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[Z06] Clutch Pedal Issues—How-To Prevent and Cure
02-15-2009, 07:25 AM
#41
Melting Slicks
02-15-2009, 08:49 AM
#42
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...Where can you find that syringe. I have one that I use but its half the size of the one you have. HAd a tough time just finding the one I have. How many times do you think it would take to flush through the valvoline with the new prestone to get through the whole system? Thanks
I'd suggest 10 swaps; then drive it for a few days; followed by another 10 swaps. That may be excessive but it won't take long or cost much.
Ranger
02-15-2009, 08:59 AM
#43
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Hey my friends. Hoping to see you both again at Track Attack 2009. I'm hoping to be there unless I'm off-the-grid again. Won't know for sure until late-April. 
02-15-2009, 12:54 PM
#45
Melting Slicks
The MixMizer is widely available in auto part stores. And it can usually be found the the auto section at Walmart on a pegboard near the gasoline cans.
I'd suggest 10 swaps; then drive it for a few days; followed by another 10 swaps. That may be excessive but it won't take long or cost much.
Ranger
I'd suggest 10 swaps; then drive it for a few days; followed by another 10 swaps. That may be excessive but it won't take long or cost much.
Ranger
02-15-2009, 01:46 PM
#47
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Ranger thanks for providing a video with instructions.
My fluid has 16K miles and is very black. Is it OK to use the Prestone which will mix with the stock GM fluid?
Thanks!
My fluid has 16K miles and is very black. Is it OK to use the Prestone which will mix with the stock GM fluid?
Thanks!
02-15-2009, 03:01 PM
#48
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Ranger
02-16-2009, 06:49 PM
#49
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Fluid Flow between Master and Actuator (Slave) Documentation
Brought over from a the Autocross/Roadracing board from a parallel thread on the topic.
Hi Rob.
It’s always a good idea to go to the source document for a definitive description of the operation of the clutch hydraulics. In this case the Corvette Service Manual 2006, Volume 3, page 7-360, and I quote:
The clutch hydraulic system consists of a master cylinder and an actuator cylinder.
When pressure is applied to the clutch pedal (pedal depressed), the pushrod contacts the plunger and pushes it down the bore of the master cylinder.
In the first 0.8 mm (0.031 in) of movement, the recuperation seal closes the port to the fluid reservoir tank, and as the plunger continues to move down the bore of the cylinder, the fluid is forced through the outlet line to the actuator cylinder mounted to the driveline support assembly.
As fluid is pushed down the pipe from the master cylinder, this in turn forces the piston in the actuator cylinder outward.
As the actuator cylinder moves forward, it forces the release bearing to disengage the clutch pressure plate from the clutch disc.
On the return stroke (pedal released), the plunger moves back as a result of the return pressure of the clutch.
Fluid returns to the master cylinder and the final movement of the plunger opens the port to the fluid reservoir, allowing an unrestricted flow between system and reservoir….
There you have if from the source.
Summary: Clutch fluid circulates between the master and actuator (slave).
Note: The volume of fluid in the entire system is a very few ounces. One ounce is in the master cylinder reservoir until diminished as you depress the pedal and create the flow described above.
Hope that helps.
Ranger
Ranger, just to be 100% clear, you're saying that the clutch fluid circulates? As you pump the pedal, a fluid molecule marches down from the master to the slave cylinder, past the bleeder and then returns to the reservoir? There is a circular path here that traverses most of the system?
It’s always a good idea to go to the source document for a definitive description of the operation of the clutch hydraulics. In this case the Corvette Service Manual 2006, Volume 3, page 7-360, and I quote:
The clutch hydraulic system consists of a master cylinder and an actuator cylinder.
When pressure is applied to the clutch pedal (pedal depressed), the pushrod contacts the plunger and pushes it down the bore of the master cylinder.
In the first 0.8 mm (0.031 in) of movement, the recuperation seal closes the port to the fluid reservoir tank, and as the plunger continues to move down the bore of the cylinder, the fluid is forced through the outlet line to the actuator cylinder mounted to the driveline support assembly.
As fluid is pushed down the pipe from the master cylinder, this in turn forces the piston in the actuator cylinder outward.
As the actuator cylinder moves forward, it forces the release bearing to disengage the clutch pressure plate from the clutch disc.
On the return stroke (pedal released), the plunger moves back as a result of the return pressure of the clutch.
Fluid returns to the master cylinder and the final movement of the plunger opens the port to the fluid reservoir, allowing an unrestricted flow between system and reservoir….
There you have if from the source.
Summary: Clutch fluid circulates between the master and actuator (slave).
Note: The volume of fluid in the entire system is a very few ounces. One ounce is in the master cylinder reservoir until diminished as you depress the pedal and create the flow described above.
Hope that helps.
Ranger
02-16-2009, 11:41 PM
#50
Melting Slicks
ranger ..thanks...
started your clutch protocol about 3 yrs ago on my c5 z,just sold it with 63k mileson it and had no issues with the original clutch still in car...
got an 06 z last mo..first thing i did was clean the reservoir..it was black...now it be clean
bud
started your clutch protocol about 3 yrs ago on my c5 z,just sold it with 63k mileson it and had no issues with the original clutch still in car...
got an 06 z last mo..first thing i did was clean the reservoir..it was black...now it be clean
bud
02-17-2009, 01:03 AM
#51
Le Mans Master
Curious, just clicked 76,000 miles without a clutch hangup or fluid change, also on 5th set of rears, all in 21 months. 
Last edited by jimman; 02-17-2009 at 04:05 PM.
02-17-2009, 01:10 AM
#52
Team Owner
02-17-2009, 11:17 AM
#53
Safety Car
Of course he's driving like an old lady!
He's averaging just over 15,000 miles on each set of rear tires!!
When my car was new the clutch fluid was black before there was 200 miles on it and as I was breaking it in, there were no clutch dumps and I don't think it had even been beyond 3500 rpm.
It would have been nice if GM had spent an extra 50 cents and installed a bleed line on the slave cylinder.
Grant
He's averaging just over 15,000 miles on each set of rear tires!!When my car was new the clutch fluid was black before there was 200 miles on it and as I was breaking it in, there were no clutch dumps and I don't think it had even been beyond 3500 rpm.
It would have been nice if GM had spent an extra 50 cents and installed a bleed line on the slave cylinder.
Grant
02-17-2009, 04:57 PM
#55
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New Information
I've edited the following into Post #1 on the thread....
------------------------------
Update February 17, 2009
------------------------------
Today I spent time at the workbench with two Chevy master technicians (one who’s worked on Corvettes since the C3 was first released). We examined the operation of the Corvette clutch actuator and concluded following:
1. The bell housing is fouled with blown clutch dust during aggressive driving.
2. Clutch dust is penetrating the accordion shield on the actuator main shaft. That is obvious from visual inspection.
3. The piston slides along the shaft sealed by an O-ring. The shaft has a film of lubricant or clutch fluid on it. During aggressive driving, this film gets coated on each stroke with a fine layer of blow clutch dust. That is obvious from visual inspection.
4. The O-ring slides along the shaft and squeegees some of the clutch dust down the shaft where it contacts the clutch fluid and is infused.
5. The conclusions were unanimous and seemed obvious from a physical exam of the surfaces involved.
Plus, keep in mind that it is confirmed that clutch dust is getting into the fluid. The question is how. We believe the answer to that is in points 1-5 above.
Ranger
------------------------------
Update February 17, 2009
------------------------------
Today I spent time at the workbench with two Chevy master technicians (one who’s worked on Corvettes since the C3 was first released). We examined the operation of the Corvette clutch actuator and concluded following:
1. The bell housing is fouled with blown clutch dust during aggressive driving.
2. Clutch dust is penetrating the accordion shield on the actuator main shaft. That is obvious from visual inspection.
3. The piston slides along the shaft sealed by an O-ring. The shaft has a film of lubricant or clutch fluid on it. During aggressive driving, this film gets coated on each stroke with a fine layer of blow clutch dust. That is obvious from visual inspection.
4. The O-ring slides along the shaft and squeegees some of the clutch dust down the shaft where it contacts the clutch fluid and is infused.
5. The conclusions were unanimous and seemed obvious from a physical exam of the surfaces involved.
Plus, keep in mind that it is confirmed that clutch dust is getting into the fluid. The question is how. We believe the answer to that is in points 1-5 above.
Ranger
Last edited by Ranger; 02-17-2009 at 08:34 PM.
02-18-2009, 12:01 AM
#56
Melting Slicks
say what you want...then, after doing regular fluid changes , i never had that occur again...
so, i'm a believer, and i will do the same with my new c6 z..
bud
02-22-2009, 06:43 AM
#58
Team Owner
Thanks Ranger....I will be doing that as soon as it warms up. 10k miles and I bet when I look at the fluid it will need changing.
02-22-2009, 09:48 AM
#59
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GM does not publish the specifications of its clutches, except in the most general term. So there is no precise answer to your question.
The LS7 clutch at launch is less robust than any Corvette clutch I've driven. It's fine on shifts at power levels from stock to +3% to +7%. Depends on driver habits and techniques.
Ranger
Last edited by Ranger; 02-22-2009 at 02:15 PM.
02-22-2009, 02:11 PM
#60
Cool!
This got me thinking about how it feels when I shift now compared to when I first bought the car. So I go check on it and fluid is BLACK, I use Prestone DOT4 for other stuff so I have it readily available. Did the routine four times until absolutely cleared and went out for a ride. Hope this is not a placebo effect thing since not too many simple changes you could do to a car are really noticeable.
Got the deja vú sensation since it now engages smoother now, and performs as consistent as before. It´s official, I had clutch issues.
Got the deja vú sensation since it now engages smoother now, and performs as consistent as before. It´s official, I had clutch issues.
Last edited by Black_Mamba; 02-22-2009 at 05:52 PM. Reason: typos