Farmall Cub

Walk me thru the actual mechanical actions of a clutch.

I still have the grinding sound when stepping on the clutch, (trans in neutral).Engine running.

With the clutch fully depressed (engine not running) the clutch plate is free and will spin easily.
The fingers on the pressure plate are fully depressed.The throwout bearing is fully engaged with the fingers on the pressure plate.

What disengages the shaft to the trans?

Stupid question: with the engine running and the clutch not depressed does the pressure plate (and the fingers) turn at the same speed as the engine? It sounds like when depressing the clutch(engine running) that the shaft from the clutch to the trans is turning and has not released and that I am trying to engage the trans without a clutch.

I can start the engine with the trans in neutral and there is no noise.Only when I try to depress the clutch.

Any advice when I split the tractor?

Neophyte when it comes to the many problems with my Cub.

brazos wrote:With the clutch fully depressed (engine not running) the clutch plate is free and will spin easily.

How do you know this?

brazos wrote:What disengages the shaft to the trans?

The clutch disk is keyed to the transmission input shaft. When you depress the clutch pedal you are moving the pressure plate disk away from the flywheel - thus freeing the clutch disk.

brazos wrote:Stupid question: with the engine running and the clutch not depressed does the pressure plate (and the fingers) turn at the same speed as the engine?

Yes. The pressure plate is bolted to the flywheel and both the flywheel and pressure plate turn at engine speed (RPMs).

brazos wrote:It sounds like when depressing the clutch(engine running) that the shaft from the clutch to the trans is turning and has not released and that I am trying to engage the trans without a clutch.

Several causes for this. Worn out throwout bearing. Pressure plate fingers not adjusted properly. Worn or torn clutch disk lining. Pilot bearing freezing or frozen to transmission input shaft. And possibly damaged mechanical linkage.

brazos wrote:I can start the engine with the trans in neutral and there is no noise.Only when I try to depress the clutch.

Same symptoms and same possible causes as described directly above.

brazos wrote:Any advice when I split the tractor?

Spend some time looking over the service manual and search this board for help on safely splitting the Cub.

I used a ratchet strap and tied the clutch down, looking thru the inspection port, I can freely spin the clutch plate. It seems to spin freely not moving any other part or shaft.

Brazos,

The pressure plate is bolted to the flywheel, which is bolted to the crankshaft. So engine. flywheel, and pressure plate are turning as one unit.

Now the clutch plate is splined to the transmission input shaft, so if clutch plate (disc) turns, so does the input to the transmission.

The workings is that the pressure plate "squeezes" the clutch disc between itself and the flywheel, with a huge amount of force. When "squeezed", the clutch disc becomes one with the pressure plate/flywheel/engine combination discussed above.

When you depress the clutch pedal, the throwout bearing "opens up" the gap between the pressure plate and flywheel (via the fingers), to allow the clutch disc to spin freely again.

It sounds like your disc doesn't quite spin freely. Several possible causes, most in Eugene's response.

- fingers out of adjustment, so pressure plate doesn't open up completely. Look up posts on how to set fingers.
- clutch free play in the pedal not correct, also causing pressure plate to maintain slight pressure on clutch disc.
- pilot bearing, which guides transmission input shaft into the center of the crankshaft, might be "dragging" on the input shaft, which gives same effect as if clutch disc was dragging.

If you are going to split, be prepared with a new pilot bearing. The easiest way to remove old pilot is with a tap, look up this in posts as well. My bet is on the pilot bearing, as I've seen several cubs with this issue, and have one right now. However, it truly could be any of the above.

I don't mean to insult your knowledge, just find that straighforward explanations work best for me. Research all the posts available on splitting/servicing the clutch. It's not that big a mystery, it is easier with two people, and re-aligning all the pieces can be a bit tedious. Be sure to use an alignment tool when putting the clutch disc back in, and pressure plate back on. Keep us posted on progress and findings.

brazos wrote:I used a ratchet strap and tied the clutch down, looking thru the inspection port, I can freely spin the clutch plate. It seems to spin freely not moving any other part or shaft.

I assume this is the 1952 Cub purchased in Missouri. Have you been able to drive this Cub?

The clutch disk is splined to the transmission input shaft. With the clutch pedal depressed and the transmission in neutral - when you spin the clutch disk the transmission input shaft "should" spin. With the clutch pedal depressed and the transmission in gear, the clutch disk should not rotate.

From the description, either the center of the clutch disk has broken out or the splines in the clutch disk or the splines transmission drive shaft (perhaps both) are stripped.

In any event. I think it's time to split the tractor and locate the problem(s)

It sounds as though the throughout bearing is hitting the fingers on the pressure plate when you depress the clutch all the way. Is it a loud ticking noise and can you feel it in the pedal. It may just need to have the fingers adjusted, the T/O bearing can also be worn down thin.
Boss

With the blessings of the other half of this marriage(she thinks it will reduce my stress level ) I have decided to take the tractor to a local shop (oldtimer who repairs tractors--not a dealer) and have the clutch,pressure plate,bearings etc replaced. I just don't have the correct equipment etc to split the tractor and be able to move it apart safely.
The clutch plate does move with the shaft ,I just wasn't looking close enough.

Thanks for the help, at least now I know what to look for and what to have replaced. Thought it was best to replace everything connected with the clutch system.

Will let you know how things turn out.

Brazos

Seems as good a time as any to post my first message... as I discovered over the weekend, while replacing the clutch on my grandfather's '48 Cub - with the tractor all apart - the rear main seal is right there with the pilot bearing. In my case, the tractor hasn't started in 45 years, so the seal's likely dried out. On your tractor, it may make sense to do it too. But, I've just learned that the original seal is unavailable and requires either engineering (i.e. silicone, etc) or replacement of the housing for $150. I'm going to try a local bearing company today to see if they have a recommendation/cross reference. Thought I'd mention this to you, since you're paying out of pocket to have someone repair - it would be a shame to either have him/her put it back together and then discover it leaks - or, almost worse, be waiting forever to get your tractor back while waiting for a part to arrive. I don't think this is an example of "going overboard," as you can do with any project, but simply warding off Murphy's Law.

I'm going to spend some more time today researching the archives for info on the seal. Unless someone has recent information about a replacement seal?!

The original seal O. D. is about .003 larger than the replacement seal that you can get today. You have about a 50/50 chance of gluing it in the housing and having it work without leaking. (I know).

The best repair is to contact Rick at Kubkraft.com (one of the site sponsers). Rick remachines the housing and installs an oversize seal for a fair price.

The one problem is that Rick is shutdown right now while he expands to a new shop. Rick does excellent work, which leads to continued sucess and the need of a larger facility. (his former shop was very small)

I do not know if anyone eles is doing this machine work, rumor was that someone else was doing this in the mean time.

Mark

Son----

Welcome to the Cub Forum.
A great place to gather and share info on/about cubs.

Seem you have already picked up on several good points.

Keep us posted on how your tractor is going.

brazos wrote: I have decided to take the tractor to a local shop (oldtimer who repairs tractors--not a dealer) and have the clutch,pressure plate,bearings etc replaced. I just don't have the correct equipment etc to split the tractor and be able to move it apart safely. Brazos

Brazos, Very nice post.

These clutches can be a real nightmare!
Be careful about giveing carte blanche to a repair shop.
Some of those parts might be just fine and do not need replaceing.
IE, the pressure plate. It may need adjusting only.

Good luck and keep working on that Cub.

Just so I know ,doesn't the throwout bearing contact the fingers in order to release the clutch plate?

The sound I hear is exactly like you described, something hitting the fingers.

Right now there is about 1/8 of an inch gap between the throwout bearing and the fingers. What should the correct gap be?

I can't get it to the shop until Wed so I have time for one more attempt to fix it. It runs and was driveable although it acted like the clutch wasn't quite releasing, as the gears would grind when I put it in gear. Then for no apparent reason it really started grinding and stepping fully on the clutch would kill the engine.

thanks

Brazos

If you hear a "clackety-clack" sound when you press your clutch, it does sound like you may have a problem with finger adjustment and pedal free play adjustment.

Your clutch fingers can be adjusted with the tractor together, but it is SO much easier with the tractor apart. If you can get under the tractor to look through the hand-hole in the bell housing, you should be able to measure the distance between the surface of the clutch finger to the backing plate on the pressure plate. It is supposed to be 1.25"...if yours is less than that, the throw out bearing can hit the mounting for the fingers and will cause the clacking. That clacking is causing damage to your throw out bearing as well as your pressure plate, and needs to be adjusted and corrected before much more expensive damage occurs...

Mike in La Crosse, WI

My current thought is that the throwout bearing is worn out, permitting the side of the throwout bearing to hit the pressure plate fingers. And/or not allowing the pressure plate to sufficiently release the clutch disk.

The throwout bearing is a solid carbon piece. This carbon piece wears out.

In any even it still calls for splitting the Cub.

Eugene and everyone else who has sent tips:

I just went out and did a quick inspection and can see where the bracket that holds the throwout bearing is hitting the fingers. Thus the clackety clack noise.

Just as a guess it appears the fingers need to be adjusted further out and the clutch linkage pulled back or shortened.

Tomorrow I will attempt to adjust both the fingers and the clutch pedal linkage and see if that helps, if that fails I can always take it to the repair shop.

Thanks,Brazos