BSA Unit single, and Triumph Cub Gear Change Shaft Replacement.


Video at bottom of the page...


The difficulty I have found trying to find a decent gear selector shaft with the splines still in tact is very near impossible.

 And now after carrying out this shaft replacement I understand why?

 Well the forged steel used is very soft and the slightest mistreatment to the splines will destroy them.

 Well there are some replacement repair shafts drifting about the Net, probably from the Wassell catalogue.

 So with the need to replace one of these shafts, and seeing the bodge that had been carried out on the engine I had just bought, with an attempt at using one of these shafts, I thought I would have a go.

 So the photos and captions underneath should show the way I went about the job.

 And it seems to have turned out OK...



A Collection of shafts  to repair...and some lengthen...



You Can see the damage to this shaft! splines all but gone and a hole drilled through to use a split pin instead. And the New replacement shaft.




Before you start to do this opperation, measure the length of the shaft you need to end with, it is so easy to do all this work and make the shaft too short...




I firstly removed the spring stop spring, by gently taping it out with a small drift?

This is so that I could fit this end into the chuck on the lathe.

 I then took an Hacksaw to the old shaft ( Yes it is that soft) sawing it off close to the boss.



Holding the Boss in the chuck of the lathe was tricky, making sure the flat of the 3/8" shaft was pushed up firmly against the jaws of the chuck.

 I then centre drilled the remains of the old shaft, before drilling to the measured depth with a small drill, then drilling again with  a bit bigger drill, increasing the size four times, before drilling out to the correct 1/2" for the shaft.

The stages of drilling were carried out, so not to put undue pressure onto the turning surface as the hold by the jaws was not that great, and it was better to be careful rather than sorry.



The shaft was then fitted into the boss, and the length of fit checked, and also trueness of line.




The heat used to braze this stub into the casting looks more intense in this shot, but as long as you let the item cool slowly the heat dissipates without causing problems.




The boss was gently clamped in the vice and the shaft painted with brazing flux before heating and brazing the shaft into the boss.

This was then left to cool while I walked the dog before it got too dark out side.

The shaft was dressed with a file and emery paper in the lathe and once again checked for trueness.

The spring stop was then pressed back into the boss, and "Job Done" ready for refitting the plungers and springs that had been removed at home.



Another part recycled. Good Hey.



There you go Mel's picture is better than mine .

But you should see the Snazzy Phone he has,

Well he is still looking for the old one he put down about a month ago, teach him to be careless, But that is a good Picky.

Much more recycling later.