A friend has a problem with his speedometer on his late TR6. The speedo (and
odo)
is off by about 20% (it reads high as I remember). He has tires very close
to stock size and no other modifications. He did send the transmission to TRF
for a rebuild before he noticed the problem.
I can find no explanation for the 20% error on his car. I am wondering if some
other car (a saloon?) with a TR6-style transmission had a different speedometer
drive ratio. The TRs have 25 teeth on the scroll gear on the mainshaft and 10
teeth
on the speedo drive shaft, resulting in a 2.5:1 reduction of the driveshaft RPM
to
speedo shaft RPM.
I am hypothesizing that he has 8 teeth on the speedo drive shaft instead of 10.
Has
anyone ever seen such a thing? If I am incorrect about the HIGH reading, then
his
speedo drive shaft might have 12 teeth.
-Tony
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