There is end play on the lay- and mainshaft. Where should I put shims.? Maybe on the right side of the shafts ? I remember an explanation from Ian on this forum but I cannot find it Where are those shims for sale ?

Thanks

John

email (option): john.kater@chello.nl

Hi John..I think you can still get gearbox shims from Russel Motors..The mainshaft shims go between the oil flinger plate on the shaft and the hardened thrust washer that sits against the smaller of the gearbox bearings. Layshaft shims fit behind the flange of the layshaft bush in the inner cover. Saying that though I have sometimes found the positioning of the shaft is better if they are behind the flange of the bush in the main gear case, so some trial and error may be required here. Float on both shafts should be approx. .005" after shimming. Also remember that the nut that screws on to the kickstart ratchet pinion end of the mainshaft should only be done up finger tight and be backed off slightly so you still have the .005" float. The tabwasher and locknut then secure it in that position...check for end float after tightening the assembly. The selector fork shaft should also not have excessive play..If the face of the steel bush in the main case is worn it will need to be replaced. The face of this bush should be flat with no wear recess. Shims are also available for this shaft and are fitted against the face of that bush, over the shaft spindle. However, with good bushes at both ends they are frequently not required.Use the thin paper gearbox inner cover gasket and fit it dry until you have finalised settings. I find the best way is to shim each shaft individually in the case and then refit the entire gear cluster....Ian

email (option): ian@wright52.plus.com

Can you explain the reasoning with the tightening of the kickstart rachet nut. I would think it does affect the endplay of the mainshaft.eg If it was done up firm, there would be more endplay. Also is it critical if the nut was in fact done up firm. I have rebuilt a box years ago, but not used it. I remember I done up the nut tight. Would it tend to mushroom the end of the bronze bush over time. Don't want to pull the cover off, if I don't have to.

Thanks Keith

"Also remember that the nut that screws on to the kickstart ratchet pinion end of the mainshaft should only be done up finger tight and be backed off slightly so you still have the .005" float"

email (option): keithatkinson@hotmail.com

Hi Kieth..The mainshaft is 'floating' within the main case after shimming, limited at one end by contact between the splines on the mainshaft and the inner face of the sleeve gear and at the other by the thrust washer and shims that sit against the fixed oil baffle plate and bearing inner race.
So, if you fully tighten the nut outside the case the shaft will be pulled fully in that direction and will be locked in place against the bearing...so there won't be any end float.
As you have surmised wear/end load on the bush is the most likely reason to avoid this situation.
This is from the relevant BSA factory worksheet...
'The ratchet mechanism may now be refitted to the mainshaft'....'ratchet, bush,ratchet pinion, spring and shouldered nut. The latter should be tightened by finger pressure only...'...Clearly the best way to be sure that this nut has not got tighter during tightening of the locknut is to test that the end float is still present after tightening...Ian

email (option): ian@wright52.plus.com

Thanks Ian for your quality answer. Much appreciated.
Regards Keith

email (option): keithatkinson@hotmail.com