slipping clutch - extra spring?

[Captain Chaos]

Hi,

my mate's blow through GSX-R1100N started to show some clutch slip since we rebuilt the engine last winter with Busa pistons. We estimate the power now around 180 hp at the back wheel. 

To cure the clutch slip, we have put an extra diaphragm spring in it, now 3 instead of 2. And it's not slipping anymore.

Are there any downsides to this mod, besides a bit more lever pressure needed? Will anything break or wear faster?

[Kristjan]

I've heard about this mod before, if it does the job then it should be fine.

 

I know that many swear by OEM clutch plates, but given that kevlar discs are claimed to be grippier and not so sensitive to slipping damage as cork plates, why aren't these recommended often? Of course they won't be as durable, but I'm thinking of giving them a try. Been reading about Barnett kevlar being rubbish but any opinions on EBC?

Edited August 3, 2015 by Kristjan

[Gixer1460]

Please don't use EBC's with a turbo - dunno what it is but they plain don't work - they slip and burn up too easy! I've had Barnett Kevlars in my 1186 for ages and they worked great when NA but are quite grabby with the turbo. I've got a lock-up fitted so can use std / soft springs which was good when racing and handled the power (210hp) fine. Used OEM fibres and steels on some stupidly powerful engines and can take abuse with plain lock-ups and slider clutch set-ups!

[jonny1bump]

My m clutch handled 170 fine with one standard and one heavy duty spring, lever pressure was noticeably harder.

[slingy1157]

Hi,

my mate's blow through GSX-R1100N started to show some clutch slip since we rebuilt the engine last winter with Busa pistons. We estimate the power now around 180 hp at the back wheel. 

To cure the clutch slip, we have put an extra diaphragm spring in it, now 3 instead of 2. And it's not slipping anymore.

Are there any downsides to this mod, besides a bit more lever pressure needed? Will anything break or wear faster?

I just put 2 barnett springs in my b12 motor, seems not too hard still to pull. I had heard of pepole using 2 barnett and 1standard so out of interest tried it. Holy fuck, could hardly pull the lever in and the pressure plate didn't lift as much or evenly.

If you use 3, would you need to machine down the collar that compress the diaphrams by the thickness of 1 spring so they end up compressed to the same point as with 2. Does that make sense? It struck me, that with the third spring, rather than the centre nut pulling the convex diaphragm flat, the extra thickness of the extra spring actually pulls them concave and causes alot of stress. I know lock ups are the go anyway, but just wondering what people have done in the past. I know most of the proboost bikes don't use lock ups and they just say the clutch has been modded to take the power. 

[slingy1157]

Oh and how much boost out of interest? 

[Captain Chaos]

 

If you use 3, would you need to machine down the collar that compress the diaphrams by the thickness of 1 spring so they end up compressed to the same point as with 2. 

yes we have been looking at this, that's why I ask.

[Captain Chaos]

Oh and how much boost out of interest? 

don't know exactly, I think he said 0,6 bar. Which is around 9 psi.

[Leblowski]

Did you do the Swedish conversion? Or just added another spring?? Adding another spring isn't enough.

I have a an extra spring and did the Swedish conversion, 230 bhp and 190 nm torgue no clutchslip at all.

 

[Leblowski]

I just put 2 barnett springs in my b12 motor, seems not too hard still to pull. I had heard of pepole using 2 barnett and 1standard so out of interest tried it. Holy fuck, could hardly pull the lever in and the pressure plate didn't lift as much or evenly.

If you use 3, would you need to machine down the collar that compress the diaphrams by the thickness of 1 spring so they end up compressed to the same point as with 2. Does that make sense? It struck me, that with the third spring, rather than the centre nut pulling the convex diaphragm flat, the extra thickness of the extra spring actually pulls them concave and causes alot of stress. I know lock ups are the go anyway, but just wondering what people have done in the past. I know most of the proboost bikes don't use lock ups and they just say the clutch has been modded to take the power. 

this is wat they call the Swedish conversion just take away the thickness of one spring or ad a ring wich has the same thickness of a spring wich i did.

I need too look up what has too be done exactly I have it written down somewhere

Lahi has it also on his 300 plus bike

Edited August 5, 2015 by Leblowski

[slingy1157]

Ah, right. I thought this must be the only way it would really work.

I did think about spacing out the top hat fitting by the thickness of the extra diaphragm but the nut is already at the end of the threads so didn't seem feasible...... Unless I machined the nut down by the same amount I suppose.  Think it better to machine down the top Hat spring retainer by the thickness of the extra spring.

So, on my bandit motor ,I could fit a complete gsxr1100L/M diaphragm clutch to gain the bigger steel basket, then do this mod with 3 springs and be good for 200+ BHP?

 

[slingy1157]

Did you do the Swedish conversion? Or just added another spring?? Adding another spring isn't enough.

I have a an extra spring and did the Swedish conversion, 230 bhp and 190 nm torgue no clutchslip at all.

 

if you can share some more info on this it would be AWESOME! 

[Leblowski]

Just take away the extra thickness of the spring you ad from the central nut, the trick is that the angle of the spring does not change. 

Only thing is you need too do some work in the gym cause the clutch gets a little stiffer then normal.

I believe two springs is standard, ride with three, a friend of mine with four 311 bhp.

 

BTW I am talking about diaphram clutches here 

Edited August 5, 2015 by Leblowski

[slingy1157]

Ok, great,  thanks for info.;-)