need HELP with clutch!

snowcat

Registered User
1990 Cougar 5sp
I have been trying to fix my clutch now for over a week. here's what I’ve done: new master cylinder, new hydraulic line, new slave cylinder and the clutch it self was new a year ago. I know they can be hard to bleed by all the posts I've read. But we have tried just about everything. The clutch feels great, good pedal, lots of travel & you can feel it engage, but it is not engaged and we can not get any more air out of the system. The only thing that I find strange is using a flat blade screw driver I can push the release bearing back off the clutch fins about 3/8" before it stops and will not go back any further. this tells me there is still air in the slave cylinder ...BUT as soon as you step on the pedal and it moves just slightly the release bearing starts pushing the clutch fins in?!?! Because of all the new parts I'm thinking the system just needs to be bled. I'm I missing something here?? I'm thinking of pulling the slave cylinder off and bench bleeding it, can this be done? Does anyone have a fool proof way of bleeding these systems?
Could my clutch it self be seized?
any help or suggestions would be greatly appreciated.
 
Sounds like you are not familiar with how clutches work. Thus it is hard to understand what your problem is exactly.

The clutch pedal pushes on the master cylinder which drives a hydraulic piston generating pressure in the clutch master cylinder to slave cylinder line. This pressure pushes on the slave cylinder pushing it forward. As the slave cylinder is pushed forward, the throw-out bearing is pressed up against the pressure plate spring fingers. As these fingers are pressed, spring pressure is released inside the pressure plate allowing the clutch disk to spin freely.

When you release the clutch pedal, the hydraulic pressure is released, the pressure plate fingers push the slave cylinder back via the throw-out bearing and the clutch disk becomes clamped between the pressure plate and the flywheel.

If, your problem is that even after you release the clutch pedal, the clutch disk is not clamped between the pressure plate and flywheel, then one of two things has happened. The pressure plate/clutch disk have broken such that no spring pressure can be developed inside the pressure plate. Or the slave cylinder/throwout bearing are hanging up on the input shaft, failing to release all of the clutch pressure.

If your problem is that even though you have the clutch pedal pushed all the way down, the clutch doesn't release, then the problem is most likely due to a clearance issue between the stroke of your master cylinder, and the distance the slave needs to move to fully disengage the clutch disk. This can happen if the flywheel is re-surfaced and an appropriate shim isn't added behind the slave cylinder. To correct this, you typically shim the slave cylinder so that the throw of the master cylinder is sufficient to disengage the clutch.
 
yes, I fully understand how a clutch works.
My problem would be the second one you noted. I am fimilar with shimming a slave cylinder/release bearing for special applications BUT Being all new 'stock' parts you would think it would not need to be shimmed (the plate has not been turned, to my knowledge), plus I have not seen a shim kit nor has any of the documentation I've seen refere to one.
does one exist? (or are you shimming it forward with washers or what ever is handy?)
what you suggests makes sense but I still want to know why I can push back the release bearing off the clutch fingers, is this normal??
 
The confusion came from you describing, pressing the clutch pedal to "engage" the clutch. pressing the clutch pedal dis-engages the clutch disc from the pressure plate and flywheel.

I don't know if it is normal that you can move the release bearing off the pressure plate when the clutch pedal is released. I assume it is normal for there to be some clearance there, otherwise things would wear out faster if there was zero clearance on a released clutch. Repair shops will shim the flywheel when turning the flywheel.

I don't know of anyone that has done the measurements to figure out when you need a shim and when you don't. But here is a link to a discussion about this for LS1 engines.
http://www.ls1tech.com/forums/manual-transmission/1030815-does-your-clutch-setup-need-shim.html
 
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