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Speedometer repair



>
>First of all... I want to thank you all for helping me out to deal with my 
speedometer. 
>You've been very helpful. 
>
>I have put everything back in place, and everything works properly. Yes... 
the root 
>cause was the speedometer cable. It was broken. But the process did affect the 
>speedometer. When I opened the speedometer assembly, on the input shaft (I 
refer to 
>Jim's explanation, thanks) I found that there was a little play on the 
shaft, so the 
>magnet can move back and forth a little. I don't know whether this play is 
normal, but 
>when I gave a little force while turning the shaft, It did make that 
strange noise. In 
>addition, before the speedo cable permanently broke, along with the noise 
occurance, the 
>speedo needle didn't move smoothly. I think the magnet touched the cup in 
its rotation, 
>due to that play in the input shaft.

A jumping needle is a sign that the cable is catching on something once per 
revolution. It then stops briefly at the speedo end while the wheel keeps 
turning, thus "winding up" the cable until the cable breaks free.  This 
stick-slip operation gives rise to the pulsing needle phenomena which is 
eventually followed by a broken cable.

The small amount of play in the input shaft is normal.

BTW, I once had a speedometer head which was sticky and caused the pulsing 
needle problem.  It turned out to be that the spinning magnet was just a 
snug fit on the input shaft and had slipped down to where it could rub on 
the clip that maintains the axial position of the shaft in the housing.  
Once I realized that I could move it, I just slipped it back out enough that 
it could no longer touch the clip and the problem vanished.

Jim
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       Melissa Kepner                                    Jim Adney
       jadney@vwtype3.org              jadney@vwtype3.org
                             Laura Kepner-Adney
                             Madison, Wisconsin
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