Clutch pilot-bearing seized

Wed Aug 04, 2004 10:40 am

I have a '50 Cub (S/N 103850) that has been in the family since 1958. It hasn't been run in about 15 years because the clutch pilot-bearing seized, effectively welding the transmission input shaft to the crankshaft. The tractor can't be split until this has been broken loose. Anyone have any ideas?

JohnS

Wed Aug 04, 2004 11:01 am

John, you've come up with a good one. The pilot bearing is a brass bushing. It will be difficult, but I would suggest reaching through the handhole cover and spraying some penetrating oil onto it. Due to the pressure plate you probably won't be able to spray it directly, but using an aerosol can with a tube on it you may be able to spray enough to get some on it. Probably will need to replace the clutch disk anyway. Are you sure it is the pilot bushing, and not the pressure plate and disk that are stuck to each other, and the disk rusted to the transmission shaft? You could unbolt the crankshaft from the engine, but it is so heavy compared to the size of the transmission shaft your chances of bending the trans shaft would be pretty high.

Wed Aug 04, 2004 4:59 pm

I'm with John on this one. It doesn't seem possible for the pilot bearing to grab the transmission shaft... and if it did, it shouldn't be difficult to pull the bushing from the crankshaft. On the other hand, the clutch shaft sticking in the clutch disk spline seems possible. In that case, it should be possible to un-bolt the clutch from the flywheel to get the tractor split.

The corrosion necessary to make it stick sounds like a mouse problem. Were both covers in place?

Wed Aug 04, 2004 7:01 pm

I guess I'd better 'fess up and explain a little farther: I know it's the pilot bearing because I was driving the tractor at the time it seized. I was coasting down a long hill with the clutch in and got up to about 30-35 mph when everything locked up as though I'd sidestepped the clutch. The right rear wheel began to spin backwards and it was all I could do to hang on and keep it from getting sideways.

Up until then, the clutch was working fine; and as far as I can tell, it still is. The only other problem with the tractor was very low compression, possibly the result of a poor "overhaul." Of course, after sitting all of these years, it's in need of a complete restoration.

I haven't tried to force it apart yet for fear a damaging the shaft. I wanted to get it to where it will rotate first. It looks to me like if I just take out the bolts and try to force it apart, it's bound to tear up something.

How can I put some serious torque on it with tearing up anything?

Wed Aug 04, 2004 7:35 pm

John,

What are we missing here? What do you base your conclusion on that it is the pilot bushing? There are more likely failures in the clutch and transmission.

With the PTO in gear and the transmission in neutral, will turning the PTO shaft crank the engine?

Wed Aug 04, 2004 7:49 pm

Sounds like you found out why the owners manual has warnings about coasting with the clutch down. I'd be terrified coasting at 30 mph on a cub. Georges idea of reaching through the hand hole and unbolting the pressure plate may still be a good idea, it will let you see a little better, and part of your problem ,may be that the disk has disintegrated. If you can't accomplish anything theat way, your best bet might be to bight the bullet and use a Sawzall to cut the transmission shaft off and replace it after the cub is apart. The transmission shaft is cheaper than damaging a crankshaft or mount of a main crank bearing from the force seperating it.

A couple old wood chisels that you don't want anymore might work to drive in the joint to seperate the halves, but remember about the possible damage. Also I hate to ask a dumb question, but did you remeber to remove the flywheel cover (not the handhole cover) at the rear of the crankcase? They are very difficult to seperate more than about an inch with it bolted inplace. :oops:

Wed Aug 04, 2004 11:01 pm

I'm with John and GW :!: :!:

30 to 35 mph :!: :!: :!: Something else is wrong :!: :!: These old tractors don't like going that fast.

Wed Aug 04, 2004 11:32 pm

I did that same thing on a TO-30 that I used to have. (sold-it)