Author Topic: How to dismantle a six spring clutch  (Read 563 times)

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Offline ThomasC11

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How to dismantle a six spring clutch
« on: February 22, 2016, 07:44:09 AM »
Hi all! Attached is a pdf about how to dismantle a six spring clutch. There is also some information about additional improvements. Cheers, Thomas
1946 BSA C11
1937 Sunbeam Model 9

Offline BSAussie

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Re: How to dismantle a six spring clutch
« Reply #1 on: March 01, 2016, 10:29:26 AM »
Thanks for this Thomas, I'm just piecing the clutch together for C10 from boxes of bits. With these photos it will be a great help. The BSA WORKSHEETS are a great place to start, but as a learner I need a bit more information.
Are there any more of these pdfs about?
Paul
C10 1946
MGB 1971
Jag E-type 1970

Offline ThomasC11

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Re: How to dismantle a six spring clutch
« Reply #2 on: March 01, 2016, 04:08:50 PM »
Hi Paul, the BSA worksheets are not perfect for beginners as me. For my clutch I also got external support. The only additional information I know (no pdf) is from Brooklands for a three spring clutch. http://bsac10c11c12.co.uk/smf/index.php?topic=5368.0
Maybe it gives you some more feeling for your work. But as I wrote, the six spring clutch is actually straight forward. Don't hesitate to ask the forum in case of trouble.
Cheers, Thomas
1946 BSA C11
1937 Sunbeam Model 9

Offline Tug

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Re: How to dismantle a six spring clutch
« Reply #3 on: March 21, 2016, 03:44:23 AM »
Six spring clutch question, on my C11 the clutch is working well until I have travelled about 6 miles and then it starts to drag not allowing a smooth gear change, so after adjusting the cable to compensate it then slips when cold, am I correct in thinking the push rod could be incorrect length,
Any advice would be appreciated  :)

tug   

Offline timsdad

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Re: How to dismantle a six spring clutch
« Reply #4 on: March 21, 2016, 06:59:35 AM »
It may be the push rod but you need to go back to basics, Tug, and set it up correctly.

Plenty of previous posts on here but you first need to get the springs tensioned correctly, take the wobble out so it lifts and spins cleanly and then get the angles correct at the gear box end of the cable and the pushrod. This may mean a longer or shorter pushrod and finally you adjust the free play at the lever.

Obviously, the cable needs to be the correct length, with nice, shallow bends and no kinks, and nicely lubed if it's not nylon lined.

If the six miles you've travelled are the only miles you've ridden it then it may have just bedded in and will need re-adjusting on the springs, push rod and cable.


Ray
Just a motorcyclist.

Offline Tug

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Re: How to dismantle a six spring clutch
« Reply #5 on: March 22, 2016, 03:50:38 AM »
Ray

Thanks for the reply, i will have a look at the clutch and check for the wobble also I may play with the spring adjustments but sorry not sure what you mean about the angles at gear box end, the cable maybe incorrect as it seems a tad tight with no let out adjustment, I have travelled a few miles on her but have been busy with other problems on each ride out,
I got the bike from a guy who had rebuilt it approximately ten years ago and had never started it.
I have already had to replace parts of the gearbox what was missing
After starting the bike it broke two push rods due to a very badly worn cam
The engine nipped up after getting too hot, I am thinking the re-bore the guy had done had to fine a tolerance.
Also two blown head gaskets, now after reading on here I have made a solid gasket which seems to be holding.
To just name a few of the problems, which are getting less every hour spent  with the bike.

regards
Tug
new to british bikes

Offline timsdad

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Re: How to dismantle a six spring clutch
« Reply #6 on: March 22, 2016, 07:21:26 AM »
You don't say which gearbox you've got, Tug, but the set-up for the clutch is the same. However, the 3-speed box suffers from only having a very small amount of push rod adjustment so the length of the push rod is quite critical.

You need to have maximum travel on the push rod for the most clutch lift. Therefore, if you remember any geometry from school, this means the angles between the end of the cable and its lever and also the end of the push rod and its little lever in the gearbox, have to start out at just under ninety degrees, go through the right angle and finish up at a slightly obtuse angle on full lift. If they start and finish at over 90 degrees, or perhaps under 90 degrees, then they're going through a smaller arc and the clutch lift is suffering.

Because there is only a small amount of adjustment on the grub screw in the gearbox, the push rod needs to be just the right length to get the angle of travel correct. I experiment with a dummy push rod, say a bit of 6mm threaded rod, by grinding the ends down until the angles are just right. A new clutch pushrod can then be made from a bit of silver steel with the ends hardened.

You may be able to cut your present rod in half, shove a 1/4" loose roller bearing in between the halves and then play with the lengths of the two bits until you get it right. The cut ends will need hardening again and this is an easy job and has been discussed on here many times.

This is all part of the fun, apparently, and no one said it would be easy if you buy someone else's cock ups!


Ray
Just a motorcyclist.

Offline Tug

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Re: How to dismantle a six spring clutch
« Reply #7 on: March 22, 2016, 01:03:20 PM »
The gearbox is a 3 speed, after your explanation of the angles you revered to I fully understand thanks.
I am away for another 3 weeks but will get to it as soon as I get home, there’s not a lot of this little c11 engine without my fingerprints on now.
Thanks for the help

Regards
Tug