Clutch effort ZF-2

[Steve Sandoval]

Maybe a silly question, I am running a ZF-2 behind a 302, KEP bell housing, center force pressure plate with matching clutch plate, pantera adjustable TO bearing, external slave cylinder. Just assembled everything and I tried to engage the clutch - I would like to think I'm no slouch, but the force necessary to engage the clutch seems to escape me. I have gone online to see what the release pressure for a center force clutch should be, can't find the info I need. I haven't run hydraulic lines to it yet, is there a mechanical way to replicate the action or is that not recommended?

 

[Jac Mac]

Maybe a silly question, I am running a ZF-2 behind a 302, KEP bell housing, center force pressure plate with matching clutch plate, pantera adjustable TO bearing, external slave cylinder. Just assembled everything and I tried to engage the clutch - I would like to think I'm no slouch, but the force necessary to engage the clutch seems to escape me. I have gone online to see what the release pressure for a center force clutch should be, can't find the info I need. I haven't run hydraulic lines to it yet, is there a mechanical way to replicate the action or is that not recommended?

If you don't have hydraulics hooked up yet I have to assume your trying to disengage the clutch by simply pushing on the diaphragm spring or release bearing, if so your giving yourself a false indication of the effort reqd.... your clutch pedal will have something in the order of 4/1 or 5/1 leverage plus any size difference in master/slave cylinder bores.... all of which means the effort reqd at the pedal might only be 1/8th of the effort your expending pushing directly on the clutch release ring/bearing... good exercise programme to kick off 2016 tho....... Now if you had stayed with the OE ZF release brg you could have applied a lever to the factory arm to check the actual clutch operation....... and a further thought..I hope you have left the clutch plate alignment tool in place while doing your test because if you do manage to release the clutch without it the plate might move away from center.

 

[Steve Sandoval]

Well maybe I'm using the wrong terminology, I mean the engine and transaxle are already mated, the clutch alignment tool had to be removed to do this. What I am wondering is how much force is needed to press the throwout bearing against the clutch diaphragm fingers to allow pressure to come off the clutch disc and allow free rotation of the engine from contact with the flex plate. If the mechanical advantage of the hydraulic system is on the order of a factor of 8 then sure I am not gonna be putting 400 lbs of pressure on the system externally today and I should stop what I am doing. Let me know what you think, thanks.
-Steve

 

[Jac Mac]

Yes, correct, leave it til you have the hydraulics & pedals hooked up, I assume you want to check it for correct clutch release etc which is a good plan. I don't know why others don't simply make a temporary line from master cyl to engine/trans assy on the floor before its fitted to car to check clutch operation, saves removal / refit etc with all other connections.

 

[Mike Drew]

Leverage is your friend.

You can slide a small-diameter long pipe over the actuating arm and then manipulate the clutch. Assuming there is no piece of the car in the way. It works on Panteras but may well be impossible in a GT40.

Mike