Gearbox Oil Leaks

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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PeterJCorby
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Joined: Thu Nov 21, 2013 3:05 am
Location: Perth Australia

Gearbox Oil Leaks

Post by PeterJCorby »

Hello Good People,
So I took out the gearbox today as it seems to be leaking oil into the Primary Cover. Now this bos has been rebuilt recently and all the Bronze bushes replaces as well as the main shaft oil seal. Besides the leak from the cracked o ring in the Quadrant Bolt, I also have a leak from the Steel rod (forget the correct name) that passes through the clutch. I do not recall there being an o-ring in the channel but may have just fortgotten. Memory seems to be failing me lately.

suggestions?
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robcurrie
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Re: Gearbox Oil Leaks

Post by robcurrie »

Gearbox oil can pass through the splines on the mainshaft (behind the clutch). You could put silicon sealer on the splines before fitting the clutch.

Rob C
PeterJCorby
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Joined: Thu Nov 21, 2013 3:05 am
Location: Perth Australia

Re: Gearbox Oil Leaks

Post by PeterJCorby »

Hey Rob,

My G12 is from your part of the world, or rather close by. From Mad Bob country - Ex Rhodesian Police Bike.

The Oil is most definitely leaking through the main shaft through the clutch release pushrod. Any ideas as to of there are any seals on it? Only way to tell to to reopen the gearbox and this I do not want to do unless I really have to.
Mick D
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Re: Gearbox Oil Leaks

Post by Mick D »

Hi

If oil is passing along the main shaft through the clutch push rod drilling it would suggest the box is over filled, did you fill to the level plug?

Regards Mick
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robcurrie
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Re: Gearbox Oil Leaks

Post by robcurrie »

Peter, we have a lot of ex Rhodesian bikes and bits here, things really did go "south" after Bob pulled some moves. As Mick says, I think your box is overfilled. There is a level plug facing rear in the cover behind the kickstart. There is no seal on the clutch rod, and the oil level should be way below it. I fill mine to about kickstart shaft height (then it dribbles out and finds its own level) :?

Rob C
PeterJCorby
Posts: 37
Joined: Thu Nov 21, 2013 3:05 am
Location: Perth Australia

Re: Gearbox Oil Leaks

Post by PeterJCorby »

Hey Mick, Yep, Correct qty of oil was in the box, measured to the plug,

I will however drain it all as the box ix now on my work bench, having replaced the two o-rings in the Quadrant and cam bolts. Any other place the oil could be coming from? I placed the box sprocket side down to see if any oil runs out, Its been a few hours now and its still dry.
The reason I believe the oil is coming from the drilling (hollow main shaft) is the steel rod was visibly full of oil on removal, but given the below perhaps i have it wrong.

After the first long ride I pulled into my driveway and left a major puddle of oil all over my pavers. Looking back to the street I could see the drip matks as i approached home. Back tyre was soaked. The oil tank breather is dry. Primary case oil level was slightly higher then it was when I had originally filled it, but not enough to overflow into the breather pipe.
Back of the primary chain case was wet and on removal I can see that oil has been sprayed out between the Primary and gearbox.

Gearbox was recently rebuilt and all seals and bearings( roller and bronze) were replaced.

Any other suggestions please? Like I said gearbox is on the bench, so now is the time to check all options.
Mick D
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Re: Gearbox Oil Leaks

Post by Mick D »

Hi

Sounds like it could be the inner primary case leaking from the main shaft felt seal, (behind the clutch), or the breather hole below the cast shield and just above and to the rear of the alternator lead grommet, both symptoms of over filling.

Regards Mick
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ajscomboman
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Re: Gearbox Oil Leaks

Post by ajscomboman »

It wouldn't be the clutch push rod as that would simply just fill the chaincase and certainly wouldn't cause a drip trail under any circumstances. Depending on year the sliding seal wouldn't have a felt seal, I think this was dropped for 60 onwards models and to be honest the rolled over type of the later cases is a pain as it's nigh on impossible to seal them. I'd agree with Mick and I'd be taking a long hard look at the sealing around the mainshaft/chaincase sliding seal.
raffles
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Re: Gearbox Oil Leaks

Post by raffles »

Sounds like it was ridden with a sump full. Worth a look?
Tony
PeterJCorby
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Location: Perth Australia

Re: Gearbox Oil Leak

Post by PeterJCorby »

Ok Folks, seems like I posted in the Buyers guide section, as asll as this one some how. Must be clever ( or not ) than I thought I was. Apologies.
Thank you to those who have provided suggestions to the leaky Gearbox. I am going to reassemble today, after replacing those orings from the Quadrant and Cam. One of them actually had a teeny little oil seal in it in lieu of an oring.

I will drain the gearbox and refill according to the Manual.Lets see how we go with the dreaded leak thereafter.
Thanks again
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