Author Topic: Another oil leak mystery  (Read 3868 times)

Offline renos-a10

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Re: Another oil leak mystery
« Reply #15 on: 08.04. 2013 12:22 »
Thanks Muskrat !!!
1954 BSA A10 Plunger
Cyprus

Offline Pete Gray

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Re: Another oil leak mystery
« Reply #16 on: 03.08. 2014 19:38 »
Here are pictures of the seal and modified backplate.
However after still getting oil leaks + a diabolical clutch I reached out to Bob Newby for the ultimate solution to this long running pair of irritations, total satisfaction (at a price)

Pete

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Offline cyclobutch

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Re: Another oil leak mystery
« Reply #17 on: 04.08. 2014 15:17 »
Did your chain case come off without disturbing the exhaust, footrest and brake pedal? Or are you now riding an open drive to show it off?
Various, including ...
'58 Iron Head Flash Bitza


Offline Pete Gray

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Re: Another oil leak mystery
« Reply #18 on: 07.08. 2014 20:21 »
'Did your chain case come off without disturbing the exhaust, footrest and brake pedal? Or are you now riding an open drive to show it off?'

Good question !
I had to remove said items to do the job but when I t
ook the photo had lashed everything back together without the cover to be able to test the clutch under driving conditions.

Pete

1961 Swinging arm A7
2000 BMW R1100R

Offline wilko

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Re: Another oil leak mystery
« Reply #19 on: 08.08. 2014 00:43 »
The trouble with the oil seal conversion is every time you pivot the gearbox for chain adjustment the oil seal will be distorted out of round from the sideways movement against it. That's the way I see it anyway.

Online Brian

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Re: Another oil leak mystery
« Reply #20 on: 08.08. 2014 01:25 »
I reckon you are right Wilko so when I did the oil seal conversion to mine I made a bronze cup for the seal but with a hole in the outside the same size as the mainshaft. When I adjust the gearbox the shaft pushes the bronze part and not the actual seal that is carried inside of the bronze piece.

Next time I have it apart I will take some pics.

Online muskrat

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Re: Another oil leak mystery
« Reply #21 on: 08.08. 2014 09:19 »
That's a neat idea Brian, but with ware of the bronze cup and/or shaft the seal will distort (but a lot less). Without the bronze cup the sliding plate would need to slide very freely causing another oil leak.
I luv my dry belt primary *whistle*.
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Offline trevinoz

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Re: Another oil leak mystery
« Reply #22 on: 09.08. 2014 00:37 »
I don't know what you blokes do wrong but my Flash is stock standard and doesn't leak a drop from anywhere.   *whistle*

Online Brian

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Re: Another oil leak mystery
« Reply #23 on: 09.08. 2014 00:54 »
I think most of the problem with oil leaks in that area are from the felt ring rather than the scroll.

I had trouble with my A10 leaking so I did the seal conversion. I also have a swingarm B33 and it also leaked so I replaced the felt seal (which was new) with some of that rubber impregnated cork that was slightly thicker than the felt ring and it doesnt leak.

I think all the felt seals that are available are not quite thick enough.

Offline trevinoz

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Re: Another oil leak mystery
« Reply #24 on: 09.08. 2014 00:57 »
Could be Brian, mine is an original.

Trev.

Online BSA_54A10

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Re: Another oil leak mystery
« Reply #25 on: 09.08. 2014 01:50 »
I don't know what you blokes do wrong but my Flash is stock standard and doesn't leak a drop from anywhere.   *whistle*

not supprising from your avitar I can see it has been sitting on that drive way ever since I have been on this list  *roll*
Bike Beesa
Trevor

Online BSA_54A10

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Re: Another oil leak mystery
« Reply #26 on: 09.08. 2014 01:56 »
And just a little word on scrolls which oft gets lost on the modern rubber oil seal generation ( me included )
1) they only work while the engine is spinning . when stationary they actually form a leak path so I found out when I left the Roller parked on a steep drive when picking up the bride, her dad was not impressed.
2) to work, the clearence between the scroll and the case it revolves in is fairly critical and will vary according to the viscosity of the fluid it is supposed to be retaining.
Thus the BSA scroll designed to work with 30 wt engine oil in your primary case will have too much clearence to work properly with ATF ( 5-10 wt) and that is not allowing for wear over the past 50 years.
Bike Beesa
Trevor

Online orabanda

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Re: Another oil leak mystery
« Reply #27 on: 09.08. 2014 03:53 »
As well as the oil seal conversion, I drill a small hole (6 mm approx) in the (rear) alloy chaincase up high, just below the magneto points cover, and fit a Yamaha DT series breather.

Oil doesn't seem to come out of a breather when located in this area, but the otherwise  inevitable pressurization of the chain case cavity is prevented. The filler / inspection cap is also less likely to drip, because of the breather.

With the original scroll type of sleeve pressurisation could not occur, because of the clearance. Unfortunately, it could be leak free either, which is why we install an oil seal conversion.

Richard