FH - gearbox

 First off let me just say that I'm not going to rebuild the GB gearbox on the Huntmaster just yet. The gears select well, there's no play in the mainshaft, no lateral play in the gearbox as far as I can tell and whilst there's a little bit of movement in the sleeve gear it's no worse than other gearboxes I've looked at at the outset. Turning the shaft by hand doesn't reveal any strange noises so I think we'll just leave it be for the moment. 

However, there is something strange going on. When I assembled the clutch I discovered that I couldn't get the plates to touch, even when the screws were done up relatively tightly against the springs which made me think that perhaps there were two ball bearings within the main shaft. I fitted a new one when I replaced the push rod but now that the pushrod assembly is effectively over long I think there may be two. 

Of course I can't remove the ball bearings from the clutch side because they are right down at the other end of the mainshaft and I've no means of pulling them out. Therefore I've got to remove the kickstart case cover, have a look at the clutch mechanism and remove the balls from that end. This will give me a chance to polish the kickstart case cover to match the timing cover. Secondly it will give me a chance to look at the mainshaft end float and to learn a little bit about the gear selector mechanism on the GB, which I've never looked at before.

The kickstart quadrant is in lovely condition:

It looks very clean inside and it's immediately obvious that the design is a little more sophisticated than the BA/CP type that I'm used to. The mainshaft has no detectable end float that I can find. It's obvious that the gearbox has only had oil in it; though I will probably use the Morris K400EP grease in it as usual.

Moving the pushrod from the clutch side, having pulled the lifting mushroom out revealed something rather strange. There's a large lump of what appears to be oily rust sitting at the end of the main shaft:

I pushed this out and then ran a little roll of paper up and down the inside of the mainshaft swabbing out the remaining muck. It was at this point that I realised that the quarter inch push rod that I had made in a previous post is the wrong diameter for the GB gearbox. Speaking to the various members of the club, including the gearbox specialist, revealed that GB gearboxes use a 5/16" diameter push rod. 

While waiting for some new bits to arrive I'll polish the end cover: