Gearbox oil leak

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Dubbsy
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Posts: 26
Joined: Thu Dec 02, 2021 4:07 pm
Location: Bedfordshire England

Gearbox oil leak

Post by Dubbsy »

Hi, I've managed to get a nice tight oil free engine after a rebuild.... However I do have an gear box oil leak somewhere round by the chain sprocket area ( it's difficult to see up inside this area). It's defo nice clean gear oil and this level is dropping. I have a spare g/box ass in bits from the previous owner and attached an image for ref, is the main drive to chain sprocket a common leak item , looks like this takes a seal, there is also a threaded plug and a core type plug / blanking plate. Any help is greatly appreciated
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Red Gauntlet
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Location: Dorset UK

Re: Gearbox oil leak

Post by Red Gauntlet »

The seals do leak if not new, but more likely to be worn bushes in the sleeve gear. Unless someone has been there before you and damaged the steel core plug caps.
Dubbsy
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Posts: 26
Joined: Thu Dec 02, 2021 4:07 pm
Location: Bedfordshire England

Re: Gearbox oil leak

Post by Dubbsy »

Thanks, can the sprocket main drive seal be changed once the box is out, but without a full dismantling of the gearbox?
Red Gauntlet
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Location: Dorset UK

Re: Gearbox oil leak

Post by Red Gauntlet »

It can be done but it is a pain, you would be better off giving the whole thing an overhaul. You can check all the bushings and bearings at the same time then, better to do the whole job than regretting later.
ChrisTheChippy
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Location: Essex

Re: Gearbox oil leak

Post by ChrisTheChippy »

There's a seal right at the back of the gearbox and I think that's your problem. This seal is available from Villiers spares. I can't remember the part number. It solved the leak from my gearbox but it now leaks from the kickstart shaft and from the gear lever shaft! oil tightness is very difficult to achieve on these boxes. There is a way of machining in a dowty washer around these two shafts which i will be exploring in the near future. I saw it had been done to a lightweight at the last jampot. I had a quick conversation with the owner and they said it works well. I will be experimenting over the winter months. Just fed up with leaks.
Red Gauntlet
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Location: Dorset UK

Re: Gearbox oil leak

Post by Red Gauntlet »

You can buy the X ring upgrade from the club along with the inner gear shaft rings and marginally bigger O rings for the kickstart shaft online, however, I found that just using the X ring and a set of new O rings from the club has solved all the leaks at the busy end. Assemble with a bit of Castrol Heavy grease and it all works well.
Dubbsy
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Posts: 26
Joined: Thu Dec 02, 2021 4:07 pm
Location: Bedfordshire England

Re: Gearbox oil leak

Post by Dubbsy »

Many Thanks Red Gauntlet & Chris,
Could you help me on the X ring upgrade ? im not familar with this, and it sounds a worthwhile action once the box is out.

I see the seal that seems to cause problems is a mainshaft oil seal Pt No 0141267, the prev owner did this but way back 10 years ago- Chris I've seen the link on the villiers one as well. The other problem is 2 little core blanking plugs for the shafts Pt No 041394 & 041395, AMOC is not showing these at all nor is AMC classics. Would anyone have an alternative provider ?
Red Gauntlet
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Location: Dorset UK

Re: Gearbox oil leak

Post by Red Gauntlet »

The core plugs just pop out from the inside, clean them, and the area with brake cleaner / IPA or similar and then Araldite (not my preferred method) them back in if they are really leaky, as there is no real pressure behind them you can also use a Loctite sealant (better) with equal effect if they are snug. If they are a really poor fit then get a big ball bearing and place it in the plug and tap with a hammer gently until they are correct size again, you have to be a bit careful here as they are normally fitted from the inside and without removing the bushes you will have to reverse fit them, bearing in mind that they are peened from outside of the rear of the box. When the oil seal 041267 leaks, it's often: A, Because it is old, B, The bearing is worn on the sleeve gear, check the two bushes in the sleeve gear when it is out and replace and ream if more than a few thou clearance, and C, If the chain sprocket is loose.
The X ring upgrade is as simple as removing the old O ring and replacing it with the new X ring one, make sure you clean any crap out before you fit the new seal though.
SPRIDDLER
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Joined: Wed Sep 01, 2004 1:00 am
Location: WEST SUSSEX UK

Re: Gearbox oil leak

Post by SPRIDDLER »

There are a couple of L/W gearbox overhaul and rebuild articles in the links below which may be of interest.

http://archives.jampot.dk/technical/Tra ... ebuild.pdf

and this excellent one is by a Jampot member.

http://archives.jampot.dk/technical/Tra ... erhaul.pdf
I poke badgers with spoons......
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