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MG Midget and Sprite Technical - speedo

Hello,
On my GAN1, I have a smith speedo.
I have an old part on stock, but no idea from which car it comes: speedo Jaeger SN6121.
It has the double speed marking (mph and km/h)
Do you know if I put this Jaeger, the speed read will be correct, or do I need to make it recalibrate?
laurent
laurent

Laurent,

The SN6121 I dont know but after this mark there is a second and a third mark. Something like SN6121/05 900

The /05 is a following number but the 900 is importand. If 2 speedo's have the same number you can replace them and the reading will be the same. Thats the revolutions per mile mark.

Bas
Bas Timmermans

SN6121/16A 1248
on the white midget SN6142/00 1472
blue midget SN6142/06A 1376

the two midget are 948cc with smoothcase gearbox. So If I have well understand, at the same speed, the speedos will give two different results with a difference of nearly 10%.

Does anyone knows the real revolutions per mile mark on the Jaeger speedo used on MKI Midget 948?

laurent
laurent

Thats in Horler, If you dont hace a copy at hand I'll check later this evening.

Bas

This is only correct if the original diff is stil under the car.
Bas Timmermans

the white as got a speedo calibrated for 4,22:1, and the blue has got a speedo for a 3,9:1 ratio.
laurent

Just checked Horler. 1472 rv/mile is the number for the Frog. Thats with 4.22 diff. I guess thats the same for the later MK I midget.

But Horler is very precise with the frog and the later Midgets but lacks a bit of detail at this point for the MK I and MK II Midgets.

Bas
Bas Timmermans

This thread was discussed between 02/09/2008 and 03/09/2008

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