Hi,
a quickie hopefully. As you may have all suffered at one time or another I have a dragging clutch that often loses is adjustment sometimes within a few miles of starting off. The adjustment is another matter but I wanted to ask about the dragging issue first.
I dismantled the bike today to inspect the clutch in the hope that I could resolve it and found the following:

1. Although the whole basket does not move from front to back or up and down it does wobble on the shaft quite a lot. Is this normal ?.

2. When I pull the clutch lever the plates do not disengage in a uniform manner, i.e. one side lifts before the other and I think this is contributing to the drag. Is this normal and if not what do you suggest is the cause.

Any thoughts
Cheers
Gavin

Hi Gavin...If you're talking about an M20 and a single spring clutch, go to the Technical Section of the website...There is a detailed piece there covering the clutch/settings etc....Ian

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

Hi , yes its an M20 from 1947....Single Spring Clutch. I will have a look cheers.
If anyone else has any ideas I would be interested to hear from you.

Thanks

I came across this a few years ago and it looked interesting. Don’t know any more about it though and never followed it up. It uses a a ring with several small springs to replace the single clutch spring.
I can’t find much on their website, don’t know if they still sell it and haven’t heard of anyone using it but it might be something to think about if you are really stuck.
Cheers
Pete
http://thb-support.nl/webshop/product_info.php?products_id=35

I only can que up in the row of 'clutch-difficulties'. I can't find my 4th gear anymore, after a few miles. Quite a problem when cruising on a highway! Is it a matter of tension (cable) or the plates that won't separate sufficient? Any help or advice is welcome.
Peter.

email (option): p.pauwels@hetnet.nl

I have been riding this guys (Gerrit Bruggink) BSA M20 and the clutch and gearbox feel like a modern motorcycles gearbox. I was totally amazed by how well this clutch works.

I have one of his clutch springs but didn't fit it yet.

Removing two plates from the clutch also transforms it.

Henk.

email (option): ahum@quicknet.nl

Cheers guys, I have removed two plates previously as putting the spring nut on was a nightmare and I reckon I am pretty handy with the spanners as a rule. !! I wouldn't mind so much but the thread is so fine it just begs to be crossed.
I am a real fan of keeping thing original but if I can find a way to make it a little better I will do so and keep everyone updated. As it is I would be happy for no drag and a chance to grab neutral every now and then.

Hi Gavin..I run a completely standard clutch on my M20 (apart from the removal of two plates)and have done for 27 years and over 100,000 miles. It is light, doesn't slip or drag and is pretty trouble free...They do require an occasional strip down to clean out accumulated material that has worn off the fibre plates..but it is entirely possible to get them working well...I'd recommend that you get your hands on the modified spring compressor tool...It cuts out all the struggling to get the nut back on....Ian

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

Even though they are a dry clutch, has anyone run one without the outer cover? Do they really slip if run with oil?

With std plates, if oily, yes they slip, BSA didn't fit a cover and gasket just for fun.
May be different with Kevlar plates, but so far I have never felt the need for them.

M20 single spring clutch is much maligned, but properly set up, I have found it to be bullet proof and durable.

If no special clutch compression tool available, take entire clutch off mainshaft.
Clutch spring can be compressed and with due care, the nut started easily and squarely by putting assembled clutch in large vise, or under a press, or with bolt, nut and washers, or use a jack under a solid workbench or shelf, an old ballrace against nut also helps reduce friction, but you can get by without.

You will need an extractor to get clutch off mainshaft, but if you are not prepared to acquire some tools, get rid of your M20 and take up collecting Barbi dolls, train spotting, or computer games.

Above all, RTFM.

First, do no harm.

email (option): n.gentner@bigpond.com

I don't think I mentioned not getting any tools..so I will stick with the bike if that is ok with you.

Cheers Ian, I will crack on with it. I suspect it comes down to lots of wear so I will give it a good strip down and hopefully get her up and running again asap. I may machine a suitable spring compressor to make my life a bit easier if I am successful I will let everyone know.

Hi Gavin...One thing that does affect the operation of these clutches is the state of the spring..The two ends of the spring should be parallel.. Stand the spring on a flat surface and put a straightedge across the top to check this...If the ends are not parallel, which they frequently aren't with old springs, the clutch won't lift squarely and the plates don't separate fully. A new spring generally sorts this problem out. Another alternative is to make the REME alteration to the clutch nut to give some adjustment to compensate for the springs uneven performance...Ian

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

Cheers matey will do

I noticed a bit of questioning here about runing clutches wet & dry & just thought I would mention I have an earlier mid thirties BSA 500 which runs a wet single spring clutch as standard (Different to M20 one) in an oily environment (designed to operate without the domed cover that later machines had)
Its a good clutch as well.

I also run a "special" which uses the late 30's BSA 6 spring clutch without primary covers & apart from the bearing grease (which stays in OK) the clutch has been running dry & performing well.
I am about to enclose this & go back to oil bath as I got a "kick" from it when my foot got to close & chain wear is fast.

I make a clutch spring compressor, and the "toothed" spanner for the flat nut. Ron Pier will have a new batch soon.

Recently, I adapted a Honda clutch to my 41 G3L, and am looking for a ratty nasty clutch basket and hub so I can try to do the same with a BSA single spring set-up.

If anyone has a nasty clutch they want to get rid of, please let me know. I'll trade a tool or so for it.

I'm in the States, but have a secret pipeline to get to me cheaply.

Cheers

email (option): britool51@hotmail.com

Hi guys, well I made myself a spring compressor tool which worked really well with a large G clamp for pressure and was so much easier than using the other method of a screw driving the nut and the spring down together. The cages were in a very bad state with notches worn into it everywhere and these would have prevented the plates from separating evenly and smoothly. I have filed these all down and fitted a new spring and am keeping my fingers crossed that it will all work well once reassembled....I figure that it can only be better than before.
I will keep you updated on the result.

Has anyone got a diagram/plan/drawing of a spring compressor tool that will fit my WM20's "Empire Star" single spring clutch?

Thanks
Ian

email (option): fozzie001@hotmail.com

I made mine from an old piston and some metric studding. The ring has a rebate both sides. One side for the piston to locate and the other side for the spring to locate. The hole in the middle is big enough to pass over the nut. A thread on the end of the studding to screw into the gearbox shaft and a nut to screw down on the piston to compress the spring. I wouldn't be without it. Ron

email (option): ronpier@talk21.com

Robb Nortier (britool51@hotmail.com) made a very good one to dismantle the clutch 'in situ'. But if you have the clutch on the work bench there is info for a tool in the Technical Section: "Clutch spring tool"

email (option): viaconsu{#}planet[dot]nl