clutch won't disengage

[steve meltzer]

I’m having a heck of a time with the clutch on my Kirkham. Here are the facts:
The car is in the process of assembly, and all clutch parts are new....it hasn’t run yet (and the way I’m goin’ it maybe awhile!).

427 engine with 4 speed toploader
Centerforce II disc and pressure plate, correct mechanical T/O bearing
3/4” Wilwood Master
1” Wagner Lockheed slave
Lakewood bellhousing

Problem: I can’t get the clutch to completely disengage.

What I’ve done:

Hyrdraulics of the master and slave are leak-free, and bled several times...no air in system.

The fork and scattershield have been modified so that there is nothing rubbing on moving parts to obstruct their travel.

The pedal pressure is reasonable and the transmission input shaft fit smoothly into the pilot bearing...bolted up easily.

The pivot bracket within the bellhousing has been shimmed as much as possible to create the best fulcrum for the clutch arm and the “vertical” piece of the pivot bracket is on the inside most part of the housing (which is correct, I thank).

The master cylinder and the slave as well have been adjusted “out” as much as possible to move the T/O bearing as much as possible.

Despite this, the clutch won’t totally disengage...with a strong effort, you can barely rotate the output shaft with the car in gear and the clutch to the floor.

Any thoughts on this? I was thinking about going to a larger MC, maybe a 7/8”, but Wilwood doesn’t make one for this application. Could go to a smaller slave, maybe a 7/8” there with the 3/4” Master. I’ m totally befuddled here. thanx steve meltzer, KMP #174

[KobraKarl]

Steve ,

Your condition is not too uncommom....I had to cope with this myself , and it pops up here at CC frequently.

Are you absolutely positive you but the disc in facing the correct way?

Have you removed ALL slack from your linkage? (all but 1/8")

Are you using a return spring on your linkage to keep slack out ?

How are you exerting the "strong effort" ?...the gearbox alone can take a fair amount of energy to turn when in gear.

KK

[strictlypersonl]

Of course it depends on the mechanical advantage of your clutch pedal, but we've found that the diameter of the clutch master and slave should be about equal. In fact, some small block clutches require a larger master cylinder diameter to fully release.

If you're using a standard clutch throwout arm, you'll need approximately .7" of throw where the slave linkage connects.

[steve meltzer]

Thanx to all for your prompt replies. I'm certain that the disc is facing correctly...it was labeled as such from the factory. All of the slack is out of the linkage, but the only return spring is from the arm to the engine, to return the arm after it is actuated.

We put the drive shaft yolk on the output shaft and used an 8" pry bar to rotate the shaft.I'd say it took about 40-50# of force. It seems like you could hear the disc against the flywheel.

I'll have to measure the throw of the slave linkage.

thanx again.

[niles]

Steve:
You seem to have been through in you trouble shooting.
Try one more thing before changing cylinder dia's.
Have someone press the pedal in about 3/4in while another observes the action of the slave. If the slave and arm are moving; then there is no slack/air in the system.
Tilton makes MC's incremented every 1/16th of an in.

gn