BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: RogerSB on 23 August, 2017, 17:01:10

Title: Simplified diagram of BSA clutch
Post by: RogerSB on 23 August, 2017, 17:01:10
My BSA GF has a 6-spring clutch, although working well, it doesn't have the adjustment I'd really like (and no I don't want to change it for a 4-spring version or a modification).  Laying in bed at 3 am this morning and thinking about it (like you do) I was trying to get my head around what, if anything, to do about it now. There are two things I suspect - but I won't bore you with that. I intend to strip it, fit a different cable and lever set up and renew the push rod when I lay the bike up after the summer but as I ride regularly I don't want to lay it up now unless I really have to - even for just a  day or so.

As an aside, I have been preparing for it and ordered a different cable, cable adjusters and a new push rod in preparation. The push rod was delivered from a retailer (with an f in their name) but it was undersized. They told me they couldn't replace it as all the push rods they had in stock were undersized (and they still advertise them) so I had to send the useless push rod back to them so they could have more of them (at my expense for postage I may add). That was a week ago and still no refund!!!

Anyway, I started to produce a very simplified diagram to show the relationship between the clutch adjusting components so I could study it without it just being a picture in my head and I thought it may be of use to some others to see a simplified diagram of what does what and how and so I added a bit of extra info for that reason.

Title: Re: Simplified diagram of BSA clutch
Post by: TTJOHN on 24 August, 2017, 11:39:14
This is no different to what you already have, so I cannot see your point in this.

TTJohn
Title: Re: Simplified diagram of BSA clutch
Post by: RogerSB on 24 August, 2017, 17:03:08
It's a bit of a lengthy story to repeat here. That's in my previous post: 'Clutch cable ferrule and gearbox abutment puzzle' 9-8-17.

My A10 GF was delivered to a dealer in Bristol 7 Jan 1960 so it would have been assembled in the factory during 1959).

I recently fitted a new clutch cable pt no 42-8774 (for 1960 - 62 models). Gearbox inner cover has cable abutment lug for earlier 1958 - 59 models (with slot at top and internal thread for adjuster) so I had to modify the later cable's ferrule.

I'm thinking: Could BSA have assembled it with an earlier gearbox to use up previous 58 - 59 model parts. Or has someone in the past fitted the earlier gearbox. I know the internals are the same, only the control cables with adjusters at the handlebar levers and the cable lug on the gearbox was changed for 1960 -62.

What I was trying to fathom out is why I have 'only just' the minimum free play with the new cable and the drawing was done purely for me to have something to look at to help me to work out if anything else could be causing it.  I posted the drawing as I thought it could help someone else not too familiar with the working of the clutch.

I now think my lack of free play can only be caused by the combination of the later 42-8774 cable and the clutch push rod being too short, so my next step is to try an earlier 67-8681 cable with the adjuster at the gearbox end and fit slide-in adjusters at the handlebar lever end and if that doesn't solve it try a new push rod . . . . if I can find anyone who has one of the correct length.
Title: Re: Simplified diagram of BSA clutch
Post by: Martin on 26 August, 2017, 11:20:43
Roger,

To a non-mechanical mind like mine, your diagram mirrors several sketches I made when I tried to fathom out the moving parts on my A65 Lightning 3-spring clutch, so you're not alone in resorting to the basics.

The clutch operation is really good now, even without the SRM modification, by tensioning the nuts so that only a light touch is needed on the handlebar lever, and after several exasperating attempts to get the plates to run in parallel I finally got them spot-on. I think that dealing with those two factors alone contributes more to the elimination of noisy clutches than anything else, in addition to the splendid advice I've had from experienced members.
Title: Re: Simplified diagram of BSA clutch
Post by: bikerbob on 26 August, 2017, 15:01:32
As regards push rod length I believe the six spring clutch is 11.5" and the 4 spring is 12". If you have rod that is too short you could cut it in half and put a 1/4" ball bearing in the middle but you would have to harden the ends, some people do this mod anyway saying it improves the clutch operation, I did it on an A10 some twenty years ago but never noticed any difference in the clutch operationbut it was still working OK when I sold it 4 years ago.
Title: Re: Simplified diagram of BSA clutch
Post by: RogerSB on 27 August, 2017, 16:03:25
Thanks bikerbob,

I've been trying to buy one 11.1/2" long.  First one (pt no 42-3108) bought from f---- two weeks ago measured 11.3/8". I was asked to send it back for a refund because all they have in stock are undersized, so sent it back next day 1st Class - 2 weeks later still waiting for the refund. Second one from another online retailer measured 11.7/16.  >:(

No wonder there are so many problems with clutch.
Title: Re: Simplified diagram of BSA clutch
Post by: JulianS on 27 August, 2017, 16:14:44
The below parts service bulletin from 1956 shows the correct length for the push rod 42 3108 as 11 17 /32 inch.

I do not know why the 1954/55 push rod for swinging arm models was shorter at 11 13/32 inch?
Title: Re: Simplified diagram of BSA clutch
Post by: RogerSB on 28 August, 2017, 19:51:17
Thanks Julian, I did know the size should be 11.17/32". The only retailer I've seen that states that in their advert is Dragonfly. As far as I can tell most seem to advertise 42-3108 as 11.5". But it seems it's pot luck on what you actually get. I've tried two so far and both have been the wrong size. On the first one ordered I believed the advert and just ordered it, second one I made a point of checking with the retailer first and they confirmed the size but what I was sent was 11.13/32.  >:(  Thats 29-3860 for up to 1955.  So my next try is to order from Dragonfly to see if theirs is the length they actually state.

I think they just take us for a ride (excuse the pun).
Title: Re: Simplified diagram of BSA clutch
Post by: JulianS on 28 August, 2017, 19:59:39
Have you tried C and D Autos?
Title: Re: Simplified diagram of BSA clutch
Post by: Bess on 28 August, 2017, 20:16:38
Hi,
    Have you considered purchasing silver steel of the correct diameter, cut to length and harden the ends yourself. It saves all the heartache of suppliers providing the wrong item...

Best wishes....
Title: Re: Simplified diagram of BSA clutch
Post by: RogerSB on 28 August, 2017, 20:23:29
Hi Julian, no, not yet, must wait for a reply from from Dragonfly to confirm the size of the 42-3108 they advertise. If no joy I will definitely ring C& D autos (their website not up and running yet). Used them years ago for my D1 and C15 rebuilds when they advertised with whole pages of spares in Exchange & Mart.
Title: Re: Simplified diagram of BSA clutch
Post by: Bess on 28 August, 2017, 20:25:39
Hi,
    Here's a reasonably priced supplier:

http://www.ebay.co.uk/itm/SILVER-STEEL-BAR-7-32-13-long/230404930395?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Best wishes...
Title: Re: Simplified diagram of BSA clutch
Post by: RogerSB on 28 August, 2017, 20:34:18
Hi Bess, thanks for reply. Yes and no, just wanted to save myself some work but may end up having to do that in the end.
First undersized push rod from f---d delivered just over 2 weeks ago, sent them an email same day as it was received pointing it out and reply received next day asking me to send it back for a refund because when they checked all their 42-3108 push rods were the wrong size. Fair enough, mistakes happen. Sent it back the next day by 1st Class post, but still no refund to date and no replies to my further emails.  :-\  They are still advertising it though!
Title: Re: Simplified diagram of BSA clutch
Post by: RogerSB on 28 August, 2017, 20:37:27
Thanks Bess, I'll make a note of it in case. I was going to ask you that in my reply a minute ago as I'm getting to the stage when I think if you mention Brit bike you'll be palmed off with something (like the wrong steel) and it'll be US.
Title: Re: Simplified diagram of BSA clutch
Post by: JulianS on 28 August, 2017, 21:06:28
A lot of poor quality parts around and unfortunately a lot of it comes from the same wholesaler and most sellers sell stuff from the same source so little real choice.

I like C and D because you get to talk to a real person rather than point and click. Same family since they opened in 1946.

Title: Re: Simplified diagram of BSA clutch
Post by: RogerSB on 28 August, 2017, 21:32:28
Yes, and their name begins with a W?
Title: Re: Simplified diagram of BSA clutch
Post by: Bess on 29 August, 2017, 07:38:41
Hi Roger,
              I have issues with parts from f...d, they have refunded me but I had to phone twice to remind them. I to have wasted money in the past with different suppliers, especially engine parts. In my experience SRM parts and service have been the best, they have been worth the extra money I've paid.

Best wishes...
Title: Re: Simplified diagram of BSA clutch
Post by: RogerSB on 29 August, 2017, 09:54:51
Hi Bess, I won't be as peevish as to say I'm glad I'm not the only one - but it is comforting to hear I'm not the only one they seem to want to drive away. A couple of months ago I ordered a pair of pillion footrest rubbers from them (they were advertised to be sold as a pair) - only one was delivered. Phoned same day as delivered and got a grumpy answer saying they'll put another in the post. They did do that but there was no apology made and I was made to feel it was my fault.

Now this push rod and them not following through quickly with a refund has made me learn my lesson and I won't order anything from them again. Instead I'll make use of their website (for free) when I want to check part numbers etc. and then order from someone else.

On a positive note, I've ordered a few bits from Priory Magnetos and received excellent and quick service. Andrew is very helpful and efficient.  Also had my chronometric speedo repaired recently by Philip Woods, also excellent. he quoted me for the repair but he found that there wasn't as much to do as he envisaged - so he charged me considerably less that he quoted. Not a lot would be that honest when it comes to easy money.
Title: Re: Simplified diagram of BSA clutch
Post by: EDDIE SIMPSON on 29 August, 2017, 22:50:00
the problem with the standard 6 spring clutch is the centre captive ball in the end plate doesnt work with the pushrod. i fitted a  jap bike clutch mushroom  to the end of the pushrod [ground down slightly]. the other end was stepped if i remember correctly and so i drilled out the centre of the lift plate to locate it and the centre i believe was drilled to be held in place with a washer and split pin. i m sorry i didnt take any photos but it was fit and forget and not to difficult to make.
Title: Re: Simplified diagram of BSA clutch
Post by: RogerSB on 30 August, 2017, 12:16:48
Hi Eddie,
Do I understand correctly that you mean the slightly rounded circular metal piece (as opposed to captive ball) inside the pressure plate?
Rgs.
Title: Re: Simplified diagram of BSA clutch
Post by: EDDIE SIMPSON on 30 August, 2017, 16:44:59
hi roger, to understand the principle and what to drill etc you will have to look at a parts diagram of a s*****i gs750 [it uses a clutch pushrod also]. you could start with the hollow mushroom part that lifts the plate. you dont need the flat needle washer, but if you could squeeze it in, well done. i ve seen the same  fittings  on aftermarket triumph lift plates, 3 and 4 spring.
Title: Re: Simplified diagram of BSA clutch
Post by: RogerSB on 30 August, 2017, 21:16:49
Many thanks Eddie.
Title: Re: Simplified diagram of BSA clutch
Post by: RogerSB on 30 August, 2017, 21:45:27
Eddie, what do you reckon on this (PE400)?
Title: Re: Simplified diagram of BSA clutch
Post by: EDDIE SIMPSON on 31 August, 2017, 22:07:13
hi roger,
yes youve got the idea. the shaft is hollow and the pushrod fits? the nut and bolt on the end makes it a little long and may hit the clutch cover. i would remove the ball and drill the end plate so the middle section passes snuggly through the clutch end plate. find a right size thick washer and to hold the washer in place, drill a hole in the step for a 1/4 " split pin[ touch the surface with a grinder and the drill will start easier], then cut off the excess with a saw or on the grinder if its too hard. i think i used an angle grinder on mine. so the mushroom stays with the clutch end cover. you have a adjuster for the clutch pushrod on the gearbox end and you need to size the pushrod when its fitted in the mushroom with the clutch plates and springs fitted. i cut my pushrod in half and used a 1/4 ball bearing in between.
i ve made it sound a lot of work but its not if you have a bench or angle grinder and a drill which i m sure you have.
Title: Re: Simplified diagram of BSA clutch
Post by: EDDIE SIMPSON on 31 August, 2017, 22:19:43
ah i forgot one thing roger , the hollow tube where the pushrod fits into will probably need sizing and triming for the gap between the mainshaft and the clutch end cover [1/4" clearance?]. use maximum number of plates and the hole you drill in the clutch end plate needs to be central for obvious reasons.
Title: Re: Simplified diagram of BSA clutch
Post by: RogerSB on 31 August, 2017, 22:37:37
Cheers Eddie, got all that. I've already bought another pressure plate and this'll be a job for the winter months. If I mess up I still have my original set up.

Thanks for giving me all the details.
Title: Re: Simplified diagram of BSA clutch
Post by: EDDIE SIMPSON on 31 August, 2017, 22:49:51
hi roger, like you i had been having problems with the 6 spring especially in london traffic. i did this conversion as an experiment, hence no photos , and 1 year later i ve yet to go inside the primary chaincase. never adjusted the springs since.