Clutch sticking to floor under hard acceleration????
09-23-2009, 08:41 PM
#43
Drifting
Quote:
Originally Posted by Y2Kvert4me
No doubt about the slave moving the same distance every time.
Now, what about the other moving component? Are you assuming the belleville spring fingers (in it's normal clamped state) remain in a static position regardless of RPM?
I don't assume anything when it comes to this condition, I studied the old pressure plate carefully when I removed it and I do not think that the over-center theory is plausible. I have not data or calucluations to support my claim, just my own sense of working on many things mechanical over the last 30 plus years. Based on my observation, I believe the clamping force on the LUK pressure plate increases with increased RPM, if I was designing the unit that is the way I would do it.
I think the problem is much simpler in my opinion, over time, the slave cylider concentric piston and or the cylider walls just wear out. Whether it's due to heat, scoring from contaminants (like mine), or because of the way the car is driven, there comes a point when the actuating force on the slave cylinder can no longer overcome the opposing force of the diapragm spring under a high load because the fluid ends up leaking by the piston and cylinder wall.
Originally Posted by Y2Kvert4me
No doubt about the slave moving the same distance every time.
Now, what about the other moving component? Are you assuming the belleville spring fingers (in it's normal clamped state) remain in a static position regardless of RPM?
I don't assume anything when it comes to this condition, I studied the old pressure plate carefully when I removed it and I do not think that the over-center theory is plausible. I have not data or calucluations to support my claim, just my own sense of working on many things mechanical over the last 30 plus years. Based on my observation, I believe the clamping force on the LUK pressure plate increases with increased RPM, if I was designing the unit that is the way I would do it.
I think the problem is much simpler in my opinion, over time, the slave cylider concentric piston and or the cylider walls just wear out. Whether it's due to heat, scoring from contaminants (like mine), or because of the way the car is driven, there comes a point when the actuating force on the slave cylinder can no longer overcome the opposing force of the diapragm spring under a high load because the fluid ends up leaking by the piston and cylinder wall.
09-23-2009, 09:08 PM
#45
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St. Jude Donor '03
If the scored walls of your slave were the cause of a missed actuation, what exactly has happened to come to that conclusion?
Did the pressurized fluid escape through the bad seal, or did the non-pressurized clutch dust somehow overcome the fluid pressure behind that seal? And even if it did, how did it prevent the actuation?
Basic physics, really. If you have a bad rod seal on your floor jack cylinder, guess what, it doesn't lift your car, it just squirts fluid all over the floor. The slave is much the same....if it can "go weak" it can only do so by relieving fluid pressure, and/or reducing the fluid surface area..
So...did you notice a lot of fluid loss when your clutch was problematic?
If you did, would you expect that fluid to soak the clutch and present slippage issues even in low speed driving too?
You've got a LOT more explaining to do to convince us how C5 clutches somehow overcome the basic laws of physics....but only at high RPM.
Last edited by Y2Kvert4me; 09-23-2009 at 09:12 PM.
09-23-2009, 09:26 PM
#46
Drifting
I didn't ignore it, I dismissed it because it's not a plausible theory, and it explains nothing.
If the scored walls of your slave were the cause of a missed actuation, what exactly has happened to come to that conclusion?
Did the pressurized fluid escape through the bad seal, or did the non-pressurized clutch dust somehow overcome the fluid pressure behind that seal? And even if it did, how did it prevent the actuation?
Basic physics, really. If you have a bad rod seal on your floor jack cylinder, guess what, it doesn't lift your car, it just squirts fluid all over the floor. The slave is much the same....if it can "go weak" it can only do so by relieving fluid pressure, and/or reducing the fluid surface area..
So...did you notice a lot of fluid loss when your clutch was problematic?
If you did, would you expect that fluid to soak the clutch and present slippage issues even in low speed driving too?
You've got a LOT more explaining to do to convince us how C5 clutches somehow overcome the basic laws of physics....but only at high RPM.
If the scored walls of your slave were the cause of a missed actuation, what exactly has happened to come to that conclusion?
Did the pressurized fluid escape through the bad seal, or did the non-pressurized clutch dust somehow overcome the fluid pressure behind that seal? And even if it did, how did it prevent the actuation?
Basic physics, really. If you have a bad rod seal on your floor jack cylinder, guess what, it doesn't lift your car, it just squirts fluid all over the floor. The slave is much the same....if it can "go weak" it can only do so by relieving fluid pressure, and/or reducing the fluid surface area..
So...did you notice a lot of fluid loss when your clutch was problematic?
If you did, would you expect that fluid to soak the clutch and present slippage issues even in low speed driving too?
You've got a LOT more explaining to do to convince us how C5 clutches somehow overcome the basic laws of physics....but only at high RPM.
I believed your buddy posted these pictures.
http://forums.corvetteforum.com/c5-t...cs-inside.html
Last edited by ipuig; 09-23-2009 at 09:33 PM.
09-23-2009, 09:53 PM
#47
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It is squeegee action by the O-ring seal that moves the clutch dust from the ID and OD of the main shaft back into the fluid without any fluid leaking out. It is proven. Clutch dust fouls the main shaft on every launch and high-rpm up-shift and down-shift. You can seen the clutch dust in the picture below.
The clutch dust causes stiction by the seals in the master cylinder and can also adversely impact the action of the O-ring seal of the actuator.
Those are causative factors in failure to achieve nominal hydraulic pressure.
Ranger
Last edited by Ranger; 09-23-2009 at 11:35 PM.
09-23-2009, 09:57 PM
#48
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That's the one Ranger put me on his ignore list because he couldn't answer simple questions that weren't conductive to his protocol.
I give you credit though, you wear bigger panties that don't bunch up quite as easily as his.
Ok, anyways, so now you surmise that the pressurized fluid isn't leaking externally, just traveling around, circulating within the slave, kind of acting as it's own bypass or pressure relief. Correct?
So again that leads us to how internal slave pressures differ at 6000 RPM vs 1000 engine RPM? Did the hydraulic pressure applied to the slave change, and if so, how?
Hint; if you say the pressure plate, you might only agree with what I've been saying all along.
09-23-2009, 10:03 PM
#49
so lets me throw this in the mix... i bought my z06 about 6months ago and looked at the forum threads and then looked at my clutch fluid reservoir it was black!! i changed out the fluid several times till i could drive it with out it being black. now i change it every month and the fluid is never black when i go to change it. and lately (since the weather change)when my car is cold and i start it up i put in first and the pedal goes right to the floor and i'm stuck in first until the car stalls out. i pump the pedal and pull it back out a few times and its fine once the car is warmed up so this is a "low rpm" situation my fluid is not low so i assume that im not leaking from my master or slave cylinder
any thoughts ???
any thoughts ???
09-23-2009, 10:12 PM
#50
Drifting
It is squeegee action by the O-ring seal that moves the clutch dust into the fluid without any fluid leaking out. It is proven.
The clutch dust causes stiction by the seals in the master cylinder and can also adversely impact the action of the main seal on the actuator.
Those are causative factors in failure to achieve nominal hydraulic pressure.
Ranger
The clutch dust causes stiction by the seals in the master cylinder and can also adversely impact the action of the main seal on the actuator.
Those are causative factors in failure to achieve nominal hydraulic pressure.
Ranger
The sediment & debris looked like rubber pieces parts to me, but like I said I did not have it analyzed so I cannot state that definitively. I believe the sediment and scoring is what was allowing the fluid leak-by around the concentric piston under high loads.
I think LUK clutches are very good when used within their design specifications. I would have left the slave cylinder outside of the bell-housing but that is a topic for another discussion.
For those of you that want to buy GUCCI clutches, I say go for it it's your money!
09-23-2009, 10:36 PM
#51
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so lets me throw this in the mix... i bought my z06 about 6months ago and looked at the forum threads and then looked at my clutch fluid reservoir it was black!! i changed out the fluid several times till i could drive it with out it being black. now i change it every month and the fluid is never black when i go to change it. and lately (since the weather change)when my car is cold and i start it up i put in first and the pedal goes right to the floor and i'm stuck in first until the car stalls out. i pump the pedal and pull it back out a few times and its fine once the car is warmed up so this is a "low rpm" situation my fluid is not low so i assume that im not leaking from my master or slave cylinder
any thoughts ???
any thoughts ???
Your power level (profile) looks to be about 380 rwhp now and more to come. So you are marginal with the stock LS6 clutch clamping power. If more power is in your future, you will want to start researching clutches.
Ranger
09-23-2009, 10:39 PM
#52
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I did not have mine analized when I took it apart, but there was definetly sediment within the slave cylinder and scoring of the cylinder walls. Quite frankly, from what I saw I believe my slave cylinder failed because of heat damage from me beating on it like a read headed step child.
The sediment & debris looked like rubber pieces parts to me, but like I said I did not have it analyzed so I cannot state that definitively. I believe the sediment and scoring is what was allowing the fluid leak-by around the concentric piston under high loads.
I think LUK clutches are very good when used within their design specifications. I would have left the slave cylinder outside of the bell-housing but that is a topic for another discussion.
For those of you that want to buy GUCCI clutches, I say go for it it's your money!
The sediment & debris looked like rubber pieces parts to me, but like I said I did not have it analyzed so I cannot state that definitively. I believe the sediment and scoring is what was allowing the fluid leak-by around the concentric piston under high loads.
I think LUK clutches are very good when used within their design specifications. I would have left the slave cylinder outside of the bell-housing but that is a topic for another discussion.
For those of you that want to buy GUCCI clutches, I say go for it it's your money!
Ranger
09-23-2009, 11:23 PM
#53
Drifting
I'll take your word on the analysis, like I said I did not have mine tested. I'm still having a hard time picturing how it's getting into the slave cylinder.
09-23-2009, 11:28 PM
#54
Drifting
Ahh, great thread.
That's the one Ranger put me on his ignore list because he couldn't answer simple questions that weren't conductive to his protocol.
I give you credit though, you wear bigger panties that don't bunch up quite as easily as his.
Ok, anyways, so now you surmise that the pressurized fluid isn't leaking externally, just traveling around, circulating within the slave, kind of acting as it's own bypass or pressure relief. Correct?
So again that leads us to how internal slave pressures differ at 6000 RPM vs 1000 engine RPM? Did the hydraulic pressure applied to the slave change, and if so, how?
Hint; if you say the pressure plate, you might only agree with what I've been saying all along.
That's the one Ranger put me on his ignore list because he couldn't answer simple questions that weren't conductive to his protocol.
I give you credit though, you wear bigger panties that don't bunch up quite as easily as his.
Ok, anyways, so now you surmise that the pressurized fluid isn't leaking externally, just traveling around, circulating within the slave, kind of acting as it's own bypass or pressure relief. Correct?
So again that leads us to how internal slave pressures differ at 6000 RPM vs 1000 engine RPM? Did the hydraulic pressure applied to the slave change, and if so, how?
Hint; if you say the pressure plate, you might only agree with what I've been saying all along.
09-24-2009, 12:02 AM
#55
Drifting
----------------------------------------
How the Clutch Hydraulics Work
----------------------------------------
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….
Close Quote. 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 C6 (two ounces in the C5) master cylinder reservoir until diminished as you depress the pedal and create the flow described above.
Ranger
How the Clutch Hydraulics Work
----------------------------------------
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….
Close Quote. 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 C6 (two ounces in the C5) master cylinder reservoir until diminished as you depress the pedal and create the flow described above.
Ranger
I've read your opinions, but I'm having a hard time picturing it, I also know how the freaking clutch works. I'm trying to be respectful because you have expended an enormous amount of energy on diagnosing this problem. I suggest you do the same and not patronize me with coments like that. I'm not the average lazy SOB that takes his CORVETTE down to the incompetent bufoons at the local oil and lube for routine maintenace a 10 year old boy could do with some tools, motivation and a clue.
If you want to be the supreme allied commander of the corvette clutch, go ahead, I won't challenge you for the honor.
Last edited by ipuig; 09-24-2009 at 07:16 AM.
09-24-2009, 12:15 AM
#56
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I don't need a lecture from you on source documents or technical data, it's what I do for a living, and it's not related to inconsequential car hobby stuff.
I've read your opinions, but having a hard time picturing it. I also know how the freaking clutch works. I'm trying to be respectful because you have expended an enormous amount of energy on diagnosing this problem. I suggest you do the same and not patronize me with coments like that. I'm not the average lazy SOB that takes his CORVETTE down to the incompetent bufoons at the local oil and lube for routine maintenace a 10 year old boy could do with some tools, motivation and a clue.
If you want to be the supreme allied commander of the corvette clutch, go ahead, I won't challenge you for the honor.
I've read your opinions, but having a hard time picturing it. I also know how the freaking clutch works. I'm trying to be respectful because you have expended an enormous amount of energy on diagnosing this problem. I suggest you do the same and not patronize me with coments like that. I'm not the average lazy SOB that takes his CORVETTE down to the incompetent bufoons at the local oil and lube for routine maintenace a 10 year old boy could do with some tools, motivation and a clue.
If you want to be the supreme allied commander of the corvette clutch, go ahead, I won't challenge you for the honor.
A lot has been learned and documented about the origins for clutch issues over the past 12 months. Not everyone is receptive to the research findings. Fortunately, thousands of CF members are receptive and are doing routine maintenance to their clutch fluid and running clutches properly sized to their FWTQ.
Ranger
Last edited by Ranger; 09-24-2009 at 12:21 AM.
09-24-2009, 12:31 AM
#57
Drifting
That explanation I deleted was part on my clutch care sticky. It was already prepared. I meant no offense.
A lot has been learned and documented about the origins for clutch issues over the past 12 months. Not everyone is receptive to the research findings. Fortunately, thousands of CF members are receptive and are doing routine maintenance to their clutch fluid and running clutches properly sized to their FWTQ.
Ranger
A lot has been learned and documented about the origins for clutch issues over the past 12 months. Not everyone is receptive to the research findings. Fortunately, thousands of CF members are receptive and are doing routine maintenance to their clutch fluid and running clutches properly sized to their FWTQ.
Ranger
No offense taken, thanks for the clarification.
09-24-2009, 05:21 PM
#58
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St. Jude Donor '03
I mean, if the slave (or any hydraulic seal in the system) is the culprit due to internal fluid bypassing, and can't even actuate the weaksauce stock pressure plate, it becomes quite difficult to envision how it can perform flawlessly with a 2500, 2700, or 2900# aftermarket pressure plate. (which, not surprising to me, successful results are most often reported by users who upgraded the pressure plate).
Of course, one will say 99% of folks who upgraded their clutches also put in a fresh slave at the same time, thus leaving no definitive answer as to root cause.
But then there are the many folks like Chuckster who upgraded EVERYTHING hydraulic, found absolutely no relief, then changed only the clutch, and problem solved.
09-24-2009, 08:15 PM
#59
Drifting
So then most people who bolt in a stouter clutch should experience the problem even worse?
I mean, if the slave (or any hydraulic seal in the system) is the culprit due to internal fluid bypassing, and can't even actuate the weaksauce stock pressure plate, it becomes quite difficult to envision how it can perform flawlessly with a 2500, 2700, or 2900# aftermarket pressure plate. (which, not surprising to me, successful results are most often reported by users who upgraded the pressure plate).
Of course, one will say 99% of folks who upgraded their clutches also put in a fresh slave at the same time, thus leaving no definitive answer as to root cause.
But then there are the many folks like Chuckster who upgraded EVERYTHING hydraulic, found absolutely no relief, then changed only the clutch, and problem solved.
I mean, if the slave (or any hydraulic seal in the system) is the culprit due to internal fluid bypassing, and can't even actuate the weaksauce stock pressure plate, it becomes quite difficult to envision how it can perform flawlessly with a 2500, 2700, or 2900# aftermarket pressure plate. (which, not surprising to me, successful results are most often reported by users who upgraded the pressure plate).
Of course, one will say 99% of folks who upgraded their clutches also put in a fresh slave at the same time, thus leaving no definitive answer as to root cause.
But then there are the many folks like Chuckster who upgraded EVERYTHING hydraulic, found absolutely no relief, then changed only the clutch, and problem solved.
There are far too many varibles to diagnose this problem to a common denominator over such a wide variety of failures, driving styles, mechanical aptitudes, and plain old honesty in posting what actually happened in my opinion.
I understand the desire to make the LUK pressure plate the fall guy when and individual just spent a lot of money on an aftermanket GUCCI clutch. I'd also like to point out that there are many individuals on this forum with aftermarket clutches experiencing the same problems.
09-24-2009, 09:50 PM
#60
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St. Jude Donor '03
I understand the desire to make the LUK pressure plate the fall guy when and individual just spent a lot of money on an aftermanket GUCCI clutch. I'd also like to point out that there are many individuals on this forum with aftermarket clutches experiencing the same problems.
As for aftermarket clutches...do keep in mind many continue to employ the use of the LuK pressure plate. Not surprising to me the problem usually tags along with.