The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: KiwiGF on 24.09. 2012 12:23

Title: Layshaft thrust bearing faces
Post by: KiwiGF on 24.09. 2012 12:23
Hi hopefully someone can set my mind at rest on this one. I'm putting the swing arm box back together and noticed the drive side layshaft gear that bears against the drive side "blind" plain bush thrust face is proud of the end of the splines on the shaft so the internal spline of the gear is against the thrust face of the bush (which is new and specially made to suit a worn layshaft).

The gear won't go onto the shaft any further as it it stops against the circlip on the shaft.

If looks like the thrust face of the gear will wear out the thrust face of the bronze bush very quickly causing excessive end float, particularly as the bush has slots in the thrust face as well.

Is this set up "normal" ?

I'm thinking it would be difficult to make the end of the splines on the shaft line up exactly with the face of the gear so maybe this is "normal" but I'd thought I'd better check to see if anyone has also noticed this, the layshaft end float is fine at just a few thou.

Title: Re: Layshaft thrust bearing faces
Post by: shuswapkev on 27.10. 2012 23:17
i,m parting together a rigid box..and the layshaft bush is quite worn where the gear contacts it...this may have just happened over the last 60 years...???  leaves a 3/64 ring of bush a bit proud...

i am looking for the thickness of the thrust face of the 2 bushes...so i can make the bushes up...
Title: Re: Layshaft thrust bearing faces
Post by: KiwiGF on 28.10. 2012 02:24
I've got a new layshaft bush for a s/a,  the blind one on the drive side, I could not use it as I needed and undersize one made, I'll measure it and let know the results, of course one can't be sure the supplier has got the dimensions right and you will need to check the part is the same on your box.

Out if interest what is the gear bearing face that wears against this bush like on your box? Smooth or with splines on the inside like mine?
Title: Re: Layshaft thrust bearing faces
Post by: shuswapkev on 12.11. 2012 21:03
the wearing face to the layshaft bushing is the pressed on gear...of course has the splines on the axle and gear...
i have made up a new bush...with about .100 bigger thrust face.. i dont see the neccesity of having a blind bush...all my burman boxes use a banged in welch plug...or i may just solder an end on...