Author Topic: Slippery clutch  (Read 2227 times)

Offline bsapete

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Slippery clutch
« on: 03.10. 2010 05:10 »
Hello all

I attempted a maiden voyage on my A7 Plunger last week after several weeks of fettling (or perhaps in my case fiddling) only to find that the clutch slips to the point of being unrideable and it is also difficult to engage gears when stationary. I have a particularly steep driveway and had to dismount and push to get it back up. I have recently fitted new levers so adjusted the freeplay on the gearbox side correctly. Prior to purchasing the old girl about 2 months ago she had been sitting for some time (last registered 3 years ago) and has been started periodicaly just to keep things lubricated. Could this possibly be caused by to much oil in the primary case (wet sumping) and the clutch being full of oil? If so is it just a case of removing the primary cover and draining the oil from the clutch and refilling to the correct level? The previous owner said that when he last rode it the clutch/gearbox were working well. He used her as a daily ride for about 20 years and said he never had any issues with the clutch.
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Offline a10gf

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Re: Slippery clutch
« Reply #1 on: 03.10. 2010 09:49 »
Hello, try some searching of the forum, many topics which give guidance on how to check all the workings of the clutch.

Some quick thoughts:
Quote
He used her as a daily ride for about 20 years
Maybe your problems simply come form normal wear?

Wet sumping would occur in the crankcase, not the primary, just check the oil level in the primary according to the owners manual. I suppose you have the original 6 spring plunger clutch, which is quite tolerant to oil, but not so tolerant of uneven spring pressure or component wear.  Plunger oil level > http://www.a7a10.net/BSA/manual54/im22-23.jpg

Having done the adjustments and having the correct freeplay at the lever, next would be to dismantle the clutch and clean + check all components for wear (like worn friction plates, bent plates, indentations in the slots), if ok, maybe just replace the springs and spend some time adjusting them for a very even lifting of the plates.

Service sheets & owners manuals are here http://www.a7a10.net/forum/index.php/board,17.0.html

e
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Offline Goldy

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Re: Slippery clutch
« Reply #2 on: 03.10. 2010 10:52 »
a10gf gives you a very good answer. Its not dificult to have a look at the clutch and that is where I would start. Take the clutch cover off and remove the clutch plates for inspection, looking for wear on the friction plates and damage or distortion of the steel ones. If they are ok then re assemble, but take great care in re setting the clutch to ensure that the clutch releases fully square. All the best
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Online bsa-bill

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Re: Slippery clutch
« Reply #3 on: 03.10. 2010 11:11 »
Quote
I have recently fitted new levers so adjusted the freeplay on the gearbox side correctly

As this is the last thing you have done perhaps it should be the first thing to look at.
Adjust the free play at the gearbox so that the lever is about  90 degrees to the cable when the handlebar lever is pulled back. at the same time you need a little free play at the handle bar lever.
Also try it with the old lever again there are differences in the travel of levers, many if not most levers sold are wrong in this respect

good luck
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Offline Mosin

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Re: Slippery clutch
« Reply #4 on: 03.10. 2010 11:16 »
Another thing to look out for is that some of the earlier six spring clutch baskets did not have a metal retaining strip around the outside of the basket. This allowed the tines of the basket to splay outwards with use which in turn allows the clutch plates to rotate freely inside the basket causing the clutch to slip like mad. I haven't described this particularly well, but I can supply photos of both kinds if required (can you tell that I have been in the same situation as you)!

Good luck,

Simon
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Offline bsapete

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Re: Slippery clutch
« Reply #5 on: 03.10. 2010 13:35 »
Thankyou to all who responded. I will remove the primary cover and see what treasures lie behind. A little confused as previous owner is absolutely sure the clutch was perfect when he last rode it. I have no reason to doubt him as he was brutally honest with his description of the bike prior to my purchase. Can anything go wrong from it being not ridden for some years?

Regards
Peter
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Offline bsapete

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Re: Slippery clutch
« Reply #6 on: 03.10. 2010 13:41 »
PS
I have checked the new lever against the original and it appears to be exactly the same, so shouldn't be any issue there.
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Offline bonny

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Re: Slippery clutch
« Reply #7 on: 03.10. 2010 23:13 »
maybe someone (the p.o.) might have used modern multi-grade oil in the chaincase ? i have found with my unit triumph that because it shares its engine oil with the primary drive, the use of multi-grade oil makes the clutch slip. it contains anti-friction additives which are not too good for a clutch . maybe if you wash the plates in petrol or jizer or something similar, it may help.     
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Offline wilko

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Re: Slippery clutch
« Reply #8 on: 03.10. 2010 23:45 »
Just wash your plates in petrol, reassemble and just put enough oil in the cases so the bottom run of the chain just dips in the oil and forget factory specs.
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Online Brian

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Re: Slippery clutch
« Reply #9 on: 04.10. 2010 05:07 »
We need to clear up a couple of points here.

The clutch in your bike is a dry clutch so the type or amount of oil in the case has no bearing on the clutch operation assuming the cover is not missing from the clutch.

If the clutch was working well before and has suddenly started slipping after you changed the lever then you need to be 100% certain the clutch is fully engaged when the lever is out. Take the small oval shaped cover off the gearbox and make sure the pushrod is free when the clutch lever is out, there should be no pressure on the rod at this point.

If there is definitely some free play in the clutch lever and rod and the clutch is still slipping then you will need to dismantle the clutch. Take the primary cover off and you will see a tin cover over the clutch with a ring of small nuts holding it on, remove this cover to expose the clutch. Undo the six screws and the clutch plates will come out. You will notice the back steel plate is thicker than the rest, make sure when you reassemble it that the thick one goes in first. Clean it all up and inspect the fibre plates.

If you have any doubt about the plates replace them. Buy good quality ones, not cheapies off evil-bay. I use Surflex but would also use Barnett. Put the clutch back together and do the screws up until they are level with the outerplate. Watch the outer plate as you pull in the clutch lever to make sure it is lifting even and if not adjust the pressure on the screws until it does.

At this point just put the primary cover back on and go for a short ride, no need to put the tin hat back on or put any oil in the case. If the clutch is working ok then remove the primary cover and replace the tin hat, with a new gasket, replace the primary cover, once again with a new gasket and put new oil in. When you have the primary cover off if you look at the  bottom row of screw holes on the inside you will see one of them has a notch out of it, this one is the oil level so mark which one it is on the outside with a texta. When you have it all back together slowly add oil until it starts to come out this screw hole and then replace the screw, with a fibre washer under it.

Being a sealed clutch the type of oil is not important but I use engine oil.

Hopefully this helps, good luck with it.
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Offline bsapete

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Re: Slippery clutch
« Reply #10 on: 04.10. 2010 11:45 »
G'day Brian

I didn't mention that I had not ridden the bike before fitting the new clutch lever so it would have been slipping prior to that. There's definately freeplay at the pushrod as I checked that after fitting the new lever, so I'll dismantle and check the clutch plates. Who is a good local (Aus) source for  Surflex or Barnett plates should I need them?

Rgds
Peter
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Online Brian

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Re: Slippery clutch
« Reply #11 on: 05.10. 2010 02:53 »
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