BSA A10 Gearbox problems

[Gerry120]

Hi Everybody,
I hope anybody can help me. I am helping a mate out trying to sort out his gearbox on his 1962 BSA A10 Super Rocket. The problem we are having is that it jumps out of second gear and engages again in a matter of seconds when it's going up long hills for long period in second gear, it's ok on the flat and using all the gears. We have used another box that did not help we striped down the box checked all the parts including fitting a main bearing, and it still jumps out of gear.
Any ideas on what wrong.

[wilko]

Cush drive loose?

[Gerry120]

Hi There
I will check that out and let you know if that is the problem

Cheers

[duTch]

 Hiya Gerry, mine does that a bit in third, I think it may be worn selector plate, as the part of the cutout profile is a very fine 'point', and I'm thinking if it's worn may prohibit positive engagement- I think I have a piccie somewhere, will dig it out...

[edboy]

hi , i remember from years ago that if the box tries to jump out of gear but by holding down the gearlever it goes back in then it was the camplate adjuster needed a turn. worth a look.