The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: bikerboy on 26.06. 2017 22:01
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Took the A10 out yesterday and for about 60 miles had a great ride.
20 miles from home I heard a little noise and wondered if it was a slight exhaust leak.
Barely noticable but still there at times.
Got about 1/4 mile from home and wondered exactly why my left foot was covered in oil!!!!!!!!!
Pulled over immediately (obviously) oil all over the top of the mag, all over the barrels and head, some not much on the primary case and a hell of a lot on my left foot.
Checked rocker feed (the normal cause) all good checked level (low but not drastic) started up again and very gently got it home (oil was circulating fine btw)
On inspection most of the oil seemed to be on the top fin of the barrels and in turn running down on to the mag. Wiped it off (swearing while I did it)
2 of the big screws at the front of the primary chaincase were missing completely.
Obviously with those holes going straight thru to the crankcase I now know exactly what the slight noise was and where the oil came from.
*pull hair out*
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ahhh... that's why i love my A10 - always something to figure out so the brain never gets too lazy.
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ahhh... that's why i love my A10 - always something to figure out so the brain never gets too lazy.
Dammit I might go over to No, nort, norto.
Ok I cant even say that word let alone own one *smile*
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Such fun!
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Hi bikerboy,
Losing the primary screws is a secondary happening, usually caused by loose engine to frame bolts *eek*
John
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John
I do aim to go over it with a spanner, to be fair I did notice a little more vibration than normal but put that down to having been using one of my other bikes for the lasr couple of months.
Other than the oil disappearing and a very slight vibration it ran like a dream, it has only done about 3000 since a complete rebuild and it is still as quiet as a mouse engine wise.
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I took off my chaincase last week after completing my first 20 miles after restoration to change the engine sprocket from 18 tooth to 21 tooth. I noticed that the large screws at the front were almost loose - less than finger-tight. *dunno* I know I had done them up firmly like the others. I was surprised and wondered why. I'll take John's tip and go over the engine bolts before starting it. Ran into another chain alignment problem though, so might cover that one later. *problem*
Col
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Carefully check the length of the replacement screws.
Too long and the screw will bear against the crankshaft web; engine will lock up.
Too short and the screw might come out; insufficient thread engagement.
Note that the crankshaft web is not full circle (less than 360 degrees) so check clearance through full crankshaft rotation
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Geez it must be the heat, getting the Flash ready, noticed a drip or two below the primary case so drained the oil and had completely forgot I had ATF in there and the drips I saw where not red, however got this far might as well make sure with a new gasket, went to slacken the cover screws and bingo three front big ones slack.
Figure maybe the oil drip could have come from oil weeping out of the crank via the three slack screws, belt and braces I'll use a bit of thread seal on them, and check the engine bolts
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El Plungo's are safe from this affliction *smile*
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Heh, I currently have leaks on the gearbox, primary and timing side. Not too bad so I check the levels before and after a run to see how much I lose - not enough to be concerned about though. Seems when she's hot (the bike, that is), she leaks less and vice versa. Better not let GB into this convo, could turn dodgy. *eek*
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Just a little heads up as we're on the primary chain case
as my three front screws were not tight I thought better check also the two internal studs that hold the primary inner cover on, they are wired so should be fine and they were.
However the big circular gaskets at the front had obviously passed oil so changed them, in removing the two wired studs I thought one did not seem to come out dead square, further investigation showed the holes in the steel spacer (twix inner primary and crankcase) did not mate exactly with the holes in the inner primary case, wasn't much but did make replacing the studs difficult and liable for cross threading ( I must have been fairly dexterous the last time I put them in).
Easy cure was just pass a very slightly larger drill through the steel plate, like a 1/16
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I think John Chaterlea may be able to shed some light on my Primary problem, having read his very thorough article on sprocket alignment on the Forum. http://www.a7a10.net/forum/index.php?topic=9646.msg70166;topicseen#msg70166
I took the Flash out for its second jaunt today. Did 20 miles with a cool-down halfway. (Check the photo).
I have a few problems, but the main issue is that the primary is leaking oil badly. It is coming from the gearbox shaft felt seal.
I think the problem is that the clutch centre does not protrude from the inner chaincase enough. (Todays photo from underneath). I knew at the time that it wasn't much, but thought I could get away with it. How much should be visible from the gearbox side.?? The seal is the standard BSA felt ring in the standard sliding plate.
I have just replaced the engine sprocket with a 21-tooth, up from the 18-tooth that was on it when I obtained the bike 33 years ago. I think the 21-tooth is just about right. Thanks for that advice.!
When I compared the two sprockets, the new 21-tooth had a thicker inside shoulder than the 18-tooth - up from 0.4mm to 1.7mm. This prompted me to re-align the sprockets, using a new straight-edge and in so doing, the total misalignment was 2.9mm, the engine sprocket being 2.9mm out further than the chainwheel sprocket. Obviously, it was also 1.6mm out with the 18-tooth sprocket as well. So much for my first alignment effort. *red*
So I got 2.9mm machined off from the inner face of the Cush Bearing Sleeve. The alignment is now perfect. The outer edge of the sprockets is now just perfectly level with the gasket surface of the covers, perhaps a bit further in than other photos I have seen on the Forum. No chain noises today and the chaincase remained quite cool.
One would think that with the chainwheel sprocket further inwards than it should be, that the clutch centre would also be further through the felt seal than normal. The reverse is true.
The Clutch Centre which I picked up at a SWAP Meeting (Autojumble for the UK Residents) looks normal. (Comparison Photo)
The chainwheel I purchased new some months ago, but I cannot find my purchase documents, so no further info as yet.
Any hints out there as to what it may be.?? I know to fix the leak, I have to remove it all to have a good Captain Cook at it.
Colin
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.....I have to remove it all to have a good Captain Cook at it....
'ole 'Cookie has more than a lot to answer for... *conf*
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Hi Colin
I recall something from a while back about a part that had the wrong scroll on it, was it the clutch centre?.
Any way it so happened there had been a batch of them with the scroll going the wrong way so pushing oil out instead of in, have a good look at the scroll and work out what it is going to do with reference to the direction of rotation
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Have the same problem on the SA. When I bring the oil up to level it’s leaking badly. Once the level has dropped it settles to a drop every now and then but the chain stays wet. Next mod on the list will be an oil seal behind the clutch.
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HI all.
Dave burton used to do a great sliding chain case seal that you stick it to the case with silicone sealant and still allowing thee sliding plate to move. Don't know if he still sells them but if he does they are the seal to use.
ELLIS
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A felt washer on the back of the clutch adaptor keeps the oil from leaking at that point. Just thick enought to slightly compress between the adaptor and sliding plate. The SRM clutches come with one. The scrolls not very effective.
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Next mod on the list will be an oil seal behind the clutch.
I got an oil proof foam seal off Dave Flintoft engineering. He specializes in Gold Stars.
Dave Flintoft Engineering
david-flintoft@sky.com
Telephone 01287 638677
You have to stick it onto the rear primary case with silicone, then grease the other side so that the sliding plate will slide ok. It cured my leaks.
Also seal the gap in the sliding plate with silicone.
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Have the same problem on the SA. When I bring the oil up to level it’s leaking badly. Once the level has dropped it settles to a drop every now and then but the chain stays wet. Next mod on the list will be an oil seal behind the clutch.
Same here, I keep the oil level as shown in sketch and it leaks very little, not enough to worry about, the chain is always wet so is getting enough oil. *smile* and I use ATF *fight*
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Thanks Fellas,
Bill - The scroll is correct, but looks to have slightly less turns than others (See photo from previous post). The additional SRM Felt ring may do the trick, but I do like the idea of Dave Flintoft's foam seal or Dave Burton (Ellis, do you have contact details?). Does the ID of these seals fit the mainshaft OR the scroll itself, as I am not sure I have enough scroll showing to seal on it. I wonder how John Chaterlea's X-section seal fits.? Inside or outside?
I usually fill about 250ml of oil, then drain the excess through the bottom. It still has the original "standpipe" on the drain, and I usually get about 25mls excess. So the 225ml specified by BSA is about right. I might just leave the oil level to adjust itself for while like Morris, just keep an eye on it.
It is a bit weird that the clutch chainwheel is 3mm closer to the inner cover than standard, but the scroll is not visible outside the chaincase.!
Cheers
Colin
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Hi Colsbeeza.
Sorry I'm getting the Burtons mixed up. It is Dave Flintoft who has the seals. As regards chain case oil capacity SRM recommend 190cc which is enough to lubricate the chain but not enough to Soake the clutch plates. Hope this helps.
ELLIS
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Below are the fitting notes for the Dave Flintoff sliding plate seal.
Like the SRM felt seal on the adaptor it is an effective, low tech and cheap solution.
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It is a bit weird that the clutch chainwheel is 3mm closer to the inner cover than standard, but the scroll is not visible outside the chaincase.!
Cheers
Colin
If your bike is fitted with the BSA 6 spring clutch then misalignment of clutch chainwheel can happen if the clutch sleeve fitted is from a 1954/55 half width hub swinging arm bike. There is little to distinguish between the 2 parts to the eye.
The full width hub bikes for 1956 on season were fitted with a modified sleeve offsetting the primary drive about 1/8 inch further out to make room for the fully enclosed chaincase. Also introduced at the time was the steel spacer between chaincase front and crankcase and new cush drive parts.
See brief note below from US importer Hap Alzina.
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thanks for that julianS I often wondered years ago why my chainwheel was worn, I put it right myself after fitting another chainwheel and lining up the engine sprocket, but this now comes some way to the explanation. my frame is an early 55 s/a but others through history most definitely miss matched many cush drive parts. I first thought the clutch centers were taper ground different. appreciation given.
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Thanks Ellis, I have emailed Dave Flintoff.
Julian, that may explain my problem. I did change to a 4-spring clutch. The Cush Sleeve had a collar thickness of 7.9mm. The Hap Alzina sheet lists several changes, so who knows what sleeve I ended up with. I had believed that a 7.9mm collar was normal for the late models. Thanks for the details of Dave's seal.
Cheers
Colin
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Hi All,
Julians info also infers that the cush drive sleeve shoulder must have changed at the same time ??
At this point in time though it can cause lots of headaches *sad2*
I wonder how John Chaterlea's X-section seal fits.? Inside or outside?
To fit the X ring I removed the centre part arrowed in GB's post
I machined up a disc with the centre portion thick enough to cut a groove in to accept the X ring
That was quite a few years ago now but it seems to be still OK
John