On Thu, 27 Aug 1998, J. Robinson wrote:
> 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?
Sorry, I don't have that specification, but anyway an original speedo
meant for 3.7:1 diff and Michelin X 165X15 tires still may not give you
the accuracy you want. If I remember correctly, the original Michelin X
as it existed back when the TR4 was new was a taller tire (i.e. larger
rolling diameter) than modern 165X15 radials. You can probably find out
for certain from a Michelin dealer.
If you're that concerned about accuracy, your best bet is to get your
existing speedo rebuilt and recalibrated to suit the tires you are
currently using. Any speedo shop that specializes in Smiths and British
Jaeger instruments can do that for you.
-----------------------------------------------------------------------
Chip Old 1948 M.G. TC TC6710 NEMGTR #2271
Cub Hill, Maryland 1962 Triumph TR4 CT3154LO
fold@bcpl.net
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