123 speedo into 126 cluster - PeachParts Mercedes-Benz Forum

t walgamuth · #1 09-12-2010, 03:50 PM

I am thinking of putting my five speed manual setup in my 85 sd. I seem to remember that the 85s have some sort of electronic speedo. I am wondering if I can put in a 123 speedo into the cluster and simply hook up my cable from the tranny to the speedo?

lutzTD · #2 09-12-2010, 04:19 PM

Quote:

Originally Posted by t walgamuth

I am thinking of putting my five speed manual setup in my 85 sd. I seem to remember that the 85s have some sort of electronic speedo. I am wondering if I can put in a 123 speedo into the cluster and simply hook up my cable from the tranny to the speedo?

I would check the sizes, I think the 126 speedo is flattened off at the bottom to fit in the cluster. Not sure if the 126 is larger diameter or the cluster itself is shorter. If you chage the face it appears the rest is the same, or maybe you can slice the bottom of the w123 speedo

t walgamuth · #3 09-12-2010, 04:26 PM

Thanks!

I looked at fastlane for parts and it seems that all 126 speedos are electronic. How do those work?

JamesDean · #4 09-12-2010, 04:30 PM

There is a hall effect sensor on the side of the transmission, this sends signal to the electronics at the speedo. There is a 6-pin interconnect in the drivers footwell on the right side near the gas pedal (on the center console).

You might want to look into what equipment the 124 manual cars had. I believe they had electronic speedos... 201s had mechanical/cable driven.

Alternatively, if you CAN get the 123 gauge into the 126 cluster, just run the a cable and call it a day. But as other have said not sure on fitment.

You probably wont have cruise control, unless you do some finagling. I know on my 201 there is a device that converts the mechanical signal into electrical impulses for the cruise control. I'd imagine the 126 doesnt have this contraption as its all electronic.

compu_85 · #5 09-12-2010, 06:15 PM

IIRC W124s have mechanical speedos too.

Finding a place to route the cable might be troublesome.

-J

Ryan Z · #6 09-12-2010, 07:48 PM

At one time I had replaced the speedo with a unit from another year SD.
The speedo worked, but the gauges went nutty. I thought there was a short in the system. I bought another '84 SD speedo and everything works great now. Might be something to look out for.

SirNik84 · #7 09-12-2010, 07:50 PM

I have a 124 mechanical speedo and I'm going to make it fit into my 126 cluster. Its next up on my "to do" list for the SD. I'm going to Japan for 2 weeks, but if no one has a conclusive answer by the time I get back I'll post pics of my transplant.

t walgamuth · #8 09-12-2010, 08:13 PM

Thanks guys!

Is there a way to retrofit the sensor to my five speed rom my 84 280e euro?

I was hoping it screwed into the place a cable went previously.

compu_85 · #9 09-12-2010, 11:15 PM

As I understand it the whole tail section of the trans is different on the automatic on an electronic vs. mechanical speedo.

-J

t walgamuth · #10 09-13-2010, 02:30 AM

So I would have to find a stick tranny tail piece set up for an electronic speedo?

Does one exist?

compu_85 · #11 09-13-2010, 02:37 AM

I'd assume so, they sold W126s 280S/SE cars with a 5 speed.

-J

t walgamuth · #12 09-13-2010, 06:21 AM

Quote:

Originally Posted by compu_85

I'd assume so, they sold W126s 280S/SE cars with a 5 speed.

-J

Good luck finding one of those!

vstech · #13 09-13-2010, 09:09 AM

contact Brian Carlton, he used a manual to electronic converter and used the existing speedo.

t walgamuth · #14 09-13-2010, 09:53 AM

Cool!

thanks!

lutzTD · #15 09-13-2010, 08:40 PM

Quote:

Originally Posted by JamesDean

There is a hall effect sensor on the side of the transmission, this sends signal to the electronics at the speedo. There is a 6-pin interconnect in the drivers footwell on the right side near the gas pedal (on the center console).

You might want to look into what equipment the 124 manual cars had. I believe they had electronic speedos... 201s had mechanical/cable driven.

Alternatively, if you CAN get the 123 gauge into the 126 cluster, just run the a cable and call it a day. But as other have said not sure on fitment.

You probably wont have cruise control, unless you do some finagling. I know on my 201 there is a device that converts the mechanical signal into electrical impulses for the cruise control. I'd imagine the 126 doesnt have this contraption as its all electronic.

perfect opportunity to ditch the troublesome MB cruise control and replace it with an aftermarket one. Thats next for me after I fix the AC