Change Of Plans.

[John Bowen]

Trying to figure things out from internet photos can be a bit misleading, but I've come to the conclusion that the rigid frame bike in my introduction isn't going to work with what I have. I had intended to wrangle a swingarm A-10 and gearbox into a plunger frame, but thankfully found this post by Beezermacc from this forum.

"A Swinging arm engine has an independent gearbox, consequently it is much longer than the plunger engine and gearbox. Fitting a swinging arm engine into a plunger frame is a non-starter without somehow stretching the frame."

So, rethinking my options has me leaning toward something with the Spitfire Scrambler frame I also have, but not a scrambler. Maybe a cafe racer style, but not a Rocket Gold Star replica.

[muskrat]

G'day John.
I did wonder how you were going to get over that problem and others along the way.
Cheers

[John Bowen]

Ignorance was bliss for a while. Need to do some rethinking on this. One good outcome is I'm fascinated by the swingarm gearbox mounting plates and was disappointed to learn the plunger didn't need them. Imagining some poor punch press operator labored mightily at Small Heath to make these and I'm determined to use them.

[orabanda]

Check your plates are flat; no twists.
The LH plates have a large crease pressed into them. However if any of the flat surfaces are warped, gearbox alignment to the rear wheel sprocket, and the engine primary chain sprocket can be affected.
Lay them on a flat surface (surface plate, sheet of glass, mill bed) and check if a feeler gauge can be slipped under.
Straighten using a press, or an anvil and hammer (*copper is best).
BSAeeing you,
Richard