Gearbox sleeve gear bushes wear.

Further to my last proclamation, "there is no play in the gearbox sleeve bushes," now that I have done a bit more dismantling, I have measured 10 thou play!

I have had a scan of the manual, but cannot find any wear limitations, only new bush dimensions.

Does anybody have an opinion as to how much play is too much, or know the parameters? I realise that the play will only increase, and so logic is telling me to renew.

Reggie said:

I have had a scan of the manual, but cannot find any wear limitations, only new bush dimensions.

Click to expand...

You didn't say if the bushes were still within the "new" tolerance limits or not?
If they were somewhat outside those tolerance limits, then I would have thought it would be wise to replace them?

However, As you have the box apart, as you say, the logical thing to do would be to replace them anyway?

Les I've probably accidently misled you.

Before when the primary case was on and the clutch in situ, I couldn't feel any play in the sleeve bushes. Having taken the above off with the gearbox still in the plates, I've measured 10 thou of movement on the output shaft with my dial gauge. I haven't yet dismantled the gearbox..............but probably will.

I suppose my question is, does anybody know if with new sleeve gear bushes should or could there be a slight rocking motion, i.e. 10 thou measured?

But you are right Les, the only way to "know" is to take them out and measure them.

Thanks

I am presently rebuilding my gearbox and all I can say is the new bushes are a lot tighter than the old ones. The bush on the biger of the two first gear pair I pressed in and machined to fit the layshaft, there must be about .001" of free play in that one. All the others were as they came new and were a very close fit on their respective shafts.

According to my manual, the gear bushes should be .81325" to .81200 that is also .001" of tolerance. The kickstart bush also has close tolerance .6875" to .6865" ( again .001").

I would assume .01" is a bit much and you need to replace parts to get rid of that much freeplay.

Jean

Thanks for that Jean.

The freeplay is not the same as the tolerance of the ID of the bush, the free play tolerance as fitted is the difference between the ID of the bush and the OD of the mainshaft, as there will be top and bottom limits for both take the top limit of the bush and the bottom limit of the shaft and the difference is the freeplay as it left the factory.

kommando said:

The freeplay is not the same as the tolerance of the ID of the bush, the free play tolerance as fitted is the difference between the ID of the bush and the OD of the mainshaft, as there will be top and bottom limits for both take the top limit of the bush and the bottom limit of the shaft and the difference is the freeplay as it left the factory.

Click to expand...

Here's a previous thread about that: http://accessnorton.com/post20399.html#20399

So the widest factory tolerance limits would appear to result in a maximum initial clearance of around 3.8 thou, which would seem to be rather a lot of clearance?
I measured both end bushes of a spare used low-mileage sleeve gear I have on my spares shelf, one end bush was about 0.8012-0.8013, the other was a little undersized at around 0.8010-0.8011