Hello Keith,
Only later machines, Brums, had the boss located by the notched strap type fixture, but a lot of earlier gearboxes have been thus modified during repairs and overhauls, mainly because the earlier dowel method was VERY poor. Few old gearbox end covers are without the dowel hole showing signs of tearing ! The dowel is identical to a clutch roller, ie. a 1/8″ x 1/8″ peg, no threads, and just a push fit. The damage is caused by folk starting their bikes when it is still on the rear stand….
This allows the rider’s leg to give an excessively long ‘swing’ on the pedal, letting the pedal to reach the bottom limit of the pawl slot, and then all the rider’s weight puts the dowel into an attempted shear, usually just ripping the alloy around the dowel as it tries to stop more pedal movement. Drill out the damaged alloy, and install a steel bush with a 1/8″ diameter hole in it to accept a new dowel, that can be made a lot longer than 3/16″ long, and therefore having a much stronger location into the end cover.
The moral of this story is DON’T START THE BIKE WHEN IT IS ON THE REAR STAND ! Exactly the same bit of starting advice applies to two-speeders, as the kickstart goes beyond its design limit and breaks! TWO-SPEEDERS SHOULD NEVER BE STARTED WITH BIKE ON THE REAR STAND ! DO IT ASTRIDE THE BIKE SO THAT YOUR LEG SWINGS BACKWARDS BUT NOT DOWNWARDS. ( Think of it being like a horse kicking backwards ).
Brian
