Clutch failure (AGAIN!) Ford 1100 4WD

[tosii2]

Iron Horse, I agree that a disk hanging on the shaft would produce similar symptoms EXCEPT that an 'old' plate does not lift off the disk any where near as far as a new one does. Also, the last 2 plates haven't had enough hours on them to wear enough to significantly allow the fingers to move further back. If I had had that much wear, I think I could get enough range to disengage the clutch. With a new plate and new disk when I depress the fingers with the jig I talked about earlier, the disk will drop off center about 1/2 way through the motion of my simulated throw-out bearing. With the old plate and the same new disk, the disk won't budge, even if I push at it on the edge. This indicates to me that the disk sticking on the input shaft isn't the issue since the shaft isn't even there in the set-up in the jig.
Every time I have disassembled and put back, there has been no indication of sticking or stickiness, and I have put some (small amount) anti-seize on the shaft prior to reassembly. I can't get in there from the inspection hole (believe me, I tried!) to do the penetrating oil trick. All I can see through the inspection hole is if the plate has released the disk (viewing the edge of the assembly), and even that is tough.
banjodunn, as far as I can tell, the whole assembly (fork and carrier) move easily through what appears to be the full design range. At one point I thought that the bellows dust boot might have been interfering, but I convinced myself that it wasn't.
hooked, I replaced the cross shaft and the spring pin the first time I was in there; also the bushings that support the cross shaft because they looked a bit sloppy.

Thanks again, keep the ideas coming!

 

[doall]

Just a thought. but if you put a shim or washer between the pressure plate and the flywheel would it allow your clutch to engage and still disengage? One washer or shim on each bolt.

 

[Eagleview]

Iron Horse, I agree that a disk hanging on the shaft would produce similar symptoms EXCEPT that an 'old' plate does not lift off the disk any where near as far as a new one does.

Believe it or not , the opposite happens . As the fingers of the pressure plate move out or rearward as the plate wears giving more leverage and travel to lift the pressure plate face . Not only this happens but also the free play between the fingers and the throwout bearing is taken up as the fingers move back and the linkage is able to push fingers/diaphragm further as the free play is now gone .

An "old" plate is worn thin compared to a new one so this amount of wear is also the extra amount the plate can move off the pressure plate . Combine the 3 effects and this is how much further an old plate can move with unadjusted linkages .

 

[tosii2]

doall, If I understand what you are suggesting, spacing the pressure plate body away from the flywheel would end up with the same effect as a clutch disk being worn that much and would give me more margin to disengage. It kind of begs the question, though of why I need it after I have used the clutch for 6 months or so. eg, it worked fine as installed, but I ran out of travel; what changed and why? I am also not sure if the bolts would be strong enough since spacers would put put the shoulder of the bolts off the flywheel surface, putting the stress directly on the threaded portions of the bolts.

iron horse, perhaps I wasn't clear about what I meant by plate and disk. When I referred to the plate, I mean the clutch pressure plate which shouldn't wear significantly. The clutch disk has the wear surface which causes the fingers of the pressure plate to move backwards as the clutch disk wears. I am not getting a significant amount of that wear in the clutch disk. I am also not seeing the free play change significantly. What does happen is that I need to mash harder on the clutch pedal to prevent the gears from grinding. eg with a new plate and adjusted free play, there is something over an inch of margin at the bottom of travel of the clutch pedal where the clutch is disengaged enough to shift. That inch-plus gradually decreases to nothing. My instinctive thought when this happens is that the linkage has loosened up giving me too much free play. But, currently, I cannot move the cross shaft and the clutch throw out bearing carrier far enough to disengage the clutch; it hits a hard stop somewhere in the guts. This hard stop is NOT the external adjustable stop that also mounts the starter safety switch. I can move that well out of the way and still hit that hard stop. Hitting the hard stop isn't the problem, I think; what causes the change to make the assembly be limited by the hard stop is the problem.

Thanks again folks!

Terry

 

[Hooked_on_HP]

What if the thrust bearing on the crankshaft is going out and when you push the clutch petal, insted of the pressure plate releasing the crank is moving forward. This would be easy to check by putting a dial indicator on the front of the crank and check the travel. I have seen this happen on cars.
Bill

 

[tosii2]

Bill, hadn't thought of that one.... but then, a new clutch would start out with the same problem, wouldn't it?
I will give it a check, though. As you say, it is easy enough to check... now if only I can find the spec for it in my manuals.. found it... it is only .028". I have seen these go on cars also, but hadn't seen it be bad enough to really affect the clutch.
I'll check it, but I am struggling to see how replacing the clutch assembly would 'hide' this problem initially.

Terry

 

[tosii2]

My Ford service manual has some cryptic specifications for the clutch; I have figured most of them out, I think, but it gives "Release lever height --- 1.18+_004 in" Does anyone know what that would be measured relative to and under what conditions?

 

[Eagleview]

Are you certain that the clutch disc it the correct one for that tractor ?

If the disc has a slightly longer spline casting or thicker spring enclosure , the throw out bearing carrier or the back of the pressure plate fingers could be contacting it . This would not only give you the dead stop feeling you have mentioned , it would also force the disc forward which would make it contact the flywheel and make it spin .

Do you still have the old plate you can compare too the second plate you tried ?

 

[tosii2]

Iron Horse; good thought, I hadn't thought of that one. It is certainly possible since there isn't a lot of clearance there. I don't have the original plate, although I do remember comparing the original plate with the one I replaced it with and they sure looked pretty close to identical. I remember checking the disk thickness and how much the hub stuck out front and back and those seemed the same. When I tear into it this time, I will take a close look at those clearances. It isn't that the disk is backwards; it won't go that way since the hub would hit the flywheel gland nut (bolt??) if it was backwards.

It still begs the question of what has changed to allow it to work fine initially, but then start dragging with use.

It's not that I am new to working on clutches; I have been into the guts of clutches in everything from an 8N, a 62 VW beetle, 66 GMC pickup, 86 VW Quantuum synchro, etc. This thing is SO frustrating! You can be sure that the first thing that will happen when I go in this time will be to mount my jig over the clutch so I can SEE what is happening when the fingers are depressed.

Thanks again for your thoughts!

 

[jones6780]

Get someone to press the clutch down, or use a wood block to hold it down, and look in the inspection port. Use a screwdriver to check for loose condition of the clutch disk. You should be able to see a slight gap between the disk on either side. With the trans in neutral you should be able to rotate the clutch disk.
You say it does not disengage. With the tractor running in gear and you press the clutch, does it stop? Are you trying to shift on the go? With the tractor running, in gear with clutch pressed and tractor not moving, will it shift without grinding? The 1100 is not a syncromesh transmission. If you release the clutch in neutral, the main shaft spinns and the gears on it. When you press the clutch it takes a little for everything to stop spinning.

Russell