59 Cub LoBoy Clutch Explodes!

[CharlieK]

careful about lifting the front of the cub with a jack under the oil pan

[Glen]

Before splitting a Cub, or LoBoy, you need to put wood wedges in at the front axle pivot.
They are heavier on the left side, and they can tip over when splitting them, or removing heavy parts of them from the rear, without wedging the front axle pivot.
Below is a pic of the wedges, you will need to make them.
Hammer them in tight, and be sure they aren't hitting at the small end.
They should be tight on the top and bottom sides.
They don't have to be cut at so much of an angle.
Check them some during the work to be sure they don't come loose.

The 2nd pic below shows where to measure the finger height of the pressure plate.
The clutch has to be fully assembled on the flywheel to measure the height, not off like the pic is.
The finger height changes when the pressure plate is bolted on the flywheel.

[DonMountain]

I got the Cub split this afternoon with much help from my Wife. It rolled apart pretty easily actually, after some lubrication and jack work up and down and some screwdrivers to slide in the gap that appeared between the bell housing and the engine block. After removing the clutch pressure plate from the flywheel, along with the clutch friction disk, and the throw-out bearing I inspected all of it closely. It was clearly a failure of some sort. Although I am not positive what caused the failure. I believe that one of the clutch fingers cracked probably first, before the chunk was gouged out of the carbon throw-out bearing. It appears that a crack was initiated in the threaded hole of the pivot bolt and extended up to the oval cutout in the middle of the piece and down to the fold in the metal at the outer end. It kind of got twisted out of shape and damaged the throw-out bearing, which was pretty much covered in oil/grease. So, I guess I better get some parts ordered.

Don

[Jim Becker]

Don't use feeler gauges for any operation reasonably calling for a pry bar. Let it down a little to get the small gap at the bottom. Then stick a small screwdriver into each side of the gap. jack it up enough to get a slightly wider gap at the top. Get 2 more screwdrivers and repeat until you get enough gap so it can be pried apart.

[DonMountain]

Don't use feeler gauges for any operation reasonably calling for a pry bar. Let it down a little to get the small gap at the bottom. Then stick a small screwdriver into each side of the gap. jack it up enough to get a slightly wider gap at the top. Get 2 more screwdrivers and repeat until you get enough gap so it can be pried apart.

Thanks Jim. And this is exactly how I ended up getting it apart. Once I got it out about 1/8" it pried right out with ease and stayed lined up as we pulled it apart to avoid flexing the rear shaft to the transmission. I ordered parts and I am going to spend today cleaning things up and going through the complete lubrication schedule while I am waiting. Its been 4 or 5 years since it was run and the gas I siphoned out of it looked orange in color. I used some of it for "washing" grease off of things, but what should I do with the rest of the 3 gallons that was in it? I surely don't want to put it in anything else to run?

Don

[DonMountain]

The 2nd pic below shows where to measure the finger height of the pressure plate.
The clutch has to be fully assembled on the flywheel to measure the height, not off like the pic is.
The finger height changes when the pressure plate is bolted on the flywheel.

So, if I have to adjust the finger height, does anybody know what torque is required on the locking nut? And what method of measurement is precise enough to avoid vibration? A by-eye measurement with a machinist scale doesn’t allow good comparison of the three fingers since the upper surface is rounded? Maybe a flat plate sitting on the fingers with holes drilled just off the inner curve of the finger for a dial caliper rod to get to the bottom plate? How precisely do these fingers need to be set? (All this after mounting to the flywheel of course)

Don

[Peter Person]

Don,
While you have the back of the engine exposed, it may be worth replacing the rear main seal. Tim (tst) has them on the shelf ready to go. Send your old one to him. He usually has an ad in The Vine.

[Glen]

So, if I have to adjust the finger height, does anybody know what torque is required on the locking nut?

Hi,
I tighten them firmly using a box end wrench. You probably need to hold the adjustment screw in place with a screwdriver, to keep the screw from turning, while tightening the lock nut on each adjustment.
They have said on here always check the finger height after putting the pressure plate on the flywheel, new pressure plates often come with the fingers set to the wrong height for a Cub.

How precisely do these fingers need to be set?

They should be so they make a flat surface for the throwout bearing to push on.

[Gary Dotson]

With the Cub split, all you need is the dial or digital caliper to measure the finger height.

[DonMountain]

Somebody sent me the web site for the Blue Ribbon Service Manual for the Farmall Cub, and in one of the first pages there was the torque specs for all the different sizes and grades of bolts. And looking at the 5/16" Type 1, studs only column I see a torque of 12 foot pounds called for as a minimum and 13 foot pounds as a maximum. Just as a trial, I took my torque wrench and set it to 12 foot pounds and mounted an open-end wrench socket, allowing me to insert an allen wrench in the stud to hold it, and cranked the nut to 12 foot pounds. Which was a lot more force than I could have tightened it with a small wrench through the hand hole. So, anyway, now I know what it takes to keep these studs from coming out of the clutch fingers. Maybe I should also apply some thread locker to the nut before torquing it down?

[DonMountain]

Success! I got the Cub LoBoy all back together, after rebuilding the carburetor plus the clutch job and it seems to be operating correctly now. The generator is even working after I discovered the ground wire was broken off the regulator, and I replaced that too. The clutch adjustments worked out well and it seems to be disengaging the gearbox from the engine smoothly and completely with the proper settings.

Don

[CharlieK]

another good ending

[Glen]

Hi,
Good that you have the LoBoy working again

[Urbish]

If you can get a gap opened up, you can drive hardwood or aluminum wedges in to separate the two halves. You can also use a jack to raise and lower the separation point with thin wedges or shim stock in between and it should wiggle apart if you introduce progressively thicker material into the opening gap while raising and lowering.