Panther 1935 Model 50. 4. The Gearbox.

Although it is not essential to have the gearbox ready before assembling the frame it makes life easier to have it to hand rather than struggling to fit it around the rear mudguard, engine plates and battery carrier. So I turned next to the gearbox.

This machine uses a Burman BAPH four-speed gearbox with bottom and front mountings and these are not that easy to find. As I have mentioned before I obtained most of one from Shaun Meaney in Australia and found a kickstart case cover on Ebay. 

The Australian BA box

It turned out that the Australian box had been mishandled as an attempt had been made to drive out the bearing at the kickstart end by bashing the mainshaft. This had resulted in a mushroom end to the mainshaft at the clutch end and a broken-out circlip groove to the bearing housing of the inner kickstart case. The mainshaft damage was not difficult to rectify but the broken circlip groove was a problem. I also found that the inner bush in the sleeve gear had partially worked its way out during its life preventing full engagement of top gear, a common fault with these boxes. This had led to damage to the dogs on the sleeve gear and the mainshaft sliding gear. Note that the kickstart shaft is different on the BAPH to that on the BAP box although both are in short supply.

Luckily another BAPH box turned up, this one with top and bottom mountings so, although the main case is not suitable, the inner kickstart case and all the internals are the same. This was fortunate as I could replace the damaged gears and use the inner kickstart case to replace the damaged one. After cutting some gaskets I had all the parts needed to build the gearbox.

Gearbox casings.

Kickstart case parts

Internals. Note that the oil seal shown does not fit the BAPH
as the recess is not as deep as that on the BAP.

With new bushes fitted to the replacement sleeve gear and reamed to size and the mainshaft thread for the clutch nut repaired the gearbox went together well and clicks sweetly into all the gears - on the bench at least. Time will tell if it works in service..

Finished box.