Speedo problem

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Tue 25 Feb 2003 15:37
Speedo problem - Wally Zebon
I have recently bought an Audi 80 S2. I've noticed on a few occasions that the speedo responds very strangly to rapid acceleration or deceleration.

If I am driving at 60mph and slow to 30mph quickly, the speedo will stay at 60 until I have stopped decelerating and then drop to 30.

It does similar things whilst accelerating. Whilst flooring it from about 20mph on a motorway on ramp, the speedo jumped in segments of about 25mph until I eased off the gas to a steady speed.

Is this normal, or do I have a problem? Is the speedo controlled through a cable (possibly frayed) or electronically?

Any help would be appreciated.

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Tue 25 Feb 2003 16:34
Speedo problem - Dave_TD
Exactly the same behaviour as I had on the tachograph of a 7.5t lorry a couple of months ago, it behaved as though the speedo needle was sticking, or only being updated with the vehicle's speed once every 2 seconds. Unfortunately, any tachograph fault requires immediate replacement of the whole unit, (which did seem to cure the fault!) but I don't know exactly what the fault was.
I would suggest it's more likely to be the speedo itself than the cable, do the 1/10ths of a mile on the odometer slide round smoothly, or do they seem to jerk a bit at a time? If they go round smoothly then it's probably a speedo fault.
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Tue 25 Feb 2003 19:23
Speedo problem - Peter D
Check the cable to the speedo sensor in the diff sounds like a fractured cable or intermittend connection to me thus it is only wrong whilst pulling ot pushing. had this on a Golf, broken wire at the connector. Peter
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Wed 26 Feb 2003 09:31
Speedo problem - Dizzy {P}
These symptoms are exactly as I found on my BMW after ten years and 110,000 miles and the problem was in the speedo head (electronic speedo drive). Wear in the bush was allowing the needle spindle to tilt slightly over to one side and stick.

I managed to overcome the sticking by putting a drop of 3-in-1 oil on the spindle so as to help centralise it in the bush but the problem returned after a few weeks. A new speedo head cured it but at a cost of just under £100 -- a bit pricy but still cheaper than a series of speeding tickets!
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