Help please with speedometer compatibility question
 

Greetings all. I tried to repair the odometer in my 80 240D last night but I ended up making a mess so I went into my parts bin and came up with another speedo. I believe it came out of an 80 300TD (non-turbo 300 wagon you guys know that though). The part number on the face of my 240 is 123 542 62 01 and the 300TD is 123 542 63 01. I can see that the shift marks are slightly different. Of course my real question is - how accurate will the new speedo be for mileage and speed?

Rich Mason
Chapel Hill, NC

Hey Rich,
I think this was covered in a recent thread on speedometers and rear ends. I don't remember if it was in Diesel, vintage or tech discussion but you should be able to find it with a search.

Good Luck

With part numbers that close together, I'd say install it and take it for a ride, seeing if the odometer matches up close to the mile markers. A 10 mile ride should let you know how far off you are. Pull over beside a mile marker, reset the trip meter and start driving. Count the mile markers and compare them with the trip meter. A little math skill will tell you how much difference there is, percentage wise. If it's close, say 5% less, then that translates into about a 3 mph difference on the speedo at 60mph.