Clutch pedal on floor

MtnBiker

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I had just finished cool down lap and was cruising in 3rd into hotpit lane. When I went to shift down to 2nd the clutch pedal went to the floor and would not come back up. I coasted to the parking area and by the time I stopped the pedal was starting to respond. A few minutes later it was normal. Did not have problems on next session.

Can someone explain what happened? When I owned a Corvette Z06 it would do the same thing if I glazed the clutch (burnout fail for example) but I did not glaze the clutch since I had just completed cool down lap.
 

Nine Ball

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If your car has headers, it is likely related to the heat basically boiling the clutch fluid, since that line runs right across the top of the driver's side header. I had the same thing happen to me after my 209 mph pass at the Mile. Pushed the clutch in after the pass, and the pedal stayed to the floor. Corvettes also have this problem, and it gets worse with headers.

One of my GM drivetrain (Corvette) engineer friends also says that the heat in the clutch can cause the return fingers on the pressure plate to lose some of their spring clamping force, which has also been a cause they've identified for the mushy pedal syndrome.

I've since removed the inspection cover from the bottom of my bellhousing, to aid in cooling the clutch down quicker. I also heat-wrapped (double thick) the clutch line. Hasn't done it since.

Tony
 
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MtnBiker

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Tony,

I do have headers. And the car had just done two run sessions in a row (my instructor practically begged me to drive it in, so we went out before my run group, and he drove it hard). So, yes, I can see it being heat related. I will look into heat wrapping the clutch line. I will be replacing most of the fluids this week, so I will look into a higher temp fluid.
 
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Shandon

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Put a heat shield between your headers and the clutch line. Then insulate the heck out of the clutch line also. Used to be a problem for me with the balanger headers. Not anymore. Would go to the floor regularly even with Motul 600 before I insulated it. Just too much heat in that area.
 
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