Thanks babymog. So are you saying that i should be able to pull the needle off and rotate it clockwise (by about 10 mph ) , and put it back on? So it has some detents in shaft and needle. Sounds do able. Worth a try when i get in there.

Yeah, hard to tell with these old cars what they did to em except through owning one for a year . Makes a bit hard on buyers . I know the po said it was original miles, he got it form local german -- car fax says indiana car its whole life, a couple owners which is where i bought it. It has original #14 head. Tach doesn't work either and radio wont come on. Weird is driver seat is really comfy and passenger seat is worn. Wonder if they were switched. Ok with me though :) Could use a new passenger seat. (oops went off topic). All in all, i love this car -- the way it drives, the room, awesome -- but i don't like the engine as much as 617. Just hoping it is reasonably trouble free. Don't mind fixing things and tinkering but don't want to be stranded.

thanks

Tach not working?

Replace your ovp relay.

Maybe it will fix the odo too.

I think you have a different rear end or a different cluster causing the speed difference

I have the exact same issue On my 87 300D that I just bought. The speedometer being 10 miles an hour off. Found the thread whilst searching for an answer as your are.

Is the 87 spedo electric or mechanical like the 123? Iam not familiar with the w124.

As mentioned above, someone might have been repairing the spedo at one time. and if the needle was taken off, It might not have been replace in the same spot.

On the bottom edge of the spedo face is a small white mark to the right of the resting pin for the needle. this probably can only be seen with the spedo removed.

Remove the spedo from the cluster.

Gently lift the tip of the needle over the resting pin, and see where it falls down to. It should line up with the white mark on the edge of the face. If it is above or below the mark, it will not read accurate.

If it doesn`t line up, use 2 spoons with some tape on the back side. place under the needle and pry up. the needle will pop off the stem. It is just pushed on. line the needle up with the white mark, and push it down on the stem. lift over the resting pin and you are golden.

W124s have a mechanical speedometer.

-J

Careful! Two spoons method neatly ripped the needle WITH shaft and coil spring right out of my speedo. It actually snapped the shaft in two. No way to repair that mess. If your needle doesn't pop off the shaft with mild pressure, stop trying.

I am 10mph off but I replaced the Carrier with a different ratio. Speedo says 70, Actual 60, same% off over the entire range.

Chesk your Carrier ratio.

Carrier=differential

mine is off about 10% too. the speedo and odometer reads about 10% higher than true...based upon GPS and mile maker signs over a 100 mile run.

wait. you have a lower gear ratio in your TD wagon? I thought 2.65 was the lowest gear ratio you could get in a TD... is yours from a manual equipped 124?

no, it's an auto...i would they would all be the same gear ratio for a given model....but if I'm showing 70 on the speedo it's really only going 65. After 100 mile markers on the interstate my odometer shows 110 miles.

and the tires are the stock size. i figure it's typical german speedo error. older porsche cars are notorious for a 10% higher than true speedo reading. if anything it probably helps prevent a few speeding tickets, lol

If your speedometer AND odometer are off 10%, it is a speedometer/final-drive mismatch.

As VS mentioned, you're reading 10% high it is probably a speedometer from a higher-ratio gas model (pre-'94).

You might want to add a speedo to your shopping list. Read the little white numbers on the speedo face, I think that this is the part number of the speedometer subassembly.

BTW, the speedos on my older Mercedes have all been within 2% of GPS, which is within the tolerance of tire construction and wear, pretty good IMO.

Also, are you looking for a used turbo?

so my 522,000 mile speedo came from a gasser? guess they last a long time too...lol

what's the part number on your speedo? odds are good, it was put in due to originally low indicated miles, and it's had 475K put on it since... meaning your 522K odo reading car actually has 600+K... wow. not bad for a #14 head! if it still has one.