Author Topic: Gearbox main shaft  (Read 135 times)

Offline A10 Tim

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Gearbox main shaft
« on: 24.11. 2019 09:47 »
Hi all,
       I have s/a gearbox with a spline type shaft that a friend gave me years ago.
Can anybody tell me please if any model had this as standard, and what type of clutch would fit.
It also has a 19 tooth narrow chain sprocket fitted
I have 1960 a10 with taper shaft and 4 spring clutch At the moment.
Many thanks for any info
Tim

Online JulianS

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Re: Gearbox main shaft
« Reply #1 on: 24.11. 2019 10:00 »
Plunger box mainshaft which should take a Norton clutch.

Below from Eddie Dow 1967 catalogue. I would not fit one to an RRt2 box though despite what it says.

Offline Swarfcut

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Re: Gearbox main shaft
« Reply #2 on: 24.11. 2019 12:07 »
Narrow chain used on lower powered models that share the same basic gearbox, eg B series bikes.

 The splined (rather than taper) shaft is from the earlier Plunger box. The internals of both boxes are very similar, with minor variations to the gear profiles, and a serious update to the gear selector mechanism and consequent changes to the major castings to fit the S/A Frame. Fitting a far superior (at the time) clutch was a common mod back then. By good fortune, accident or design, the Norton Clutch fitted the earlier splined type shaft.  Bushes, bearings seals, sprocket are common to both plunger and S/A boxes.

Swarfy.

Offline A10 Tim

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Re: Gearbox main shaft
« Reply #3 on: 24.11. 2019 12:38 »
Many thanks swarfy and JulianS
For the info.
I’m going to use that gearbox on my next project.
Hopefully a B33 if I can find one.
Cheers
Tim

Online duTch

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Re: Gearbox main shaft
« Reply #4 on: 24.11. 2019 13:18 »

 
Quote
..........I would not fit one to an RRt2 box though despite what it says.

 In case you or anyone else need to know, the reason for that is probably just because the RRT2 box uses a needle roller bearing ('T' is I think for Torrington bearings) in the cluster end of the sleeve gear and this needs a hardened unscrolled section of mainshaft (that's the only reason I know of anyway)....mind you, I grafted RRT2 gears into a Plunger box but replaced the needle roller with a bush- but that's parked up for the moment even though it seems to have worked out ok bbut not intended for hard use.....
 Also note that it's not possible (without major modificating ) to use a Noturn diaphragm clutch in a Plunger due to diameter
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
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Online JulianS

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Re: Gearbox main shaft
« Reply #5 on: 24.11. 2019 13:44 »
The inner diameter of the needle roller in the RRT2 sleeve gear is slightly larger than that of the bush (dont ask me why I dont know)

So if used with the RRT2 sleeve gear it does not bear on the needle roller and just relies on the outer bush.

As well as having no oil scroll the inner section of the RRT2 shaft is also stepped slightly to give the necessary slight increase in diameter.

You can see the step in the photo of an RRT2 shaft below.

Online berger

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Re: Gearbox main shaft
« Reply #6 on: 24.11. 2019 14:39 »
I have not been to the pub- yesterday or today . went friday *beer* I would have a look inside it many people used narrow chain to race them

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Re: Gearbox main shaft
« Reply #7 on: 24.11. 2019 16:14 »

 
Quote
...The inner diameter of the needle roller in the RRT2 sleeve gear is slightly larger than that of the bush (dont ask me why I dont know). ....

 I didn't bother saying that- just went for the obvious, and the layshaft beaings are also larger respective diameters by about 0.002" or so - probably' cos that's the size of the bearings
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