Author Topic: to lighten the clutch a7 & a10 ?  (Read 763 times)

Offline Signboy

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to lighten the clutch a7 & a10 ?
« on: 18.11. 2016 22:47 »
Guys,
An old biker pal of mine says that in his day, the "60s" he and his buddies would make their clutch's lighter by removing a friction plate or two as hes says the clutch baskets have friction ferodos on both sides of the basket and this counts as two plates ! is this a wind up or could it be true ?????
Signboy
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Offline coater87

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Re: to lighten the clutch a7 & a10 ?
« Reply #1 on: 18.11. 2016 23:01 »
 Well,

 If you remove anything its going to get lighter. Is it a good idea? I dont know...

 But, a clutch works on friction and pressure. So if you remove any friction surface area, your making it easier for the clutch to slip. To get the same (or more) pressure out of the reduced height you might end up making the clutch almost impossible to pull in to get enough pressure to make the clutch work.

 Would they have done that? Sure, they did a lot of things in the 60s that we see as a little odd.

 I believe hill climbers did this because they actually wanted a little slip so as not to flip the bike over as easily. I could be wrong on that but it struck a cord in my memory.
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Central Wisconsin in the U.S.

Offline Triton Thrasher

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Re: to lighten the clutch a7 & a10 ?
« Reply #2 on: 19.11. 2016 09:48 »
If a clutch that weighs less is your goal, it's a great idea.

I want a clutch that doesn't slip or drag or sprain my wrist.
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Offline BSA_54A10

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Re: to lighten the clutch a7 & a10 ?
« Reply #3 on: 19.11. 2016 09:59 »
Your mates are talking total garbage.
Yes the drum has got friction material on both side, but take i st of plates out and you have an M20 clutch which is only just  up to the 13 Hp of an M20
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Offline rocker21

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Re: to lighten the clutch a7 & a10 ?
« Reply #4 on: 19.11. 2016 12:15 »
Bsa clutches were not the best especially the old 6 spring, what a lot of people did was fit a different main shaft into the gearbox and use a Norton clutch instead and i believe the main shaft came from one of the plunger BSA gearbox, i know someone who did this back in the day and it made a huge difference .
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Offline Rocket Racer

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Re: to lighten the clutch a7 & a10 ?
« Reply #5 on: 22.11. 2016 22:18 »
If we're talking 6 spring, I have a vague recollection that the B31 had less plates than the B33 and I did even try it at some point on my B33.
I believe the benefit of less plates was that the lesser number of plates disengaged more cleanly as the main issue with the 6 spring is the  basket wobble that comes from the ball bearing arrangement and the narrow point lift of the outer plate that can often lift crookedly if not adjusted carefully, If it lifts crookedly the clutch plates don't release nicely, where as with less plates the lift per plate is greater and the release cleaner.

I certainly wouldn't consider fitting less plates on a 650 or any sporting 500, perhaps a cooking 500 might cope but still not a good idea; keep in mind these "tricks" of the 60's were typically the result of impoverished youths keeping their bikes mobile on the cheap, rather than sound practice.
My BNR clutch on the rig, has an extra plate at Bobs recomendation
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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 peter small

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Re: to lighten the clutch a7 & a10 ?
« Reply #6 on: 26.11. 2016 21:00 »
I have a Road Rocket 1954
It was fitted with a brand new 6 spring clutch when i bought it. It was terrible heavy and i could never select neutral, So i did what everybody in the 60s fitted a 4 spring Triumph clutch better but not perfect until you fit a SRM pressure plate and hey presto you have a clutch as light as a feather good as a japanese clutch and gear selection is great.
I have also found that if the primary chain tightens up like a banjo string because the gearbox wasnt locked up properly  3rd and 4 th are hard to select.
as soon as you rectify the primary chain its perfect again.


Pete
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BSA ROAD ROCKET 650cc 1954
Norton commando Roadster 750cc 1972
Triumph T140 Silver jubilee 750cc 1977
Honda Pan European ST1100  2000
Honda C90 1990