Assuming that yours is the same as my W123, The problem is that the shaft
that holds the number wheels is pressed into a pot metal gear. It is
slipping at this press fit. I fixed it by taking it apart and drilled and
tapped the gear for a 0-56 set screw.
There is a website that describes a repair using Loctite. This makes me
nervous because the assembly can be destroyed if the Loctite gets in the
If you are not up to this, I might be interested in repairing yours. You'll
will have to ship me the speedometer housing.
There are shops that you can find online that repair/rebuild them for
you. I don't have a name, but I have seen them and you can find via
Exactly what I did last weekend. The metal drive gear next to the
lowest odometer digit (i.e. the single digit) loses its grip to the
shaft, so mileage is no longer registered correctly. When the outside
temp is cold (below 10C), it may function (though mileage still off).
When the temp is higher, it does not register at all.
Take out the cluster, then the odometer. The cable drives the
speedometer and the worm gears next to the highest digit. See if the
shaft that goes through the odometer digits moves in/out. There should
be very little play because the shaft is held in place by the metal
If the shaft is loose, slide it out completely. Note how the odometer
digits go with the small advance gears on top of them. When the shaft
is out, all digits will FALL OUT. You need to put the digits back to
engage with the advance gears correctly, or otherwise the odometer may
stuck. The single and tens digits are different than the others. This
prevents the odometer goes backward.
I have a spare speedometer cable. I use it (and a drill) to check the
operation of the odometer before putting it into the cluster.
Last note. The speedometer hand and face were taken out to disassemble
the gear. I did not caliber the hand (did not know) so the speed now
shows like 10 mph faster than actual.
Mine turned out to be an electronic VDO odometer, and the small gear had 50%
of the teeth missing. I have ordered a replacement gear set. Turns out
this will be a easy fix with the correct parts.
Thanks for all the advise. I would not have taken it apart without the good
advise here on the news net.
Mine just stopped working (W140) when changing from 199.999 to
200.000. Probably same problem.
But where do you get replacement parts? (Mercedes only has comlete
instrument cluster as replacement part).
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