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Discussion Starter #1
Hi everyone,

So I have a 2008 CBR600RR fully race bike with an STM slipper clutch, and back February at the first CCS RACE my clutch started slipping ( you could hear it). After that weekend I took the bike to my mechanic and we decided to install the EBC heavy duty kevlar plates (supposedly they are HEAVY DUTY). Two weeks later, with a brand new clutch, I took my bike to a track day, with no launching or grid starts, at the beginning of the day I could feel and hear the new clutch slipping ( Not sure if its "breaking in" or its just not normal) but as the day progressed it stopped slipping.

The trackday ended, I parked my bike home and it stayed there until the next race.

When the next race weekend arrived I pushed my bike down from the stands turned it on, got into first gear, and let go of the clutch and the bike just stood there motionless and turned on (while in first gear). My mechanic later came and we took the cover off, and the whole cassette had a little free play, once taken out both disk and plates were glassed (useless)

What could have been the cause for the clutch to go bad in one trackday?
bad installation? not soaked enough on oil? is it even possible to be that bad of a rider to glaze a clutch in one trackday?

I just want to know since he's trying to charge me for the whole clutch & disks set again.

thanks in advance
 

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Discussion Starter #3
did you have your clutch cable too tight? you could have had it partially disengaged the whole time.
you mean the little freeplay the clutch lever shoud have? because it did have some. or is there another way to tell if the cable is to tight?
 

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you should be able to move the clutch release arm a bit with your fingers. if not then it's too tight.


the stm clutches are a bit weird, they use diaphragm springs instead of coils. what weight spring is in there?
 

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Discussion Starter #5
you should be able to move the clutch release arm a bit with your fingers. if not then it's too tight.


the stm clutches are a bit weird, they use diaphragm springs instead of coils. what weight spring is in there?
when I bought the bike, it already had the STM clutch, At the moment I have no idea but I can take a look and let you know.

Regarding the clutch release arm, I don't think I was able to move it. maybe it was to tight.
 

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Discussion Starter #6
I bought a new set of disk and plates, they are installed but I haven't used the bike yet... what do you recommend to do before using it? so I minimize chances of happening again

- Adjust cable tension so clutch release arm can be moved with fingers
- what else?
 

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measure the stack.

you need to measure the height of the clutch from rear hub to pressure plate, then measure the stack.

stm should list minimum stack height for their clutches.

you need a decent amount of "squish" for it to engage properly.

also check out the spring rates on your slip spring and main spring. stm should have info on those springs as well.


i really hate the stm clutches, they are a novel design, but generally a pain in the ass to work with.


also make sure when you install the plates that you do it in the right order.

you don't want the special fiber and judder first in the stack.
 

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Discussion Starter #8
measure the stack.

you need to measure the height of the clutch from rear hub to pressure plate, then measure the stack.

stm should list minimum stack height for their clutches.

you need a decent amount of "squish" for it to engage properly.

also check out the spring rates on your slip spring and main spring. stm should have info on those springs as well.


i really hate the stm clutches, they are a novel design, but generally a pain in the ass to work with.


also make sure when you install the plates that you do it in the right order.

you don't want the special fiber and judder first in the stack.
Thank you for the thorough explanation Wibbly, I'll get to it ASAP and post my findings.
 

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Out of curiosity, what oil are you using?
 
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