on going Crown clutch problem

[Roger Boisjolie]

Long story long here:
I mostly completed my Crown Corvair 6 years ago but put it on the back burner because of a non slipping posi and terrible shifting. Thanks to Chuck Rust for steering me on to Redline transaxle fluid and now the posi is slipping a wheel while tight cornering.
Now I've got renewed interest in the car. I go and drive it and I'm grinding gears trying to get into first or reverse. I got stuck a mile from home and could only get 3rd gear to engage so I had to abuse the clutch to get it home.
Rick Andersen commented that I probably needed more clutch engagement so I went and lengthened my pedal to master cylinder rod about 1/4". Problem solved! I took it for a cruise and 20 mins later I was grinding gears again. Humm?
I decided to jump up from my 3/4" bore Tilton master cylinder to a 7/8" bore Tilton. A lot stiffer pedal but it finally shifted well again. Take it for a spin and it's grinding again in 10 mins of driving around town. I vacuum bled it again and find no bubbles. I had someone push the pedal down while I watch the Quarter Master street hyd throw out bearing and I'm getting around 1/4" travel but the inside bore of the cylinder is wet with brake fluid. I puddle forms under the bellhousing now, but it doesn't drop the master cylinder level much. Humm?
I called Quartermaster and learned that I need the 3/4" master cylinder with Dot 3 instead of Dot 4. I ordered a seal kit to rebuild the throw out bearing from them.
When I'm under the car I can turn the throwout bearing's engagement face by hand but there doesn't seem to be any free play between the Center Force street pressure plate and the clutch fingers. I guess the fingers extend when you wear the clutch disc down and take up your free play?
Now I'm ready to tear the transaxle out and rebuild the throw out bearing but thinking I'll do all this work only to land with the same problem I had initially - grinding gears while running.
Couple things I haven't done: put in a pedal stop and check my pedal ratio....I hear it's supposed to be 6 to 1.
To cover all my questions on this I have a little more.......
I'm running a hydraulic throw out bearing but after this feasco I'm thinking a hyd external slave cly might be the way to go. I created my own problem with that by running a big NASCAR oil cooler with huge 1" lines coming from an oil filter adapter plate.
I would have to remove all of that stuff (it looks trick) in order to have the standard mechanical clutch pivot arm w/ a slave cyl. If so, what slave cyl and bracket configuration do you suggest. Trick looks ain't sheet if it don't work.
I'm very open for suggestions. I have 6 trick cars and everybody is drawn to the Corvair as their favorite. I can't even give people rides in it as I'm embarrassed by the shifting.
Thanks for any advice,
Roger

[Roger Boisjolie]

Here's the oil cooler. I liked it there cuz it fills the void. Probably not the best location. Thinking of ducting it and the air cleaner from a couple of clear NACA ducts mounted in thr rear drivers window. Mount them on there own plexiglass and roll the power window down to get the air to them.

[Maechtlen El Monte]

Well, that has to be hugely frustrating.
Let's think about this - If the sucker will ever go into first or reverse gear with the motor running, then the clutch must be disengaging at that moment.

If it doesn't go into gear at some other time, then something has changed so the clutch is not fully disengaging.
Some possibilities might include:
* the clutch needs more travel when warm than when it is cold
* the hydraulics aren't giving you as much travel as they did at first
* something else is moving to steal some of your travel?
* could something other than the clutch be dragging, and spinning the input shaft? Could the pilot bushing be dragging enough to cause this?

if the throwout bearing had a problem, it would probably make noise. If it drags, it might tear up the clutch releasing fingers - but it shouldn't affect shifting, unless the fingers wore so much that the release cylinder runs out of travel?

Can you observe the throwout while someone steps on the clutch? (or use a camera and run video to observe)
- Somehow evaluate how much travel you are getting, and see if anything is moving that shouldn't be?

[Rick Andersen]

As you and I have discussed, we are both suffering from the same problem. To get really fundamental, I have had someone else push the clutch pedal and watched the throwout bearing move about 1/4". I have no idea how much the pressure plate fingers need to move in order for the clutch to disengage, to allow the transmission to allow for shifting of the gears. I assumed the same thing you did, that by increasing the size of the master cylinder, you would increase the travel of the throwout bearing. Apparently that didn't work for you - at least enough to allow the clutch to disengage.

Now we are both looking for ideas from the outside world.

[Roger Boisjolie]

I've got the hyd. throw out bearing rebuild kit now. I'll try to find some help to run the car till hot and climb under to observe whats going on before I tear it down only to build it back with the same problem.

[Roger Boisjolie]

I decided to pull the motor this morning and rebuild the hyd throwout bearing. I'm going to switch back to the 3/4" bore master cylinder from the 7/8" and run it with DOT 3 as quarter master suggested. I'm thinking now that my problem is the pedal ratio on the master cylinder. I measure my stock clutch pedal from centerline of swivel to middle of pedal pad at 8.5". If I divide that by 6 I get 1.46". So should my push rod be located 1.46 down from the center line of the stock Corvair clutch transfer pipe? I've got it at 2.5" now from center to push rod hole centerline.

[Roger Boisjolie]

Read an interesting story on the web: "My trans would not shift well and grind gears once it warmed up". He said the cheapy china pilot bushing have a lot of iron in them and can cause your main shaft to turn once they get warmed up and cause premature shaft wear. Said if they are magnitic there junk.
Sure enough mine was magnitic! Went and bought a heavy duty truck one that was all bronze for$10.00. Won't know if it was the problem until I get it back together. Also switched out the aluminum flywheel that was new and now it's toast with a steel one.

[Roger Boisjolie]

All back together with bronze pilot bushing, steel flyweel, 3/4" bore master cyl. Measured pedal at 12" and my transfer rdo is at 2.25". Bleeded system.............same problem Now I'm going to drill another hole down from the 2.25" and see if I can EVER get it to work. I'm ready to yank it out again and go external slave.
I shimmed my hydrualic throw out pretty close but could spin it by hand before starting and with it's observed 1/4" of travel, it still won't release the clutch. Once started it was spinning with the clutch which leads a short life but you'd think I'd get a release like that.
Anybody have an external slave set up they want to sell? Guess I'll read the Ted Trevor artical on this and go back old school

[Roger Boisjolie]

pulled it and going with an external slave cylinder now. Just fabbing up the bracket and removed the external oil cooler. I'll have that complete set up for sale if anybody is interested.

[Maechtlen El Monte]

Did it/does it work?