Clutch advice

[Slappy]

I'm going through a 1950 Cub that my brother-in-law is going to mow with. When I got it I would step on the clutch and try to put it into reverse and the gears would grind - similar outcome for the forward gears, but not quite as bad. I adjusted the clutch pedal for play, but that didn't clear up the problem. Step 2 - I put in a new clutch, disc, TOB (greased and oiled) and pilot bearing (lightly oiled, shaft moves in and out easily), set the clutch fingers to 1.25 inches as instructed here, and readjusted pedal play - tried again - problem didn't go away.

The tractor is re-split now. My question is, can I fix the problem by readjusting the clutch fingers a greater or lesser distance than 1.24 inches? And if so, which way do I move them - toward the front of the tractor or the rear? Also, what would be a good distance change to make on the initial readjustment (I'll make any follow-up adjustments through the inspection hole)?

Maybe the clutch isn't the problem at all and one of you will know what my next step is.

Thanks in advance - Slappy

[BIGHOSS]

Before re-splitting it, did you check the free play of the clutch pedal? Too much play will keep the pedal from going down far enough to disengage the clutch, causing gears to grind.

[Slappy]

Yes.. the clutch pedal was adjusted for free play.

[Eugene]

Yes.. the clutch pedal was adjusted for free play.

Try this clutch pedal free play adjustment.

viewtopic.php?f=1&t=92235&p=731450&hilit=+clutch#p731450

[chuck ma]

Are you waiting after you depress the clutch for 5 seconds or to let the shaft stop spinning? Just a thought check the copper or brass bushing on shaft for burrs. Make sure your clutch alignment tool pulls out without any resistance.
Hope this helps
Chuck

[JohnMihevic]

This is my first post on the Cub forum, but I have read many posts and found them very helpful. I believe my Cub is a 1948. The plate = FCUB, Serial No. 11612. It has the “Electric Starting and Lighting Special Equipment” accessory.

I have been through three iterations of getting the clutch right on my Cub. The last one, I did myself, once I figured out how to split the tractor. I replaced the clutch (351773R91), pressure plate (351760R91), throw out bearing (350921R11) and pilot bearing with OEM parts.

After I got the tractor back together, I could not select any gear from neutral, without grinding the gears. I reduced the clutch free travel to zero and still could not get the gears to stop. With the engine off and rear PTO engaged, I noticed I could turn the rear PTO shaft very easily by hand after depressing the clutch pedal only half way, so the clutch was releasing and not causing the drag. The only thing left was the new pilot bearing which seemed to have enough clearance with the clutch alignment tool. I also soaked the bearing in engine oil for one day and applied grease to the shaft end before putting the tractor back together. My decision was to “wear in” the pilot bearing. I figured it would take a few hours and did not want to put a load on the throw out bearing, and crankshaft bearing with the clutch depressed and the engine running. I decided to rotate the main shaft with an electric motor driving the PTO pulley that I use for my C3 mower. I kept the clutch depressed by wrapping a tow rope around the front axle cross member and hooking it to the clutch pedal. With the pulleys I used, the shaft speed was 1100 RPM. About every hour, I checked to see if the gears would still grind when shifting from neutral. After about 5 hours of “wear in”, I could depress the clutch, wait a few seconds and shift from neutral to any gear with no grinding. After that I set the clutch free travel back to about 1 inch and a gap of 1/8 inch between the throw out bearing and clutch fingers.

A few other things I did for good clutch operation. Previously, no matter how I set the clutch free travel, the throw out bearing would bounce back and forth rattling on the clutch fingers. When I had the tractor split, I noticed that the bearing would rotate very freely in the clutch yoke. I ordered various 3/8 inch I.D. shims, the size of the clutch release yoke pivot pin (McMaster.com has a wide selection). One .047” shim, on the carburetor side of the tractor provided just the right amount of tension so the throw out bearing could rotate but not wobble freely in the yoke. I put the shim on one side only since the driveshaft was a little off from the center of the throw out bearing. The shim put it back in the center. Also, the throw out bearing does not wobble against the fingers with the engine running and the clutch released.

I was told that the OEM pressure plate fingers were adjusted at the factory. When I released the clutch slowly, I noticed a slight chatter in 1st and 2nd gear. I checked the fingers through the inspection hole while depressing the clutch very slowly. Two fingers hit the throw out bearing at the same time, but one finger required further clutch travel for contact. I rotated the adjustment screw on the “low” finger. It took almost ¼ turn to get all fingers to hit together. The clutch chatter is gone now.

Hope some of this info helps,
John M.

P.S. I would not recommend the new automotive type metal throw out bearing that you can buy as a replacement for the graphite bearing. I had one and it became extremely noisy after about a year. I believe the wide clutch pressure plate fingers on the Cub were designed for a stationary bearing like the original. The automotive type bearing is designed to spin and for use with less surface area more point contact fingers.

[Slappy]

Thanks John, that was helpful. I had read some other posts that talked about the pilot bearing being too small for the shaft. I used sandpaper and a dowel and reamed out the bushing somewhat, but was afraid to go too far. I think you have the right idea, it's just going to have to wear in - in the meanwhile it's much better than it was.

Again thanks for the help.