108 Odometer Repair

[73MB280SEL]

Howdy,

I'm sure this has been discussed a few times, but I was working on it and wondered if you'all had some insight.

I had the speedometer/odometer head out yesterday (I had to replace the light dimmer rheostat: Couldn't see how fast I was going at night). I looked at the odometer drive and the problem, best I can tell is that the alloy drive gear that is the last wheel on the odometer shaft is not turning with the speedo.

In other words, I can turn the speedo drive and the speedo works OK, but it does not click over the odometer. I can also turn by hand the pot metal odometer gear and the trip odometer turns over fine as well as the mileage indicator but it is not rigidly connected to the odometer shaft.

I looked for a set screw and did not find any (which I think would be a dandy of an idea).

I guess I'm also concerned that if it was glued on from the factory, something bound up in the odometer wheels that caused the glue to break. Or perhaps it is just old....

One more odometer problem: the trip odometer 1/10 miles indicator has to go past 2 tenths before the mileage indicator rolls over a whole mile (the trip odometer rolls over exactly, of course, at 9/10). Does this mean that I'm off a tooth or 2 on the idler wheel that drives the trip odometer from the mileage indicator?

One more question: I removed the instrument cluster but didn't take it all the way out because of the coolant temperature sensor. There was plenty of cable left, so I could pull it out far enough to work on it, but does it disconnect somehow? I'd like to work on the instrument cluster on my bench not in the car.

Thanks for your input.

p.s. We now have instrument lights!!!!!!



Sholin

[Mark DiSilvestro]

I've seen 2 causes for odometer failure on VDO speedometers.
Had the brass drive gear wear out at its contact with the speedometer
worm gear. More common fault is the gear at the end of the odometer geartrain slipping on the shaft as its just pressed on. I repaired the odometer on my 1972 250C by removing this gear and gently 'nicking' the contact area of the shaft with a wire cutter several times then reinstalling the gear. My gear was plastic. If you have a metal gear with enough 'meat' on it and are good at micro-surgery, drilling and tapping for a setscrew may be an alternative.
The 'cable' to the temp guage is a capillary tube with fluid inside so don't try to disconnect it from the temp guage! Better to unscrew the guages assy before removing the cluster or leave the cluster in the car and unscrew the speedo assy from the cluster.(Which ever is easier)
As for the trip odometer being off-
you'll have to 're-time' its gearset
when you get the speedometer apart-a real pain keeping all the numbers lined up when you reassemble it!
(Or you could send it off to VDO and
let them deal with all of it!)
Good Luck, Mark DiSilvetro
1972 250
1972 250C
1961 180b
And 2 DKWs!

[MikeTangas]

Sholin,

I'm in the state right now as well. There is enough slack to VERY gently ease the temp capillary line through the firewall, allowing a little extra roon. Once you have the speedo cable removed and the bowden cable for the shift indicator, if equipped (bowden disconnects from the top of the steering column, can't describe how to locate other than by feel), you can move the cluster out a little farther to access the oil pressure line, 10mm I think.. Disconnect the electrical connection and you can rotate the cluster a bit, the remove all the screws holding the back on. Once that is accomplished you can replace the monitoring gauges loosely in the opening and have the cluster in hand to clean and repair etc.

As for the speedo/odometer repair, I opted to farm that out to Palo Alto Speedometer. They have rebuilt the speedo head and odometer, recalibrated the ratio to match the actual ratio of my car (I filled out the ratio test form). The speedo had been calibrated to 1.19:1 but the revolutiuon count on mine, with a new speedo cable was 1.22:1 (12.25 revolutions in 52' 9.5"). That probbably explains why the speedo was showing 10 MPH faster than actual at highway speed. I sent it out Monday, and they sent it back Friday last week. It should be here by Tuesday at the latest.

If you want/need more info on them go to http://www.paspeedo.com

[MikeTangas]

Got the speedo back from Palo Alto today. I can see a lot of new parts in the gear works, according to the invoice they replaced $40.00 in parts, and $90.00 labor. Tax and shipping, came out to $146.00. Can't wait to find a replacement faceplate for the heater controls so I can re-assemble the dash and test out the speedo/odometer, especially at highway speed.

[73MB280SEL]

You know Mike, sending it off for VDO service isn't too bad an idea. I'm thinking I could probably perform this repair, but I'm thinking also that I could probably butcher it.

I should get the worm drive gears replaced anyway as they are pretty old and won't last forever.

Thanks for the tip.

Sholin

[73MB280SEL]

Mike:

Also, you said your car has the Bowden cable. My car does not have this option and has floor shift. Does your car have floor or column shift?

I checked on fastlane here at mercedesshop.com and they sell a new bowden cable/indicator assembly, but I emailed tech support and they said that this will not work on my car. I don't know why, but having a shift indicator would be a nice upgrade to my car (even if it is floor shift).

Sholin

I believe you can get a new speedometer for your car for around $100. Check with one of the parts houses in Atlanta, New Orleans, or Pompano Beach,Florida. The last one I bought cost about $95.
Bill Lewallen Lexington,Ky.

[73MB280SEL]

Bill,

Thanks for the info. Do you have specific sources? I'm assuming that you are talking about new-out-of-the-box VDO speedometer/odometer, not a reconditioned one.

I did get a quote back from http://www.speedometer.com (recommended on the Mercedes mail list) which also seems reasonable.

Thanks,

Sholin

Sholin,and others,
Here is a list of places where you may find a speedometer for yor car.

IPCO(Atlanta area) 1-800-635-8590
Brinson Co.(New Orleans) 1-800-535-8788
KW Parts (Pompano Beach,Fla.) 1-800-327-8984
KW Parts (Fort Mill, SC.) 1-803-547-3400
German Auto Parts(Atlanta area) 1-800-241-9900
Wholesale Auto Parts (Atlanta area) 1-800-741-5252
All speedometers i've bought from them are VDO, and come with 2 miles already logged on them. I assume that was for testing.
Let us know how you make out.
Bill Lewallen Lexington,Ky.

[73MB280SEL]

Thanks for the links. I'll let you know when I get the Odometer back (or if I decide to order a new one).

Sholin