gearbox - layshaft and loose gears

[Triffid]

Hi folks!
I’m having a problem with my gearbox. Basically, when the loose gears (in the correct orientation) are stacked on the upright layshaft, they are equal to if not slightly below the end of the layshaft – Sticky’s book points out that the loose gears have to be above the end of the layshaft for it to be usable when shimmed up. My point is that given this situation is the same for two sets of loose gears on two different layshafts, would it be possible to have some metal turned off the end of the layshaft ( not the bearing surface where the roller bearing goes, obviously) so as to get the necessary clearance (of at least 0.1mm, if memory serves)? Cheers!

[Wack]

That's what I do, just take a fraction off on the flats where the large shim sits.

[Triffid]

Thankyou Wack. It seems the only practicable solution as there's no guarantee that I would'nt have the same issue with another new layshaft.

[holty]

i had the same issue with a sil gearbox, turned out the 4th gear was at fault, replaced with a new gear and the stack of gears was then slightly higher than the layshaft, and shimmed up fine.

[Triffid]

Thanks Holty. I'll have a fiddle with the two gearboxes I have although I prefer to keep them as a set. Lambrettas, eh? Dontcha love 'em?

[rossclark]

It does strike me that if it doesn't sit higher that this must be a sign of wear, either on the layshaft where the gears sit or on the gears themselves.

[Triffid]

Hmmmm.....that's an interesting idea, Rossclark. I shouldn't have thought there would be much wear between the gears themselves although wear on the layshaft is possible. I shall go away and ponder on this. Cheers!

[Wack]

Although the layshaft and mainly 4th gear can wear the LI 150 box is well documented in Stickys book for being lower. I've had new layshafts that needed machining even when trying several different boxes.

[Triffid]

Thanks again, Wack. I have a machine shop near me - one of those old-fashioned places full of lathes and pillar drills - so I might get a few thou taken off as you said in an earlier post.