John the only shims that I've seen are the main shaft shims. I know Ian and Neil Gentner have both given there suggestions for the end float for the 3 shafts. But is it actually in a BSA worksheet? I'll check in the standards book tomorrow. When Ian first rebuilt my box probably 20 years ago, he machined something for my Layshaft on his lathe.
I've built half a dozen boxes myself over the years and usually manage to find shims in my box of shims or cut something from shim stock or take a punt on ebay. I've bought boxes of main shaft shims and genuine 007" gaskets off Les.
I find it easier to build up a box with no gasket and zero end float. Then finalise it with a 007" gasket, thus giving 007" end float. I know Ian works on 003" end float. Ron
I found they change gear better if they are a bit sloppy.
The most important thing is to have the dog rings clear the same amount each side.
They are not very accurately machined.
So swapping them around can help.
I found they change gear better if they are a bit sloppy.
The most important thing is to have the dog rings clear the same amount each side.
They are not very accurately machined.
So swapping them around can help.
Mark[/quote]I agree. I have rebuilt a few of the M series gearboxes where it did not shift properly if the clearance was set correctly. So the shims came out and now it is loose and all works perfectly.
The fact that BSA put an inspection cover on the back of the gearbox shows they knew that just measuring the clearance does not always make a good running gearbox.
Now why every other British motorcycle maker besides BSA could make a motorcycle gearbox that did not need shimming or an inspection cover that you just assembled and it worked is beyond me? Shimming ads cost and time to making the gearbox and allows for mistakes in assembly. Were the machines tools making M20 gearboxes really that worn out that they could not make all the parts the same dimension?
I have in my opinion too much lateral movement in the layshaft & also the control arm
It shifts nicely but I would rather less movement
So
I found an engineering shop not far from me which has various bags of shims & can modify existing ones that I have
Next week I can see what difference these additions make if at all
