Layshaft endfloat mystery

[Peter Naulls]

I have recently rebuilt a 4 speed synchro box with new bearings and springs etc. Prior to dis-assembly it turned freely.

On disassembly I noticed that the layshaft had been fitted without any gasket under the flange on the rear of the shaft. Before reassembling I re-fitted the shaft and gear to check endfloat and found that there was none - in fact it needed a 10 thou paper gasket under the flange to allow the gear to turn freely. Where had the clearance gone?

I did gently heat the casing with a heat gun to help remove the bearings. Is it possible the casing has distorted with the heat?

Peter.

[Chris KC]

I doubt you distorted the case Peter, unless you went crazy with the heat gun. I bung mine in the oven; or hang them above my Aladdin stove for a bit.

Obvious question I guess but did you replace, repair or otherwise disturb the layshaft gear bushes?
On disassembly was there a gasket under the bush at the opposite end of the layshaft?

[Peter Naulls]

Hi Chris,

That's reassuring thank you. No I didn't remove the front bush, nor do anything to the gear or shaft, though clearly something has moved. Anecdotally I was expecting to find some excess wear, not the opposite.

I have a close ratio box I want to rebuild at some point so I'm learning what I can from this one.

Peter.