Author Topic: Crank main shaft diameter wanted  (Read 1124 times)

Offline mark

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Crank main shaft diameter wanted
« on: 14.09. 2012 06:07 »
Can anyone supply the factory dimensions for the Crank drive side mainshaft late A10.

Regards to all
Mark
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Offline gavinoz

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Re: Crank main shaft diameter wanted
« Reply #1 on: 14.09. 2012 07:06 »
Others will have much more detail, but quote from Beeza Bills website "but The crankshaft is machined to a diameter of 1.180 inches [the same size as the Drive side] " if thats a start.
Gavinoz
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Offline mark

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Re: Crank main shaft diameter wanted
« Reply #2 on: 14.09. 2012 07:25 »
Thanks Gav, mine measures 1.180 but the bearing is a sliding fit and has chewed up a shim. I can have it built up but I'd like to know the factory specs for the interference fit. The bearing is 30mm which is 1.181 which tells me that I have 1thou clearance.
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Online Billybream

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Re: Crank main shaft diameter wanted
« Reply #3 on: 14.09. 2012 07:36 »
Hi.Sounds like clearance is not excessive, is it round, my recommendation would to use a bearing fit type Loctite retainer together with new bearing and shims, once you have established end float, a good idea is to use dummy bearing to first check out end float before final assembly with new bearing.
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Offline mark

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Re: Crank main shaft diameter wanted
« Reply #4 on: 14.09. 2012 11:55 »
Reading a few previous posts it seems that it is not unusual to have a sliding fit for the bearing and it shouldn't be a problem if the nut is done up correctly. My problem is that I had the SRM cush nut done up correctly and the bearing has obviously spun. The only thing that I can think of is that somehow the spacer wasn't pulling up against the bearing. I am running a belt drive but that shouldn't cause a problem. I wil check that the spacer is being pulled up correctly before replacing the bearing.
Regards
Mark  

 
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Online KiwiGF

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Re: Crank main shaft diameter wanted
« Reply #5 on: 14.09. 2012 13:36 »
Hi Mark I do (edit: don't) know the oem figure but 001 more than the I.D of the bearing should be about correct for the crank given the heat expansion of both (steel) parts should be effectively the same unlike with ally parts.

It's a judgement call as whether you think it worth building up the crank dia. Personally I'd like to have an interference fit.

If you trust the bearing to be correct you could give the bearing to the company doing the building up and get them to make it to suit.

Just my cents worth.

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Offline muskrat

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Re: Crank main shaft diameter wanted
« Reply #6 on: 14.09. 2012 21:03 »
G'day Mark,
               the bearing is a 30mm ID, the shaft needs to give a light interference fit (1/2 thou) so should be 1.1815".
The spacer is tapered on the inside on one side. This side goes inwards. If put in backwards it won't clamp the bearing.
Cheers
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Offline duTch

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Re: Crank main shaft diameter wanted
« Reply #7 on: 14.09. 2012 23:23 »

That's interesting Musky, that'd mean the shaft would have a slight taper too, so measured at the outside will be a half thou or so smaller than the inboard side to match??
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
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Offline mark

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Re: Crank main shaft diameter wanted
« Reply #8 on: 15.09. 2012 05:35 »
I am going to do it properly and have the shaft built up to a slight interference fit. Musky, yes I am aware of the correct way to assemble the spacer and to be perfectly honest I didn't notice which way it was when I removed it, I could have had a seniors moment when I put it together. However I would prefer to believe that there was something else that stopped it pulling up tight, although it seems ok now. Dutch the spacer is chamfered on one side of the inner dia to allow it to clear the shoulder of the shaft and pull up on the bearing, the bore of the spacer is not tapered.
All the best
Mark
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Offline duTch

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Re: Crank main shaft diameter wanted
« Reply #9 on: 15.09. 2012 11:08 »

 Hey I was off track there,thinking bearing ID/shaft tapered(?), and I can't even quite blame it on 'senior moment'- just comes natural....but I know the spacer you mean(67-1138), which is not same as the plungers..phew! *eek*
 cheers duTch
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Offline wardleybob

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Re: Crank main shaft diameter wanted
« Reply #10 on: 28.10. 2012 18:57 »
I would youse bearing fit