Author Topic: Clutch Spring Adjustment  (Read 11433 times)

Offline Howard

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Clutch Spring Adjustment
« on: 31.05. 2011 22:53 »
I`m sure this will have been covered before, however, I have just fitted the clutch (6 spring) to my 51 A7 which I brought as a basket case and I`m not sure how far to tighten up the 6 spring nuts. I don`t want to fit the primary cover and then have to remove it all if they are not adjusted correctly. Would it be best to leave the cover off, get it running, make sure the clutch clears etc then fit the cover ??  thanks, regard Howard

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Re: Clutch Spring Adjustment
« Reply #1 on: 01.06. 2011 06:59 »
G'day Howard,
                   I do mine up till the base of the nut is level with the cups. Then use a zip tie to hold the lever in to the handle bar and turn the motor over and check the pressure plate is lifting square. Adjust nuts till it is, say within 10thou. I use a dial gauge but any sort of pointer will do.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
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Offline Howard

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Re: Clutch Spring Adjustment
« Reply #2 on: 01.06. 2011 11:19 »
Thanks Muskrat, appreciate the info...Regards Howard

Offline tombeau

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Re: Clutch Spring Adjustment
« Reply #3 on: 01.06. 2011 11:35 »
Glad to see questions like this covered.
It can be frustrating to come across things in manuals like "ensure the springs are properly adjusted" with no further info, cant it?

Offline BSA_54A10

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Re: Clutch Spring Adjustment
« Reply #4 on: 01.06. 2011 13:32 »
The trick with the clutch is to adjust it for equal lift then readjust it for  strength then go back and check the lift.
The settings in the "book" are usually way too hard but BSA had to do this so that the clutch did not slip & an owner got flattened on their bike.
The aim is to have the lightest spring pressure that dose not slip.
This will not only be a pleasure to use but substantially reduce wear to all the pivot points.
Usually I put the front wheel against something solid ( like a brick retaining wall ) , pop the bike in 1st then apply pressure on the kick starter. If the clutch slips, tighten all of the nuts 1/4 turn and try again, if it dose not slip then loosen them all 1/4 turn. when you find the spot where the clutch just slips, do them all up 1/2 to 1/4 turn, start the bike , engauge 1st then feed out the clutch. If the engine loads & stalls then you are there, if not , then just a little tighter.
From here, put the pointer back on and check for truth.
Because the pressure plate is a pressing and because it has a random alignment with regards to the rolling direction it may distort differently after you add more weight to the springs so the need to true it again.
Bike Beesa
Trevor

Offline Mosin

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Re: Clutch Spring Adjustment
« Reply #5 on: 02.06. 2011 13:42 »
It's perfectly acceptable to ride the bike with the primary cover off while you make rolling adjustments to get the clutch spot on. But if you are doing so, just remember to leave your trusty 'flares' in the wardrobe before you start!
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Offline Goldy

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Re: Clutch Spring Adjustment
« Reply #6 on: 02.06. 2011 16:22 »
BSA_54A10 is spot on with what he says. It,s a combination of having the nuts tight enough so that the clutch does not slip, but not too much that the clutch lever is too difficult to operate.
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Offline Topdad

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Re: Clutch Spring Adjustment
« Reply #7 on: 08.06. 2011 13:46 »
Never could get the hang of this type, liked the plunger unit and very Interesting reading what I should have been doing all these years and never did with 6 springers , I can't get the memory of the little bearig ring always giving up the ghost at the worst poss time so i reverted to 4 spring type and threw the other  bloody useless thing's in the bin best wishes Bob hebdon.
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Offline BSA_54A10

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Re: Clutch Spring Adjustment
« Reply #8 on: 09.06. 2011 14:49 »
Hey,
Don't get me wrong.
BSA 6 spring clutch is an engineering atrocity and the world would be better off if they all went to Japan and came back as 1.5 Toyotas.
OTOH if that is all you have then you may as well adjust it properly.
I have only ever found one that ran what I would call "sweet" and that was no a bike owned by a fanatic who adjusted his lift with a tickler gauge to +/- .002".
Apart from being bad engineering the pressure plate is pressed out of straight rolled steel so is asymmetrical stiffness wise.
Pressure plated should be either cast ( spun cast by preference ) , pressed from cross rolled steel or made from a laminated material.
Bike Beesa
Trevor

Offline trevinoz

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Re: Clutch Spring Adjustment
« Reply #9 on: 09.06. 2011 22:13 »
I have good results with the 6 spring clutch with a bit of work.
First I set up the sleeve on a main shaft and fit the splined plate.
Set up in the lathe and machine the face true to the shaft.
I get the plain driven plates machined flat by a friend who has made a device to hold them.
Assemble on the bike and set the spring pressures, I use a dial guage but that is probably over-kill.
Also, ensure that the clutch lever is 1 1/16" fulcrum.
With all of this, I have a clutch which allows me to select neutral after stopping and which allows selection of first gear while standing without a crunch.
But it is a cheap and nasty bit of gear!

  Trev.

Offline wilko

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Re: Clutch Spring Adjustment
« Reply #10 on: 09.06. 2011 23:17 »
It's easy enough to get nil runout for the pressure plate but you'll never get it for the basket, wobbling around on those narrow ball bearings.Even with the 1/4 rollers on most other brit clutches you'll have a hard time.

Offline trevinoz

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Re: Clutch Spring Adjustment
« Reply #11 on: 10.06. 2011 00:37 »
Yeah Wilko,
                       But the wobbling basket doesn't matter a bit if you have enough square lift.
How much does it really wobble with the engine running?

 Trev.

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Re: Clutch Spring Adjustment
« Reply #12 on: 10.06. 2011 04:59 »
My plunger clutch wobbles about 1/16" at rest and a little running but nil when the lever is pulled in.
The lytedrive on the cafe is nil in or out.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
Australia
Muskys Plunger A7

Offline wilko

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Re: Clutch Spring Adjustment
« Reply #13 on: 10.06. 2011 23:33 »
Yeah, i know it doesn't matter, in fact it's needed to help separate the plates. I was just explaining to people who might be trying the impossible.

Offline redbeeza

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Re: Clutch Spring Adjustment
« Reply #14 on: 09.07. 2011 16:51 »
I'm having trouble resetting my clutch after a minor problem.  I had the clutch working lovely; it lifted square, it was light at the lever, no problems with slipping or creeping, and I could select neutral OK most of the time.  My minor problem was the disintegration of a bodgy shim I'd made out of thin alloy sheet (beer can) to take up slack where the clutch arm pivoted in the gearbox cover (the hole had worn oval).  When the 'shim' crumbled during a ride, the clutch stopped working and after a few crunched, clutchless gearchanges I stopped and that was the end of the ride.

I took the 'box cover off and sent it to Groily who did a grand job of making up and fitting a bush to the clutch arm hole (thanks again Bill).  Clutch arm now nice and smooth with no wobbles.  Trouble is I can't get clutch adjusted right again now (maybe it was a fluke I got it right first time!).

I've had the clutch apart and checked the plates for flatness.  The centre nut is not loose.  The nut on the end of the gearbox mainshaft is not loose.  The rod is ok and moves smoothly.  The splines are set right and parallel with the clutch arm.

I've set the plates up to lift squarely; first time with the screws screwed in roughly how they were before the problem occured (approx 12 turns in).  When I did this the pressure plate or a screw head fouled the inside of the primary cover (when kicked over the action was stiff and scraping sounds came from primary side, also very light scoring on inside of primary cover).  Even so, clutch would not engage (when in first gear with clutch pulled in couldn't push bike).

So, I wound screws in a few turns and set up to lift square again but the clutch will still not engage (same trouble, can't push it in gear with clutch pulled in).

I've attached a photo of spring/screw settings as of now.  There is one screw that is always in a very different position to the others.  In order that the screw does not stick out too far and foul the cover, I have to wind the other screws in a fair way to get the plate to lift square.  Do I need a new set of springs now?  And the fact that it worked so well before was just flukey??

Regards,
Terry
1962 A10 Super Rocket.  First Brit bike, first rebuild.