Changing my transmission in the '55, no drivability problems just changing updating my Saginaw 4 speed on a SBC with a tight mechanical linkage. Question has come up if I had my throwout set correctly. Searching past threads go either way without a definitive answer. I had set my throwout set for constant contact with very minimal pressure on the pressure plate fingers (bearing always spinning). Thats how I thought it was done? I've also read thats wrong... and needs to be set up with a few thousands air space between the plate fingers and bearing - bearing should only be spining when engaging the pressure plate fingers to change gears. Not sure which set up is right? or if Im killing my bearings life?
Gap,/play, 1/8 to 1/4 inch free play is good,before it starts on clutch fingers. If it is in constant contact=it will good bad fast; not designed for spinning the hole time engine is running.
I've always given the pedal 1'' - 1 1/2'' free play - I like the release point right in middle of travel.
It's a good idea to set it up with significant clearance between the bearing and fingers. It only needs a few thousandths, but as the clutch wears, the clearance decreases, and you don't want to be adjusting it every week.
Like what @302GMC says... 1 to 1 1/2" of freeplay at the pedal. That's all that's really needs to be worried about. The distance between the fingers and the bearing is a constant at that point. Don't over think it.
Throw out bearings are not designed to run all the time, they need clearance or they will wear out faster than the clutch life. About an inch of pedal free travel is the norm for any make of car for about 100 years
One more vote for one inch of free travel. Meaning that if you set a on the floor or kick board in line with the travel of the clutch pedal you should be able to press the pedal down one inch with your hand before you feel the throw out bearing contact the fingers on the pressure plate. Make sure that you have a return spring on the clutch pedal too. From there it is 303GMC said in post 3. where you like the pedal when the clutch releases. The clutch in my C30 is spot on for what I like but the one in my F250 never feels right. I had a shop in town put a clutch in it as both my son in law an I were too bunged up at the time to do it ourselves out in the driveway and still am not sure they used the right parts. It works fine but is the worse feeling cutch I have ever driven.
Another thing, must have a good clutch pedal return spring so the linkage and fork don't slop around and make random contact on the throw out bearing. Which comes out to part time full contact. Adjustment is something you will learn over time. Over time you will learn what feels right. Always buy the best clutch throw out bearing you can find. I've seen/had cheap ones that start to go dry and drag on the pressure plate arms wearing those down as well. Throw out bearings and pilot shaft bearings. Pulling a tranny just to replace a few of those is a PITH. Just my opinion, like butt cracks, everyone has one.
I was always curious about the "1 inch or so clutch pedal free-play" spec so common in shop manuals, and finally bought the mid-'70s "Tom Monroe Clutch and Flywheel handbook" before I started building clutch linkages, learning the normal overall clutch operating ratio was in the 11 to 1 range, which will result in the 1" or so pedal free-play spec with minimum T/O bearing to pressure plate distance. All that's really needed is about .100" (1/10th") clearance, as long as full dis-engagement doesn't exceed recommended disc to plate clearance, based on the pedal ratio and pressure plate design. Simply put, at-rest pedal free travel is the result of throw-out bearing to pressure plate distance X overall clutch linkage ratio. Tom's book is still widely available, and although dated, is still a very good source of clutch related information today.
You may be getting advice from some folks that are used to working with later model, off-topic clutch set-ups. Some hydraulic clutches and even cable actuated clutches with automatic self-adjusters run the T.O. bearing in constant contact with the pressure plate fingers. And those bearings seem to be considerably more "spendy".
The Jalopy Journal
