Model A clutch mystery

J

jimyAA

Junior Member
I have a 1931 Ford Model A. About 3 years ago I was driving along and went to shift from first to second gear and I heard a snap and the clutch pedal went to the floor. Thinking it was the arm on the clutch shaft I went under the car and it was fine. I took the car apart and removed the clutch and pressure plate. I could not find anything wrong with the pressure plate or the fork inside the bell-housing. I put in a new USA disc and new pressure plate and assembled everything back together. I noticed the trunion nut had some wear but decided to change it later so set the 1 inch pedal travel. The car drove fine and I put probably well over 5000 miles on it with no problems. Last week getting the car ready to do some touring I noticed it was getting a little more difficult to shift smoothly so I decided to change the worn trunion nut and reset the 1 inch pedal travel. I moved the car around the yard and it was good, went out for a road test and shifting smoothly no grinding gears, until I stopped and then started off shifted from 1st to 2nd and again a loud snap and pedal to the floor. I got the car home and removed the floor boards and opened up the inspection cover only to find that all 6 fingers seem to be evenly sitting deeper in the pressure plate and the throwout bearing can't travel that far causing the pedal to go right to the floor without touching the fingers. The pressure plate seems to be sitting flat against the disc so I ruled out if something had jammed between the plate and disc. Just wondering if anyone else has experienced this or knows what would cause it.
 
Clutch disc lining torn loose and doubled up could cause that, but that would be next to impossible to happen, and it shouldn't make a sudden snap. It does seem you're going to have to pull it apart anyway, so then you'll find the cause.
 
I think Tom has it. Think "meniscus tear" of the lining and a "dog ear" fold in the lining. Which are keeping the plates apart, i.e., simulating you pressing on the pedal.

It may have happened before but the dog ear got torn off and you'll find that piece in the bottom of the bell-housing.

Joe K
 
It could be that one of the springs has come out of position and jammed in the front side of the disk. If you installed one of the poor quality clutch disks that have been floating around the hobby for the past ten years that does not have support flanges around each spring this could well be the problem.

A number of the better suppliers now carry a quality clutch disk that is similar to the Nova clutch of yesteryear. The photo shows a Nova clutch. The Nova folks went out of business about ten years ago. Bratton's I know carries a quality clutch disk.

Look through the inspection port in the bell housing while rotating the engine and see if there is a spring in each of the little windows.

Tom Endy
 

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Hi Tom, looked during the first inspection and all springs on the disc are in-tacked. The clutch kit I installed was bought at the Hershey Pa flea market 25 years ago that was USA rebuilt I imagine, long before the Chinese started re-manufacturing the parts. I have found a reputable clutch re-builder here in Canada called Euro Drive clutches inc. you can find them on-line. I had a pressure plate and disc overhauled by them this week and was really impressed with the workmanship and quality and the price was unbeatable. I will take some pictures.
 
Thanks Joe I will try and see what has happened and let the group know. The mystery is the loud snap and then pedal going to the floor. Last time couldn't find anything out of the ordinary either so just changed the whole assembly.
 
Sounds dangerous> Imagine sitting at a crosswalk with your foot on the clutch and hearing a snap and the clutch suddenly engages lurching the car forward into pedestrians ?
 
The same thing happened to a customer of mine. What happened is that he had the throw out bearing forks set on the non machined area of the forks. he had set the clutch free play with that setup and it worked for some time. One day when he was driving the forks slipped into place on the throw out bearing and the clutch went to the floor. a simple readjustment of the clutch free play solved the problem. a long shot, but worth looking at before pulling the engine.
 
midgetracer said:
The same thing happened to a customer of mine. What happened is that he had the throw out bearing forks set on the non machined area of the forks. he had set the clutch free play with that setup and it worked for some time. One day when he was driving the forks slipped into place on the throw out bearing and the clutch went to the floor. a simple readjustment of the clutch free play solved the problem. a long shot, but worth looking at before pulling the engine.
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X3

I have seen the same problem over the years.
 
Yes had a look at the adjustment and turned to the max and it still only just touched the fingers on the pressure plate. Time to pull it apart and investigate.
 
Tom Wesenberg said:
It could, but that wouldn't explain the pressure plate fingers being too far forward.

Might as well bite the bullet and remove the disc.:mad:
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I had an AA do that, first the fingers are well depressed once the PP is tightened up. The issue was the pin in the clutch pedal shaft. Before I pulled the trans for a few pennies I would replace that darn pin. Could be the pin is either broken or badly bent. Just a guess. passing on personal experience.
 
A club member told me that she thought her overdrive unit had a malfunction as when she shifted into low range the car refused to move under its own power. I removed the clutch cover inspection plate and noticed that the center hub had torn away from the disc.
 
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