clutch problem/ rpm related

Jeremy001995

Jeremy001995

diesel mecanic
hi , got an old southbend double disc competition clutch with 3850 pressure plate, it dont slip, but got a problem rpm related, if i spin the engine at 4000-4500 rpm i loose the clutch pedal at the end of the track, if i stay under 3500rpm its all fine, i have change the hd hydrolics but no change, any idea? tanks! nv4500 transmission
 
Man this brought back memories of LS1Tech haha this was a problem with some GM cars. 4th gen Trans Ams for me. There was a drill mod, the Tick oversized master and what I think was the true problem was the self adjusting pressure plate of the LS7 clutch people liked to run.

Check all your hydraulics and make sure the slave isn’t being blasted with exhaust or getting hot enough to boil the fluid. Interested to see what the cause is.
 
bateman said:
Check all your hydraulics and make sure the slave isn’t being blasted with exhaust or getting hot enough to boil the fluid. Interested to see what the cause is.
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I think we have a bingo here. Try wrapping the slave up with some header tape or heat blanket.
 
What do you mean by looses the clutch pedal at over 4k rpm?

Is it that you push the pedal down and the clutch doesn't disengage until under 3500?

Sounds to me like a centripetal force issue, the slave cylinder isn't strong enough to overcome the levers, and disengage the clutch.
 
I’m betting pedal goes limp at high rpm. Might not fall to the floorboard but will have no resistance when pushed.

If the slave couldn’t over come the pedal wouldn’t move or would be really stiff. Can’t compress a fluid so it’s got to go somewhere if the pedal moves.
 
I had this same issue and it was the springs on pressure plate arms was to weak .. swapped pressure plate and fixed it .
 
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at the end of the track the clutch dont disengage when i press the pedal, and it is very soft, have to pump the pedal or wait 1 min and the pedal is normal and the clutch disengage

but the clutch never slip, its olding strong!
 
Like I said yes same issue .. this issue is several years old and was one batch of pressure plates .. centrifugal force caused the arms to shove the throw out bearing away from the pressure plate .. Peter at south bend was aware of the issue ..
 
Rich dzl said:
I had this same issue and it was the springs on pressure plate arms was to weak .. swapped pressure plate and fixed it .
Click to expand...

Rich dzl said:
Like I said yes same issue .. this issue is several years old and was one batch of pressure plates .. centrifugal force caused the arms to shove the throw out bearing away from the pressure plate .. Peter at south bend was aware of the issue ..
Click to expand...

will have to order a new pressure plate then, tanks!
 
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