Author Topic: 4 or 6 spring clutch  (Read 1259 times)

Online berger

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Re: 4 or 6 spring clutch
« Reply #45 on: 02.10. 2019 21:45 »
and here is the spare  chainwheel

Online Triton Thrasher

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Re: 4 or 6 spring clutch
« Reply #46 on: 02.10. 2019 22:10 »
This is my Tony Hayward belt drive basket that takes a Triumph 3-spring centre.

I glued cork mat to it instead of starting with a lined plate.  It meant I got an extra plate into the clutch.

I also picked the lining off the Surflex lined plates and glued cork mat to them as well. 

After all that, the clutch no longer slipped, even with the spring adjusters backed off to a light pressure.



Online RDfella

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Re: 4 or 6 spring clutch
« Reply #47 on: 02.10. 2019 22:32 »
A diaphragm clutch (eg Norton) would be better still. The further you release it, the lighter it gets, whereas coil springs work the other way round.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Offline muskrat

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Re: 4 or 6 spring clutch
« Reply #48 on: 03.10. 2019 13:11 »
G'day RD.
I agree. The Notrun diaphragm clutch on my Cafe is a joy to use. It does squeal a bit on spirited takeoffs.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
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Muskys Plunger A7

Offline Rocket Racer

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Re: 4 or 6 spring clutch
« Reply #49 on: 07.10. 2019 01:22 »
I did try a suzuki clutch which was very good compared to a 4 spring, but on my race engine... love my Bob Newby Racing (BNR) clutch, never given me any trouble and goes brilliantly with a TT industries 6 speed BSA box.  *whistle*
http://www.bobnewbyracing.co.uk/products.html?LMCL=joPaTW&LMCL=EYL6NV

the old pre unit 6 springs can be made to work reliably but are not great, the 4 springs were better but if money permits better options exist and beware of rubbish pattern parts
A decent belt drive quietens down a motor significantly

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.
New Zealand

Offline stev60

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Re: 4 or 6 spring clutch
« Reply #50 on: 27.01. 2020 18:33 »
The six spring seems to get a lot of knocks, I have one on a 51 plunger with all new plates,etc. took a while to get set up, but is light on the hand and works perfectly

Offline a10gf

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Re: 4 or 6 spring clutch
« Reply #51 on: 27.01. 2020 19:16 »
^^^
The six spring seems to get a lot of knocks, I have one on a 51 plunger with all new plates,etc. took a while to get set up, but is light on the hand and works perfectly

Like mine. Parts in decent shape + adjusting springs for even lift. Behaved really good, was never on any 'need improvement' list.

A10 GF '53 My A10 website
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Offline muskrat

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Re: 4 or 6 spring clutch
« Reply #52 on: 27.01. 2020 19:21 »
G'day Steve.
I agree, the early six spring is a pleasure to use.
As a side note. I just went through my rubble and found a new 4 spring. Totally destroyed  *sad*
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
Australia
Muskys Plunger A7

Online WozzA

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Re: 4 or 6 spring clutch
« Reply #53 on: 27.01. 2020 22:09 »
The early 6 spring on my 51 plunger works well...   *smile*
The later 6 spring on the 57 swing arm was a nasty piece of work  *problem* & replaced with a Suzuki clutch.   *wink2*
'51 Golden Flash Plunger
'57 Golden Flash Swingarm

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The biggest lie I tell myself is
"I don't need to write that down, I'll remember it"

Online chaterlea25

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Re: 4 or 6 spring clutch
« Reply #54 on: 29.01. 2020 21:11 »
Hi All
Some People do not seem  to realise that there are different 6 spring clutches on the rigid / plunger and the later swing arm models , so when owners of the swing arm models decry the later 6 spring clutch, owners of the earlier models jump to the defense of their clutches   *conf* *conf*

Also take note that BNR and Suzuki derived clutches are also six spring  *pull hair out*

John
1961 Super Rocket
1963 RGS (ongoing)

Online BSA_54A10

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Re: 4 or 6 spring clutch
« Reply #55 on: 30.01. 2020 01:39 »
Hi All
Some People do not seem  to realise that there are different 6 spring clutches on the rigid / plunger and the later swing arm models , so when owners of the swing arm models decry the later 6 spring clutch, owners of the earlier models jump to the defense of their clutches   *conf* *conf*

Also take note that BNR and Suzuki derived clutches are also six spring  *pull hair out*

John

I will have to take that up with a certain physics professor ( ret ? ).
From an engineering point of view the 6 spring wet clutch is garbage particularly when the truth of the whole assembly is dependent upon the thick back plate sitting square against the center controlled by 6 ( from memory ) tiny 1/4" wide tabs thus any wear to the back plate or hub in this area gets amplified by the radius of the drum.
And despite being argued own I do know because we etched pressure plates to check, when you get a pair of spring holes and the center hole all aligned along the grain line these plates do flex.
Now considering that the total lift is quite small, it does not take much flexing of the pressure plate to cause the clutch to drag.

This random alignment happens because the plates were manually pressed from pre cut blanks , a very bad practice.
It is even worse on the 4 spring pressure plates where you get prefferencial necking across the rolling direction
The take away from this is if you have a pressure plate that you can never seem to make lift true, toss it and get another.

You can not get the same thing happening with odd number springs and if you look at the Burman clutches of the day you will notice they are 5 or 7 spring.
Even now days most clutches I have come across have odd spring numbers as do many flywheels
Bike Beesa
Trevor

Offline Swarfcut

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Re: 4 or 6 spring clutch
« Reply #56 on: 30.01. 2020 09:23 »
 My take on this is that the spring pressure forcing the plates together needs to be applied evenly over the entire assembly. So, the more springs (or a diaphragm) the better.  Enter the cost accountants, production engineers etc and we get the compromise we enjoy today.

 Don't forget these were mass produced products for a world just happier for a reliable means of transport, which in most cases were only owned for a relatively short time and minor design or performance shortcomings were accepted.

 The plunger clutch is a far more substantial setup, presumably the basic design slimmed down for the early S/A models. A single row chainwheel to the original basic design would seem to me to have been a far better evolution.

Good stuff there from '54's previous post. Wonder how may folks don't realise one plate is just a bit thicker put it in the middle of the pack, an easy mistake to make, or worse, missing from that basket case bargain.

 Swarfy

Online chaterlea25

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Re: 4 or 6 spring clutch
« Reply #57 on: 30.01. 2020 20:43 »
Hi All
Am I correct in thinking that the plunger clutch is a Burman or Burman design ?
I know the BSA C models with 3 spring clutches are Burman design

John
1961 Super Rocket
1963 RGS (ongoing)

Offline ironhead

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Re: 4 or 6 spring clutch
« Reply #58 on: 30.01. 2020 21:41 »
Probably is John, Burman clutch plates fit.
SA