Oil leak, suspect gearbox

Information relating to the Matchless G5 or AJS Model 8 350cc Lightweight
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Griffy
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Joined: Sat Oct 26, 2013 3:22 pm
Location: HAMPSHIRE UK

Oil leak, suspect gearbox

Post by Griffy »

I recently acquired a G5 from a friend, and since it had not been serviced for a while renewed the oil in the engine and topped up the gearbox according to the manual.. just below the inspection cap. Since doing so the bike has leaked fresh oil (which is why I suspect the gearbox) when left for a while. Any ideas on what may be causing the leak?
RG
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Ozmadman
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Joined: Wed Dec 14, 2011 1:02 am
Location: ESSEX UK

Re: Oil leak, suspect gearbox

Post by Ozmadman »

Has the level dropped in the box? normal places for the box would be the kick start or gear change shafts and the rear main seal at the other end (possibly oil running down the centre stand)
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
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clanger9
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Joined: Sat Jun 20, 2015 9:38 am
Location: Chester, UK

Re: Oil leak, suspect gearbox

Post by clanger9 »

"They all do that, sir" :roll:

Seriously, leaks from the kickstart or gearchange shaft are common. If there's nothing visible from the kickstart end, then it's probably leaking from the rear seal (as Paul says).

Despite what the owners manual says, there's a service bulletin that says correct oil level is 1/2" below the oil filler hole:
http://archives.jampot.dk/technical/Ser ... cation.pdf

That could well be correct. Mine leaks noticeably more if I fill it right up to the top, so I leave it between 1/4"-1/2" below and it barely leaks at all...
1989 Moto Morini Dart 350
1993 Ducati 750SS
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