VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1940 Clutch Adjustment issues

Everyone, I'm having a terrible time trying to adjust my clutch on my 1940 Chevrolet. Clutch is new, Pressure plate refaced and housing rebuilt (It's the original housing), bearing from Chevs of the 40's which I will replace with an original NOS part. (I used the original bearing to make adjustments after I couldn't get the correct ones with the replacement.) Very little wear on the bottom hole of the clutch rod lever, no wear on the rod attached to the lever, clutch fork rod is as new and I have two other rods and all are the same measurement wise where the fingers attach to the release bearing. Fork ball is like new with no wear. When you go to adjust the clutch you have to go to the very end of the adjustment lever to the point the bolt is almost off the rod. At that point you still have 1 1/2" of free play with the pedal. I've searched all the threads and I can't find anything that I have done wrong to fix this. Just to throw it out there, can I adjust the ball out a bit to make up some of the slack? There must be something I'm missing. When I got the car the adjustment was at the end and the clutch was slipping badly. It was of course ruined. So somewhere in its history there was a major issue here. This is just one problem with the car. I have been able to solve everything else. (What a story about the steering box! That's for another day. Thanks for any help.

This describes the same problem I had with my ”˜46 half ton a few years ago. The entire assembly had been installed by the previous owner, but never tested before he passed. Many years later I bought the unfinished restoration project in many many pieces. It turned out that replacement (rebuilt) pressure plate was incorrect. I ordered a clutch kit from Rock Auto for about $100. The part was ordered on a Saturday afternoon and delivered the following Monday morning.
Good luck!

Thanks for your reply. I have two spare engines and the pressure plates are the same in each one. So that part is good. I triple checked everything I have against my spares and everything is the same.

I know these are probably not the issue but sometimes we miss the basics.

Is the clutch disc installed the correct direction?

When the flywheel was refaced I assume that the machine shop removed a similar amount of material from the mounting surface for the pressure plate.

Is it possible that a portion of the clutch linkage was re-assembled incorrectly?

Are the engine and transmission mounts in good condition? Is they are bad the engine and transmission could move when you try to disengage the clutch rather than the clutch linkage moving the throw out bearing.

Is the clearance between the transmission mount and the u-plate within spec and equal to the front and rear? That clearance limits the fore/aft movement of the engine.

Is the new throw out bearing the same height (thickness) as the old one? A small difference there makes a big difference at the clutch pedal.

Hope you can determine what is causing the problem.

Rusty, Thanks for your suggestions. I don't know the history of this car. I was able to get it at a good price and it looks gorgeous. Other than that, everything has been an issue. Yes, clutch is in correctly. Today I'm taking the clutch back out and check the flywheel. I have two here I can compare it to. I went over the assembly of the linkage with the manual and many posts online and I do have it together properly. Mounts are new though they were loose (I couldn't believe it!) Transmission mount also is a NOS part I had here. When I press the clutch pedal down I do it by hand to check the measurement. The new throw out bearing was.010" shorter than the original. I ordered an original bearing to put in. I'll try the flywheel and see what that brings. (I did a test fit with the tranny out with the original bearing and it was like when I got the car. I'm thinking probably the flywheel might be the culprit. We'll see.)

I agree that .010" on the throw-out bearing is not the problem. That is really just normal manufacturing variation for that type of assembly.

I also agree that if you are just using your hand to take up the free-play on the pedal you are not applying enough pressure to move the engine.

While you have everything apart you might want to measure the disc lining thickness. That may or may not be a factor but it is another variable.

I wonder if the clutch arm is bent or the socket is heavily worn. If the prior owner rode the clutch there could be more than normal wear where the fork ends fit into the throw-out bearing.

Let us know what you see with the flywheel.

Rusty, I think it is the clutch disc. Flywheel is good. Everything else is good. I compared my clutch arm to my spares. They are all the same. Same with the ball socket. All the same. I'll know in a few days. Had to stop for a bit. Thanks for your help.

Ok, I have it fixed. Same issue that Rusty had. The clutch I had was not the correct one. It was thicker than spec. Of course you can't adjust the clutch since it pushed on the pressure plate. All in and adjusted to spec. Long journey but thanks for everyone's help. Now to the next issue as it presents itself.

Great to hear that you have everything under control again.

I have not had a disc thickness issue on my ”˜37 but have encountered it on other cars. If you think about the overall leverage ratios in the clutch linkage it does not take much variation in disc thickness to really mess things up. The pressure plate does not move very far to engage and dis-engage the disc. In your case the situation would have improved as the linings wore.

I have become so paranoid due to replacement parts problems that I think I spend more time searching for good parts than I do installing them. That is for almost any vehicle I work on. I always do everything I can to have the old and new part side by side before I start putting things back together

Rusty, You are so correct about replacement parts. This particular car was made the first or second week of production. Lots of little things that are different than a mid year car. On to the next issue.