Here it is... The Slave Cylinder EXPOSED. Pics inside.
Thread Starter
Race Director
Joined: Mar 2000
Posts: 17,602
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From: Palm City Florida
I've got an aerospace friend working on a low(er) friction TOB assembly that also should provide some thermal barrier, or at least heat reduction to the back of the TOB/"piston" seal. He made these type units for another car I used to race, and they worked well in reducing finger wear/heat. I guess I'll be the test pig on this C5 one. I think a SS ring with a single seal O ring may help reduce heat transfer to the fluid as well.
From a 30,000 ft view I agree keeping fresh fluid in there is a good idea. Remote bleeder, and GOOD high temp fluid, especially for those that track. But I'm curious of other things, as I think we are dealing with more than just hydraulic stuff for some of these issues (ie a fully released hanging PP at high rpm, etc).
FWIW I'm building a house right now (actually a garage with a detached house) and my free time is limited, so limited it took me several weeks to put a clutch in my 01Z06 after a plate failure at Road Atlanta back in May. For "testing" purposes, I left the 18,000 mile slave in there along with a few other components to try to duplicate/and or isolate other problems. The only thing I didn't get a chance to do was get a temp probe into the TOB/fluid area, but I may work on this in the coming weeks as things slow down.
I've never had a pedal stick but I am fairly new to the C5, at about 6 months, with only a few hundred open track miles and a few drag passes to date. But I can tell the pedal feels a bit weaker/softer after a few hard drag passes.
Looking forward to finishing the stupid house so I can play/expirement more
From a 30,000 ft view I agree keeping fresh fluid in there is a good idea. Remote bleeder, and GOOD high temp fluid, especially for those that track. But I'm curious of other things, as I think we are dealing with more than just hydraulic stuff for some of these issues (ie a fully released hanging PP at high rpm, etc).
FWIW I'm building a house right now (actually a garage with a detached house) and my free time is limited, so limited it took me several weeks to put a clutch in my 01Z06 after a plate failure at Road Atlanta back in May. For "testing" purposes, I left the 18,000 mile slave in there along with a few other components to try to duplicate/and or isolate other problems. The only thing I didn't get a chance to do was get a temp probe into the TOB/fluid area, but I may work on this in the coming weeks as things slow down.
I've never had a pedal stick but I am fairly new to the C5, at about 6 months, with only a few hundred open track miles and a few drag passes to date. But I can tell the pedal feels a bit weaker/softer after a few hard drag passes.
Looking forward to finishing the stupid house so I can play/expirement more
I'd be interested to see the temp probe on the Slave. PRobably can mount it right to the aluminum housing. Curious to see how hot it gets.. I'd lay a bet though.. No matter how hot it gets It wont even come close to the temps seen in a brake caliper.
Ok so the slave sits in an enclosed space.. but its just AMBIENT heat soak from the engine and headers. Even if it is 400 degrees. (which I doubt).. The DOT 4 fluid is designed to handle that temp. I personally use NEO 5.1 in my clutch.
Not like the heat from a braking system being directly generated from a glowing rotor..
by the way.. Just got done playing FORZA 2 and Road Atlanta is a Biotch...
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
We live and drive in the real world. Thousands of LS1/LS2/LS6/LS7 and aftermarket clutches out there racing without pedal issues. Many who do suffer pedal woes cure them for good with a rigorous fluid changes.
Despite that, some owners continue to have pedal issues no matter which clutch they install. They usually blame the hardware. The last thing they seem to want to look at is their own technique, the driver-interaction with the clutch. A look their may bear fruit. And might take a good look at their installers too; useful perspective can be found in this school-of-hard-knocks clutch post.
Waiting for availability of revised hardware such as a reengineered slave is a prescription for non-stop disappointment.
Ranger
Despite that, some owners continue to have pedal issues no matter which clutch they install. They usually blame the hardware. The last thing they seem to want to look at is their own technique, the driver-interaction with the clutch. A look their may bear fruit. And might take a good look at their installers too; useful perspective can be found in this school-of-hard-knocks clutch post.
Waiting for availability of revised hardware such as a reengineered slave is a prescription for non-stop disappointment.
Ranger
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
I'd be interested to see the temp probe on the Slave. PRobably can mount it right to the aluminum housing. Curious to see how hot it gets.. I'd lay a bet though.. No matter how hot it gets It wont even come close to the temps seen in a brake caliper.
Ok so the slave sits in an enclosed space.. but its just AMBIENT heat soak from the engine and headers. Even if it is 400 degrees. (which I doubt).. The DOT 4 fluid is designed to handle that temp. I personally use NEO 5.1 in my clutch.
Not like the heat from a braking system being directly generated from a glowing rotor..
by the way.. Just got done playing FORZA 2 and Road Atlanta is a Biotch...
Ok so the slave sits in an enclosed space.. but its just AMBIENT heat soak from the engine and headers. Even if it is 400 degrees. (which I doubt).. The DOT 4 fluid is designed to handle that temp. I personally use NEO 5.1 in my clutch.
Not like the heat from a braking system being directly generated from a glowing rotor..
by the way.. Just got done playing FORZA 2 and Road Atlanta is a Biotch...
You've missed a lot of clutch threads. That report was two months ago.
Ranger
Thread Starter
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
Crew chief of a SCCA Corvette team briefed me on their clutch experience. They bleed the clutch every track day and measure the temp in excess of 400F. At the end of a race day the brake fluid in the clutch is as bad as what comes out of the brake hydraulics.
You've missed a lot of clutch threads. That report was two months ago.
Ranger
You've missed a lot of clutch threads. That report was two months ago.
Ranger
Ok so this is an SCCA racing team...I guess they must be right...I'll accept those temps.. Again what I still cannot accept is..
Casual and 1/4 mile racers wont ever see those temps. But even if they did, the fluid is designed to handle that temp. So I am not seeing anything out of the ordinary that would cause the slave to make the pedal hang...
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
Friction from disc slip produces heat.
(1) A burnout from 3500-6000 with the brakes applied until the tires drag the motor down. That friction punishment = heat.
(2) Launch at 4000-5500. Even with a very fast clutch release, the friction surfaces must absorb the pain. They do and make most heat.
(3) three shifts at redline. Every one entails more slip of the friction surfaces and more heat.
The aggregate friction-produced heat is transferred to adjacent surfaces inside an unvented bell housing. Ambient temp at the crankshaft is 230-240 under serious load. Add the incremental heat produced by the clutch. It's over 400F.
Degraded clutch fluid boils at way less than 400. Those of us with fresh fluid like Super DOT4 are inoculated to 500F.
But, of course, several of the doubters who view nasty azzed clutch fluid as no big deal, just a natural occurrence leeched from the seals, are in big trouble when the temp hits 400F. Their fluid is boiling. Think the slave component will behave normally then?
Ranger
Le Mans Master
Joined: Dec 2006
Posts: 7,251
Likes: 16
From: Phoenix Arizona
It seems interesting that aluminum (heat sink) would be the material of choice for the piston tube, unless the fluid is being purposely (sacrificially) used to dissipate the transferred heat.
Based on the orifice size into the slave, plus the fact the manufacturer didn't officially recognize a heat-related fluid issue until 10 years later, I highly doubt that is done by design. But then again, this is GM.
Since the popular theory forced upon us is that of heat transfer into the fluid is the culprit of all pedal woes, someone should duplicate the slave piston tube out of SS, hard chrome or ceramic coat it to minimize heat transfer, and see what happens.
Just thinking out loud here....
Based on the orifice size into the slave, plus the fact the manufacturer didn't officially recognize a heat-related fluid issue until 10 years later, I highly doubt that is done by design. But then again, this is GM.
Since the popular theory forced upon us is that of heat transfer into the fluid is the culprit of all pedal woes, someone should duplicate the slave piston tube out of SS, hard chrome or ceramic coat it to minimize heat transfer, and see what happens.
Just thinking out loud here....
good job! 
Race Director
Joined: Oct 2002
Posts: 10,864
Likes: 196
From: Southern CA
It would be interesting to expand/compare the hydraulic clutch systems of other high performance cars to our Vettes. For example at an event today there was a Gallardo & a Noble running (autox & hot laps - parking lot).
If we discuss how other marques solve the problem it might add knowledge to the Vette issue.
I wish I could post some tech info in that area but I have none.
Anyone?
If we discuss how other marques solve the problem it might add knowledge to the Vette issue.
I wish I could post some tech info in that area but I have none.
Anyone?
Thread Starter
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
Oh, my oh my, Chuckster.
Friction from disc slip produces heat.
(1) A burnout from 3500-6000 with the brakes applied until the tires drag the motor down. That friction punishment = heat.
(2) Launch at 4000-5500. Even with a very fast clutch release, the friction surfaces must absorb the pain. They do and make most heat.
(3) three shifts at redline. Every one entails more slip of the friction surfaces and more heat.
The aggregate friction-produced heat is transferred to adjacent surfaces inside an unvented bell housing. Ambient temp at the crankshaft is 230-240 under serious load. Add the incremental heat produced by the clutch. It's over 400F.
Degraded clutch fluid boils at way less than 400. Those of us with fresh fluid like Super DOT4 are inoculated to 500F.
But, of course, several of the doubters who view nasty azzed clutch fluid as no big deal, just a natural occurrence leeched from the seals, are in big trouble when the temp hits 400F. Their fluid is boiling. Think the slave component will behave normally then?
Ranger
Friction from disc slip produces heat.
(1) A burnout from 3500-6000 with the brakes applied until the tires drag the motor down. That friction punishment = heat.
(2) Launch at 4000-5500. Even with a very fast clutch release, the friction surfaces must absorb the pain. They do and make most heat.
(3) three shifts at redline. Every one entails more slip of the friction surfaces and more heat.
The aggregate friction-produced heat is transferred to adjacent surfaces inside an unvented bell housing. Ambient temp at the crankshaft is 230-240 under serious load. Add the incremental heat produced by the clutch. It's over 400F.
Degraded clutch fluid boils at way less than 400. Those of us with fresh fluid like Super DOT4 are inoculated to 500F.
But, of course, several of the doubters who view nasty azzed clutch fluid as no big deal, just a natural occurrence leeched from the seals, are in big trouble when the temp hits 400F. Their fluid is boiling. Think the slave component will behave normally then?
Ranger
Ranger, for the sake of getting to the real cause of the the Pedal not returning, I agree with you on all the temperatures you are stating..
However, none of that data is compelling enough for me to relate it to the Physical pedal not popping back up. After pulling the slave apart and realizing that all there is is a thick rubber piston between the fluid and the Clutch.
The Clutch Springs (if working properly) are exerting more than a few Hundreds of pounds of force or more on the throwout bearing assembly which is directly resting on that cheasy rubber piston. About the only think that I can think of that could stop that much force from pushing everything back is LINE LOCK...
So are we all to believe that dirty fluid is capable of holding back that much force? Also, why does it only happen when the clutch is spinning at a high rate? As long as the the throwout bearing is doing it's job the slave and the fluid has no idea how fast it spinning.. so why does it make a difference?
I'd really like to hear your comments on this..
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Thread Starter
Race Director
Joined: Mar 2000
Posts: 17,602
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From: Palm City Florida
Here are a few comments on Overcentering with Diaphram based clutches. Seems that old timers have know about this issue for quite a while... I googled these..
Overcentering is when the diaphragm springs fingers get pushed past the normal centerline of the diaphragm spring. When this occurs, centrifugal force keeps the fingers of the spring disengaged causing the clutch pedal to stick to the floor during high RPM shifts, like when speed shifting
diaphragm clutch pressure plates have been sticking to the floor since they came out in the 60s when power shifting. my 67,68, and 69 Z-28s did it when power shifting. it is caused by overcentering the diaphragm fingers when pushing in the clutch and then centrifugal force takes over and that is why a clutch pedal stop is needed.
And from an American Motors Forum...
I don't trust the diaphragm style clutches, and at least one of my friends has had problems shifting at high (6000) rpm with the clutch hanging up (overcentering is a problem peculiar to diaphragm clutches)
I can see the next Tech Bulletin coming from GM..
Problem - Clutch Pedal Sticks to floor
Remedy - Lower Rev Limiter to 4000 rpms.
So the bottom line here is .. Get an adjustable master or add an clutch pedal stop.
And keep your fluid clean as needed.
Overcentering is when the diaphragm springs fingers get pushed past the normal centerline of the diaphragm spring. When this occurs, centrifugal force keeps the fingers of the spring disengaged causing the clutch pedal to stick to the floor during high RPM shifts, like when speed shifting
diaphragm clutch pressure plates have been sticking to the floor since they came out in the 60s when power shifting. my 67,68, and 69 Z-28s did it when power shifting. it is caused by overcentering the diaphragm fingers when pushing in the clutch and then centrifugal force takes over and that is why a clutch pedal stop is needed.
And from an American Motors Forum...
I don't trust the diaphragm style clutches, and at least one of my friends has had problems shifting at high (6000) rpm with the clutch hanging up (overcentering is a problem peculiar to diaphragm clutches)
I can see the next Tech Bulletin coming from GM..
Problem - Clutch Pedal Sticks to floor
Remedy - Lower Rev Limiter to 4000 rpms.
So the bottom line here is .. Get an adjustable master or add an clutch pedal stop.
And keep your fluid clean as needed.
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
If over-centering is the issue, it would be possible to duplicate the pedal issue easily with the tranny in neutral. Yet no one has been able to do that.
With hundreds (perhaps thousands) of owners solving pedal issues by keeping the boiling of the fluid high, the question is not does that work, but why.
I'm a practical guy trying to help owners avoid the pedal woes that gave me grief on my 01 Z06. I found a cure that's solves the problem for most owners and alerting folks to the facts has paid off.
From the accumulated evidence heat is the root cause. If it weren't heat then changing the boiling point of the fluid would have no effect. The open question is what forces change in the clutch hydraulics when subjected to high heat over many, many heat cycles.
Ranger
With hundreds (perhaps thousands) of owners solving pedal issues by keeping the boiling of the fluid high, the question is not does that work, but why.
I'm a practical guy trying to help owners avoid the pedal woes that gave me grief on my 01 Z06. I found a cure that's solves the problem for most owners and alerting folks to the facts has paid off.
From the accumulated evidence heat is the root cause. If it weren't heat then changing the boiling point of the fluid would have no effect. The open question is what forces change in the clutch hydraulics when subjected to high heat over many, many heat cycles.
Ranger
Last edited by Ranger; Jul 23, 2007 at 09:41 AM.
Thread Starter
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
If over-centering is the issue, it would be possible to duplicate the pedal issue easily with the tranny in neutral. Yet no one has been able to do that.
With hundreds (perhaps thousands) of owners solving pedal issues by keeping the boiling of the fluid high, the question isn't not does that work, but why.
I'm a practical guy trying to help owners avoid the pedal woes that gave me grief on my 01 Z06. I found a cure that's solves the problem for most owners and alerting folks to the facts has paid off.
From the accumulated evidence heat is the root cause. If it weren't heat then changing the boiling point of the fluid would have no effect. The open question is what forces change in the clutch hydraulics when subjected to high heat over many, many heat cycles.
Ranger
With hundreds (perhaps thousands) of owners solving pedal issues by keeping the boiling of the fluid high, the question isn't not does that work, but why.
I'm a practical guy trying to help owners avoid the pedal woes that gave me grief on my 01 Z06. I found a cure that's solves the problem for most owners and alerting folks to the facts has paid off.
From the accumulated evidence heat is the root cause. If it weren't heat then changing the boiling point of the fluid would have no effect. The open question is what forces change in the clutch hydraulics when subjected to high heat over many, many heat cycles.
Ranger
I think you missed the folks who chimed in that said their pedal stuck when cold.. Add me to the list. The Bottom line is I had the problem. I chased it for over years.
Nothing fixed it until I put a new clutch in. Why did this spring handle not overcenter? Maybe they did not use any shims behind the Slave? and when the pedal hit the floor the springs were not overcenter.. I just know it fixed it for 4 years. and I never changed the Clutch FLuid that whole time.
So I will give in to one more thing on your behalf.. Dirty fluid only exacerbates the problem. For example.. let's say the spring is on the hairy edge of being held by centripetal force. Dirty fluid may introduce just enough resistance to slow down the return of the diaphram to keep it there until the rpms drop.
But the root cause it still and always will be the diaphram overcentering and the centripetal force on it at WOT...
It's all good bro.. You see it one way I see it the other. I just wish I could be sitting down with you drinking a beer while solving this problem...
We really need to build a FAQ from all the info being discussed here..
Last edited by chuckster; Jul 23, 2007 at 09:41 AM.
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
Ranger, you admitted yourself you never had a pedal stick. You never had the unfortunate luck of trying to troubleshoot it..Heat is not always a factor.
I think you missed the folks who chimed in that said their pedal stuck when cold.. Add me to the list. The Bottom line is I had the problem. I chased it for over years.
Nothing fixed it until I put a new clutch in. Why did this spring handle not overcenter? Maybe they did not use any shims behind the Slave? and when the pedal hit the floor the springs were not overcenter.. I just know it fixed it for 4 years. and I never changed the Clutch FLuid that whole time.
So I will give in to one more thing on your behalf.. Dirty fluid only exacerbates the problem. For example.. let's say the spring is on the hairy edge of being held by centripetal force. Dirty fluid may introduce just enough resistance to slow down the return of the diaphram to keep it there until the rpms drop.
But the root cause it still and always will be the diaphram overcentering and the centripetal force on it at WOT...
It's all good bro.. You see it one way I see it the other. I just wish I could be sitting down with you drinking a beer while solving this problem...
We really need to build a FAQ from all the info being discussed here..
I think you missed the folks who chimed in that said their pedal stuck when cold.. Add me to the list. The Bottom line is I had the problem. I chased it for over years.
Nothing fixed it until I put a new clutch in. Why did this spring handle not overcenter? Maybe they did not use any shims behind the Slave? and when the pedal hit the floor the springs were not overcenter.. I just know it fixed it for 4 years. and I never changed the Clutch FLuid that whole time.
So I will give in to one more thing on your behalf.. Dirty fluid only exacerbates the problem. For example.. let's say the spring is on the hairy edge of being held by centripetal force. Dirty fluid may introduce just enough resistance to slow down the return of the diaphram to keep it there until the rpms drop.
But the root cause it still and always will be the diaphram overcentering and the centripetal force on it at WOT...
It's all good bro.. You see it one way I see it the other. I just wish I could be sitting down with you drinking a beer while solving this problem...
We really need to build a FAQ from all the info being discussed here..
I spent about six weeks working with the dealer to get the problem resolved. That included four replacements of the clutch. I've posted all this many times. Once the post-install vibrations were solved by a two-man GM field engineer team, the clutch pedal began sticking again within a short time.
I solved the issue by bleeding the clutch the old fashion way and thereafter keeping the fluid clean. About 500 passes later on four different stock clutches...still no pedal issues.
Heat degrades the fluid. Once the fluid contains water from heat cycles, that water in a high enough concentration can boil at 212F. Where does the water settle? Does it disproportionately settle in the slave? What is the temp of the slave in conservative driving? Probably a little above the temp at the crank (230-240).
If it's an over-centering issue, why can't it be duplicated with the tranny in neutral?
Ranger
Le Mans Master
Joined: Feb 2006
Posts: 5,267
Likes: 40
From: Phoenix AZ
When the pressure plate face moves forwards and backwards, it has to ride on some kind of pivot point. That point is taking all the radial load. If that point has worn a grove or is binding, then that could cause the problem as it is "stuck" in that position and cant return back over the hump untill the rpms come back down and the centrifical forces relax.
Thats why I want to tear apart a sticky clutch pressure plate. I meant to do this to mine when it was replaced, but I was so happy that my Spec 3+ didnt stick, that I forgot all about it and the shop threw it away.
Thats why I want to tear apart a sticky clutch pressure plate. I meant to do this to mine when it was replaced, but I was so happy that my Spec 3+ didnt stick, that I forgot all about it and the shop threw it away.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
I had pedal woes on my 2001 Z06 with the original clutch fluid after about 80 passes at the drag strip. [that was using a very fast release).
I spent about six weeks working with the dealer to get the problem resolved. That included four replacements of the clutch. I've posted all this many times. Once the post-install vibrations were solved by a two-man GM field engineer team, the clutch pedal began sticking again within a short time.
I solved the issue by bleeding the clutch the old fashion way and thereafter keeping the fluid clean. About 500 passes later on four different stock clutches...still no pedal issues.
Heat degrades the fluid. Once the fluid contains water from heat cycles, that water in a high enough concentration can boil at 212F. Where does the water settle? Does it disproportionately settle in the slave? What is the temp of the slave in conservative driving? Probably a little above the temp at the crank (230-240).
If it's an over-centering issue, why can't it be duplicated with the tranny in neutral?
Ranger
I spent about six weeks working with the dealer to get the problem resolved. That included four replacements of the clutch. I've posted all this many times. Once the post-install vibrations were solved by a two-man GM field engineer team, the clutch pedal began sticking again within a short time.
I solved the issue by bleeding the clutch the old fashion way and thereafter keeping the fluid clean. About 500 passes later on four different stock clutches...still no pedal issues.
Heat degrades the fluid. Once the fluid contains water from heat cycles, that water in a high enough concentration can boil at 212F. Where does the water settle? Does it disproportionately settle in the slave? What is the temp of the slave in conservative driving? Probably a little above the temp at the crank (230-240).
If it's an over-centering issue, why can't it be duplicated with the tranny in neutral?
Ranger
But it just seems odd to me that boiling the fluid causes the opposite of what happens when you boil the brake fluid - boil brake fluid, foot to the floor like air in the lines and no brakes. The pedal comes up...but now that I think of it, a bit slowly. Boil clutch fluid, you'd expect to not be able to disengage the clutch... but you can disengage it, the pedal just doesn't come up after you do so! I'm not an engineer so maybe I'm just an idiot on this. But doesn't that seem odd to you too?
I suppose....thinking while typing here.... that perhaps the PP diaphragm on a high rpm shift DOES push back on the slave, as designed (this makes sense as the clutch is fully engaged when this happens, and not slipping, so the clutch is indeed engaged properly - this contradicts the overcentering theory, which would result in the clutch slipping which it does not when this happens), and the slave, with boiled fluid, compresses the air bubbles instead of moving the fluid back to master as designed. And thus the pedal does not come up. After you physically use your foot to transfer the fluid by pulling up the clutch pedal, it works properly again. I'm sure the cr&p in the fluid trying to pass through that tiny orifice Chuck shows above doesn't help any in the fluid transfer so fresh fluid would help there also.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
When the pressure plate face moves forwards and backwards, it has to ride on some kind of pivot point. That point is taking all the radial load. If that point has worn a grove or is binding, then that could cause the problem as it is "stuck" in that position and cant return back over the hump untill the rpms come back down and the centrifical forces relax.
Thats why I want to tear apart a sticky clutch pressure plate. I meant to do this to mine when it was replaced, but I was so happy that my Spec 3+ didnt stick, that I forgot all about it and the shop threw it away.
Thats why I want to tear apart a sticky clutch pressure plate. I meant to do this to mine when it was replaced, but I was so happy that my Spec 3+ didnt stick, that I forgot all about it and the shop threw it away.
This is a fun esoteric exercise. Bottom line, fresh fluid, and in some cars, deleting the overcenter spring up on the clutch pedal is free to try and seems to work for almost all including Goodwood and gtodoug. Since it's free, it's foolish not to try!
Melting Slicks
Joined: Apr 2003
Posts: 2,285
Likes: 16
From: Nashville TN
Dude, serious....if your symptoms are clearly not a fluid quality issue, you will not get a response from Ranger.
He can tell you all about the benefits of clean fluid, and will likely do so another 20 times before this thread is done, but it seems he knows nothing beyond that.
I hate to flame the guy, because his fluid swap is very good advice, but until he can get beyond protecting his precious reputation by acknowledging other problems may exist, posting any clutch issue in this forum is futile at best, it will only be be redirected into a fluid topic.
We both know other problems not related to fluid DO exist, but trying to discuss that is a wasted effort here,
He can tell you all about the benefits of clean fluid, and will likely do so another 20 times before this thread is done, but it seems he knows nothing beyond that.
I hate to flame the guy, because his fluid swap is very good advice, but until he can get beyond protecting his precious reputation by acknowledging other problems may exist, posting any clutch issue in this forum is futile at best, it will only be be redirected into a fluid topic.
We both know other problems not related to fluid DO exist, but trying to discuss that is a wasted effort here,
I am glad that I am not the only person. I am tired of seeing every clutch problem turn into a fluid issue. Yes that may be part of the problem in some cases, but more times than not it is clutch related, ie. pressure plate, etc.
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 32
From: Central Florida
If you care about the topic, do yourself a favor by reading the LS1Tech Transmission board and this school-of-hard-knocks clutch post.
Also from my site:
Originally Posted by rangeracceleration.com
A WARNING on clutches that are slipping under load.
As you add horsepower/torque to a motor, the load may eventually surpass the rated clamping-force of the existing clutch. Once that happens, the friction surfaces will slip excessively in high-demand circumstances, producing even more heat than normal. These heat loads can cause malfunction of the slave.
A slipping clutch placed under the demands of launch and strong shifts may suffer a catastrophic failure. You may have seen pictures of those events. Quite ugly and not warrantied by anyone. Last one I saw cost the car owner $13K in out-of-pocket repairs. Pressure plate exploded; clutch fluid sprayed the headers causing a fire. Not a happy ending.
Moral of the story. Know the limits of your clutch and don't exceed them. If the clutch is slipping, get a new one with appropriate clamping power.
As you add horsepower/torque to a motor, the load may eventually surpass the rated clamping-force of the existing clutch. Once that happens, the friction surfaces will slip excessively in high-demand circumstances, producing even more heat than normal. These heat loads can cause malfunction of the slave.
A slipping clutch placed under the demands of launch and strong shifts may suffer a catastrophic failure. You may have seen pictures of those events. Quite ugly and not warrantied by anyone. Last one I saw cost the car owner $13K in out-of-pocket repairs. Pressure plate exploded; clutch fluid sprayed the headers causing a fire. Not a happy ending.
Moral of the story. Know the limits of your clutch and don't exceed them. If the clutch is slipping, get a new one with appropriate clamping power.
Originally Posted by rangeracceleration.com
Alternative 4. Change to an aftermarket clutch and hope for relief. Unfortunately, some aftermarket clutches suffer pedal woes too, particularly those using stock GM clutch hydraulic components (clutch master cylinder and clutch actuator cylinder (the slave). This is especially true if the clutch fluid is not given preventative maintenance.
Thread Starter
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
I just thought this through typing my post above. If the pressure plate was overcentering, I think the clutch would stay disengaged, and slipping, when the pedal stuck down. It does not. The clutch is fully engaged and not slipping when the pedal is stuck to the floor. So I think that puts the kibosh on the overcentering theory.
This is a fun esoteric exercise. Bottom line, fresh fluid, and in some cars, deleting the overcenter spring up on the clutch pedal is free to try and seems to work for almost all including Goodwood and gtodoug. Since it's free, it's foolish not to try!
This is a fun esoteric exercise. Bottom line, fresh fluid, and in some cars, deleting the overcenter spring up on the clutch pedal is free to try and seems to work for almost all including Goodwood and gtodoug. Since it's free, it's foolish not to try!
Actually Joe, the spring on the pedal is not the OVERCENTER spring. and not the spring in question.. The pedal spring is morely to pull the pedal back to the home position and allow the master cylinder to pull the piston all the way back. It was determined a while ago that the compound bow effect of this spring can occasionally introduce more force on the pedal further exacerbating the original problem.
Overcentering is a condition that happens to the big diaphram spring in the pressure plate.. I should have taken pics of it when I cut mine apart..
Also, when my clutch pedal stuck to the floor my motor hit the rev limiter.. so no.. my clutch was not engaged when my pedal stuck.
soon: 