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BSA Clutch Spring Conversion

BSA six spring clutch to four or three spring Triumph clutch

Our #42-3170/A hub for three or four spring clutches is better than the original #42-3170.
It is designed for use with thrust washers #57-3931 or #57-3931/A (has a 1/2" bigger OD, and six oil holes in the thrust surface).

SRM design ensures that the chainwheel is supported from wobble by the thrust washer.
Recommended to use in conjunction with SRM needle roller lift clutch pressure plate.

The centre adaptor is to fit the BSA A7/A10/Goldstar swingarm gearbox shaft.
It then takes the stock four spring BSA/Triumph clutch with solid centre, or can fit the later T120/T140 three spring clutch.

Options are as below:

(A) Convert to three spring Triumph clutch by purchasing the following components:

As you are retaining the crankshaft cush drive, the additional clutch cush centre with rubbers will give you an extremely smooth bike!

(20) #57-0394    ROLLERS
(1)  #42-3170/A  ADAPTOR
(1)  #57-3931    WASHER OR #57-3931/A WASHER
(1)  #57-4435    CLUTCH CENTRE ASSEMBLY WITH RUBBERS
(3)  #57-1560    SPRING
(3)  #57-2526    NUT
(3)  #57-4754    BOLT
(3)  #57-1931    CUP
(1)  #57-2156    PRESSURE PLATE WITH #57-2159 ADJUSTER AND #14-0403 NUT, OR:
(1)  #57-2156/A  ALLOY PRESSURE PLATE COMPLETE WITH NEEDLE BEARING
(1)  #42-3274    CLUTCH PUSHROD
(1)  #42-3267    NUT
(1)  #57-0420    WASHER
(1)  #57-0524    TAB WASHER
(6)  #57-1362/E  CLUTCH FRICTION PLATE, HEAVY DUTY
(6)  #57-1363    PLAIN CLUTCH PLATE

Or (B) Convert to a four spring clutch with solid clutch centre:

(20) #57-0394    ROLLERS
(1)  #42-3170/A  ADAPTOR
(1)  #57-3931    WASHER OR #57-3931/A WASHER
(1)  #57-0872    SOLID CLUTCH CENTRE, 4 SPRING
(4)  #57-1560    SPRING
(4)  #57-2526    NUT
(4)  #57-4754    BOLT
(4)  #57-1931    CUP
(1)  #57-0986    PRESSURE PLATE, CL, P.U. TRI/BSA, 4 SPRING, OR:
(1)  #57-0986/A  ALLOY PRESSURE PLATE COMPLETE WITH NEEDLE BEARING
(1)  #42-3274    CLUTCH PUSHROD
(1)  #42-3267    NUT
(1)  #57-0420    WASHER
(1)  #57-0524    TAB WASHER
(6)  #57-1362/E  CLUTCH FRICTION PLATE, HEAVY DUTY
(6)  #57-1363    PLAIN CLUTCH PLATE

Or (C) The ultimate solution:

Convert to a belt drive with option (A) above, but omit the clutch plates, as the belt drive comes complete with eight plain and eight friction plates!
Then purchase the additional parts for a four or three spring clutch for the belt drive.