Clutch Problem

Roland:

Sometimes you just have to take everything apart and carefully inspect everything. I would inspect the clutch disk carefully. According to Les Andrews' book the thickness should be a nominal .340". Check the outside diameter and the diameter of the inner metal hub to make sure nothing is binding. You may have a disk that is not correct for a Model A. If you are using the original Henry clutch set-up check the dimension of the flywheel step the pressure plate sets in. The measurement should be 1.123". If the clutch surface has been machined a number of times the dimension may have been lost. Check that the springs in the clutch disk are not rubbing the heads of the flywheel mounting bolts. This is caused by a flywheel that has been resurfaced too many times. You can sometimes grind the heads of the bolts down somewhat to provide clearance. If you are running a V-8 clutch set-up there are other things to look for. See the article on V-8 clutches on the "tech Articles" page at www.ocmafc.org.

Hope you find the problem.
Tom Endy
 
Tom:

Thanks for your comments. I will check all items carefully when I get it apart and report back at that time as to findings. Hopefully I can help someone else avoid problems. As posted above, the clutch disc was purchased from Mac's in Lockport NY. It is a Model A setup, not V8. The flywheel clutch was machined and the dimension of the step was supposedly held at 1.123". At this point, however, nothing can be taken for granted.
 
I don't understand: "The flywheel clutch was machined and the dimension of the step was supposedly held at 1.123". ".....
Paul in CT Is disc installed correct way?
 
When you have it apart put the disc on the trans, spin it and check how much the disc wobbles --runout, perhaps the disc is bent.

A bent disc hub can give you a dragging clutch and still have full engagement with the pedal quite high.
 
To 1931 Flamingo: I'm pretty certain the disc was installed the right way. I recall checking this at the time of assembly to be sure it was on correctly but as I said, at this point I can't take anything for granted.

To Kurt in NJ: You made a good point about a bent disc or hub. It is something I hadn't thought of.

Thanks to all for your interest.
 
Are you sure you installed the clutch disc properly and not reversed ? You should have 1" free play at top of pedal to be sure the throwout bearing is not running and should not engage until you come out about 1' off the bottom.

You probable have checked these things but don't hurt for me to mention them.

Ron
 
I had the same problem on a 28 fordor, i pulled it all apart and the clutch was installed backwards. I am still getting ribbed for that mistake 20 years ago.

Mike
 
Today I took the transmission and clutch apart. I did not find anything that would account for the problem. The clutch disc was installed correctly. It was stamped "flywheel side". It ran true when rotated on the spline without wobble. It did not contact the flywheel retaining bolts. It slid freely on the spline. The thickness of the disc is .400". I have purchased a Disc from Fort Wayne Clutch for backup. It appears identical to the one that was in the car except it is .385" thick. I have not yet checked the distance from the clutch mounting surface to the friction surface on the flywheel so I will do that when I am able to get back to the project.

The transmission shaft spins very freely with lube drained from the ******. I was looking for more drag here but without lube, it"s hard to tell.

It is not clear to me what force causes the disc to back away from the flywheel when the clutch is released. Can anyone explain this to me?

Again, thanks for any help you may offer.
 
No special force moves the disc away from the flywheel, but when the pressure plate isn't clampping it tight, it should just float between the flywheel and pressure plate surfaces. The 600W oil should help stop the movment. After driving my A for a few miles and getting the ****** oil warmed up, when stopped, it takes about 10 seconds or so after the clutch pedal is pushed in before I can shift into first without grinding. I use Mobil 636 gear oil.
 
Hi, I have had some trouble grinding gears and was told to slow down the idle. It worked. The 600 W trans gear oil from MACS sold today is not the 600 of yesteryear, read the label. I hope this helps. JIM.T.
 
I last posted about this issue on 9/29 after I had dismantled the clutch and transmission. I was out of town for a while and got back to work on it 10/12. A close examination of the clutch disc splines revealed a residue on one spline surface that first looked like a bit of rust.

When I assembled the flywheel, clutch and transmission, I had the engine on the stand in a verticle position so I could use a hoist to lower the heavy parts onto the assembly. I put a drop or two of loctite on the part of the transmission shaft that inserts into the pilot bearing to insure that the shaft would not rotationally slip in the pilot bearing when the clutch was disengaged.

After assembly, I tilted the engine back to the horizontal position in preparation for assembly into the chassis. Evidently, the loctite had not set and a small amount ran down and back into the spline, locking it so the clutch disc was held against the flywheel and not able to float between the flywheel and pressure plate.

The splines were cleaned and the transmission was was reinstalled and now the clutch operates normally. Loctite was not used in the re-assembly.

Thanks to all for your interest and comments about this issue.

Roland
 
i am not sure exactly what you mean about the use of the loctite to stop the input shaft from turning in the pilot. all i ever use is a little grease on the input nose at the pilot. anyway glad your up and going now
 
Roland, I have been following you post about the clutch problem with great interest. Reason being I got my engine out getting rebuilt and when I get it back I don't want to have the same problem. Way to much double work involved to have to pull it all apart again. My question is WHY the lock tight? I never heard of that. Best of luck and glad the problem is fixed. Must say very interesting post.
 
Bearings mounted on rotating shafts are usually designed so that they are a shrink or press fit. This prevents rotational slippage between the shaft and bearing inner race. When there is clearence between the two, this slippage causes wear over time. This is considered acceptible in automotive design practice for the pilot bearing only since most cars are not expected to run as many miles as our model A,s. The more clearence, the faster the wear occurs. My input shaft was a few thousands undersize but not enough to consider a sleeve or welding up and remachining. I thought the loctite could help prevent the movement and reduce future wear.

As Mitch//PA points out, a lubricant on the nose of the shaft also can help prevent wear at this point even though the slippage continues to take place.

Roland
 
Roland/Pittsburgh said:
Bearings mounted on rotating shafts are usually designed so that they are a shrink or press fit. This prevents rotational slippage between the shaft and bearing inner race. When there is clearence between the two, this slippage causes wear over time. This is considered acceptible in automotive design practice for the pilot bearing only since most cars are not expected to run as many miles as our model A,s. The more clearence, the faster the wear occurs. My input shaft was a few thousands undersize but not enough to consider a sleeve or welding up and remachining. I thought the loctite could help prevent the movement and reduce future wear.

As Mitch//PA points out, a lubricant on the nose of the shaft also can help prevent wear at this point even though the slippage continues to take place.

Roland
Click to expand...

roland not trying to bust your stones but i think i understand better now that you were locktiting the nose of the input shaft to the inner roller bearing cage of the pilot. i never heard of doing that before to stop wear between the two. also what about crankshaft end play that would create in and out movement of the pilot on the input shaft. there is expansion and contraction from heat of the 2 components. i dont think you will have any kind of wear problem. am glad you got it going alot of extra work though just use grease next time. IMO..
 
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