Leaking primary chain cases

[Oggers]

Gents

Matchless G9 appears to be leaking lube oil from the pressed steel primary chain case. Not a great design, held in place with a steel band/turnbuckle arrangement around the circuference. All ideas much appreciated - apart from the ususal gasket sealant - in order to impove matters.......

[mini-me]

The have been whole sagas of epic proportions written about this on the AMOC jampot site; best you read that, you'll only get exactly the same cockeyed advice about silicone, patent rubber seal and more from here as you'll find on Jampot. Having said all that the permanent positive way to go about it is in their archives.

All I will say, as someone who has owned, ridden, maintained Matchless machines for over 50 years, if you put it all together properly it won't leak. Mine don't.

Putting it together properly starts at the crankcase not by fiddling with the joint.

[iansoady]

Mini-me is of course correct as always. However, I found the Buckingham seal worked well.

Like all those band type chaincases (Velo is another example) they are a real pain. And when you're also dealing with the dynamo driven from the primary so you're for ever opening it up. It can drive strong men to tears. Not me - I sold my G80S. However, my younger brother failed to learn from my example and is now struggling with his Ajay Model 18........

[Oggers]

Ian - I fear you may have a very good point! However, I'll remove it and have a look at the Buckingham seal you mention. Unsure why crankcase appears to be root cause - surely this is simply a case of the added chain bath lube oil just leaking out of the joint?   

[mini-me]

Pay attention at the back 

I did not say the crankcase is the cause, I said you need to start there.

I am sending you a lengthy PM, read study and digest and all will become clear.  It was aimed at singles but  it all holds true for twins.

[Oggers]

Mini - I have it, and I am digesting. Very many thanks. To add to my woe, I also managed to mash the speedo drive this weekend, but therein is a whole different ballgame - I fear poor PO assembly........

[mini-me]

There is a lot on the amoc site re that problem, basically the manual is wrong. yes wrong.

The correct way of assembling is on there.

might also find solution to that on Christians archives

I have done it myself once so you are in good company.

[Oggers]

Just a thought on the primary chaincase. I am asssuming it is leaking from there - as when it was running, quite a quantity of oil dripped out (when the bike was stationary and presumably when running) in the vicinity of the lower portion of the chaincase and I have noticed a weep there beforehand. However, when left for a few minutes after running and when cold, there are no leaks at all.

I am wondering therefore if the leak is not from elsewhere - as if it were chaincase, would it not continue to drip?

I guess I can measure the level of oil inside and see if it is dropping......

[mini-me]

I am not as up on the twins as I am the singles, but the singles have a breather pipe that ends just behind the case, these often have a fair bit of oil drip after a run, a bit of rubber pipe to just below the case lets it drip instead of  just smearing the back of the case and looking as if its the case leaking.
might be worth seeing if same applies?

I learnt to live with the odd oil stain on the floor.

[john.k]

the twin  breather discharges into the primary via a hole in the crank...........and since there are no oilways to block,no person can have any objection to using silastic in sufficient quantity to stem any leak in the joint............howver there are still other holes in the case that cant be blocked,and oil can run out of these........especially after a run at speed.

[Rex]

The days of filling the primary (especially on leak-prone tin cases) are over. Just ensure that the clutch bearing(s) are greased and that the primary chain is given a squirt of oil before each trip.

[iansoady]

Some of us can manage to get leak-free tin primaries.....

[Rex]

Clearly so Ian, but for those whose cases may be damaged or who can't be arsed to put the effort in, there is an acceptable alternative.

[mini-me]

who can't be arsed to put the effort in

Well, if they cannot be arsed to put effort in why should we here put the effort in to help them?

I for one get well pissed off with the types that come onto forums with rubbish bikes made from left over scrap and lawn mower bit, expecting free help to rectify  their junk.

If you can't fix it, don't buy it.