Diyman25

This weekend track some thing strange happens
Update lightweight flywheel earlier this mo
So was excited about testing

Only find out the clutch pedal will stick to floor
On certain corner , typical at hard brake corner with 2 down shift
Car was perfect on upshift or single gear down shift

Hard to see at video , but u can see me fishing the pedal up with my left foot on some corner
And u can clearly heard the car over rev a bit
Due to stock clutch

Loki

iTrader: (1)

Hmm. Does it do this if you just pump the clutch several times without actually changing gear?

Diyman25

No pumping
Just use left foot to fish out the pedal

Loki

iTrader: (1)

I meant will the clutch go to the floor if you pump it a few times, without changing gear?

TeamRX8

iTrader: (25)

replace the slave cylinder, it could possibly be the MC but the slave get’s most of the abuse with heat and such

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trackjunkie

i had clutch pedal stuck to the floor on me before on after market clutch. it happened during high rpm shift. later found out it was because the pressure plate diaphragm went past center and the centrifugal force prevent the diaphragm from springing back to normal. i got a different clutch before fixing the issue but after some investigation, i was sure that was the cause. i added a clutch pedal stop with the new clutch setup. you said your pedal stuck during braking down shift, so it might not be the same issue.

TeamRX8

iTrader: (25)

I would have suggested that, but he said it’s a stock (OE) clutch while you have the 5.5” Tilton race clutch. Completely different situation.

So now assessing this further I’m maybe assuming too much and not really clear on what’s happening. When you say the clutch pedal is stuck on the floor is the clutch in/disengaged or out/engaged when this happens?

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trackjunkie

true. but the clutch that i had issues with pedal sticking to the floor was a spec clutch. not exactly oem but pretty close to oem.

TeamRX8

iTrader: (25)

yeah, that’s what made me ask the prior question for clarification.

Diyman25

Found this in my garage
Hopefully with more caution bleeding the air
Out
Will solve my problem at 6/6 track day testing

TeamRX8

iTrader: (25)

you didn’t answer the question though, because that will help figure out the problem; when the pedal stayed on the floor was the clutch in/disengaged or out/engaged?

Diyman25

The clutch pedal will stick to floor
If i am at turn 1 and turn 10
Which is hevey brake turn with two downshift
The pedal will not come back until i use my left to fish out the floor
Once i did that clutch pedal is firm and
Perfect up shift and single gear down shift

TeamRX8

iTrader: (25)

I don’t think you understand the question

when the pedal was stuck to the floor, was the engine and transmission connected together like when the clutch pedal is normally out or were they separated like when the clutch pedal is normally pressed in?

Diyman25

Now I get it
Pedal to the floor
Clutch was separated like normal
Thus u heard it bonus on limiter
At the corner that requires 2 down shift

TeamRX8

iTrader: (25)

it’s probably the clutch pressure plate hanging up as mentioned by trackjunkie, because it’s the pressure plate spring that pushes it back. So that wasn’t happening; hung up pressure plate spring, likely over-extended.

trackjunkie

yeah exactly like my case. pedal stuck at the floor, engine banging off the rev limiter because clutch is disconnected. as i mentioned in our PM, try to add a pedal stop or adjust the pedal to limit the slave cylinder travel.
on my spec clutch, since the disk was new and thick, if i limit the pedal travel too much, it wouldn't disengage the clutch completely. so i was thinking of adding shims between the pressure plate flywheel to raise the height up a little. that would give full clutch pedal travel while still reduce chance of pressure plate fingers going past center and get stuck during high rpm. but i just decided to go with 5.5" clutch setup instead. lol

Diyman25

At track
I did a sos repairs with rubber hose zip tide on stock clutch pedal stop
It help a bit , after reading this thread now even with Slave rebuild
I would add thicker hose to limit. Travel even more

Thanks for all reply ~ appreciate

Diyman25

Rebuild the slave, rebleed the clutch
Install this adjustable rod on slave
Should cure this problems

Diyman25

I found out the problem today

With full hydraulic system rebuild
The symptoms improve but still happend time to time which really mess out my rhythm

So already made mine going to change this clutch

Been always want to try carbon clutch
Since 90s

So swap out this mint condition Clutch to it

And while i was there i am careful inspection the old clutch and notice
Some things weird

The diaphragm spring leg is not line up
As u can see the pic

Mabe from the track used the spring walk away from its original location

With this i think this is reason why my pedal stick to floor when i downshift at track

Loki

iTrader: (1)

What's weird is the mark the throwout bearing left on thr diaphragm fingers... it's a circle where I think it should be evenly worn to the ends of the fingers. What clutch and throwout bearing are these? It's really hard worn too.

Something is​​​ off here.

trackjunkie

yeah check your through out bearing. it might have seized. not moving freely which can cause the top fingers to shift.

thats nice fancy carbon disk. the low MOI will allow you to shift really quick.

Diyman25

No weird noise from depression the clutch pedal
So I doubt is throw out bearing

Test drive the carbon clutch , very easy engagement, less shock load on wot up shift
But engagement feel change a bit when clutch disc fully warm up

Diyman25

This clutch is ORC 250 light

TeamRX8

iTrader: (25)

A carbon clutch will typically gain more grip or grab as the discs become hotter. So the more you push it, the more grip it has to not slip. It’s a good feature.

I’m assuming it’s the same OE size & style and not a mini race clutch type, no? Never mind, I see it in the pics now. I bought one of those used and am sitting on it as a backup to my Tilton mini clutch. It’s still pretty heavy with the steel flywheel and full size disc and pressure plate.

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Diyman25

More u push it, more grip it get
But still not as harash as full metal one

Japanese are specialty like to make part
Cross between full race and aftermarket
This is one of them , due to charter character
Of carbon clutch they have design special pressure cover to reduce charters noise for
Semi street people