pilot bushing too tight?

[brewzalot]

Started my '61 for the first time after total restoration, good news she fired right up, only a few minor issues I should be able to work out.
Bad news however I have the classic drive shaft still spinning when the clutch is engaged syndrome. Gears and pto grind when trying to engage them.

Clutch is new, adjusted, and working fine otherwise.
Pilot bushing is new, I did put a dab of grease in it at assembly(not enough?), and I don't believe the drive shaft is bent. Worked fine before tear down.

I would like to try Johns approach below of "wearing in" the pilot bushing only with a different , safer twist.

If I make an adaptor arbor for a drill so I can spin the pto shaft, and with the tractor engine OFF, pto engaged, clutch tied down (fully engaged), gear shift in neutral, spin the pto shaft with the drill until it "frees up" the drive shaft. Will this have the same affect as John's approach?

My thinking is this way there would be no wear on the TO bearing(flywheel is not turning) and I can spin it as long as needed, very safely. Not to mention not having to split the tractor .

Thoughts? thanks, Tim


Postby John *.?-!.* cub owner » Wed Feb 25, 2015 10:49 pm

I had a similar problem with a cub I put a combine engine in. The pilot bushing had never been used, and it had just enough drag in the pilot bushing it was hard to shift. With the clutch down I could turn it using the pto shaft, or with a wheel jacked up, but it was stiff. After doing that for a while and no noticeable change I took a different tactic. I chained it to another tractor (brakes locked and in gear) and pulled the chain tight, then tied the clutch down and put troubled cub in 3rd gear. I then started the troubled cub and let it set there and idle for several minutes. My reason for using 3rd gear was that if the shaft bound up in the pilot bushing it would not have enough torque to drag the other cub backward. After about 10 or 15 minutes all was well.

[challenger]

I am trying to figure out this issue. Was John's approach used to make sure the drive shaft bearings got lubed during the wear in? Otherwise, I see no reason to jack up the wheel to 'wear in' the bushing. I would fashion a belt or rope around the pto pulley and tie it off somehow to prevent the pto from turning. Then I would engage the pto shifter and start the tractor in neutral and let it run.

One more thing I forgot, you will need to tie the clutch down for this to work.

[brewzalot]

The way I'm seeing it- we are both doing the same thing. Only Johns way is holding the drive shaft still and spinning the flywheel where mine is holding the flywheel still and spinning the drive shaft- without the tractor running.

I'm mostly trying not to wear on the TO bearing anymore than I have to. With the engine running and clutch engaged that is not possible.

[challenger]

You're right. It is just the same approach from the opposite direction. Take your pick!

[Criswell]

Clutch is new, adjusted, and working fine otherwise.
Pilot bushing is new, I did put a dab of grease in it at assembly(not enough?), and I don't believe the drive shaft is bent. Worked fine before tear down.

What was the ID of the bushing after installation? Page 25 of the GSS-1008 Specification Manual lists the ID after installation as 0.626" to 0.627", pressing in the bushing will cause it to deform. More than likely it should have been reamed to size after installation.

[Smokeycub]

I sincerely hope that one of the two approaches solve the problem. There will be considerable drag on your drill I would think, depending on how much resistance there is.

Clutch is new, adjusted, and working fine otherwise.

How does the clutch pedal feel when the tractor's running and when you depress the clutch? If the pedal throbs or pulses under your foot then the fingers on the pressure plate need adjusted. The clearance between the face of the TOB and the fingers on the pressure plate should be 1/8". How's the free play at the pedal? There needs to be about 1" of free play before the TOB engages the pressure plate.

[John *.?-!.* cub owner]

I am trying to figure out this issue. Was John's approach used to make sure the drive shaft bearings got lubed during the wear in? Otherwise, I see no reason to jack up the wheel to 'wear in' the bushing. I would fashion a belt or rope around the pto pulley and tie it off somehow to prevent the pto from turning. Then I would engage the pto shifter and start the tractor in neutral and let it run.

One more thing I forgot, you will need to tie the clutch down for this to work.

My approach was due to the fact I had installed a combine engine, and of course the pilot busing had never been used, and it was a little tight.

[brewzalot]

I see no reason to jack up the wheel to 'wear in' the bushing.

John only did this to test it not do the procedure I believe .

What was the ID of the bushing after installation?

That is a very good question- too bad I don't have a very good answer as I did not measure it. I did dab it with grease and tried the shaft in it before assembly, if I remember correctly it felt ok at the time. Not much problem putting tractor halves back together.

How does the clutch pedal feel when the tractor's running and when you depress the clutch? If the pedal throbs or pulses under your foot then the fingers on the pressure plate need adjusted. The clearance between the face of the TOB and the fingers on the pressure plate should be 1/8". How's the free play at the pedal? There needs to be about 1" of free play before the TOB engages the pressure plate.

I made a jig similar to the one in the service manual for adjusting the clutch on the bench. Everything was assembled to exact measurements, the clutch pedal has the 1" free travel, 1/8" clearance at the TOB. Clutch looks good from below, and works fine for stopping-just doesn't shift into gear or pto engage without grinding. Everything I have read here points to a bent drive shaft or pilot bushing. Looking at the clutch from below I had my wife spin the pto, drive shaft seemed to spin very true. I didn't realize if you line up the clutch and the clutch disc just right, you can see the pilot bushing very well, I can see grease around the shaft there so I don't think its too dry, just too tight. Grease can take up more space than oil- I wish now I would have just oiled it.

I was able to run the pto with a 1/2" drill today. Worked really well and less resistance than you would think. I ran it off and on all afternoon- but with 40 mile/hour winds, sleet, and now a manifold stud sprung a leak, I couldn't take it out and give it a good test . Will let you know the results when I do.

Tim

[Smokeycub]

works fine for stopping

Sounds like you started it up in gear. I almost suggested you try that but thought the tractor may be in a bad spot to try that. Just curious, did the clutch pilot tool have trouble fitting in the pilot bearing? Sounds like it just needs "worn in".

My thinking is this way there would be no wear on the TO bearing(flywheel is not turning)

I personally wouldn't worry too much about that. Properly adjusted, etc., the TOB endures many hours of being engaged in it's lifetime.
Hope it works out!

[brewzalot]

Sounds like you started it up in gear

Once I realized what was going on (I have to admit I did grind her a couple of times into gear- I know, I know) I started it and left it in gear. Played around after that with just stopping and starting to make sure the clutch functioned good otherwise.

Just curious, did the clutch pilot tool have trouble fitting in the pilot bearing?

.

I didn't have one, I used the drive shaft itself to line it up, I thought it went in ok- the 2 halves went together well too, so I don't think I " boogered" up the pilot bushing, but then I cant rule out anything at this point. I wish as Criswell asked that I had measured it but at the time this wasn't on my mind. I thought the dab of grease would take care of it.

I had to put a threaded insert in a PO's badly messed up, and now leaking, manifold stud hole tonight (hole was re-threaded way crooked, stud was then bent "straight", I retrieved the end of broken tap laying just inside the hole with a magnet) waiting now for sealant to cure on new stud. Hopefully I'll get to play around tomorrow after work.

thanks for all the replies so far.

[brewzalot]

Took the tractor out again tonight, same symptoms only this time the more I ran it the worse it got. Got so bad that if I just sat still with the clutch in, it would slowly start moving and could not stop it , even with the brakes. Figured it was time to park it, backing it in the shop I heard a high pitch squeal like metal on metal just before I shut it off.

Had the little misses spin the pto while watching the pilot bushing...confirmed my fear that squeal was the pilot bushing now spinning in the bore (at least I think that's what I was seeing- squinting, and looking with one eye through my new bifocals). Unless someone has a miracle cure for that without splitting the tractor, that's what I'll be doing. Will update when I get in there-obviously "running it in" in this case wasn't the answer.

On a high note, I got my coolant leak fixed and the governor surging stopped. She goes from idle to full throttle like a dream.

Tim

[brewzalot]

I got my tractor split late tonight- clutch looks good but the pilot bushing and end of shaft burnt/dry. The last 1/8" of the drive shaft is rubbing hard on whatever is behind the pilot bushing? The shaft end looks like it was chamfered with a coarse file. I'm confused on what is going on-the step in the drive shaft is 1 1/2" long that goes into the pilot bushing . I put a measure through the pilot bushing to where it is rubbing and that measures 1 5/8" to the front of the pilot bushing. To me that says the drive shaft cant move forward, something behind the pilot bushing is moving backward in order to rub?

Need help on this one- will post a pic in the morning, just wanted to throw this out tonight in case anyone has seen this before or can help.

thanks,Tim

[tst]

Was the imput shaft removed from the transmission?, the material behind the bushing would be the back of the crankshaft

[brewzalot]

No, the transmission was left completely together along with the drive shaft. That's why I cant figure out what changed. Even if the drive shaft moved forward out of position , it should rub on the shoulder of the shaft before the end against the crankshaft? Unless the pilot bushing slid forward at assembly and pulled back again when I split and that's throwing off my measurements. It was a little hard to get them apart, but I thought that's because it was dry and galled up some.

When I lay a straight edge across the face of the torque tube the drive shaft sticks out past flush about 1/8". Would that be right?

[Eugene]

Years ago, B Farmall. Aftermarket pilot bushing was to tight. Purchased the pilot bushing from IH, perfect.