Inner Primary Chaincase/mainshaft oil seal

Information relating to the Matchless G5 or AJS Model 8 350cc Lightweight
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Inner Primary Chaincase/mainshaft oil seal

Postby Martin.S » Fri Aug 17, 2018 9:12 pm

I don't know what you call it but the steel pressings that hold the mainshaft felt seal behind the clutch - this one was obviously leaking as it was plastered in Red Hermatite - so I drilled out the spot welds. Inside were some what I can only describe as elastic bands. Is this assembly available?
I seem to recall but yet to find a reference to someone turning up some alloy ones and using an O ring as a seal for their Commando.

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Re: Inner Primary Chaincase/mainshaft oil seal

Postby clanger9 » Sat Aug 18, 2018 8:25 am

Yes, it's available from club spares: "910101 FLOATING SEAL KIT"
Cheap & easy to fit!
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: Inner Primary Chaincase/mainshaft oil seal

Postby Martin.S » Sat Aug 18, 2018 9:51 am

Thanks Paul, £7.54 - Excellent.
Does the felt seal included fit inside the two discs or around the mainshaft?

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Re: Inner Primary Chaincase/mainshaft oil seal

Postby clanger9 » Sat Aug 18, 2018 11:12 am

It goes between the discs - you fit a disc either side with the felt circle in between & pop rivet the assembly together. Once the felt has got some oil on it, it swells to fit the mainshaft. Here's a photo of mine from a while back (ignore the oil leak...)
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1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: Inner Primary Chaincase/mainshaft oil seal

Postby Martin.S » Sat Aug 18, 2018 3:16 pm

Ah, that's what I thought, so nothing seals the steel discs to the alloy chaincase - what I imagine the elastic band type material on mine was trying to do?

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Re: Inner Primary Chaincase/mainshaft oil seal

Postby clanger9 » Sat Aug 18, 2018 3:32 pm

That's right - there's no seal between the discs and the casing. No need, because it's just a gentle splash here (and there's a reasonable amount of "springiness" in the plates to hold them tight against the casing...)
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: Inner Primary Chaincase/mainshaft oil seal

Postby Ozmadman » Mon Aug 20, 2018 11:15 am

More to keep the dirt out than the oil in I think!
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed

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