Speedo off kilter. - PeachParts Mercedes-Benz Forum

PanzerSD · #1 03-18-2009, 02:48 AM

The Speedometer in the 450 is of by about 10kmh. 40 is 50 and 50 is 60.
the needle still moved fluidly, and the numbers turn. can this be remedied by cleaning and oiling the internals?

Mark DiSilvestro · #2 03-18-2009, 08:38 PM

Is the odometer also off by the same amount? It's possible to adjust the speed reading, but if the odometer is off the same amount, then there may be something else wrong - incorrect speedometer or rear-end ratio. I have inaccurate speedometers and odometers on two of my W123 diesels. One reads about 10% slow, while the other is about 10% fast. I suspect previous owners replaced them with incorrect ones.
Also keep in mind these old VDO odometers often develop wear & slippage in the drive gear, which should be checked and repaired before testing the accuracy of the odometer readings.

Happy Motoring, Mark

PanzerSD · #3 03-18-2009, 09:20 PM

I did notice that the odo is not moving

after I cleared the trip counter, I'll have to take a look.

and how is the speed reading adjusted?

Mark DiSilvestro · #4 03-19-2009, 10:08 AM

Quote:

Originally Posted by PanzerSD

I did notice that the odo is not moving

after I cleared the trip counter, I'll have to take a look.

and how is the speed reading adjusted?

If you're going to try it yourself, you should fix the odometer first so you can determine if the error is actually in the speedometer itself.

In the past on a '72 W115 220 that read slow, after removing the speedometer, I gently lifted it's pointer over the low-position stop-pin to get an 'at-rest' reading, then turned the pointer around past the max-speed pin to slightly 'stretch' the spring enough to increase the reading by just a few miles. It was a pretty crude process, that required some trial & error, and there was some risk of damaging the speedometer, but it worked for me.

It helps if you a find one of those police roadside speed-monitor display boards to verify any 'adjustment'.

Alternately, if you have a reliable tach in the car, you might be able to take a reading at a specific engine RPM before and after the adjustment. If your car is automatic, try to duplicate the tach-test conditions on the same stretch of road, so slippage in the tranny doesn't throw your readings.

Or you could just send the speedometer to VDO fo repair.

Happy Motoring, Mark

diametricalbenz · #5 03-19-2009, 10:58 AM

North Hollywood speedometer did mine and it has run perfectly ever since. I think it's up to $100 for repair, and cleaning now...

PanzerSD · #6 03-19-2009, 02:43 PM

Quote:

Originally Posted by diametricalbenz

North Hollywood speedometer did mine and it has run perfectly ever since. I think it's up to $100 for repair, and cleaning now...

That's not too bad! how long does it take for them to get it, repair it and send it back? would they be willing to zero out an odometer if I asked them to?

diametricalbenz · #7 03-19-2009, 04:20 PM

I would call to confirm the lead time. http://www.nhspeedometer.com

I dropped the 6.9 off in person and it took only a few hours (I paid a little more since I didn't know how to remove it at the time) and they cleaned, repaired, it replaced it and put the whole car on a speedometer rig in the parking lot. It's been running dead accurate ever since.

PanzerSD · #8 03-19-2009, 11:32 PM

I E-mailed Hartrmut, and He replied with an approximate turnaround time and price! he said $130 to $150 US. If it means a working accurate speedometer, then it's very reasonable.

So whenever I get the chance I'll sway in my SD speedo while I have the other being fixed..probably in a couple months, if I can't get it to work myself first.

Anyone know if a SD speedo is gonna be way out of whack in an SEL?