AJS & Matchless Owners Club

Enclosed is a photo of my gearbox layshaft. Should the bronze bushes be a tight fit on the shaft or in the gears? Mine appear to be tight on the shaft. Is that correct? Thanks

I recently stripped one of the very similar Burman BAP boxes. The layshaft bushes were as yours are, tight fit on the shaft and a running fit in the bore of the gears, so I would say that yours are just fine. As a precaution against possible seizure I would suggest that you fill the box with the correct semi fluid grease rather than any other type. Penrite do a suitable grease for these boxes. Later CP and BAP boxes had better sealing arrangements and could use gear oil!

Thanks for that. Any idea what clearance they should run? Between the bush and gear that is.

Sorry, can't give you a definitive answer to that one. As these are phosphor bronze, they need a little more clearance than oilite bushes require. In the BAP box which I rebuilt, the gears were a good free fit on the bushes with very little 'waggle' on the gear when assembled. Not very scientific but it is the best way I can describe it!
One observation I would make is that Burman boxes seem to work best when everything has plenty of clearance. Some 25 years ago I rebuilt a B52 with all new bearings and bushes, all carefully reamed to give minimal clearances. It was the worst B52 I have ever used, very stiff gear change action and slow changes. After some 20000 miles it is now quite pleasant again.