Drives

We supply quality Smiths type speedo drives for nearside or offside fitting giving clockwise output which is standard for most British machines.

The most common type is offside overslung or underslung in ratio’s of 2/1 15/12 or 1.25/1 giving clockwise output.

For Norton commando MK3 and Trident T160 with rear disc brake the speedo drive is fitted to the nearside again giving clockwise output.

A J S and Matchless motorcycles with full width alloy hubs fit a special speedo drive with a very large centre hole.

The Smiths reference numbers for the above were BG.5330 to BG.5333 and had a body thickness of .895 inches. These types of drives replaced BG.5101 and BG.5103 which had a body thickness of .802 inches

Earlier 52283/50-88 type drives were much thinner so the later types may not always fit.

When replacing the earlier type with the latest type the correct thickness spaces must be used so as not to exert too much pressure on the gearbox casing causing damage to the drive gears.

In certain cases we can also supply the very early front wheel speedo drives and gears for pre war machines.

Note: these speedo drives were also used on many British Two Strokes  i.e. James, Francis Barnet & Greeves during the 1950 1960 period.

The part numbers for these drives changed two or three times.

The most common part numbers were as follows.

34159 now BG2504 70458 now BG2511 25224 BG2500 and 70458 - now BG2510.

Tachometer Drive Gearboxes

The rev counter gearboxes we supply are of the ball race bearing type giving a smooth silent out put.

These gearboxes reverse the rotation of the shaft to which they are attached

Example Clockwise shaft gives anticlockwise cable rotation and vice versa. The rotation is determined by looking at weather the gear that is going to drive the gearbox, rotates clockwise or anti clockwise when viewed end on. Most British four stroke machines take the drive from the camshaft or magneto giving half true engine speed. Most common types used are 1/1 or 2/1 reversing gearbox.

Example Gear driven in anti clockwise direction at half engine speed would take 1/1 reversing gearbox matched to a 2/1 rev clock (Doubling cable speed) = true crank RPM Likewise a 2/1 reversing gearbox would match a 4/1 rev clock. It is assumed clockwise cable rotation is required at the tacho head WHEN VIEWED FROM ABOVE LOOKING DOWNWARDS. Some machines have clocks that require anti clockwise cable drive Examples are some Enfield twins, Triumphs,and Vincent’s. Many part numbers have been used by Smiths in the past the ones below on the left replace previous ones used

Prices

BG1508/04 = BG1507/08 =BG1508/00 1/1 REVERSING =£160.00

BG1508/06 = BG1507/02 = BG1508/08 2/1 REVERSING  =£160.00

BG1508/03 = BG1508/03 4/1 REVERSING  =£160.00  

BG1508/02= 1/1 NON REVERSING  = £160.00

BG1508/07= 2/1 NON REVERSING  = £160.00

2:1 Ratio Reversing Box

Suitable for the following Classic Motorcycles and many more

Norton
Comando Fastback (1969-70)

Velocette Motorcycles
Viper 350 cc, Viper, Mss, Clubman, Scrambler 1962-69
Thruxton, Venom 1965 - 67 on
Venom Sports, MSS, Venom Veeling (1970) on

1:1 Ratio Reversing Box
Suitable for the following Classic Motorcycles and many more

BSA
DBD 32 & DBD 34
Goldstar (1962 - 63)

Norton
500 SS 500cc 1962 - 63
88 SS 500 cc 1964 - 66
ES2 & 50 MK2 1965 - 66
650 SS 650 CC 1962 - 63
99 & 650 CC 1964 - 68
Mercury 650 CC 1969
Atlas 750 CC 1964 - 68

Triumph Tachometer Drive Gearboxes