Author Topic: 6 spring duplex clutch  (Read 1553 times)

Offline mrshells

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6 spring duplex clutch
« on: 02.10. 2012 16:22 »
Hi am I right with this ? First plate in is the thickest (plain) so next goes friction,plain,friction,plain,friction,plain,friction,plain,friction,plain and then the steel pressure plate? Surely this can't be correct,plain plate against the pressure plate?  Draganfly lists 1 thicklpate and 5 friction and 5 plain so whats the order? hmmmm
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Online muskrat

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Re: 6 spring duplex clutch
« Reply #1 on: 02.10. 2012 18:07 »
 G'day mrshells, that's how it goes. Seemed strange to me too 30 odd years back. It's a sweet clutch that hasn't needed touching since.
Cheers
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Online morris

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Re: 6 spring duplex clutch
« Reply #2 on: 02.10. 2012 21:32 »
Hi mrshells,

I also found the setup strange, but mounted it anyway, it didn't give any trouble, and as muskrat mentioned, it's very sweet.
I have a theory it's like that because of the oil from the chain seeping in between the first plate and the clutch housing, and between the pressure plate and steel end plate.
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Online RichardL

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Re: 6 spring duplex clutch
« Reply #3 on: 02.10. 2012 22:38 »
The plain plates and the outer pressure plate both turn together with respect to the clutch center basket, so no friction there. The clutch runs wet, so not really an issue of the lubricant "seeping" in. I think most guys here, including myself, are successfully running ATF.

Richard L.
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Online Brian

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Re: 6 spring duplex clutch
« Reply #4 on: 02.10. 2012 23:30 »
Actually the plunger clutch is designed to run dry, hence the cover. They will run ok without the cover however.

There should be one thick steel plate which goes in first and then four thin steel and five friction plates, the pressure or outer plate acts as the last steel.

Its quite common with aftermarket plates to not be able to fit them all in as the aftermarket friction plates are often thicker than they should be so quite often you will pull a plunger clutch apart to find only four friction and three thin steel plates.

I run engine oil (20/50 multigrade) in all my plunger primaries.

Personally I belive they where the best clutch BSA made, having six springs they dont require quite as much pressure on the springs and lift more evenly than the later four spring. They go on a splined shaft so no problems with keyways or tapers.
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Online RichardL

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Re: 6 spring duplex clutch
« Reply #5 on: 03.10. 2012 02:16 »
Actually the plunger clutch is designed to run dry, hence the cover. They will run ok without the cover however.

But it's the swingarm clutch that has 5 and 5 plus the inside backer. Right? [/quote]

There should be one thick steel plate which goes in first and then four thin steel and five friction plates, the pressure or outer plate acts as the last steel.

Still talking about the plunger. Right?

Its quite common with aftermarket plates to not be able to fit them all in as the aftermarket friction plates are often thicker than they should be so quite often you will pull a plunger clutch apart to find only four friction and three thin steel plates.

Does this same problem apply to Swingarm 6-spring clutches? It's been some time since mine was apart, but I think I have the 1+5+5+outer pressure arrangement. I think I'm right about the rotation-in-unison point, but open to correction.

I run engine oil (20/50 multigrade) in all my plunger primaries.


Non-conformist!

Personally I belive they where the best clutch BSA made, having six springs they dont require quite as much pressure on the springs and lift more evenly than the later four spring. They go on a splined shaft so no problems with keyways or tapers.

Having only one bike, unlike you, and mine having a 6-spring clutch, I am obliged to say it is the best clutch BSA made.

Richard L.
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Online Brian

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Re: 6 spring duplex clutch
« Reply #6 on: 03.10. 2012 02:33 »
Crikey Richard, I'll go cross eyed reading all that lot.  *eek*

The six spring in the s/arm models is a different animal to the duplex (plunger) clutch that mrshells was alluding to. The s/arm has a thick plate behind the chainwheel and then normal steel and friction ones in front.

I would think the thicker aftermarket plate problem would apply to any clutch, I've run across it a few times and thats one of the reasons I will only use "Surflex" plates these days, they are top quality and made to original specs.

I run engine oil in all the primaries on all my bikes, always have. Tried ATF once but couldnt detect any advantage and it leaks out easier.
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Online muskrat

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Re: 6 spring duplex clutch
« Reply #7 on: 03.10. 2012 03:31 »
 Here ya go.
Cheers
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Online RichardL

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Re: 6 spring duplex clutch
« Reply #8 on: 03.10. 2012 05:07 »
Brian,

Thanks for putting up with it. Your comment regarding "Surflex" sent me looking for the real deal, very interesting and very Italian. ( http://www.surflexclutches.com/Surflexclutches.com/Home.html ) I was wondering about them because I think "Surflex" is a sales word used for some garbage out there. It turns out I was within about 20 miles of their factory when I was in Italy on vacation this summer, however, not a place on my wife's must-see list.

Muskie's picture shows steel-to-steel at the outer pressure plate, but I suppose it would work either way if the last plain plate had to be removed. Can't read Italian, but it seems like Surflex says the Plunger takes 1+5+5. Just chatting and understand that experience and reality may be different from catalog knowledge.

Richard L.

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Online Brian

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Re: 6 spring duplex clutch
« Reply #9 on: 03.10. 2012 05:40 »
Richard the 1+5+5 is a mistake that originates from the parts book. There should be one thick steel, four thin steel and five friction. 

You start with the thick steel in first then a friction, a thin steel and so on until the last one to go on is the pressure plate. With the plunger clutches and also the s/arm 6 spring the pressure plate is also the last steel.

Wish I could go to Italy for a holiday, I would like to go to the Guzzi factory. And I would go there even if it wasnt on the wife's list.  *ex*
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Online muskrat

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Re: 6 spring duplex clutch
« Reply #10 on: 03.10. 2012 09:02 »
 There you go. Don't believe everything you read. Like I said "Seemed strange to me too 30 odd years back. It's a sweet clutch that hasn't needed touching since." So haven't paid much attention to it.
Cheers
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Offline duTch

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Re: 6 spring duplex clutch
« Reply #11 on: 03.10. 2012 10:44 »

 I agree with all,and tried fitting all the plates in prescribed order a while back and even a bit worn, the pressure plate was only just on the splines, so I think someone on the assembly line had the wrong amount of fingers. Been away with work for a bit but will attack it again in the next few days(manyana), personally I think the S/A 6 spring is pus, Richard you must've got lucky, and I also had a look at the surflex site a while back,in wondering what was so u-beaut about surflex (translation is a job for Renos)?
   Brian, that's about what I'd settled on, and I'll back you up re- Moto...

 Also worth keeping in mind I think the springs are different between each three types(not surprisingly), but not sure on specs?
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Offline Topdad

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Re: 6 spring duplex clutch
« Reply #12 on: 03.10. 2012 12:27 »
Hi 30 yrs is impressive Musky, my first A10 was a plunger and the clutch once fitted worked well and took an untold amount of abuse from yours truly both covered and then open without a case , Richard I agree with Dutch you must have been born under a lucky star and got a good 6 springer, i still can't abide the things despite the fact that other people can use 'em and love 'em . As a matter of fact I refitted my 4 springer last weekend took all of 1/2 an hour and it's lovely , smooth and light but only took 2 small adjustments to get everything moving equally . Regards all BobH.
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Online RichardL

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Re: 6 spring duplex clutch
« Reply #13 on: 03.10. 2012 15:22 »
Ignorance is bliss. Therefore, knowing no other, I have been very satisfied with my 6-spring clutch which seems to work nearly perfectly. I brazed the studs to the back of the aftermarket basket because they were loose, then filed the slots smoother than the original stamping. I made my own friction inserts for the chain wheel from a piece of sample stock I got for free from the manufacturer of the material. No need to explain my approach to spring adjustment, being nothing special other than careful.

And, yes, as an inexperienced clutch builder, I suppose I was lucky.

Richard L.
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