Weird pedal @ WOT
03-16-2008, 09:56 PM
#1
Weird pedal @ WOT I've been doing alot of searching and I've read the sticky but I still some one to explain this to me. Ok, my 00' SS has an LS7 clutch with 10k mile on it and I also replaced my master & slave with the updated 01+ hydraulics when I changed to the LS7 clutch. I also did the drill mod and made my master adjustable while I had everything apart. At WOT my pedal gets kinda weird, It either goes to the floor, or the pedal effort doubles. After WOT my clutch engages right off the floor. My fluid doesnt look that dark. When it happens its hard to get it out of what ever gear your in and it wont go back into any gear for about a minute or so. Could it be my clutch?
Now lets say it is an hydraulic issue. Why would it only happen at WOT? If the fluid is getting hot, whats making it get hot (Slipping clutch maybe?) The car just started doing this last night.
My car use to have the centerforce DF clutch that slipped and cooked my fluid which is the reason I went to the LS7 and new hydraulics. Is the the same case?
Now lets say it is an hydraulic issue. Why would it only happen at WOT? If the fluid is getting hot, whats making it get hot (Slipping clutch maybe?) The car just started doing this last night.
My car use to have the centerforce DF clutch that slipped and cooked my fluid which is the reason I went to the LS7 and new hydraulics. Is the the same case?
03-16-2008, 10:02 PM
#2
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Sounds like your car is doing the same thing mine is. I am going to try the DOT4 syn. fluid with the heat tape but I am not sure what heat tape to use. See my other thread
03-17-2008, 12:39 AM
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if it grabs off the floor, most likely your fluid boiled and created air bubbles in the system! have you done the drill mod? first try bleeding the complete system and move to syn DOT 4 prestone, i had the same problem as you and i always noticed my fluiid getting dark and nasty after a few hard runs! but now after the drill mod high heat tape wrap and DOT 4 i can run run all day with no problems what so ever! my pedel still goes down a little bit then comes up after i lift it, but that is due to me having stock clutch and slave and master, but give those a try and see if it would work
03-17-2008, 07:57 AM
#7
if the brake fluid boils, it will change how the pedal feels. Sounds exactly like the fluid is roasting under WOT. Especially if you have longtube headers that are not ceramic coated. Even worse if it's not stainless steel.
Inspect the hydraulic line. There are 2 areas in which the line can be exposed to exhaust heat. The first is right in the bay right where the primaries head down towards the bottom of the engine. That section can cook the fluid at that spot. If the master has been changed, odds are the line is even MORE exposed to the headers than before. This is the section of the line before the heat shield coming off the master. The next section that gets roasted is after the heat shield. It is the area near the collector that plugs into the transmission. That area is exposed to heat as well. Combine the 2 sections and you will find your fluid boiling and causing all your problems.
Since it's already shown signs of boiling under WOT, I'd flush that fluid out with Dot 4 synthetic, wrap the line with heater hose and aluminum tape up to as close as you can get to the master. Should solve your hydraulic problems.
Inspect the hydraulic line. There are 2 areas in which the line can be exposed to exhaust heat. The first is right in the bay right where the primaries head down towards the bottom of the engine. That section can cook the fluid at that spot. If the master has been changed, odds are the line is even MORE exposed to the headers than before. This is the section of the line before the heat shield coming off the master. The next section that gets roasted is after the heat shield. It is the area near the collector that plugs into the transmission. That area is exposed to heat as well. Combine the 2 sections and you will find your fluid boiling and causing all your problems.
Since it's already shown signs of boiling under WOT, I'd flush that fluid out with Dot 4 synthetic, wrap the line with heater hose and aluminum tape up to as close as you can get to the master. Should solve your hydraulic problems.
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03-17-2008, 08:18 AM
#8
I would pull the master, wrap the line with hose and heat tape just to feel better about that, then bench bleed the master well with new fluid, preferably DOT 4+ spec brake fluid. It definitely sounds like a hydraulic issue and the above steps will eliminate a lot of issues as the culprit.
It's the line being so close to your headers that people say makes the fluid boil. A high spec brake fluid shouldn't have any issues boiling, though.
It's the line being so close to your headers that people say makes the fluid boil. A high spec brake fluid shouldn't have any issues boiling, though.
03-17-2008, 08:36 AM
#9
Dot 4 has a 446F boiling point. Headers can run hotter than that at WOT, heck toss in a lean condition and you can see headers glow red in normal daylight.
To put in perspective NOX begins to form around 2800F and skyrockets in formation after that temp, since I've yet to see a car pass an emissions test with 0 NOX readings, it's safe to assume at least 500F of heat has been exposed to the headers which in turn will pass on that heat to its surrounding environment. Take into account WOT cares LITTLE for emissions during that time and it's easy to imagine the fluid getting a little boiled there.
To put in perspective NOX begins to form around 2800F and skyrockets in formation after that temp, since I've yet to see a car pass an emissions test with 0 NOX readings, it's safe to assume at least 500F of heat has been exposed to the headers which in turn will pass on that heat to its surrounding environment. Take into account WOT cares LITTLE for emissions during that time and it's easy to imagine the fluid getting a little boiled there.
03-17-2008, 09:06 AM
#10
Dot 4 has a 446F boiling point. Headers can run hotter than that at WOT, heck toss in a lean condition and you can see headers glow red in normal daylight.
To put in perspective NOX begins to form around 2800F and skyrockets in formation after that temp, since I've yet to see a car pass an emissions test with 0 NOX readings, it's safe to assume at least 500F of heat has been exposed to the headers which in turn will pass on that heat to its surrounding environment. Take into account WOT cares LITTLE for emissions during that time and it's easy to imagine the fluid getting a little boiled there.
To put in perspective NOX begins to form around 2800F and skyrockets in formation after that temp, since I've yet to see a car pass an emissions test with 0 NOX readings, it's safe to assume at least 500F of heat has been exposed to the headers which in turn will pass on that heat to its surrounding environment. Take into account WOT cares LITTLE for emissions during that time and it's easy to imagine the fluid getting a little boiled there.
). Just my personal experience.But whether it's boiling or not, wrapping the line can't hurt but may help, so I say go for it since it costs next to nothing. It's just a bitch putting that damn master back in. If I ever have to pull it again, I'll probably wrap it just for the hell of it. Peace of mind is worth a lot of money.
03-17-2008, 01:29 PM
#12
Once it's been boiled it's pretty much done as far as fluid goes, flush it first before suspecting something other than hydraulics. If it's still acting up despite new fluid, I'd suspect the pressure plate may be shot or the slave.
03-19-2008, 04:13 PM
#14
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I've been doing alot of searching and I've read the sticky but I still some one to explain this to me. Ok, my 00' SS has an LS7 clutch with 10k mile on it and I also replaced my master & slave with the updated 01+ hydraulics when I changed to the LS7 clutch. I also did the drill mod and made my master adjustable while I had everything apart. At WOT my pedal gets kinda weird, It either goes to the floor, or the pedal effort doubles. After WOT my clutch engages right off the floor. My fluid doesnt look that dark. When it happens its hard to get it out of what ever gear your in and it wont go back into any gear for about a minute or so. Could it be my clutch?
Now lets say it is an hydraulic issue. Why would it only happen at WOT? If the fluid is getting hot, whats making it get hot (Slipping clutch maybe?) The car just started doing this last night.
My car use to have the centerforce DF clutch that slipped and cooked my fluid which is the reason I went to the LS7 and new hydraulics. Is the the same case?
Now lets say it is an hydraulic issue. Why would it only happen at WOT? If the fluid is getting hot, whats making it get hot (Slipping clutch maybe?) The car just started doing this last night.
My car use to have the centerforce DF clutch that slipped and cooked my fluid which is the reason I went to the LS7 and new hydraulics. Is the the same case?
I had the same exact issues with my LS7 clutch. Everything down to the T was the same. I tried all new hydraulics, bled the **** out of them, wrapped the line blah blah blah. Clutch never slipped and I could drive spiritedly with no problems. Ended up being the LS7 PP, it wouldn't disengage after going WOT past 6k rpms.
03-19-2008, 04:33 PM
#15
Yeah, like I said. When you have that problem, it's TYPICALLY the pressure plate and you most often see it in stock clutches that can't handle the power. There are exceptions, of course, but if you're making decent power and running the stocker, or more than the clutch can handle, you'll see this problem.
03-19-2008, 09:37 PM
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Yeah, like I said. When you have that problem, it's TYPICALLY the pressure plate and you most often see it in stock clutches that can't handle the power. There are exceptions, of course, but if you're making decent power and running the stocker, or more than the clutch can handle, you'll see this problem.
03-20-2008, 06:40 AM
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I've Got The Same Problems With Fluid, My Cars Got 49k On It The Fluid Is Black As Night And I've Looked Under The Car I Can Physically See Were The Clutch Master Cylinder Line Has Been Burnt From The Headers. I Smell A Master Cylinder Replace + Dot4 Flush Coming Up.
But Your Problem Sounds Mechanical Not Hydrolic.
But Your Problem Sounds Mechanical Not Hydrolic.