In a message dated 98-08-27 01:04:34 EDT, you write:
<< Anybody on the list know how to tell an OD calibrated speedo from a non-OD
speedo on a TR-4? There was a thread on this recently covering TR-6 which
jogged my curiosity since I have a similar problem, a speedo with mph
consistently running 6-7% fast on my non-OD equipped TR-4. >>
There is no "overdrive" speedo unit. An OD doesn't change the rpm of the
output shaft in relation to the rear wheels. Same speedo.