Author Topic: 3 spring?  (Read 1294 times)

Offline Rocket Racer

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3 spring?
« on: 23.11. 2015 07:21 »
There seems to be a resurgence in clutch threads, now I have never considered a 3 spring from a unit model, but it is obviously possible and presumably should be more readily available than the 4 spring second hand  *dunno*. Would someone in the know like to comment on...
I stumbled across the attached picture, hopefully it speaks for itself
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Offline Tomcat

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Re: 3 spring?
« Reply #1 on: 23.11. 2015 07:39 »
Thanks RR, I never considered the unit clutch. I have just dismantled the Super Rocket and the 6 spring clutch is beyond re-using, so was looking at options.  I have some A65 clutch parts in stock, so will try a mix and match.  Looking forward to any replies from anyone who has gone down this path. Cheers TC
'48 A7 '59 SR '74 850 Commando TDM900

Offline Rich B

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Re: 3 spring?
« Reply #2 on: 23.11. 2015 12:37 »
Not an A10, but the clutch is the same beast....my Gold Star had a 3 spring center in it when I bought it. It didn't work very well, as in it slipped. No adjusting would cure the slipping.

Since the bike needed a complete mechanical rebuild, the clutch was on the list to fix.

The amount of plates (friction and steels) was correct for the single row basket. After a lot of head scratching and playing with the clutch, finally found the culprit. The spring cups were bottoming out in the clutch center. I added one more steel plate at back of the stack as a "stuffer plate" against the basket.

That one extra plate fixed the slipping. Clutch works nice. Still running stamped pressure plate, thinking about going to alloy since I like the improvement the alloy pressure plates make in a unit twin clutch feel.

Offline Tomcat

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Re: 3 spring?
« Reply #3 on: 02.12. 2015 08:22 »
The 3 spring clutch I have doesn't fit straight onto the A10 gearbox *sad2*, different taper and a duplex chain.
But I did dig out this beaut mod by Brian as it is a great idea http://www.a7a10.net/forum/index.php?topic=9505.0
Cheers TC
'48 A7 '59 SR '74 850 Commando TDM900

Online RichardL

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Re: 3 spring?
« Reply #4 on: 02.12. 2015 12:16 »
Would someone in the know like to comment on...

Well, leave out the "in the know," because I really know nothing about the 3-spring clutch. However, it seems that, unless this is a belt drive, I'm expecting a left leg covered in ATF.

Richard L.

EDIT

Looking at the lack of a dynamo, I suppose this bike is for scrambles or (given the tax badge), short-haul and infrequent day-time riding. Maybe, then, all that's needed is the occasional squirt of lubricant on the primary chain. Not sure, really.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online RichardL

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Re: 3 spring?
« Reply #5 on: 02.12. 2015 12:24 »
"              [I know this is where rich had planned to say hello and introduce himself.]          "

Rich,

I understand why you might not like to make anything out of having just joined the forum, but you clearly have knowledge and experience that will be appreciated here. So, please allow me to maintain the subtlety you intended and quietly say:


"WELCOME TO THE FORUM, RICH!!"
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline duTch

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Re: 3 spring?
« Reply #6 on: 02.12. 2015 19:19 »

 
Quote
.my Gold Star had a 3 spring center in it when I bought it. It didn't work very well, as in it slipped. No adjusting would cure the slipping.

 maybe the wrong springs ?
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Offline Rocket Racer

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Re: 3 spring?
« Reply #7 on: 02.12. 2015 20:09 »
so are the 3 and 4 spring centres interchangeable?
The biggest fault with the 6 spring (swingarm frame type) was its inadequate dual ball bearing set up, whereas the semi unit plunger engines at least have rollers as do the 4 springs. So less basket wobble, so the plates engage and disengage more cleanly. On top of that the thin rod centre push exacerbates basket lift as it lifts in such a local point that the plates can lift crookedly. All modern clutches typically have a decent bearing so the basket is held true to start with.
Presumably 3 spring baskets are also duplex chain driven, so a 3 spring pre units would be a mixture of 4 spring centres and baskets and three spring centres
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Offline Rich B

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Re: 3 spring?
« Reply #8 on: 02.12. 2015 23:08 »
maybe the wrong springs ?

The spring cups would bottom out in the center with the correct plate count for an early clutch. Adding the stuffer plate gave enough clearance to allow it to work.

Richard L

Wow, not sure I have ever gotten that type of greeting when joining a forum! Thanks.

You must not know me  *smile* the greeting wouldn't have been so warm  *eek*

Offline oka

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Re: 3 spring?
« Reply #9 on: 03.12. 2015 15:43 »
My Gold Star has a 3-spring clutch consisting of:

42-3170 Clutch hub (The same as for 4-spring. SRM sells an improved version with a larger diameter and a separate copper disc, the same style as used on an A65.

3-spring clutch center from A65.

42-3266 Aluminium chainwheel from Lyford (LCS3021B)

7-plate Surflex

Aluminium pressure plate

It is works very well and is light in use. In fact I am still experimenting with lower spring pressure as there is no slipping.

Ole

Online RichardL

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Re: 3 spring?
« Reply #10 on: 03.12. 2015 17:01 »
I can't believe I get to use this same stupid joke twice under the same topic!

Could you guys, please, post introductions that tell us a bit about yourselves, the bike (or various bikes) you have, how you came to be interested in BSAs, about where you are located, etc. This is suggested in the forum instructions. It helps keep us on a friendly level, even while the number of members approaches 1000. 


"              [I know this is where oka had planned to say hello and introduce himself.]          "

oka

I understand why you might not like to make anything out of having just joined the forum, but you clearly have knowledge and experience that will be appreciated here. So, please allow me to maintain the subtlety you intended and quietly say:


"WELCOME TO THE FORUM, OKA!!"
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline oka

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Re: 3 spring?
« Reply #11 on: 03.12. 2015 17:14 »
Thank you for the welcome  *smile*

I bought an A65 six yours ago and replaced it with a Gold Star two years ago.

I have been following the A7/A10 forum for some time as there a lot of similarities with the GS, apart from the engine.

And as I happened know a little about the 3-spring clutch, I would just make a small contribution, even though I don't have the proper A7/A10  ;-)

Regards Ole

Online morris

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Re: 3 spring?
« Reply #12 on: 03.12. 2015 21:21 »
 *welcome* Ole.
You just made Richard lose his cool which already can be regarded as a great achievement... *smile*
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Online RichardL

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Re: 3 spring?
« Reply #13 on: 03.12. 2015 22:27 »
Ole,

Thanks for the intro. Glad you decided to join. I don't recall that A10 ownership is a requisite for membership. It's just expected that most of the tech topics will be A7/A10-specific.  Certainly, other bikes are discussed here from time to time . We can pretend that you have an A10 if you let us pretend we have Gold Stars (some do, of course).

Morris,

How out of touch with reality am I? I was, mostly, trying to be funny. No heat intended. *smile*

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline Dean

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Re: 3 spring?
« Reply #14 on: 05.12. 2015 21:11 »
The unit clutch has the shock absorber centre. I am sure I recall there being a discussion somewhere about whether running with the standard cush drive and the clutch centre shock absorber could create any problems.
Never tell people your troubles. Half of them are not interested and the other half are glad you're getting what's coming to you.