I am setting up the hydraulic clutch and using a Wilwood pull type slave cylinder rather that a hydraulic release bearing. How much free play should there be on the clutch fork? Is it just enough so the release bearing is barely touching the fingers pressure plate? I ask because the slave cylinder only has a 1.38" throw before it is maxed out.

  Ron Lane,  Meridian, ID

Ram recommends .150” between the TO and clutch fingers, It will be more on the linkage because of the length of the fork. I’ve set them a lot closer

On a few installations I had to put a stop on the pedal to keep the pressure plate from “oil canning”. Too much travel is not good either.

If you have a way to put a feeler gauge in between the disc and plate with the pedal down it think the gap minimum is .050”.

Hydraulic TO’s are the easiest to push too far.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

That is great information, Thanks! I will remove the dust shield from the bell housing and see if it's even possible to get a feeler gauge up there. Probably not. I am running an 11" Centerforce clutch but I guess that won't make any difference regarding the free play. Maybe I can use a magnetic base with a dial indicator to the clutch fork to shoot for the 0.050" free play between bearing surface and clutch fongers.

  Ron Lane,  Meridian, ID

Ron, either with mechanical or hydraulic I would start out with just the fork on the TO and move it by hand and check the movement it had on the trans collar. That was usually about 1/2”. With mechanical I’d adjust it so it had plenty of “rattle” then add the fork arm spring to help the TO off the pressure plate fingers.
I see no reason not to do the same with the hydraulic actuating cylinder from Wilwood. To me the spring did the work to hold back the TO from turning when you are not pushing on the clutch. They are a pretty stout spring. Dorman lists them as a clutch return spring. One end has a hook and the other is just straight so you can attach it where ever you can. What you said was the movement of the cylinder I don’t see you having any problem. Good luck.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

I imagine Wilwood provide instructions.  Do they suggest how to do it?  I would go by their recommendation before anything else.

The factory spec, for trucks, anyway is 1/4" between the pushrod and fork.  Considering the ratio of the fork, that probably is about .150" or so between the PP and TO for that application.

For what it's worth, my '88 Firebird with factory hydraulic clutch has no adjustment possible.  The Hydraulic TO bearing setup I'm using on the truck was adjust the master cylinder pushrod just until the clutch releases and then adjust just a little farther (can't remember how much).  With the Firebird, I cannot feel the bearing contact the pressure plate.  Not saying there is no clearance, only that I cannot feel it.  With the truck, I can feel the bearing touch, very much like the factory mechanical linkage but much easier actuation.

For the truck, they also recommended a stop of some sort be made for the pedal because pedal travel is quite a bit less than factory.  I just made the mc pushrod long enough and adjustable such that the floor is the stop, for now, anyway.  This required that I make an extension bracket for the upper stop, which sets the height of the pedal.


Lawrenceville, GA

Thanks Guys! The Wilwood instructions, from what I remember, only discussed the fact that you should not use the factory hole at the end of the release fork and that you had to machine a new hole, I think about 1.125" inward towards the bell housing and that the slave cylinder needed to be mounted  parallel to the tranny to pull straight back. I do have the heavy Dorman return spring on the end of the clutch fork which I'll remove for the measurements. The thing I am not used to is that the clutch pedal will only go 1/2 way to the floor before it stops dead. I think that is the limit of the throw of the slave cylinder, but I am getting plenty of travel in the clutch fork. On my 56 with the mechanical clutch, my pedal goes to about 1" from the floor.

  Ron Lane,  Meridian, ID