'm pretty sure there was no extra modification required, just fitting and bolting it. The mechanic used my old tailhousing. A good question would be what sealing agent to use when joining the tailhousing to the trans. I did not ask what was used, it was white, never leaked when the car was sold 1.5 years later. You should find out what the best sealing agent is to avoid leaks.

Hondabond is great stuff....Honda transmissions are fitted without gaskets using only this stuff between the case halves.....and they NEVER leak....Honda and Acura dealers sell it.....its a grey silicone RTV formulation.