Alan; I recently installed an overdrive into my MGB (already have one in my
TR6) and had the hardest time getting a speedometer to match the actual
speed I was going here is what I did.
I contacted an outfit in Albuquerque N.M.,( talk to Margaret)
MomManm@aol.com (NFI) she asked me to disconnect the speedometer from the
cable then mark the speedometer cable so you can count the turns of the
speedometer, as you slowly drive forward, make sure you have taken a total
of six revolutions of your wheel and counted up the total times the
speedometer turned, partial turns count, repeat this step about 3 to 4 times
till you arrive at the same answer, ( you need a passenger to do the looking
and counting) then measure how many inches it is from the center of the
wheel hub to the ground, get the differential ratio, gather all this
information place it with your speedometer and mail the whole thing to
Mommanm and according to them they set your speedometer dead on, they do
great work, NFI. solved my problem.
Bernie
74 TR6 with overdrive
71 MGB with overdrive and showing correct speed now
> I have recently completed my 1965 TR4A restoration www.triumphtr4a.com and
I
> have a speedometer problem.
> I believe my calibration is off, can anyone explain how to match the
correct
> speedo with the car? How do you ascertain the car ratio and the
speedometer
> ratio to determine the correct part?
> Alan
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