Gearbox layshaft bearing replacement

I need some clarification....when operating with GB in situ, going after layshaft bearing, is it necessary to open the primary to hold the clutch, etc. ? If so, might just bite the bullet and do the main shaft bearing too...

Tornado said:

when operating with GB in situ, going after layshaft bearing, is it necessary to open the primary to hold the clutch, etc. ?

Click to expand...

No.

L.A.B. said:

The ball bearing often doesn't require shimming, unlike the roller.

Click to expand...

It is not really a shimming issue. It is an indexing issue. The layshaft indexes to the drive side (the mainshaft indexes to the timing side, and this info alone shows why gaskets must be used), and the ball brg achieves that end. A roller does not, although with suitable shimming, it can be close.

All those who have explained that shimming does something else primarily (of course it does incidentally), were just wrong.

Shimming is still required for 1st lay engagement. Norton did not shim, but that was because they knew they could get away with it, not because it was better.

When Mick Hemmings says "the layshaft should be a sliding fit", he is wrong, and does not understand the concept. The layshaft needs to be retained by the bearing, not slide in it.