Vince
New Member
Posts: 28
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Post by Vince on May 2, 2023 16:53:43 GMT
I'm trying to get my 8e 3 speed gearbox and also the primary chain cover (on James Captain) oil tight. In over 6 years of ownership I've never achieved it. Now I'm trying again. There is no gasket on the gearbox. Any suggestions for best sealant and best fettling techniques? Anybody achieve oil tightness?  |
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Post by buttybach1932 on May 19, 2023 20:06:55 GMT
Hi Vince
Unfortunately very few of the British motorcycle manufacturers took old tightness seriously so it is difficult to keep engines, gearboxes and primary chain-cases oil tight. If we see a Velocette single that is not leaking oil we ask the owner if it has any oil in it.
It was bad enough when the bikes were new, but now they are 50+ years old and most are worn or have been abused in the past the task becomes more difficult. Unfortunately a lot of owner / mechanics had a habit of separating aluminium casings by driving a screwdriver blade into the joint which normally results in damage to the joint faces.
All I can recommend is the make sure the joint faces are not damaged and stone any little imperfections using an oiled flat slip stone. I sometimes use a fine flat swiss needle file to remove small burrs but they are only available from specialist sources and tend to be expensive.
There are silicone based jointing compounds that are good with damaged joint faces but you need to de-grease the surfaces first. You can use brake cleaner on a clean tissue and let it evaporate before applying the jointing compound..
Whilst you can normally seal the joint faces in a satisfactory manner the shafts that penetrate the casings are another matter. On older British bikes most do not have any form of sealing and just rely on a close fit or a felt washer, 50 years of wear destroys the fit so they leak oil.
Some owners have machined the casings and fitted 'O' rings to provide a seal but in many cases there is insufficient metal in the required area. On some models you can fit rubber sealed bearings in place of the originals which can stop oil leakage from the gearbox main-shaft.
If you want to keep your garage floor clean and oil stain free buy a plastic oil drip tray to put under the engine and gearbox and with a two stroke the exhaust joints. As oil condenses in the cold exhaust then drips out of the joints.
Best of luck
Butty Bach.
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Post by Admin on May 22, 2023 17:45:29 GMT
Butty
I have tried using a silicon based gasket sealant putting a thin smear either side of a paper gasket. I've done that on my 8e 3 speed gearbox and on the primary drive side. I can report that it does seemed to have worked. Did a 50 mile run on Sunday with a short blast at the end where the poor old thing wheezed its way to 50 mph. Well at least it said that on the Smiths speedo! There doesn't appear to be any leakage where previously there was always a bit of a puddle. So I am pleased so far...
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Post by buttybach1932 on May 23, 2023 18:32:38 GMT
Hi Vince
Glad that the silicone based gasket sealer has cured you gearbox oil leak. It's a useful product when used sensibly but it has been responsible for the demise of many engines.
When I was in my late teens a neighbor replaced the head gasket on his brother-in-laws 2.3 litre overhead cam slant block Vauxhall Viva. He used a silicone type sealant on the head gasket. No head gasket leaks but a couple of weeks later the engine was knackered because the sealant had blocked of the oil supply to the overhead cam. If the sealant gets into oilways it causes havoc, it needs to be used sparingly and carefully.
The old favourite was Red Hermatite Sealant. Every old engine that I strip is full of it. I usually end up spending a couple of hours cleaning all the old sealant from the engine casings. If the joint faces are in good condition we use Welworthy Wellseal. This is probably about 50 years old and in a big screw top tin. You just paint it onto both the joint faces with a small artists paint brush and let it go tacky before assembling. Any excess squeezed out of the joint is cleaned off with a cloth moistened with methylated spirit. This leaves a nice clean finish.
The Tiger Cub that I rebuilt recently needed a silicone type jointing compound because the crankcase joint faces were in poor condition and very narrow.
Regards
Butty Bach
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Post by Admin on May 25, 2023 13:14:24 GMT
I remember the smell of red hermatite from when I was a teen. I recall we used it everywhere!
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Post by buttybach1932 on Jun 20, 2023 14:05:28 GMT
Hi Administrator
I spent my working life in Building Services including pipe-fitting. We occasionally used a jointing compound called Red Stag for sealing screwed joints on iron pipework. This looked and smelled exactly the same as Red Hermatite. Think of the mess that young bodgers could make with a 1lb tin of jointing compound instead of a little tube.
You do not come across it very often but Hermatite also made a green version that set solid, this is even worse to remove. Their final version was Golden Hermatite, but that did not appear to be very popular. It may be that by the time it appeared most youngsters had Japanese motorcycles and oil leaks were less of a problem.
Regards
Butty Bach
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d7er
New Member
I'm not that new, I re-joined four years ago. I volunteered for the south Northamptonshire area rep'
Posts: 46
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Post by d7er on Jul 25, 2023 11:21:02 GMT
Hylomar anyone? Rolls Royce used to use it or so some would say. NOn setting stuff that often seems just as pliable when you take it off, maybe years later.
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