[Z06] Take Care of Your Clutch--Preventing or Curing Pedal Issues
02-15-2009, 09:21 AM
#21
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Ranger, I have a question that I have wondered for some time. When pumping the clutch after putting new fluid in the reservoir, the new fluid does not seem to be distributed after pumping the clutch pedal 30+ times. I have to drive a few miles before there is some color change in the reservoir indicating an exchange of the fresh fluid mixing with the old fluid thats in the line and slave. I have never put the clutch fluid reservoir cap back on in my process of swapping fluids and pumping the clutch since the motors off and car is not moving. In your video I saw your cap was on when you were pumping the clutch and the fluid in the reservoir was sloshing around in the reservoir with each pump of the clutch pedal. I have watched my reservoir as some one has pumped the clutch and have seen no effect, what so ever, which has me wondering. Is having the clutch fluid reservoir cap off when pumping the clutch pedal not allowing the proper exchange of fluids and is why I do not notice any color change unless I drive around a few miles?
On a C6, if the reservoir cap is off when you pump the clutch pedal, fluid is aspirated far and wide onto the paint. Fortunately, that's a mistake most make only once.
On your C5, with the cap closed, you may want to try pumping the pedal slowly and ensuring full travel of the pedal. Wait a moment, then repeat.
If that still gets no action in the reservoir, then drive the car between flushes and repeat sequentially over a few days. Once the fluid is clear, it's easy to keep clear with a periodic single change.
Ranger
02-15-2009, 09:24 AM
#22
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Ranger,
Welcome back. Great video. As usual, you have provided invaluable insight for us.
I have employed your techniques throughout the years and the results were always spectacular; whether they enhanced my driving skills or prevented premature component failure. I greatly appreciate your assistance and give you credit for a large amount of my success.
Welcome back. Great video. As usual, you have provided invaluable insight for us.
I have employed your techniques throughout the years and the results were always spectacular; whether they enhanced my driving skills or prevented premature component failure. I greatly appreciate your assistance and give you credit for a large amount of my success.
Ranger
02-15-2009, 07:56 PM
#24
Team Owner
Appreciate the testimonials to the protocol and the all generous words sent my way.
Hi ptindall,
Given the symptoms you describe, I suspect your clutch master cylinder is finally done, after 140K mile. It's the cheapest clutch part to replace. So it's the place to start.
Gotta say it, the LS6 and that stock clutch are fabulous examples of great engineering. Take a beating and keep on producing reliable enjoyment. Especially true if normal PM is followed, including the clutch fluid.
Ranger
Hi ptindall,
Given the symptoms you describe, I suspect your clutch master cylinder is finally done, after 140K mile. It's the cheapest clutch part to replace. So it's the place to start.
Gotta say it, the LS6 and that stock clutch are fabulous examples of great engineering. Take a beating and keep on producing reliable enjoyment. Especially true if normal PM is followed, including the clutch fluid.
Ranger
Thanks for the reply. I had planned on swapping and pumping a whole bunch of times, then bleeding the system with Castrol SRF and hopping for the best. If that didn't work, I was going to replace the clutch with an aftermarket one. But now, I will try the master cylinder instead. It's worth a shot and if it works, I really owe you one.
Also, I've been on the forum for a few years and this is the first I've heard of brake dust in the fluid being the cause. When did you discover this? And thanks again for your contribution to the Corvette community.
02-15-2009, 09:45 PM
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What stood in the way of testing the fluid samples I had collected was the absence of clutch dust samples of known, parallel origin. I solved that in Jan 2009 and was then fortunate to hook up with the Unovis director responsible for a sophisticated laboratory.
That lab, armed with 2006 LS7 clutch dust and a clutch fluid sample from the same car plus a fluid sample from another 2006 LS7, did the comparison with an electron microscope. Bingo clutch dust was confirmed in the both fluid samples. Common hydraulic components and common clutch friction material.
That was in Jan. then took me about a month to produce the video.
That's the chronology.
Ranger
02-16-2009, 07:21 AM
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Once installed, the remote bleeder puts the bleed-valve inside the engine bay, making it accessible.
I don't use mine because I'm used to the reservoir method which has worked well for me (keeping the clutch hydraulics clean) at 2-hours per year. So the time savings and efficiency of the remote bleeder are not significant to me. And since I'm not having any issues with the pedal, it seems my protocol is adequate to stay ahead of the level of aggressive driving I do.
Ranger
Last edited by Ranger; 02-16-2009 at 12:00 PM.
02-16-2009, 06:52 PM
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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, 07:56 PM
#30
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Hi Ranger,
I've put 12k on my 2004 & @ 30k now. I do the procedure every event so about 2x a month. Clean or cloudy I do it anyway. Zero clutch issues.
2 questions.
What's your take on the guys that remove the clutch spring?
Do you have a procedure for p/s fluid? It gets used up eventually. There is a wynns machine that does an exchange but I would rather something I do in my own garage.
THANKS!
I've put 12k on my 2004 & @ 30k now. I do the procedure every event so about 2x a month. Clean or cloudy I do it anyway. Zero clutch issues.
2 questions.
What's your take on the guys that remove the clutch spring?
Do you have a procedure for p/s fluid? It gets used up eventually. There is a wynns machine that does an exchange but I would rather something I do in my own garage.
THANKS!
02-16-2009, 08:15 PM
#31
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Hi Ranger,
I've put 12k on my 2004 & @ 30k now. I do the procedure every event so about 2x a month. Clean or cloudy I do it anyway. Zero clutch issues.
2 questions.
What's your take on the guys that remove the clutch spring?
Do you have a procedure for p/s fluid? It gets used up eventually. There is a wynns machine that does an exchange but I would rather something I do in my own garage.
THANKS!
I've put 12k on my 2004 & @ 30k now. I do the procedure every event so about 2x a month. Clean or cloudy I do it anyway. Zero clutch issues.
2 questions.
What's your take on the guys that remove the clutch spring?
Do you have a procedure for p/s fluid? It gets used up eventually. There is a wynns machine that does an exchange but I would rather something I do in my own garage.
THANKS!
David Farmer is a very savvy owner/racer. I know racers who've removed the springs without issue. So Dave is in good company.
Chevy warns to not remove the spring out of concern that a slight amount of pedal droop may occur and restrict the flow of fluid in the hydraulics.
Still my pedal spring remains in place and I have had 670 passes with clean clutch fluid without high-rpm pedal issues of any sort.
My view is if the fluid is kept clean from the beginning, the system will operate to spec providing power level remain within say 10% of stock.
Regarding power steering, that reservoir seems a candidate for a similar approach.
Ranger
02-17-2009, 11:47 AM
#32
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Hey Froggy.
David Farmer is a very savvy owner/racer. I know racers who've removed the springs without issue. So Dave is in good company.
Chevy warns to not remove the spring out of concern that a slight amount of pedal droop may occur and restrict the flow of fluid in the hydraulics.
Still my pedal spring remains in place and I have had 670 passes with clean clutch fluid without high-rpm pedal issues of any sort.
My view is if the fluid is kept clean from the beginning, the system will operate to spec providing power level remain within say 10% of stock.
Regarding power steering, that reservoir seems a candidate for a similar approach.
Ranger
David Farmer is a very savvy owner/racer. I know racers who've removed the springs without issue. So Dave is in good company.
Chevy warns to not remove the spring out of concern that a slight amount of pedal droop may occur and restrict the flow of fluid in the hydraulics.
Still my pedal spring remains in place and I have had 670 passes with clean clutch fluid without high-rpm pedal issues of any sort.
My view is if the fluid is kept clean from the beginning, the system will operate to spec providing power level remain within say 10% of stock.
Regarding power steering, that reservoir seems a candidate for a similar approach.
Ranger
I wonder what is the total capacity in the res, rack, cooler, lines of power steering fluid?
02-17-2009, 04:56 PM
#33
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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 in 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 in getting into the fluid. The question is how. We believe the answer to that is in points 1-5 above.
Ranger
02-17-2009, 05:04 PM
#34
Team Owner
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 in 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 in getting into the fluid. The question is how. We believe the answer to that is in points 1-5 above.
Ranger
02-25-2009, 11:51 AM
#36
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If the pedal isn't allowed to move to the very top of travel, the recuperation seal remains closed and fluid from the actuator (slave) does not circulate into the reservoir.
Ranger
02-25-2009, 12:38 PM
#37
Melting Slicks
Is this bad
This is what was in mine the first time I changed it out no wonder it stuck.
03-17-2009, 06:22 PM
#38
Team Owner
When I bought my car, it had dark fluid and I had the clutch problem at hte track. I cleaned the fluid by the protocal and the car was better but not perfect afterward. I could race and the clutch would function but stay halfway down at times. But I always kept the fluid clean. Then all of a sudden last month it went to hell. Clutch hard as a rock and would not disengage at all after only one lap. Works perfect on the street, but horrible at high RPM on the track. And the fluid is clean. Don't know what happened. 
(may car does have 140,000 on the original clutch, but it still has no slippage)
(may car does have 140,000 on the original clutch, but it still has no slippage)
Update: As previously stated, my car was having major clutch problems despite having perfectly clear fluid in the resevoir at all times. I took Ranger's advice and bought a new clutch master cylinder assembly from Gene Cully. (~$130) When I disconnected the the line between the master cylinder and slave cylinder, the small amount of fluid that leaked out was very dark. This told me that the fluid inside the slave cylinder also must be very dark and it is just not circulating at all. I installed the new master cylinder and wrapped the line in a heat shielding tape as it is rather close to the driver's side header. Now after every drive (only three so far) my resevoir is completely cloudy. I see this as a good sign. It means my fluid is once again circulating. I will continue to swap it out after every drive with SRF until it remains clean. I am confident this will remedy my problem and I will not need to replace the clutch and slave cylinder.
03-17-2009, 07:32 PM
#39
on my c5z can i use dot4 or dot3 only as it says? when i drive my z06 in the summer in the bay area it can get 110 in the day so i'd prefer to use do4 since it has a higher boiling point. let me know thanks!
03-19-2009, 06:43 AM
#40
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Update: As previously stated, my car was having major clutch problems despite having perfectly clear fluid in the resevoir at all times. I took Ranger's advice and bought a new clutch master cylinder assembly from Gene Cully. (~$130) When I disconnected the the line between the master cylinder and slave cylinder, the small amount of fluid that leaked out was very dark. This told me that the fluid inside the slave cylinder also must be very dark and it is just not circulating at all. I installed the new master cylinder and wrapped the line in a heat shielding tape as it is rather close to the driver's side header. Now after every drive (only three so far) my resevoir is completely cloudy. I see this as a good sign. It means my fluid is once again circulating. I will continue to swap it out after every drive with SRF until it remains clean. I am confident this will remedy my problem and I will not need to replace the clutch and slave cylinder.
Ranger