C6Z Temporary Clutch Failure on Track
09-24-2008, 12:15 PM
#1
Burning Brakes
Thread Starter
C6Z Temporary Clutch Failure on Track
This past Monday we were at NJMP Lightning Track at a member guest day.
We managed to sneak in 2 twenty minute sessions back to back and about 2/3 way through the second session I am coming down the front straight into turn 1 at almost 150mph and put both feet on the clutch and brakes to start my downshift and turn.
The clutch goes to the floor with no resistance..it disengaged so I make the shift but did not come back up. Luckily I was able to brake hard enough to glide through the turn but man did it scare the crap out of me.
Its an 07 stock Z with about 5K miles on it. I am running Motul DOT4 fluid. It came back to normal by the time the next shift was needed, about 30 seconds later.
I was pushing the car pretty hard for the last few laps trying to reel in Turbo50mike.
Anybody have similar experiences?
We managed to sneak in 2 twenty minute sessions back to back and about 2/3 way through the second session I am coming down the front straight into turn 1 at almost 150mph and put both feet on the clutch and brakes to start my downshift and turn.
The clutch goes to the floor with no resistance..it disengaged so I make the shift but did not come back up. Luckily I was able to brake hard enough to glide through the turn but man did it scare the crap out of me.
Its an 07 stock Z with about 5K miles on it. I am running Motul DOT4 fluid. It came back to normal by the time the next shift was needed, about 30 seconds later.
I was pushing the car pretty hard for the last few laps trying to reel in Turbo50mike.
Anybody have similar experiences?
09-24-2008, 12:37 PM
#2
Former Vendor
I wrote this for a pm and then posted on a thread. I hope it helps you understand a few issues that I have seen. One thing that you should unlearn from your driving. Don't use the engine to slow you down. Brakes are cheap, drivetrains are big money. It is a classic way of breaking timing chains and banging valves off the piston.
I can't even tell you how many problems we have had with this issue. There is three main things that it can be. Real easy to find with GM C6 closed bell housing, NOT. The guys in the shop bitch about the c6's all the time.
But anyways. Pressure plate is getting over thrown, Compond bows work simular to the pressure plates. As the fingers move toward the straight position they get weaker and weaker. To the point were the throwout bearing pushes the finger past center and then there is no spring left to push back the throwout bearing, which makes the hydro system work right. Heat makes steel weaker, which explains most reported problems, and once it gets hot, it doesn't come back that isn't how steel works. I know GM had a recall on some models, but not others, it maybe worth a look.
Other issue can be the slave itself, the bearing will go up and down. But with a slight twist in the bearing carrier the bearing will stop half way up. Then with some more playing around you can get it to work great again. Two minutes later, hung up again. There is a couple fixes to this problem, but is best dealt with a replacement. Junk parts made half way across the world, is where the blame should be pointed on this one.
I would be willing to bet your problems come from one of these two issues above.
Heat, as the fluid grows, if nowhere to go. Will push on the slave-bearing. Which will put stress on the bearing to the point of over-heating. Simply because there is no time to cool off inbetween shifts. Headers and over filling are common finds. This happens also with windshield washer fluid coming out the nossle during track events or hot runs or sitting in traffic. Run the washer bottle 3/4 full and problem goes away.
What can be done in every car to prevent some of these problems. After start up, get off the clutch pedal. This will allow the bearing to get lubed up without the added stress of the pressure plate. The other thing is never rev up the engine with your foot on the clutch. More stress. Also, dipping the clutch should be used during all high rpm shifts. This will give the bearing less of a chance of building too much heat.
I can't even tell you how many problems we have had with this issue. There is three main things that it can be. Real easy to find with GM C6 closed bell housing, NOT. The guys in the shop bitch about the c6's all the time.
But anyways. Pressure plate is getting over thrown, Compond bows work simular to the pressure plates. As the fingers move toward the straight position they get weaker and weaker. To the point were the throwout bearing pushes the finger past center and then there is no spring left to push back the throwout bearing, which makes the hydro system work right. Heat makes steel weaker, which explains most reported problems, and once it gets hot, it doesn't come back that isn't how steel works. I know GM had a recall on some models, but not others, it maybe worth a look.
Other issue can be the slave itself, the bearing will go up and down. But with a slight twist in the bearing carrier the bearing will stop half way up. Then with some more playing around you can get it to work great again. Two minutes later, hung up again. There is a couple fixes to this problem, but is best dealt with a replacement. Junk parts made half way across the world, is where the blame should be pointed on this one.
I would be willing to bet your problems come from one of these two issues above.
Heat, as the fluid grows, if nowhere to go. Will push on the slave-bearing. Which will put stress on the bearing to the point of over-heating. Simply because there is no time to cool off inbetween shifts. Headers and over filling are common finds. This happens also with windshield washer fluid coming out the nossle during track events or hot runs or sitting in traffic. Run the washer bottle 3/4 full and problem goes away.
What can be done in every car to prevent some of these problems. After start up, get off the clutch pedal. This will allow the bearing to get lubed up without the added stress of the pressure plate. The other thing is never rev up the engine with your foot on the clutch. More stress. Also, dipping the clutch should be used during all high rpm shifts. This will give the bearing less of a chance of building too much heat.
09-24-2008, 12:41 PM
#3
Drifting
In my 03 that never had a sticky clutch problem, it stuck after I banged the rev limiter in 3rd. I was stuck behind some slow traffic waiting for the point by and thought I was in 4th. It hit the rev limiter about 6 times before I realized what the hell was going on and shifted to 4th. At the end of that straight it stuck when I down shifted to 3rd. I pulled it back up with my foot and it never happened again. I'm running DOT 4 as well. I must have boiled the fluid. I change the fluid every time I bleed the brakes.
09-24-2008, 01:07 PM
#5
Race Director
09-24-2008, 01:16 PM
#6
Former Vendor
09-24-2008, 01:48 PM
#7
Team Owner
Member Since: Feb 2005
Location: FL
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CI-7-8-9-10 Veteran
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St. Jude Donor '05-'06-'07-'08-'09-'10-'11,'19,'22
St. Jude/CI Name Tag Designer
I had the same thing happen to me late in the day after many 1-mile autocross runs. I launched in 1st, with some possible clutch slip. When I shifted to 2nd, the pedal went to the floor. I finally got it into 2nd, finished the run, let the car cool, did several more runs and have never had it happen again.
'08 Z, 3,400 miles.
'08 Z, 3,400 miles.
09-24-2008, 03:49 PM
#8
Burning Brakes
Thread Starter
I was in 4th ripping down the straight then brakes and clutch in at the same time. Heel-toe to blip the throttle for the downshift to 3rd so I could accelerate OUT through the turn.
If you are engine-braking the car as you head towards your turn-in, then you are probably way too early for the turn and mostly likely should be in one of the beginner groups.
The rest of your post was helpful though, thanks.
09-24-2008, 04:01 PM
#9
Team Owner
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St. Jude Donor '05-'08
Regarding the clutch - this sounds all to familiar with the C5 clutch. Many people mod their cars and the C5 clutch sticks to the floor. There have been many different opinions on what fixes it, but all that seem to really work is going with a good after market clutch.
09-24-2008, 04:22 PM
#10
Burning Brakes
Thread Starter
http://turbomike.net/Z06/Vids/NJMP/NJMP_ER.wmv
This is from Turbo50mike's car and i don't see a tire wall.
About 1/2 way through I get in the video with the black C6Z chasing down the Ferrari F430.
09-24-2008, 08:05 PM
#11
I hope you're not angry, but while you were eating chicken fingers, I put some Krazy Glue on the back of your clutch pedal. It was the only way I could catch your car.
Next time I'll just pull a spark plug wire or two.
Next time I'll just pull a spark plug wire or two.
09-25-2008, 12:29 PM
#13
Former Vendor
I wasn't downshifting to use the engine to slow down for the corner.
I was in 4th ripping down the straight then brakes and clutch in at the same time. Heel-toe to blip the throttle for the downshift to 3rd so I could accelerate OUT through the turn.
If you are engine-braking the car as you head towards your turn-in, then you are probably way too early for the turn and mostly likely should be in one of the beginner groups.
The rest of your post was helpful though, thanks.
I was in 4th ripping down the straight then brakes and clutch in at the same time. Heel-toe to blip the throttle for the downshift to 3rd so I could accelerate OUT through the turn.
If you are engine-braking the car as you head towards your turn-in, then you are probably way too early for the turn and mostly likely should be in one of the beginner groups.
The rest of your post was helpful though, thanks.
Randy