Clutch springs

[Phil C]

Good morning all,

When I took out my clutch nuts and springs yesterday, I had the same slight problem I had last time: when I turned the nut it kept wanting to spring back to where it started. I guessed maybe the spring was snagged inside the hole somehow? Anyway this was to the extent that some of the springs got distorted in the process of unscewing the nuts (see pic.) This morning, looking at Draganfly's parts diagram, I realised something: I don't think I've got any cups. Would explain the problem?

Secondly, Rupert Ratio advises using a special clutch nut screwdriver (61-3700) or grinding away the centre of the tip on a big plain screwdriver. I don't see (on my bike anyway) (1965 B40F) why you'd need to grind away the centre. Is it because on some bikes the stud comes proud of the centre of the nuts?

Many thanks.   Phil

[Pete C]

Yes. you should have the spring cups

The springs don't seem to like turning then you unscrew the nut and the pip on the undersite catches on the end of the spring. I slip a penknife blade or similar between nut and spring to overcome this.

Sometimes the stud does protrude through the nut (on my  B31) and a ground down screwdriver can be useful.

cheers
Pete

[DAVE BRADY]

Hi,

There must be cups otherwise the clutch would not have worked.  If you have taken the pressure plate off you will see them.  Do the RR books have any illustrations?

Dave.

[Phil C]

Ah, yes, sorry, they appear to be part of the pressure plate.

[Phil C]

Ah, yes, sorry, they appear to be part of the pressure plate.

Or maybe just jammed on there.
Anyway, I've just ordered new springs, nuts, chain and chainwheel.  Thanks as always for your advice everyone.
Phil

[Beesy]

I had that issue with some new springs I bought. There was a slight burr on some of them that would catch as you tried to undo the screw.

All it took was a little bit of filing and Bob's your uncle. Worth checking the new ones before you stick them in.

[Mike Farmer]

 
I had to drill thro the nut and push the spring down with a screwdriver.

Mike

[PeteRae]

On the b40 its best to use a broad bladed screwdriver Phil...and a good load of direct arm force....the new springs are pretty strong!!! I've just replaced mine then wire locked them in pairs...just in case!
Pete

[Greenfield]

Hi Phil, have a look at Oct '19 Star for info on the B40 clutch and spring fitting tool.
Having revisited the clutch after not many miles I found some of the nuts had slackened. I've now drilled the nuts and wired them. When a nut gradually slackens, as well as producing an out of balance clutch/slipping clutch, it can score the inside of the cover.

[Phil C]

Thanks Paul. Great tool. Wish I had a welder!   Phil

[courtney]

To add to this, I've read that the nuts should be lock wired to stop them coming loose. Is this necessary and recommended and, if so, can anyone advise how to do this or show any pictures? I'm unsure what it's supposed to look like and where holes should be drilled.

I rebuilt my C15 last year but it got left over winter, so I am hoping to get it sorted now the weather is getting better.

Thanks

[DAVE BRADY]

Hi,

I think if the nuts needed to be wired then BSA would have made provision for this.  On the part of the nut that the spring sits against there is a bit that protrudes.  The idea of this is that it stops the nut from undoing as it catches on the end of the spring. So the nut should always end up with the nib just past the end of the spring.  The brass nuts in particular are prone to this protruding bit from breaking off so the nut can in theory undo.  I would leave the slight burrs on the pattern springs as although if makes undoing them difficult it must also make it less likely for them to undo on their own.  I think someone suggested sliding a thin blade in between the nut and spring to aid undoing so do this rather than making it easier for the nuts to undo on their own. 

Dave.

[Phil C]

Can anybody please confirm what the spring length should be?   Phil

[Phil C]

I ask because I've read 48mm, 43mm, and 1.6" (40.6mm)

[Phil C]

My new ones were about 40mm (like the ones I replaced.) I understand stud lengths and cup lengths changed at one point, so perhaps there's more than one answer? Anyway, I've fitted them and they seem fine.  Phil