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Clutch not lifting square

I am making progress with assembling the pile of bits I bought and its starting to look like a bike.
I had rebuilt the clutch but after I installed it the other day I could not get it to release. So, suspecting oil impregnated friction plates I have obtained and fitted some new ones. Now I'll need to find a longer push rod as the new one I have does not protrude through the gearbox cover plate and so the operating arm ball only just contacts it!

I can resolve that but here is my question: I used a spare roller to temporarily extend the push rod so I could check that the clutch would separate. I could get plenty of movement of the pushrod now and the pressure plate lifted but the clutch did not slip (tested by operating the kick start). I noticed that the pressure plate was not lifting square: one side lifted and the opposite side did not. Easy to resolve with a multi-spring clutch but how do I fix this in the single spring clutch?

Any advice would be very gratefully recieved.
Cheers
Dean

Re: Clutch not lifting square

Hi Dean,

Some new clutch plates are a little bit too thick.

Lots of people, including me run the clutch baskets with the omission of one plain plate and one friction plate. It makes the whole operation much smoother and does not cause any problems at all.

I presume the clutch pushrod is a new one and therefore hasn't worn down.

With regards to the basket not lifting perfectly squarely, I wouldn't worry too much about it if you are not getting slip or drag and the gears are engaging as best as they should for an old gearbox design.

Just check there is no obvious signs of play anywhere.

Regards

Pat

email (option): sacombsashtrees@hotmail.com

Re: Clutch not lifting square

Patrick
many thanks for your reassuring and practical words of advice. Your comment about the thickness of new friction plates accords with my suspicions. I'll leave a steel and friction plate out and can alwsys pop them back in when they've worn a bit.
regards
Dean

Re: Clutch not lifting square

The clutch not lifting squarely is caused by the 'settling' of the main clutch spring that can result in the two ends of the spring not being parallel...

This is usually clearly visible if the spring is stood on a flat surface and you then 'sight' across it...Alternatively use a straight edge...

In that condition it will not lift squarely...There are two solutions to the problem...Firstly, replace the spring with a new one.
Secondly, modify the clutch spring nut by drilling and tapping four small holes through it to accept grub screws fitted with lock nuts...These screws bear on the spring when screwed in and can then be adjusted to alter the lift of the spring and square it up again...

It is a time consuming operation to set it up initially as the clutch pressure plate has to be removed each time an adjustment is made, but it does work effectively...

Originally this was a REME workshop modification. I've used it more than once. As the supply of original springs dwindles this may be the best option eventually...Ian

email (option): ian@wright52.plus.com

Re: Clutch not lifting square

Ian, thanks for your information and suggested fix. I have removed a friction and steel plate and this is still a lot of drag (kicking over with clutch operated still revolves engine. GRRRR?

So I might have to look at your suggestion, or a Triumph 4 spring.

Why could BSA never get their clutches sorted?

Re: Clutch not lifting square

('Why could BSA never get their clutches sorted?..)

The single spring clutch works well if the plate stack is the correct thickness, the main spring is good and the rollers and roller tracks are in good order...Many springs and other components have been in use for far longer than BSA intended I would say which is bound to lead to problems...

The six spring clutch that replaced the single spring unit was a poor design IMO and I never fit them personally...Some of the pattern parts for them are pretty dire as well which doesn't help...

I know people will argue in favour of this clutch but the fact BSA adopted the Triumph clutch after taking that company over in the 50's pretty much says it all...

The Triumph units are pretty trouble free and there are good new parts available...I always use L.F Harris parts myself...Usefully, a modified clutch adapter is now available with the taper diameter altered to suit the earlier boxes. So, it's a 'straight fit' to WD models and later plunger and rigid models with the later version of the WD box...Ian

email (option): ian@wright52.plus.com

Re: Clutch not lifting square

Well I'm now a happy if somewhat perplexed chappy today.
I stripped the clucth again to check the spring as per Ian's advice. The spring measured up ok so I decided I'd reassemble the clutch and wait and see what its like when I get the engine running in the next month or two. Having put the clutch back on the bike I thought I'd just remind myself how bad it was and low and behold it separated perfectly! I have no idea how it fixed itself. Feeling positive I was about to replace the plates I'd left out but decided not to tempt fate and to leave it as is as its working.

Re: Clutch not lifting square

Just replace the single spring for this and your worries are over.

http://thb-support.nl/webshop/product_info.php?cPath=38_25_47&products_id=35

It works for me.

John

email (option): john.kater@chello.nl

Re: Clutch not lifting square

Wow John that looks great, glad to hear it works well!

(If it helps) For reference here is the 4 screw mod for the clutch spring nut on my bike. It certainly does keep the spring pressured flat and level. I had it apart earlier this year.

https://i.imgur.com/gKn7kEf.jpg

Re: Clutch not lifting square

john Kater
Just replace the single spring for this and your worries are over.

http://thb-support.nl/webshop/product_info.php?cPath=38_25_47&products_id=35

It works for me.

John


Yes, that is a great idea, have not tried it myself but it is very clever and a much neater solution than the 4 little adjusting screws.

Thanks for reminding!! Michiel

Re: Clutch not lifting square

it spins as long as it slips when pull clutch in.

Re: Clutch not lifting square

Hooray! My clutch problem is sorted. I took it to a good m/c engineer to do some machining as the problem lay in the clutch locking up when the large centre nut was tightened. After quite meone head scratching he identified that the chainwheel bearing race had not been fully pressed home, and was not in sguare. Race now fully home and the clutch now separates beautifully. I have left a friction and steel plate out.
I also treated it to a new spring nut from Draganfly which is beautifully made and does up nicely.
Thanks to all who gave me advice on this topic. I'm still assembling so stand by for more pleas.

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