Many thanks to all who have responded to my initial question concerning the
TR-4 speedo.
After a trip out to the garage, I found that my speedometer is part number
209182, which is the speedo which corresponds to the 3.7 rear axle ratio
fitted to non-OD cars matched with 550/590X15 tyres. The number under the
odemeter reads 1184 which I am assuming is the turns per mile number. Looks
like all the hardware that came with car from the factory is still there.
The likely problem is that I am running 165X15 tyres which according to the
data a couple of you produced, means that to match the tyres I am running, I
need to have my speedo calibrated to the turns per mile spec of part number
209188. Anybody have this handy?
Again, thanks to all who contributed.
Jordan
Don Spence wrote:
> 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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