Question about odometer/speedo
 

Hi Guys, I'm getting ready to sell my 300E pretty soon as I've finished the 300SD project and don't need two cars. The main problem with the 300E is that the odometer only tracks about half the miles I cover. Also, the speedometer is off. It rests at about 20mph and is "calibrated" to be accurate at about 60mph. In other words, it reads high up to 60mph, then low beyond 60. Now I have had my 300SDs instrument cluster out and tinkered with it pretty extensively, but the w124 cluster looks like a different beast. First off, are all of the w124 speedos mechanical? Seems like a step back from the electronic signal from the w126. If it is mechanical, that would lead me to believe the odometer is a completely separate problem, perhaps with the hall sensor? Would the incorrect hall sensor cause these problems? I am hoping my problem is not bigger (i.e. wrong trans or rear end on it) but I should get a good look under there this weekend to confirm. I did check the FSM on these issues but its not clear.

Early models are mechanical, later are electronic with the transmission change. If you tell us your year it will help.

Sorry, forgot I had taken it out of my sig. Its a 1990

Yours is mechanical then.

I'd remove it, send it somewhere (check local) and have them bench it and check if its the speedo/odo -- shouldn't cost much at all. If they experience no issue, you know its a cable, transmission or diff issue.