1963 G2 Gearbox oil leak but not the usual suspects

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Chris859
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Joined: Sat Mar 19, 2016 7:25 pm
Location: FLINTSHIRE UK

1963 G2 Gearbox oil leak but not the usual suspects

Post by Chris859 »

Hi

I'm new to the club having just purchased my first British bike a 1963 G2 CSR (factory release November 1962) and was looking for a bit of help?

I have been through all the previous posts for gearbox oil leaks and from that I thought it was going to be a core plug but after stripping the clutch and final drive sprocket off the core plugs were both fine.
The issue is a small 2mm hole to the left of the top lay shaft core plug it's a very precise hole so don't think it's a defect but could be a previous owners brainwave? and I cant find any pictures of this end of the gearbox with the sprocket off to compare (see attached picture)
G2 Gearbox Output Shaft..jpg
When I fill the gearbox with the required 3 pints of oil it leaks through at a steady rate and looses about 1/4 pint until it reaches a level as the hole is slightly lower than the fill level on the opposite side this then start again once on the side stand and when moving

Happy to block the hole off but didn't really want to do that until I understood 1. What it was for? 2. Should it be there?


Thanks in advance for any help
Chris
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clanger9
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Re: 1963 G2 Gearbox oil leak but not the usual suspects

Post by clanger9 »

Hi Chris,

Welcome to the club!

That hole is very odd. I just had a look at my spare gearbox and there's no hole there...
I'd suggest plugging it.

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Chris859
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Joined: Sat Mar 19, 2016 7:25 pm
Location: FLINTSHIRE UK

Re: 1963 G2 Gearbox oil leak but not the usual suspects

Post by Chris859 »

Thanks Clanger9 that was my I original thought but just wanted to check it should not be there first
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Ozmadman
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Re: 1963 G2 Gearbox oil leak but not the usual suspects

Post by Ozmadman »

I have 3 gearboxes and none if them has this hole, can't think why anyone would drill a hole here especially as they have enough leaks of their own without the help of some lunatic with a drill. On that note, if that is the only leak you have then you are doing well. I am wondering whether someone has drilled the lay shaft bush to help retain it or to stop it from turning in the casing?
Last edited by Ozmadman on Fri May 13, 2016 11:14 pm, edited 1 time in total.
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
Chris859
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Re: 1963 G2 Gearbox oil leak but not the usual suspects

Post by Chris859 »

Thanks Paul I will plug it now as happy it just didn't belong there!!!
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Ozmadman
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Re: 1963 G2 Gearbox oil leak but not the usual suspects

Post by Ozmadman »

Here is a picture of the inside, notice this layshaft bush has a notch cut out for a retainer as some of the Norton lightweights used the same bush (same part number) and used a retaining pin to stop it spinning in the casing. Our lightweights rely on a press fit/loctite and do not heed the retaining pin so I reckon a previous owner has fitted a "Norton" bush as I have done but unlike me, decided to fit a retaining pin and drilled right through the casing, this is the only option I see for a hole in that position
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Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
Onedayrestoration
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Re: 1963 G2 Gearbox oil leak but not the usual suspects

Post by Onedayrestoration »

If it worked, a nice mod I'd say. My Indian Bullet gearboxes are woefully sloppy, with the same issues. Bush movement in their casings has to be seen to be believed!

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Alan
It's Nice To Be Nice : 8-)
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