Model A - Making the kickstart shaft

From the features and dimensions in the previous post, we have some idea of what we have to make - if we are to avoid cutting the excess length out of the old shaft and welding it up again, with the cotter flat in the correct orientation.

This would be a waste of an original part and wouldn't be half as much fun, but it is worth remembering that what we are trying to here is produce a replica of the 'Panther' shaft we have, but shorter and with the kickstart lever cotter in the right orientation.

We'll start by defining a list of features, so we can talk about making the shaft sensibly and without getting confused. Here we go:

• A - the pawl carrier minor diameter
• B - the hole for the pawl spring
• C - the holes for the pawl pivot pin
• D - the larger 'stop flat'
• E - the smaller 'stop flat'
• F - the bore for the layshaft bearing, and the bearing itself
• G - The flat the pawl sits on
• H - The kickstart lever diameter
• I - The main shaft diameter
• J - The flat for the kickstart lever cotter
• K - The pawl carrier major diameter, 2"

Of course the key question is in what sequence do we machine these features?

This is what I'm thinking at the moment:

1. Face and centre both ends of the 150 mm chunk of EN16 round bar (diameter 55 mm) that I've bought from eBay.
2. Holding the stock in the 3-jaw with the end supported in a live centre, machine away the material to make diameters H, J and K
3. Reverse in the chuck and machine a flange on the waste end, with a 5mm hole to register with the pin in the centre of the rotary table.
4. Hold feature I in the milling vice and use the vertical slide and an end mill to machine feature G.
5. Clamp the waste flange to the rotary table and use an end mill to machine features D an E.
6. Use the rotary table to machine feature A.
7. Use a slot drill to machine the tangential hole B.
8. Hold feature I in the chuck and machine off the waste flange.
9. Machine feature F.
10. Hold feature I in the milling vice and drill feature C.
11. Last job will be the flat for the cotter. We'll assemble the shaft into the box and then work out where the lever wants to be.

The blank we will have after step 3 will look like this:

Model A - Kickstart Shaft

 The Model A arrived with a complete gearbox, apart from the kickstart spring, cotter, and spring shroud. The kickstart shaft was also strangely long and fitting the lever left the kickstart pedal very low, since the flat for the cotter was in the wrong place.

What we are trying to here is produce a replica of the 'Panther' shaft we have, but shorter and with the kickstart lever cotter in the right orientation.

A close up of the pawl, the pawl spring with it's plunger and the two-diameter pawl pin:

This is the flat for the kickstart lever cotter. The shaft I show here allows the kickstart to sit too low - it's for a bike that has the gearbox fitted horizontally, rather than at the angle used by Ariel and Brough Superior. The shaft is possibly from a Panther, who used these boxes horizontally in 1929.

The flat will have to move for the new shaft.

This is the flat where the pawl sits, with the axial holes for the pawl pin and the tangential hole for the pawl spring:

These two flats engage with the two plates in the gearbox that stop the pedal travel and disengage the pawl:

This is the bore for the layshaft, with it's bush:

A few dimensions to help us choose the stock for the new shaft:

We see here that the total length of the 'Panther' shaft is 164 mm or thereabouts.

This is the 'Panther' shaft fitted to the bike. This is the excess length - just over 47 mm. That means the total length of the new shaft will be 164 - 47 = 117 mm. Our blank is 150 mm long.

Lastly, here are a couple of pictures from AOMCC member Michael, showing the original arrangement: