problem with science of speed clutch
Former Sponsor
Joined: Mar 2002
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There's a big difference between knowing how to replace a clutch and knowing how it actually works. Any hydraulic system with a reservoir on the master cylinder is self-adjusting. Our brake system is self adjusting, and our clutch is even more self adjusting (due to the spring inside the slave cylinder).
Here is a quote from this site, which does a good job explaining how a clutch works. I've highlighted part of it in red, since this is the issue I suspect may be part of the problem with the OP's clutch. If the OP's clutch pedal was incorrectly adjusted, or there is some issue with the master cylinder, then that could have prevented the system from self adjusting as described below.
Here is a quote from this site, which does a good job explaining how a clutch works. I've highlighted part of it in red, since this is the issue I suspect may be part of the problem with the OP's clutch. If the OP's clutch pedal was incorrectly adjusted, or there is some issue with the master cylinder, then that could have prevented the system from self adjusting as described below.
Hydraulic clutches
Hydraulic clutches are usually self adjusting: The friction material on the clutch plate gradually wears down. The position where the disengagement mechanism begins to take up therefore changes and the clutch mechanism must adjust to compensate. Hydraulic mechanisms rely on the diaphragm to return the hydraulic fluid through the master cylinder and into its reservoir as it pushes the disengagement mechanism and the slave-cylinder piston back. The master cylinder contains a valve to allow this to happen fully but the valve is open only when the clutch pedal is fully raised - otherwise the disengagement mechanism would never operate. Resting a foot on the clutch pedal full-time therefore prevents the clutch from self-adjusting, puts load on the throwout bearing and can cause it to fail prematurely. Similar problems can occur from resting a foot (long-term) on the pedal of a cable-operated clutch.
Hydraulic and cable-operated clutches are adjusted so there is a little essential "play" (check the manual) before the pedal starts to operate the disengagement mechanism. In a hydraulic clutch this ensures that it can self adjust. In a cable-operated clutch it ensures that the throwout bearing is under no load unless actively changing gears; manual adjustment may be necessary every few months as the clutch plate wears or the cable stretches.
The fluid level in the reservoir of a hydraulically operated clutch should be checked weekly and the fluid should be replaced annually because it is hygroscopic and water causes corrosion. The slave and master cylinder seals can fail and it is a good idea to carry spares (and hydraulic fluid) if travelling in remote locations. Racing drivers can change gear without a clutch and you can too in an emergency to drive a vehicle without using the clutch. The starter motor is powerful enough to start a vehicle in first gear on the flat or even up a slight slope, although it is not recommended as common practice! (Also useful if stuck with a dead engine on a railway crossing when the express is due.) Running up to say 3000rpm in first gear, back off the throttle to take all load off the transmission and put the gearbox into neutral. Get the engine to about 2000rpm (assuming adjacent gears are in the ratio 3:2) and, with care, you should be able to engage 2nd gear with no clutch. Other gear changes are managed similarly. The engine must be turned off and the process repeated if you have to come to a halt. There will probably be a good deal of gears "grating" but with care, "feel" and lots of patience this can get you back to civilisation.
Hydraulic clutches are usually self adjusting: The friction material on the clutch plate gradually wears down. The position where the disengagement mechanism begins to take up therefore changes and the clutch mechanism must adjust to compensate. Hydraulic mechanisms rely on the diaphragm to return the hydraulic fluid through the master cylinder and into its reservoir as it pushes the disengagement mechanism and the slave-cylinder piston back. The master cylinder contains a valve to allow this to happen fully but the valve is open only when the clutch pedal is fully raised - otherwise the disengagement mechanism would never operate. Resting a foot on the clutch pedal full-time therefore prevents the clutch from self-adjusting, puts load on the throwout bearing and can cause it to fail prematurely. Similar problems can occur from resting a foot (long-term) on the pedal of a cable-operated clutch.
Hydraulic and cable-operated clutches are adjusted so there is a little essential "play" (check the manual) before the pedal starts to operate the disengagement mechanism. In a hydraulic clutch this ensures that it can self adjust. In a cable-operated clutch it ensures that the throwout bearing is under no load unless actively changing gears; manual adjustment may be necessary every few months as the clutch plate wears or the cable stretches.
The fluid level in the reservoir of a hydraulically operated clutch should be checked weekly and the fluid should be replaced annually because it is hygroscopic and water causes corrosion. The slave and master cylinder seals can fail and it is a good idea to carry spares (and hydraulic fluid) if travelling in remote locations. Racing drivers can change gear without a clutch and you can too in an emergency to drive a vehicle without using the clutch. The starter motor is powerful enough to start a vehicle in first gear on the flat or even up a slight slope, although it is not recommended as common practice! (Also useful if stuck with a dead engine on a railway crossing when the express is due.) Running up to say 3000rpm in first gear, back off the throttle to take all load off the transmission and put the gearbox into neutral. Get the engine to about 2000rpm (assuming adjacent gears are in the ratio 3:2) and, with care, you should be able to engage 2nd gear with no clutch. Other gear changes are managed similarly. The engine must be turned off and the process repeated if you have to come to a halt. There will probably be a good deal of gears "grating" but with care, "feel" and lots of patience this can get you back to civilisation.
Thread Starter
Joined: Nov 2009
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From: edison new jersey
Well the verdict is in, and gernby was right all along, this is why i never ever blasted s.o.s, like i said from the start i love this clutch and the question was posted for any info leading to the cause. Due to a mistake made it caused the clutch to begin to prematurely fail, but i can now offer some insight to any prospective s.o.s clutch buyers, when installing this clutch we adjusted the pedal height to the spec of 7.44 which is stock pedal height, when installing this clutch i suggest you take a pedal height measurement then inspect your master cylinder rod, you will notice the master cylinder rod extends way far out of the cylinder in turn either cutting off its self adjusting capability since theres not much more rod travel, or since the rod will eventually reach ots limit start to force fluid back through the system, causing it to barelu disengage, but enough to slip under load. Thanks to gernby pointing me in the right direction i was able to realize the fault was mine and save myself the trouble of being stupid with s.o.s. what i can suggest is when the clutch is installed check the rod travel, if its too far out adjust your pedal accordingly. After moving my pedal height down almost 3/4 of an inch the clutch is working fine, it still slips under heavy load but NOWHERE near as bad. This slip is the result of me not paying proper attention after install. If i had adjusted the clutch day one knowing this i would have saved myself from buying another clutch so early. In my defense there is no notation of this anywhere, although it is my fault and i have no excuse. All i can say is when installing ANY new clutch pay extra attention to this. If the rod sticks out of the cylinder too far you will destroy a clutch thousands of miles early. Im just glad that i was offered ideas of where to look, and i deserve the flaming for my stupidity. Damn i feel dumb but i guarantee this $1100 mistake will never happen again
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Joined: Nov 2009
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From: edison new jersey
Im hoping so, and thank you again, believe me i know i deserve to get flamed for making such a simple stupid mistake, but in my defense i made 100% certain i went through everything that i could before bringing the matter to s.o.s and in no way do i think s.o.s sells bad parts, quite the opposite, their parts are top notch as is thrir customer service
Thread Starter
Joined: Nov 2009
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From: edison new jersey
Maybe a more mechanically inclined person can chime in, but what i found is once the clutch is installed look under the dash at how far the master cylinder piston rod sticks out from the master cylinder with the clutch pedal not engaged, if its all the way extended out that means its going to force pressure back through the line keeping pressure on the clutch fork, which means the pressure plate will never fully engage ( or disengage its confusing ) meaning the clutch will slip,, maybe not at first but as the clutch disk wears out it will get worse, partly because theres no more travel left in the master cylinder rod, so it cant clamp as hard on a wearing disk. The way i fixed mine and im assuming is how you should adjust for a new clutch, is to check pedal pressure after install, if theres alot of free play while pushing in the clutch pedal before you get resistance from the clutch youll want to limit it. You want there to be only about half an inch to 3/4 of an inch of free pedal travel before resistance. This way the master cylinder is not operating at max length and it still has a bit of actual travel. You can adjust the pedal travel by loosening the 14 mm nut on the unit that contacts ( with a black push switch ) the top of the clutch pedal and then with it loose use your hand to slowly push the clutch pedal to the point of feeling resistance. At that point hold the clutch pedal and turn the loosened unit cloes to the pedal to the point that the black push button almost touches the pedal. At that point still holding the clutch not moving it in or out from the resistance point , tighten the 14mm nut once finger tight , try to start the car, if it starts no problems , then go back under the dash loosen the 14mm nut and turn the unit 1 full turn back then tighten it down completely. This way your master cylinder is operating with room to spare and the pedal will push the switch when depressed. , long winded explanation i know, and my punctuation is garbage and leads to one long sentence. But it works and should cause no worries. Just rember though a clutch pedal too low is as bad as a clutch pedal too high. Too low and the pressure plate will never fully engage or disengage, too high and it puts pressure on the pressure plate causing the same. The owners manual says stock pedal height is 7.44 inches from the floor, but i figured out the stock pedal height for the sos clutch should have been around 7 max. Hope this helps
Former Sponsor
Joined: Mar 2002
Posts: 15,526
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There's really no need to adjust anything unless you just don't like the way your clutch pedal is adjusted now. I have adjusted my pedal a couple times just to deal with a gear grinding issue, but I didn't have any need to adjust my pedal when I replaced my clutch. Honestly, if you are about to install a new clutch, then I suggest adjusting your pedal before installing the new clutch. That way, if you adjust it incorrectly, you'll just toast the old clutch...
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