Gearbox, layshaft bush, driveside

Information relating to the Matchless G5 or AJS Model 8 350cc Lightweight
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Re: Gearbox, layshaft bush, driveside

Postby vigo » Thu Mar 19, 2020 7:00 pm

So I now have layshaft bush together with gearbox. It's been pre reamed to a nice snug clearance. All sounds great doesn't it, not quite. I set the bush in the casing using epoxy resin not loctite, reason being the bush location has suffered either from corrosion or bad casting. As I was doing said job I had "line up" doubts, and rightly so. The layshaft will not engage completely when closing the box the last 12mm.
My choice now is to either ream for more clearance or remove bush and reset to line up. At the moment I'm favouring ream as I do not wish to subject the casing to any more undue stress removing bush.
Any thoughts?

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Re: Gearbox, layshaft bush, driveside

Postby clanger9 » Thu Mar 19, 2020 7:06 pm

Oh, tough one. If you put the casing in the oven, might the epoxy degrade enough so you can tap the bearing out?
Then you can do it again, but this time with the layshaft in place... ;)
1989 Moto Morini Dart 350
1993 Ducati 750SS

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Re: Gearbox, layshaft bush, driveside

Postby vigo » Thu Mar 19, 2020 8:51 pm

Yes I suppose that's worth a try. Just as nearing completion it's a step backwards. I may try lapping a few thou as the clearance is snug. I'll sleep on this one.

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Re: Gearbox, layshaft bush, driveside

Postby clanger9 » Thu Mar 19, 2020 9:00 pm

I'm sure it'll be OK with a bit of slop. These are not precision gearboxes...
1989 Moto Morini Dart 350
1993 Ducati 750SS

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Re: Gearbox, layshaft bush, driveside

Postby vigo » Sun Mar 22, 2020 12:36 pm

I'm actually getting somewhere. I gave layshaft bush a bit more clearance but decide to remove it. Having done that and a dry box assy run I then set the bush with epoxy, closed the box together and left overnight, bingo result. It was indeed the crooked alighnment of layshaft bush causing the problem due to a less than perfect casing condition.
The kickstart side casing is at the moment temporarily screwing all together and I think all geares can be selected, difficult to tell turning and selecting, anyway tomorrow. I think I may fill with oil for leak check afterall that's the reason I started this can of worms.

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Re: Gearbox, layshaft bush, driveside

Postby clanger9 » Sun Mar 22, 2020 2:59 pm

Excellent! May I ask you got the epoxied bush out?
1989 Moto Morini Dart 350
1993 Ducati 750SS

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Re: Gearbox, layshaft bush, driveside

Postby vigo » Sun Mar 22, 2020 3:25 pm

I drifted it out with high frequency light taps using the old bush for exact diameter until it let go. I didn't pre heat

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Re: Gearbox, layshaft bush, driveside

Postby clanger9 » Sun Mar 22, 2020 3:36 pm

Nice one. It's good to know that works!
1989 Moto Morini Dart 350
1993 Ducati 750SS

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Re: Gearbox, layshaft bush, driveside

Postby vigo » Fri Mar 27, 2020 5:45 pm

This is intended as the last input to the "layshaft bush" saga. The box is back in the bike and all is assembled. All oil levels (except chaincase) filled, not one leak anywhere,yet. All gears select when rolling, I think the box is good. I wouldn't say I've become an expert but I saw this machine in my sleep.
I want to thank all who passed advice and I am now a lot wiser.
Moving on now to get the engine running properly for which I think it best to open another subject involving "spitfire multispark" and ngk BR7EIX plug.

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Re: Gearbox, layshaft bush, driveside

Postby vigo » Fri Mar 27, 2020 5:54 pm

Almost forgot one last thing I wanted to show in the absence of a metal oil cap seal for the layshaft bush kickstart side, a cork. Tapered cork epoxiwd in place, let's see if it holds.
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