One more clutch theory
06-02-2008, 11:53 AM
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One more clutch theory
I posted this over in the tech forum but you guy's will give me better feed back.
I ran my car at TWS in Feb. and it was 28F. The tires never would heat up so most of the morning I ran only in 4th gear. The peddle moved on it’s own ½ to the floor (I never touched it for 5-6 laps). I yanked the helper spring off the clutch peddle and boom no problems? That made no sense to me but it worked?
My first theory, I thought the problem was purely mechanical. PP fingers at high RPM’s coming in contact with the throw out bearing, pushing the slave cylinder back and then as the RPM’s lowered the slave was moving back into position so quick it was “sucking” the master cylinder piston back with it.
I don’t think this process could happen quick enough to cause such a suction that the flow of fluid would not just pull from the reservoir to fill the slave cylinder back up.
Second theory? The PP fingers are coming in contact with the throw out bearing at high RPM”s. This causes the fluid in the slave to heat up and boil. The boiling fluid push fluid back into the reservoir. Now it starts! The RPM’s are lowered and the fingers move back from the bearing. The temperature in the slave falls back below the boiling point of the fluid. BAM! The gas pocket collapses, the reservoir cannot keep up to fill the void with fluid and the master cylinder piston is sucked forward to fill the void.
When the master cylinder the sucked forward it covers up the return port to the reservoir (the peddle is ¼ way depressed on its own now). The next high RPM run boils the fluid and pushes the master cylinder piston back opening up the return port and a little more fluid goes back into the reservoir, followed by a low RPM cool down and another collapse of the gas pocket. After a enough cycles of this, the piston in the master just moves back and forth never opening to the return port to the reservoir (peddle is stuck somewhere around ½ way depressed area?).
This is why I think new fluid (higher boiling point) and removing the helper spring both seem to work. The helper spring assists the driver in depressing the clutch up to a point then assists the clutch in returning. The helper spring is helping the suction (from the collapse of the gas) to compress the internal master cylinder spring to get this whole process started (once the piston in the master moves over the return port on its own the hydraulic loop a closed system).
Design of the system is poor, but as a cheap fix I think if you place a spring on the peddle to can keep the master piston from moving on its own and stopping the piston fromcovering of return port to the reservoir and letting the fluid expand and contract from the reservoir as it heats and cools.
What do you all think?
I ran my car at TWS in Feb. and it was 28F. The tires never would heat up so most of the morning I ran only in 4th gear. The peddle moved on it’s own ½ to the floor (I never touched it for 5-6 laps). I yanked the helper spring off the clutch peddle and boom no problems? That made no sense to me but it worked?
My first theory, I thought the problem was purely mechanical. PP fingers at high RPM’s coming in contact with the throw out bearing, pushing the slave cylinder back and then as the RPM’s lowered the slave was moving back into position so quick it was “sucking” the master cylinder piston back with it.
I don’t think this process could happen quick enough to cause such a suction that the flow of fluid would not just pull from the reservoir to fill the slave cylinder back up.
Second theory? The PP fingers are coming in contact with the throw out bearing at high RPM”s. This causes the fluid in the slave to heat up and boil. The boiling fluid push fluid back into the reservoir. Now it starts! The RPM’s are lowered and the fingers move back from the bearing. The temperature in the slave falls back below the boiling point of the fluid. BAM! The gas pocket collapses, the reservoir cannot keep up to fill the void with fluid and the master cylinder piston is sucked forward to fill the void.
When the master cylinder the sucked forward it covers up the return port to the reservoir (the peddle is ¼ way depressed on its own now). The next high RPM run boils the fluid and pushes the master cylinder piston back opening up the return port and a little more fluid goes back into the reservoir, followed by a low RPM cool down and another collapse of the gas pocket. After a enough cycles of this, the piston in the master just moves back and forth never opening to the return port to the reservoir (peddle is stuck somewhere around ½ way depressed area?).
This is why I think new fluid (higher boiling point) and removing the helper spring both seem to work. The helper spring assists the driver in depressing the clutch up to a point then assists the clutch in returning. The helper spring is helping the suction (from the collapse of the gas) to compress the internal master cylinder spring to get this whole process started (once the piston in the master moves over the return port on its own the hydraulic loop a closed system).
Design of the system is poor, but as a cheap fix I think if you place a spring on the peddle to can keep the master piston from moving on its own and stopping the piston fromcovering of return port to the reservoir and letting the fluid expand and contract from the reservoir as it heats and cools.
What do you all think?
