A65 gearbox fettling

[DAVE BRADY]

Good morning,

I am in the process of putting an A65 gearbox back together and want it to be the best it can be so new bearings obviously and selecting the best of what parts I have.
I have also found some very interesting and useful stuff on the BritBike Forum that I have followed as best I can.  This involves swapping some gears around to get fresher dogs to help with engagement and getting the shimming right.  What I did notice, however, is that the selector cam plate could do with a bit of a tweak.  With 1st gear engaged there is still a bit more to go on the dogs but the selectors are at the limit of their movement.  Ditto with 2nd gear.
Has anyone tried modifying the selector tracks to improve this?
I have compared several cam plates from different years and they all pretty much identical.

Dave.

     

[A10 JWO]

For what it's worth I had problems after re-assembly with a stuck plunger where is had been in the parts washer and then laying about on the bench. Just thought I would throw this in.

[DAVE BRADY]

I always try to be very clean when doing bike stuff as it pays in the end.  I am in the process of getting the layshaft end float right and will have to order some of the over size shims.  I must have about 20 standard (thinnest) but too much end float.  It should be barely detectable.  Once this is done every part will be thoroughly cleaned for final assembly.
Improving the selector plate is the challenge as the track for the selector needs to be about a 1/16" longer to push the dogs fully in to the 1st gear pinion.  Sounds simple but the shape of the track must also help to hold the selector in place.
2nd gear is more of a challenge as the roller that runs in the selector track sits on a point.  Ideally this needs to be a bit higher to again push the dogs fully home but the track would have to ever so slightly widened to compensate but this at probably the weakest part of the plate.
I will probably sacrifice a selector plate to see if I can make the improvement or find something easier to do whist we are all restricted.

Dave.

[JOHN KAY]

  HI THERE I USED TO HAVE A PROBLEM TRYING TO SELECT NEUTRAL WHILST AT A STANDSTILL AND WHAT I DID WAS GRIND A LITTLE MORE MATERIAL OFF THE CAMPLATES NEUTRAL POSITION GROOVE WHERE THE PLUNGER CONTACTS THUS MAKING THE GROOVE A BIT DEEPER SO THAT THE PLUNGER WOULD SIT A BIT BETTER AND NOT SLIP PAST IT SO EASILY > HOWEVER YOU HAVE TO MAINTAIN THE SAME GROOVE SHAPE AND I DO NOT KNOW IF THERE IS ANY CASE HARDENING HERE IF IT WOULD BE AFFECTED > IT WORKED A TREAT FOR ME THOUGH > REGARDS JOHNBOY >

[DAVE BRADY]

Hi Johnboy,

I have done this on an A10 box in the past and it does work.  The A65 plates that I have all seem to have a good indent for neutral but as for hardening, the plunger is probably the hardened part as it does wear a track in the edge of the cam plate.  Interestingly the wisdom on the BritBike forum is to shorten the spring in the plunger to make moving the cam plate a bit easier.
A bit counterintuitive as it is this pressure that keeps the gears in mesh but it is commonly stated that it makes gear changing smoother.

Dave.

[ChrisG]

Yes, the A10 has such a paltry indent for neutral so much so that many years ago on a camping trip in Brittany, my mate Brian's A10 got stuck in top. We stripped the outer cover off the gearbox when we got back to camp. I couldnt only see three indents and thought they must have missed the neutral one out.
Didn't make any difference as the lock up was due to something else. Full story in The Star in the next few months.