The cable spins a plate which magnetically couples to the speedometer
cup causing a rotational force that is balanced by the return spring.
The odometer has a pair of reduction gears which drive the set of
number cogs.  In short they're separate and if the cable is faulty
generally the speedo bounces or doesn't work at all.  I'd guess it's
the odometer gear train.  Only a SWAG though.

Al

On Tue, May 4, 2010 at 5:37 PM, miguel pacheco <mundopacheco@gmail.com> wrote:
> Wow, that is a long way! Throw in a flood in western Tennessee and it
> gets longer. Trooper ran great! Not one hiccup and I am VERY happy
> with it!......although, recently, on a trip to Leadville, Co., the
> odometer (88 Westy 2wd manual) stopped working. Upon inspection, it
> turned out to be the classic, where the shaft backed out. I put it
> back in place and using the Tencent method, I installed a 'stop' ahead
> of the gear so the shaft would not back out again (it simply can't
> now.) I bench tested it and speedo + odometer work fine, but installed
> and blowing down the road, the odometer did not work. Pulled it again
> and checked it and it works fine. The speedo is fine but noisy....the
> odometer still does not work. Could it be that the cable is the
> problem? Does the cable spin two different gears, one for the odometer
> and another for the speedo?
> Thanks!
> Miguel
>
> I have not failed. I've just found 10,000 ways that won't work.
> �- Thomas A. Edison
>