[flyinmonque]

....... seen or had this happen?

The mechanical tachometer cable ate up the gear in the accessory case. Cable was down to what looked more like a cylinricial (sp) brush for an electric motor with a large amount of metal fine enough it looked like graphite. Was not though. The case gear is wollowed out to the point that no key way is left. This set up had just been run for the first time after a (zero) time rebuild. No sign of wear at engine removal. ????

 

[Quacked]

I have had the same thing happen to a tachometer on a motorcycle. The metal end of the cable seemed to have been unbalanced and it had oscillated inside the housing and tore the plastic apart. I can only assume that the eventual total destruction of the gears were because of the amount of movement produced in the hollowed out housing.

I wrote it off as one of those miscellaneous production defects that occur in a nominal percentage of anything mechanical. I put over 100k miles on the replacement unit without ever seeing a problem and they were identical from any visual inspection that I could see.