C15 Chassis Rebuild part 1

The black bits. I have completely stripped down each part to bare metal and after spraying with a primer, painted each piece by hand with 'Black Enamel' paint. The frame is now ready to bolt back together with the swinging arm and rear suspension units. The hubs are waiting new rims & spokes.

I have made a stand out of 2" square tube 'old car tow bars' onto which the frame will be bolted and it is now possible to start building up the bike, despite the fact that the wheels are not yet built and ready to fit. The front forks can now be re-assembled and fitted into the shrouds, with the headlamp nacelle.

Yes, this is a picture of my frame. I used a white back clothe when taking the photo and then edited it to put in the grey background. Having bolted the frame back together, I have started to rebuild the front forks.

I have started to clean down the tin ware as the wheels are now rebuilt and only need the brake plates polishing and painting. The tank was first to be done, and as can be seen this revealed a some dents on each side. While the centre section is done I have sprayed the tank with gray primer. I will then fill the dents and spray the tank in a dark blue. The mudguards and oil tank will follow. I have also decided to convert to 12 volt electrics and have brought a new horn and coil. A friend has a heat sink and diode for sale and I will make the wiring harness myself.

The bike is starting to look like a motorcycle once more. The tank is now ready to go back on and the front mudguard is back in place. I have also started painting up the tinware:- Oil tank, side covers, etc. The wheels are waiting the brake plates being polished and painted.

New stanchions, bushes and seals have been fitted in the forks and 100ml of 20 grade fork oil poured into the legs. I have also greased the top of the stanchions to prevent rust as this part is hidden behind the nacelle.

When fitting the front mudguard there seems to be a technique.
1) Bolt the fixing brackets to the fork legs.
2) Twist the fork legs through 180 deg so that the brackets are on the outside.
3) Position the mudguard in place.
4) Rotated the fork legs back to bring the brackets into position.
5) Bolt mudguard to brackets.

I decided that it would be easier to do a good job of painting the front cover if the air-cleaner box was removed. In my case the box was brazed in place, so I applied heat from a blow lamp and gently prized the two apart. Having stripped them down to bare metal I primed them and then before applying the top coat I eased the shape of the front cover to match the oil tank and other side cover. After painting the air-cleaner box was refitted with 'Epoxy glue' to hold it in place. The ignition switch hole has also been enlarged as I am fitting a proper 'Key Switch' as part of the 12 volt conversion.

The front wheel has been rebuilt with Stainless rims and spokes. The cover plate and brake plate were then polished and the centre section painted black. The rear wheel has been done to match.

The oil tank and centre panels have been fitted to the frame and you can see the new ignition switch fitted in place.

The rear mudguard has been fitted and the rear of the bike is now looking like a motor-cycle once more. I have started to fit some of the electrics back into the frame area under the seat. The wiring is coming together and extra to the original design is an earth wire which runs from the front headlight to the rear tail light. BSA used to rely on the frame for an earth, which did not work very well.

The seat has been clean down with wash-up liquid and a scrubbing brush to remove the dust and grime. There are no splits or cuts and the sponge seems OK, so I carefully re- shaped the base to restore it's original lines. Bolted back in position it is looking good and feels comfortable too. The tank is ledged in place and still requires the chrome trim strips fitting.

The Number plate has been painted and the new registration details fixed in place. The rear light unit has been cleaned and a 12 volt bulb fitted after new wiring was soldered onto the bulb socket. The whole assembly was then fitted onto the mudguard and the wiring connected into the electrical harness.

Next the chain guard and other bits around the rear wheel need fitting. They are already painted black. The front headlamp also needs bolting in place to finish off the electrical side of things, but first I need to make a bracket to hold the speedo in place.

I decided to fit the engine into the frame to finish off the assembly work. This has advantages.

Not so much weight to lift into position.
Clutch pressure plate adjustment is made easier.
Stable unit to work on.

As can be seen the cylinder head, rocker box and engine covers have not yet been fitted.

It is possible to fit the cylinder head while the engine is in the frame, but to facilitate this I had to remove the centre rocker cover stud. Tightening the head down to the correct torque is not made easy by the BSA design, but where there is a will, there is a way.

The contents of these pages are for your reference and while care has been taken to ensure authenticity no liability can be accepted by the author.

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