d7 3t clutch trouble

[mb8796]

Well I'm back askin for help on this machine again. I adjusted the clutch because it didnt lock in and I just ran it this morning after I changed the engine and transmission fluids and tried to grease all the little points I could find along with one that was pointed out here. Trouble is the clutch doesn't lock in or have a snap to the lever that I can tell and that's why I was adjusting it in the first place. I pulled off the floorboards and the transmission interlock lever wasn't hooked up. Thought that was it. Stood on my head again and got that all hooked up and still no clutch lock in. Anybody have any suggestions? I don't want to change the lever length but it looks like that may have already been done as I cant get it to lock in no matter how hard I pull the lever. I also noticed where the clutch lever goes thru the housing is kinda wallered out some. Any suggestions would be greatly appreciated.

[Billy D7 4T]

Somehow I never completely grasped how that interlock is coordinated, but looking at the description in the book and on the tractor, seems it's needed to hold things in place, particularly the transmission gears when the clutch is engaged. It's clear how it works and if that linkage is off, the plungers that lock in will miss the holes the way I see it. I don't see how that would affect anything but the transmission, lots of times the plungers or parts are worn and they pop out of gear. The clutch should still have that snap over center effect regardless, or as I see it.

The manual, states not to adjust the linkage. " The length of the rod between the flywheel clutch control lever and the crank assembly that actuates the clutch yoke should not be changed as its length is set correctly at the factory. "Changing the length of the rod could render the gear shift interlock mechanism inoperative.

Quote from a military tech manual for a D7 7M, TM5-3070 7M3572-7M5827 inclusive, seems to describe the interlock linkage adjustment, which I think does not change on these tractors, though they did change the clutch release collar ( one is ball bearing type) per what is in other manuals. I do stand to be corrected there.

Page 163 "ADJUSTMENT With the adjustable link (10) correctly adjusted, the interlock lever (11) will move approximately to the position shown in the illustration when the flywheel clutch is engaged. When the clutch is released the lever will move back until it is approximately perpendicular to the link. If the adjustable link is too long the interlock mechanism will not release; if the link is too short, the interlock mechanism will not lock"

I would think the wallowed out holes in the linkages would make things sloppy, a lot of these are well worn in those areas, but you would think it would have to be severe to cause problems. Have you checked/inspected the friction material on the plates ? Even then, I think you still have enough adjustment when thin or near worn out, to still get that distinct snap over. Only thing I can think of would be to check the 3 clutch release links on the clutch assembly, I think they can wear, not sure if a combination of everything being worn adds up cumulatively to what you are getting. This should not be to difficult to root out, hopefully someone can add to this as I am just looking at books and whats on the bench.... the 2 dry clutch assemblies I have out, maybe I'm missing something here, has to be some excess slack somewhere, you just need to find it.

[catskinner]

Does the clutch slip when put under a load? If so, it needs to be tightened up some more. The snap in is gotten by tighting up the clutch not the linkage. Adjust it up some more untill you have some snap in when you pull it back. You don't want it to pull in real hard. My boss told me that is the way to do it. I got to where I could pull the clutch out in 45 min. and have it sitting on the fender. Finally I started adjusting it so it was a softer "pull in", and I never had the problem of pulling the clutch out again. catskinner

[Jack]

The crank that goes through the side of the clutch housing and operates the thing just has a sleeve bearing in the left side of the housing. When the shaft and sleeves get well worn, plus wear in clevis pin holes, etc. you could easily have enough slop to keep your clutch throwout bearing from being pushed all the way in. Does the hand lever hit the seat or the back of the notch in the floorboard?

Adjust the transmission lock-in with the clutch rod disconnected; get it so it works right. Then adjust the clutch so it works with the lever moving in this established range.

One quick check: reach in through the inspection port with a bar and see if you can snap the clutch the rest of the way in after you have engaged it in the normal way, engine shut off of course. That will tell you if you are dealing with lost motion.

The engagement crank--a lever on each end of a shaft, about 7/8" dia. as I recall, isn't hard to repair. Weld up the worn spots on the shaft with a wire welder and return it in a lathe. Making a new one would be easy, EXCEPT that those woodruff key slots have to be right on rotation wise. The bushings are just brass and any machinist could reproduce them. Or, Cat may still actually have those parts.

One other thing: there are shims on the drive links at the flywheel that are used to position the driving plate between the driven plates. If these shims are seriously out of order it can make the clutch not work right because the pressure plate is closing against the links instead of clamping up to the forward driven plate. But that's a long shot.

It's not a high tech clutch. You'll get it right.

[mb8796]

Thanks to all for all the help. I finally got it adjusted and now works great. Got some engine vibration but will check out that later this weekend or next week. Still have to adjust the brakes some more and may have to use a thicker oil in the turning cluthes hydrailic assist unit as it leaks down while turning but at least it will push dirt now. Thanks again for the information.

[Billy D7 4T]

If you have engine vibration, DO check that bearing inside the driven plate, my 4T did this and vibrated, got worse, bearing failed, bore in the plate wallowed out, and the drive links failed soon after.