There were several speedos fitted to the TR range, all calibrated
differently according to fitment.
TR4-A spare parts catalogue (original) page 62, shows 8 different
speedos fitted.
209182 speedometer-mile and
209183 speedometer-kilo for 550/590X15 tyre size and 3.7-1
ratio axle
209184 speedometer-mile and
209185 speedometer-kilo for 550/590X15 tyre size and 4.1-1
ratio axle.
209188 (miles)and 209189 (kilos) are for the 3.7-1 ratio with Micjelin
X 165X15" tyres
209186 (miles) and 209187 (kilos) are for the 4.1-1 ratio with Michekin
X 165X15" tyres
There were two different rear-end ratios fitted. 3.7-1 and 4.1-1. One
for normal, one for OD.
There is a number on the face of the speedo, down near the bottom that
will indicate which it is. Unfortunately I don't believe it is the same
as the part no. and I don't know the code.
On the other hand, all 4 of my 4A's had speedo's marked with the
ratio 2-1 which I believe meant that at 5000 rpm in top you were
doing 100 mph.
I could be wrong here but mine were all non overdrive cars.
Perhaps someone with an overdrive car could give you the number (6 to 8
digits as I recall) and the ratio printed on their speedo so that you
could compare with what you have.
If the numbers match, you probably have "faded magnets" in the speedo. A
good instument repair shop should be able to recalibrate it for you.
Cheers
Don
<< 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. >>
Jordan
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.
Ken Nuelle
58 TR3A
62 TR3B
64 TR4
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