Greg, the Brits loved to install overdrives, then defeat the purpose by
using higher numeric axle ratios instead of going the other way. They felt
that the OD simply offered more gears rather than offering the lower revs
we all seek. Britain is a nation of people who insist on standard
transmissions but hate to shift gears and won't buy automatics. The answer
was the semi-automatic OD which was used more as a clutchless gearshift
than a highway or urban area road gear.
TR-4s have lots of torque but don't like a lot of revs so the answer is
apparent. Fit the OD but leave the 3.71 gears along. If possible you
would be better off with something in the 3.40 range but I doubt that
anything is available.
To determine the axle ratio, jack up the car, mark the driveshaft then turn
a wheel while counting the revolutions of the driveshaft (obviously the car
is in neutral). If the shaft turns more than 4 times for one revolution of
the wheel you have a 4.1. If it turns less than four times you have the
other.
John
>Folks,
>
>I'm in the process of converting my '64 TR-4 to overdrive. All my reference
>materials say that the OD version came with a 4.1:1 rear end. Does anyone
>know how I can determine the rear end ratio that's currently in the car? I'm
>pretty sure its the standard 3.7:1 version...If so, any thoughts on just using
>that or do I really want to go to the 4.1:1?
>
>Also, does anyone know where the OD relay box (not the solenoid, but the relay
>that sits between the OD column swith and the power source) is supposed to be
>mounted?
>
>Thanks,
>
>Greg Schuett
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