Farmall M clutch

I have been reading through the archives but have not found the answer to my questions. I installed a new clutch plate in my M. I tightened the 6 bolts in the back plate untill they were snug, as I thought I found them. Now there is no spring tension on the three engagement forks. Am I supposed to leave these six bolts backed out? Is that part of the adjustment or am I doing something wrong? Please provide as much detail as possible. I have never been into a clutch before. Thanks.

The bolts fastening the pressure plate to the flywheel should be tight. They should be at a certain torque setting, but I don't know that offhand. I just go for "tight" by feel, myself, and nothing's fallen apart yet

There should be three bolts in the back of the pressure plate that will relieve the spring pressure on the clutch, making the whole works easier to service.

The procedure for removal was to remove three of the six bolts from the back plate and install them in the holes provided to compress the springs. This worked good. I removed the three remaining bolts and the clutch came out. I replaced the clutch plate and reinstalled in reverse order but now tightening the six bolts in their original holes appears to compress the springs all the way, as if I still had three of them in the holes provided for that purpose. If I loosen the six bolts the back plate will come back and put tension on the forks otherwise they are completely loose. Maybe I don't have something lined up right?

This is gonna be long, I can feel it comin' so, with apologies in advance . . .

There's one of a couple or three things going on here.

One may be something mkirsch referred to. A lot of those clutch covers were built so that, when removing them, you could remove just three of the six bolts holding the clutch cover to the flywheel (every other one). With the remaining three bolts still holding the clutch in place you took the three you removed and threaded them through different holes and into the back of the pressure plate. What this got you was easier handling of the whole clutch assembly by locking the pressure plate in position and taking the not-always-desirable spring pressure out of the the R&I equation, especially handy in the re-installation part of the process. So have a look around. The only hex-heads you should be seeing are the bolts to mount to the flywheel, and the bolts and jam nuts used to adjust the clutch fingers, which will be near the outer perimeter, near where the fingeres are hinged. If there are three bolt heads nearer the center, look around and see if they are threaded into the back of the pressure plate. If so, they are the problem, and should be removed after the clutch is installed for normal operation. It's a nice touch if the clutch maker put them in there to make life easier for installation (not terribly likely), but it might have been nice to tell you they were there so they could be taken out.

It's a new clutch, you say, which raises another possibility, one more likely than the maker adding three bolts to the package. That is that the fingers were not set at the factory and need to be adjusted before installation. There was a time when a clutch would come out of the box pretty reliably adjusted. No more. It was always worth checking, even in the good old days, but even more so in these times of corner cutting. I spent most of a day helping a friend with just that problem a few years ago.

To check that out and to fix it, you need to pop the clutch back off and get it on a flat surface. If your wife has a nice granite countertop, that would be ideal, just put a piece of sturdy paper underneath everything, and DON'TDROP IT! The measurements and adjustments are easy, but will differ depending on your tractor and the clutch. Early Ms used an 11" clutch, later ones a 12".

With the uninstalled clutch (and without the three bolts I described in the first thought, so that the pressure plate is extended fully forward) and with the pressure plate resting on the bench/countertop, the distance between the surface and the lower edge of the clutch cover should be 1-3/32" for the early 11" clutch, and 1-1/32" for the 12". Any adjustment is made by loosening the jam nuts on the bolts securing the fingers and adjusting the bolts until the desired distance is achieved all the way around. It's more important (durned near critical, really) that this measurement be consistent than precise, so that the pressure plate comes away evenly. So use a measuring stick to get it close, then stack up whatever you need to, a 3/4" board and piece of 1/4" steel, maybe some feeler gauges you take out of their holder on top of that, if you're working in the kitchen, the cake spatula, whatever you have that will stack up to the desired height, and use that as the gauge that you adjust the bottom of the cover to, so that it is consistent all the way around the clutch, taking any eyeball error out of the process. Don't forget to tighten the jam nuts back down and recheck as you go.

When you're all done, you should be able to take poke your measuring stick down through the fingers to the same surface the pressure plate is resting on and lay another straightedge across any two of the inner ends of the clutch fingers, the surfaces that make contact with the throwout bearing, and find them to be 2-21/32" (on either clutch, 11" or 12") above that surface. Again uniformity is more important than hitting the actual number, though not as critical on this measurement as it is on the cover height earlier. The wobble of the throwout bearing and carrier will compensate for slightly uneven finger heights.

As long as you're uniformly adjusted, any small variance from specs can be taken up by adjusting the free-throw on your clutch pedal and be no more serious than adjusting free throw for the wear of a perfectly good and serviceable clutch.

When installed, and the pedal freeplay adjusted to 1-1/8" you should find something on the order of 1/4 inch or so between the face of the throwout bearing and the contact surfaces of the fingers.

I'm done now. Hope this helps.

Please let us know how you make out.

Your short answer came in while I was typing my LONG one.

But you've hit on the third thing. Existing cover, just a new friction disc. With the new information, it sounds like you got the disc in backwards, so that it's holding the pressure plate too far to the rear, whcih would slacken the fingers.

Thanks for the help. I did not do any adjusting to the fingers as you described so I will take the clutch assy. back out and do that.
I agree that it seems like the plate was put in backwards but I don't think so. I believe the long part of the center piece is toward the transmission which should be correct.
I will post when I have it fixed. It may be a day or two before I get to it. Thanks again.

Do not do any adjusting on the levers on the pressure plate. If they were OK with the old disk they will be OK with the new one. Unless you have the proper equipment to adjust them they are most likely adjusted closer to what you want than you will be able to do.

With the new clutch installed the levers should be pretty close to parallel with the surface of the flywheel. If the levers are real close to the pressure plate cover, the disk is probably in backwards. If the levers are in the near parallel position just adjust the free play on the clutch rod and you should be good to go.

From your last description, Jeff, I'd discourage any tinkering with the adjustment of the fingers, just as Owen said above. If you're putting the old clutch assembly back, the only things that have changed are that it has been removed and the friction disc has been changed out. If the clutch functioned normally before your work, either there's something (like the three bolts) obstructing the free movement of the fingers or pressure plate, or the disc is in backwards.

One item that needs discussed.
If the old disk was worn out, the new disk will compress the springs radically. Your description of the driven disk as being in with the spring plate To the rear to clear the Flywheel bolts is correct. If the three bolts in the pressure plate were installed to compress the springs, the disk will float free. If they are released (when the other three are nice and tight) the finger levers should move out some, but no where near as far as before This is evidence of a much fatter driven disk (perfectly normal) JimN

Both of the last two comments make sense. The old clutch plate was basically gone. Worn down to metal so there was a large difference in thickness between the old and new. However, the 3 spring loaded levers are so flat that the mechanism that depresses them will not reach them (even with the rod disconnected from the pedal). The clutch release mechanism movement bottoms out before it gets to the 3 spring loaded levers. The three bolts are not in the middle holes that are for depressing the springs and let's assume that I have not installed the clutch plate backwards (which I am 99% sure of). What else might be wrong? Is it possible someone else made some modifications in order to allow the clutch to work with a worn out plate? I have seen my current problem posted before but not the fix. Any more ideas?

Where is the mechanism bottoming out? If the outside of the clutch shaft hits the clutch housing before the bearing touches the levers you have a linkage problem. The release fork is timed to the clutch shaft by two thick washers that the bolts go through. Are they in the proper place?

Check out Owen's idea up at the top of the thread about the linkage first. It's been so long since I got up into the belly of an M that I'n not even sure what washers he refers to, but you've got the tractor there. Find them and check it out.

This gets back to the finger adjustment thing. As Jim N pointed out just above, a clutch disc wears, the fingers move to the rear reducing freeplay. Normally you take care of this by adjusting the linkage. If it could (not sure it can and still function) wear to the point that they couldn't adjust the linkage any further, it's possible someone did some tinkering on the fingers to get some freeplay back, which would produce the eymptoms you're having.

You've obviously had parts of the linkage apart so it would bear a second and third look, front to back. If you're satisfied that it's in good order, then it may be time to get the cover up onto a bench and check it out. If it's anywhere near the specs I gave, leave it alone, it's not the problem. If it's not you can try to adjust it as I described or take it to a machine shop with the specs and have them do it for you (shouldn't be TOO costly).

Because the system is still accessible, I would probably take out the three bolts and install them in the three holes. If they in deed do the release thing, I would then spin the input shaft to see if there were interference with the F/W bolts. If it is smooth, and the bolts move the lever about 1/2 to 5/8" farther than the "flat" you indicate, I would believe the clutch and PP are OK. People have done two unfortunate things (really more, but these are common) to clutches. One is to cut the linkage shorter when the adjustment runs out, and the other is to cut the mounting surface of the FW to allow the disk to be pinched harder. This requires removing the F/W (a split) so would be more intense than a new disk. It could also have been machined wrong. I do not know the step depth of the F/W, but it is available, and easy to measure.
On most new installations the fingers are almost always near flat when installed. JimN

Instead of using half moon keys between the clutch fork and shaft there are heavy washers that fit into the shaft the same as a key would. The cinch bolts on the fork go through these washers to hold them in place. If they are missing the fork can turn on the shaft and you will not be able to maintain proper adjustment.