Another layshaft/Bearing question

Hi Guys,

I took the plunge into the gearbox for bike No2 the other day, seeing that I'm still waiting for engine bits for engine No1 to return. I'm led to believe that the layshaft should be 'sliding fit' into the case bearing, so

having more of less survived a major dose of gearbox purchase OCD :mrgreen: I've yet to find a layshaft that isn't a chronic interference fit. Other than sticking the layshaft in a lathe or something to trim a few microns off...

Any tips on getting a good fit?

On this particular gearbox I don't think it's been apart since it left the factory in '71...Which was kinda cool. The case had a load of shrapnel from one of the bearings, still not sure which yet. 2nd, 3rd gears are shot as the hardening's gone. Main and Layshaft are still very usable.

The dogs are a bit iffy as the thing has been left since one of the bearings gave out, are pretty rusty. I think the only other thing I'm going to replace is the kick starter pawl.

Cheers,

Steve

The inner of the ROLLER bearing just taps onto the end of the layshaft. Gears must be replaced in pairs.

heat the case ............

I found it better that the layshaft is a tight fit into its bearing. I would not turn the layshaft down at all. That way, you can just heat the case and pull the bearing out with the layshaft.
Worked great for me.
Of course the ultimate solution is the roller bearing which lets you remove the layshaft at will.

JD75

Hegel said:

I'm led to believe that the layshaft should be 'sliding fit' into the case bearing, so

having more of less survived a major dose of gearbox purchase OCD :mrgreen: I've yet to find a layshaft that isn't a chronic interference fit. Other than sticking the layshaft in a lathe or something to trim a few microns off...

Any tips on getting a good fit?

Click to expand...

In the John Hudson NOC 'Gearbox Strip' video he reccommends that the shaft be eased down with emery tape if the bearing is too tight a fit on the shaft, and that's what I did, frequently turning the shaft during the process. It didn't take long to do, and basically only polished the shaft up a little as I didn't go as far as a 'loose' sliding fit.

L.A.B. said:

Hegel said:

I'm led to believe that the layshaft should be 'sliding fit' into the case bearing, so

having more of less survived a major dose of gearbox purchase OCD :mrgreen: I've yet to find a layshaft that isn't a chronic interference fit. Other than sticking the layshaft in a lathe or something to trim a few microns off...

Any tips on getting a good fit?

Click to expand...

In the John Hudson NOC 'Gearbox Strip' video he reccommends that the shaft be eased down with emery tape if the bearing is too tight a fit on the shaft, and that's what I did, frequently turning the shaft during the process. It didn't take long to do, and basically only polished the shaft up a little as I didn't go as far as a 'loose' sliding fit.

Click to expand...

I always thought it was kind of strange that people looked at the ball bearing as a way to control layshaft endplay and then sanded the shaft down so it would move in the inner race. I would suggest a tight fit because a fit loose enough to move will only get looser . Jim

Both the shaft to inner and the outer race to case an interference fit.
I use heat to put the bearing in and out to help maintain the integrity of the machined surfaces.