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SPEEDOMETERS UP TO 1964

Regarding Smiths speedometers a major change was made in 1964

Pre 1964 machines fitted the following.

The larger 3” instrument was of the Chronometric type. This in reality is a two in one clock a speed recorder and a distance recorder.

The speed is calculated by the same principle as used in clocks and watches which gives very accurate readings. The distance is calculated by a series of gears and ratios which move the numbers round.

Type identification numbers on the dial start

S xxx/x/x   OR SCxxxx/xx for speedo         RC xxxx/xx for Tacho

The 2” speedo was of the magnetic type still used today.

A magnet which is close to a metal disc is rotated by the drive cable and “drags” the disc round with it. A pointer is fixed to the disc which shows the speed on a dial.

A hair spring retains the disc from revolving freely. Speed is recorded by the drag of the magnet against the restraining force of the spring..

Mileage is again  recorded by gears.

Type identification numbers on the dial

X 80421 OR SN31xx/xx for Speedo    RNxxxx/xx for Tacho

 SPEEDOMETERS USED FROM 1964

In1963 the British motorcycle industry approached Smiths Industries to manufacture a cheaper 3” Speedo as the chronometric was too expensive for mass produced machines. Note British government (Police etc) still used Chronometric instruments after this time as they were very accurate and reliable.

The 3” speedometer manufactured after1963/4 used the same principle described earlier.

Type identification numbers on the dial start

SSM 3xxx/xx    SSM 4xxx/xx  SSM 5xxx/xx for speedo  RSM 3xxx/xx RSM 4xxx/xx for Tacho.

The design of the smaller 2” Speedo was changed but the principle remained the same.

Type identification numbers on the dial start SSM 2xxx/xx  Speedo RSM 2xxx/xx.

WE OFFER THE FOLLOWING SERVICES.

For Chronometric type we offer a repair only service by prior arrangement

With prices starting from £45.00.

Early 2” pre 1964 type X80421 SN31xx/xx  speedo  RNxxxx/xx Tacho.

A repair only service starting from £30.00

A full reconditioning with 12 months warranty +£120.00Late 3”starting SSM 3,4.5.  RSM 3 or

Repair only service starts at £40.00

Full reconditioning with 12 months warranty £175.00

Later 2”  starting 2xxx/xx  Speedo or RSM 2

Repair only service start at £40.00

Full reconditioning with 12 months warranty £89.00



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