Clutch Pedal Sticking :(
Thread Starter
Safety Car
Joined: Jan 2007
Posts: 4,332
Likes: 0
From: Kuwait
Clutch Pedal Sticking :(
It's a new clutch, flywheel, master/slave cylinders (LS7), while cruising yesterday I slammed the pedal and shifted to 3rd.. missed it and pedal stuck on the floor! Again it's a new clutch assembly.
My Q is
1. Is there any way to fix it? like changing the fluid?
2. Is there any racing or heavy duty master/slave cylinder other than the OEM one?
Thanks!
My Q is
1. Is there any way to fix it? like changing the fluid?
2. Is there any racing or heavy duty master/slave cylinder other than the OEM one?
Thanks!
Drifting
Joined: Nov 2007
Posts: 1,338
Likes: 1
From: Central Jersey, Union County N.J.
St. Jude Donor '10
Try doing a search there's a lot of good feedback on issues about clutch pedal sticking. I had the same problem and i tried changing the fluid but it didn't help at all not even with the best fluids. What did work was a minor mod i seen from another cf member posted. It's a clutch pedal stop. This stops the pedal from going all the way to the floor. It's mounts on the clutch pedal arm.
Last edited by chazc6; Sep 29, 2009 at 12:08 AM.
Thread Starter
Safety Car
Joined: Jan 2007
Posts: 4,332
Likes: 0
From: Kuwait
Try doing a search there's a lot of good feedback on clutch pedal sticking issues. I had the same problem and i tried changing the fluid but it didn't help at all not even with the best fluids. What did work was a minor mod i seen from another cf member posted. It's a clutch pedal stop. This stops the pedal from going all the way to the floor. It's mounts on the clutch pedal arm.
I'm confused because it's a 2 weeks old cylinders! Thx for the input.
Melting Slicks
Joined: Nov 2004
Posts: 2,408
Likes: 145
From: Northcentral, Pennsylvania
St. Jude Donor '09-'11
I'll chime in to give you a bump if nothing else. My clutch is sticking half way down on a single hot run. I can raise it back up with my hand or toe. It just started doing this recently. I have 462/418 (rw) LS2. I now use Ranger's method of keeping the fluid clear, but I think I was too late on this, as I wasn't aware until about 60,000 miles on the car. I have read that some people recommend removing the clutch spring! Also read a recommendation of using a better fluid such as Motul 600 (?). Anyone else want to chime in?
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
It's a new clutch, flywheel, master/slave cylinders (LS7), while cruising yesterday I slammed the pedal and shifted to 3rd.. missed it and pedal stuck on the floor! Again it's a new clutch assembly.
My Q is
1. Is there any way to fix it? like changing the fluid?
2. Is there any racing or heavy duty master/slave cylinder other than the OEM one?
My Q is
1. Is there any way to fix it? like changing the fluid?
2. Is there any racing or heavy duty master/slave cylinder other than the OEM one?
------------------------------------------
Glazing the Clutch by Driver Error
Update June 4, 2009
------------------------------------------
On Launch
A driver can easily glaze the clutch on launch by inducing too much slip from too high a launch rpm or riding the pedal to keep the rpm up. Either way, the friction surfaces overheat and the clutch’s clamping power decreases dramatically. Once the friction surfaces cool down again (30-60 minutes), the clamping force is fully restored without lasting damage.
Here are some other ways to glaze the clutch.
During a Burnout
Overheating the clutch during a burnout can happen when:
(1) you don't have enough water on the tire tread surface
(2) you position the rear wheels too far forward in the tacky rubber and then start the burnout. In this situation the rear tires have too much grip to spin at the hit of the clutch; so the clutch slips instead. This quickly glazes the clutch.
(3) you do everything correctly except continue the burnout too long, allowing the engine speed to be drawn down by the growing traction at the rear tires. A crossing point is reached and the clutch begins to slip. That produces a spike in heat in the rotating surfaces and the pedal reacts negatively.
During High-rpm Shifts and Power-Shifting
On a high-rpm shift (using the LS7 as an example) the flywheel spins at say 7K (pre-shift) and 200-300 milliseconds later the post-shift rpm is drawn down to 4700 (1-2 shift), 5100 (2-3 shift), 5400 (3-4 shift). Those rpm deltas produce significant heat that must be dissipated from the rotating friction surface. A power-shift makes for an even higher pre-shift rpm and yields even more heat. That's one of at least three reasons that power-shifting is risky and can have unintended consequences.
Cumulative Heat Leads to Malfunction
The LS7 clutch disc friction material has strands of raw copper interwoven to help dissipate heat from the surface. And there's substantial air-flow within the bell housing to provide cooling and evacuate clutch dust. But these design features can't deal adequately with the accumulated heat from
(1) Improper burnout technique
(2) Too high a launch rpm or too slow a clutch release
(3) Power-shifting or improperly timed high-rpm shifts
(4) Any combination of (1), (2), (3)
Once the cumulative heat reaches a break-point, the clutch either glazes entirely, losing clamping force after the launch attempt, or no longer disengages properly during high-rpm shifts.
Here's what I do to keep within the limits of the my clutch:
(1) Keep the clutch fluid clean including changes between passes at the track (usually after 3-5 passes with my driving style).
(2) Keep the launch rpm at no more than 3600-3700 and make a fast, one-piece clutch engagement
(3) Refrain from power-shifting
(4) After every pass, I lift the hood and sniff the driver's-side firewall. If I smell even a slight "eau de clutch" aroma, I know I'm not getting the clutch pedal out fast enough. That rarely happens to me because I observe rules (1) (2) and (3) just above. The alternative is an aftermarket clutch with a different personality than the stocker.
A pointed warning to owners is to recognize the limits of your clutch. That means not adopting the all-out racing launches and power-shifting advocated by some drivers with stronger and more heat-tolerant after-market clutches. Such approaches give a dramatically truncated clutch life. My approach should give at least 200 drag strip passes at stock power-levels, before the clutch requires replacement.
Glazing the Clutch by Driver Error
Update June 4, 2009
------------------------------------------
On Launch
A driver can easily glaze the clutch on launch by inducing too much slip from too high a launch rpm or riding the pedal to keep the rpm up. Either way, the friction surfaces overheat and the clutch’s clamping power decreases dramatically. Once the friction surfaces cool down again (30-60 minutes), the clamping force is fully restored without lasting damage.
Here are some other ways to glaze the clutch.
During a Burnout
Overheating the clutch during a burnout can happen when:
(1) you don't have enough water on the tire tread surface
(2) you position the rear wheels too far forward in the tacky rubber and then start the burnout. In this situation the rear tires have too much grip to spin at the hit of the clutch; so the clutch slips instead. This quickly glazes the clutch.
(3) you do everything correctly except continue the burnout too long, allowing the engine speed to be drawn down by the growing traction at the rear tires. A crossing point is reached and the clutch begins to slip. That produces a spike in heat in the rotating surfaces and the pedal reacts negatively.
During High-rpm Shifts and Power-Shifting
On a high-rpm shift (using the LS7 as an example) the flywheel spins at say 7K (pre-shift) and 200-300 milliseconds later the post-shift rpm is drawn down to 4700 (1-2 shift), 5100 (2-3 shift), 5400 (3-4 shift). Those rpm deltas produce significant heat that must be dissipated from the rotating friction surface. A power-shift makes for an even higher pre-shift rpm and yields even more heat. That's one of at least three reasons that power-shifting is risky and can have unintended consequences.
Cumulative Heat Leads to Malfunction
The LS7 clutch disc friction material has strands of raw copper interwoven to help dissipate heat from the surface. And there's substantial air-flow within the bell housing to provide cooling and evacuate clutch dust. But these design features can't deal adequately with the accumulated heat from
(1) Improper burnout technique
(2) Too high a launch rpm or too slow a clutch release
(3) Power-shifting or improperly timed high-rpm shifts
(4) Any combination of (1), (2), (3)
Once the cumulative heat reaches a break-point, the clutch either glazes entirely, losing clamping force after the launch attempt, or no longer disengages properly during high-rpm shifts.
Here's what I do to keep within the limits of the my clutch:
(1) Keep the clutch fluid clean including changes between passes at the track (usually after 3-5 passes with my driving style).
(2) Keep the launch rpm at no more than 3600-3700 and make a fast, one-piece clutch engagement
(3) Refrain from power-shifting
(4) After every pass, I lift the hood and sniff the driver's-side firewall. If I smell even a slight "eau de clutch" aroma, I know I'm not getting the clutch pedal out fast enough. That rarely happens to me because I observe rules (1) (2) and (3) just above. The alternative is an aftermarket clutch with a different personality than the stocker.
A pointed warning to owners is to recognize the limits of your clutch. That means not adopting the all-out racing launches and power-shifting advocated by some drivers with stronger and more heat-tolerant after-market clutches. Such approaches give a dramatically truncated clutch life. My approach should give at least 200 drag strip passes at stock power-levels, before the clutch requires replacement.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
A funny thing about this clutch is the varying feedback from owners of it. I use the LS7 clutch with a fidanza aluminum flywheel and I guess mine cools down quite a bit from the flywheel. I'm reaching for an explanation here. I have about 8k miles on the LS7 and 4k has been with over 700rwhp from 16psi with an ECS kit. The one thing that I never understood even back from my H/C nitrous days was that I had 560rwhp and 600rwtq and I never once even now ever had the pedal stick to the floor and I never once changed the clutch fluid after its install.
Either the flywheel is the difference, the way I had an extended break in, or the clutch people are installing isnt an LS7. A friend had a 2006 Z06 and had 550rwhp on motor plus a 100 shot making 650rwhp and over 700rwtq and his lasted 26k miles and he too used R-compounds (325 R6 hoosiers.
I guess GM has a wide variance on the LS7's clamping power.
I have a twin disc on stand by waiting for this LS7 to give up the ghost and it isnt showing any of the signs.
Either the flywheel is the difference, the way I had an extended break in, or the clutch people are installing isnt an LS7. A friend had a 2006 Z06 and had 550rwhp on motor plus a 100 shot making 650rwhp and over 700rwtq and his lasted 26k miles and he too used R-compounds (325 R6 hoosiers.
I guess GM has a wide variance on the LS7's clamping power.
I have a twin disc on stand by waiting for this LS7 to give up the ghost and it isnt showing any of the signs.
Thread Starter
Safety Car
Joined: Jan 2007
Posts: 4,332
Likes: 0
From: Kuwait
I'll chime in to give you a bump if nothing else. My clutch is sticking half way down on a single hot run. I can raise it back up with my hand or toe. It just started doing this recently. I have 462/418 (rw) LS2. I now use Ranger's method of keeping the fluid clear, but I think I was too late on this, as I wasn't aware until about 60,000 miles on the car. I have read that some people recommend removing the clutch spring! Also read a recommendation of using a better fluid such as Motul 600 (?). Anyone else want to chime in?
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Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
Before changing the clutch again....
A pedal hang during a slip-induced pedal event is different with the LS7 clutch. Please read post #6 and comment on your driver actions leading up to that pedal event.
If your clutch fluid is clean and you just glazed the clutch, then a simple driver technique change can save you the expense of a new clutch. Since learning to avoid those errors, my LS7 clutch has been OK. I'm stock 455 rwhp /435 rwtq, about the same as you.
Ranger
A pedal hang during a slip-induced pedal event is different with the LS7 clutch. Please read post #6 and comment on your driver actions leading up to that pedal event.
If your clutch fluid is clean and you just glazed the clutch, then a simple driver technique change can save you the expense of a new clutch. Since learning to avoid those errors, my LS7 clutch has been OK. I'm stock 455 rwhp /435 rwtq, about the same as you.
Ranger
Last edited by Ranger; Sep 26, 2009 at 12:54 PM.
Former Vendor
Joined: Feb 2007
Posts: 857
Likes: 0
From: DFW Texas
Interesting...
I think my clutch is going out as well. (LS7). I'm at 480/450 and I just did some minor mods but when I shift into second(WOT) the clutch slips bad.
So, any suggestions from experienced C6Z owners? For a Road Race Daily driver...
I think my clutch is going out as well. (LS7). I'm at 480/450 and I just did some minor mods but when I shift into second(WOT) the clutch slips bad.
So, any suggestions from experienced C6Z owners? For a Road Race Daily driver...
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
Ranger
Race Director
Joined: Oct 2005
Posts: 14,555
Likes: 1,255
From: Saint Albans, WV
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
After getting the fluid clean, suggest swapping the fluid in the reservoir between sessions. That way you stay ahead of accumulation. Your clutch pedal will then reward you with normal behavior.
Ranger
Team Owner
Joined: Feb 2000
Posts: 53,535
Likes: 77
From: Arizona
This 50 cent window track lock has worked for my early '05.
But you still need to change out your fluid from time to time.
I had my first relapse in 4 years recently, but the fluid was almost a year old.
Former Vendor
Joined: Feb 2007
Posts: 857
Likes: 0
From: DFW Texas
Road course sessions generate a lot of clutch dust because of all the high-rpm down-shifts. One session on many courses will produce more clutch dust than a day at the drag strip.
After getting the fluid clean, suggest swapping the fluid in the reservoir between sessions. That way you stay ahead of accumulation. Your clutch pedal will then reward you with normal behavior.
Ranger
After getting the fluid clean, suggest swapping the fluid in the reservoir between sessions. That way you stay ahead of accumulation. Your clutch pedal will then reward you with normal behavior.
Ranger
Will do...
-Adam
