Clutch Repair Kama 554

[greg_g]

It would be a waste of machining time Rob. Wait until either you get the old clutchpack on the bench, or until a new one arrives - whichever occurs first. You'll quickly see what I mean. Bolting in the clutchpack doesn't compress anything other than holding the PTO friction disc against the flywheel. It's adjusting the stack height that puts tension on the Belleville springs. And - for me - that's most easily done on the bench, with a piece of plywood simulating the flywheel surface (for measurement purposes only).

There are six nuts to adjust; three for the main drive pressure plate, three release fingers. First thing to do is insert the flywheel bolts to line up the holes. Then gap the main drive first, adjust the fingers last. When the stack height is to spec, the fingers are supposed to be on a level plane. Replace pilot bearing. Install clutchpack on tractor. Verify stack height. Replace TOB (and seat if necessary). Reassemble tractor. Adjust clutch linkages. Go back to work. The only way this particular pooch can be screwed, is if there's an indentation for the PTO disc on your flywheel fact. If you encounter that, it's still a simple matter of a few correcting turns on the 3 finger nuts.

Oh, there are three external linkage adjustments by the way; (1) neutral gap between fingers and TOB face, (2) pedal play, (3) pedal stop

//greg//

 

[SPYDERLK]

Rob, without knowing your clutch I have to resort to just knowing how things have to work. All the procedures are made up so you dont have to understand what you are trying to accomplish in order to accomplish it. The ultimate aim is to have the assembled system apply even force to the clutch plate when they are engaged and while they are transitioning between there and disengaged. To do this the fingers must come out even when its all bolted on the flywheel and each finger should be working against an equal preload resistance in the segment of the clutch circle it controls. If not the tob will experience a cocking force as the clutch operates. Assess your procedure on this basis and you cant come out wrong.
larry

 

[3RRL]

Those last 2 posts are very reassuring to me and make sense to me now.
Especially since I took the clutch apart today. (I got up here 1 day early)
It was an intimidating thought to split the tractor and tackle the clutch repair since I'd never done it before. Once I got it apart though, I got the feeling it's not that hard to do after all. And what you guys said now means something to me since I got to "see" how it all bolts up and works. I have a couple questions later about setting the stack height, but for now I wanted to show some pictures of the clutch pack dis-assembled. I labeled them all.

You can see there is no bluing or warpage on the clutch components. In fact, the main clutch was only slightly worn down and you can still see the original marks on the PTO clutch (close up). The main clutch measures 8.89-8.915mm and the PTO clutch measures 9.144-9.169mm.
What is the thickness of the new clutch?

I've decided to get new clutch plates from Chip for sure, but I can't any wear on the pressure plates or disc springs at all, so I don't think I need them. You can still see the Blanchard grind marks on the pressure plates, so I figure they are good.
What do you think?



The parts that are trashed are the fingers. So I will get new ones for sure. The other part that's trash is the throw out bearing. It's frozen and I need a new one. I pressed it off the bearing seat, which is still perfect.
My guess is somehow the throw out bearing got frozen and that's how the fingers wore out.

 

[SPYDERLK]

Maybe there are high quality TOBs that size available?

 

[3RRL]

While I was at it, I also got the 4wd shaft completely out and cleaned. Got new "O" rings ready to install upon the re-assembly.
I might paint it first?

 

[greg_g]

Thickness on a new friction disc is 9.4mm, but for purposes of calculating stack height - I rounded it up to 10mm. Anyway, you got a lot of life left in yours - but the PTO friction disc looks a bit shiny. The main drive friction disc is a bit shadowy in the other photo, but it's probably slick too. You can have a clutch shop rough them up without losing too much material, or maybe just consider a quick and dirty yourself on a wire wheel. Just make sure you keep them clean & dry. Water is bad on them, grease/oil is even worse.

I could find no readily available crossovers for that TOB, both my tractors coincidentally use the same bearing. Different pilot bearings, but same TOB. I think some older Renaults used it, but you know the odds of finding French car parts in this country. So there's really little choice but to get another OE from Chip. Note the little hole in the side of the bearing case. That's where you should have been pumpng in grease with a needle gun. If you can't find the hole right away, it might be plugged flush with clutch dust and/or metal shavings.

Besides the fact that nobody'd see your paint on the driveshaft, I'd be concerned that it would eventually decompose and swell - presenting even more difficulties when you need to remove it next time. Instead of paint, I'd recommend grease - especially on the splines beneath the coupling collar and in the front splined flange.

On the picture of the finger before removal; the lock nut is missing. There should be a silver colored one (17mm wrench) on top of the beveled black one (9/16" wrench). And the bottom bevel on the black one looks damaged. You might see if Chip has three new black ones. If not, turn yours upside down for reassembly. It should be beveled top and bottom.

Speaking of reassembly, note the six compression spring seats. The three at the base of the release fingers are a different depth than the other three. Align the pressure plates so that the shallower three holes are under the fingers. If those pressure plates are rotated one notch off, you'll never get the correct main drive clutch gap.

//greg//

 

[Brad_Blazer]

My parts book shows the TOB as a 9688213. Is that correct? I can check with the local bearing supplier to see if they can get one. They are pretty good at getting diverse bearings.

 

[GuglioLS]

Rob,

For the hours you have and the amount of work you've done, the old clutch disk look to be in decent shape with quite a bit of life left in it, however without seeing a new one to compare it to it's hard to judge how much wear it has really sustained. That clutch pack is massive, I bet it's heavy too. The fingers must be pretty soft compared to the throw out bearing for them to wear out like that. I wonder if it be worth getting the new ones heat treated?

I think the trick getting it back together is going to be getting the two clutch disc's perfectly centered to the pilot bearing, then getting the main shaft and PTO shaft splines to all line up at the same time as you side the two halves back together, not only that you got to deal with the front drive shaft splines at the same time. I suppose you could engage the PTO lever then turn the output shaft until the splines line up, maybe somehow do the same thing with the transmission so that shaft mates with the splines as well? It's going to be tricky. They always come apart much easier than they go back together. It doesn't look like your going to need very many parts for the repair so that's not bad.

Is the Throw out bearing a sealed bearing? or can it be user lubricated? I see a grease fitting at the back of the input shaft to the transmission what's that one for? I would think there is gear oil on the other side of that bearing and the grease fitting is redundant?

Man I sure would take Brad up on his offer to try and find a higher quality bearing.

Larry

 

[Rich Waugh]

Larry,

I don't think that there would be much joy in trying to get the clutch fingers heat treated. No good way to do that unless you know the exact alloy they're made of. Without that information you'd have to first do a spectro analysis on them to get the makeup and then go from there for the heat treat. It would be both time consuming and expensive, I'd think, for not much gain.

The working pressure on those fingers isn't so great that ordinary mild steel wouldn't work fine - the issue is that Rob's TOB siezed up and rubbed on the fingers, friciton heating them to red heat or thereabouts. At those temps, heat treating would do you no good unless they were made out of H-13 or some similar hot-work alloy. Any regular 10XX-series carbon steel would lose its heat treating toughness at temperatures in excess of about 500F.

With a new TOB that spins freely, the new fingers should do just fine as delivered. I had the same thing happen on my old S-10 pickup years ago and pushed the TOB right through the diaphragm fingers once they got up to red hot. That. fortunately, was much easier and cheaper to fix than a tractor clutch.

Rich Waugh

 

[greg_g]

9688213 is correct, I''ve got two of them on my spare parts shelf, the number is stamped right on the bearing. Dimensions are 102 x 65 x 23mm, greasable.

But I went through this already. My dealer told me he was unable to find an aftermarket bearing, and had no choice but to sell OE. I wasted a whole lot of time thinking I could do better. Stopped in half a dozen area bearing shops, with old bearing in hand. Asked for both sealed crossover type and greasable OE type. All I got were blank stares. Phoned maybe a dozen suppliers from Virginia to California. Even though I provided the bearing number and dimensions, everybody came up dry. No online (retail) sources either. Whereas your part of the country may be different, nobody I contacted could source it for me either. I went back to the dealer, hat in hand.

So my logic is that - if a greasable 9688213 is so hard to find in the first place - a sealed crossover probably doesn't even exist.

//greg//