JD 970 PTO clutch

[rojo]

I recently purchased a JD 970 and believe the PTO clutch might be out. The drive clutch seems to work fine, although it seems a little long on the clutch pedal. It never slips and seems strong. The problem is that when you push the clutch pedal all the way down you can not engage the PTO in without it grinding. I have shut off the tractor and engaged the PTO as soon as it starts and it seems to work fine after it is engaged, but will not stop when the clutch is pushed in. My question is do any of you experts have any suggestions before I break the thing in half? Thanks to all who reply.

 

[JC-jetro]

I recently purchased a JD 970 and believe the PTO clutch might be out. The drive clutch seems to work fine, although it seems a little long on the clutch pedal. It never slips and seems strong. The problem is that when you push the clutch pedal all the way down you can not engage the PTO in without it grinding. I have shut off the tractor and engaged the PTO as soon as it starts and it seems to work fine after it is engaged, but will not stop when the clutch is pushed in. My question is do any of you experts have any suggestions before I break the thing in half? Thanks to all who reply.

I don't own 790 but I know it has live PTO (double clutch) in the bell housing. One clutch disk and it's pressure plate operates transmission input shaft and a second set operates PTO shaft. The PTO is mechanically coupled or decoupled by your PTO lever. The coupling of two shafts normally done with a sliding gear along with a one way clutch in newer vintage tractor like yours. I do not think you have a major issue. You need to adjust pto clutch. may need to refer to IT service manual ion how to do yours, as they may be slightly different from makes and models but the concept is the same. When you push the pedal all the way the clutch disk is not disengaged from pressure plate hence, rotation of pto shaft and grinding the pto shaft coupler as a result.. Roy Jackson is quite knowledgeable and does have a 790. Wait to see if he chimes in or send him a PM to ask.

JC,


ps. I'm curious if you meant 790 rather than 970, I just noticed it.

 

[RoyJackson]

Yeah, I do own a 790, but Rojo is asking about a 970 2 stage clutch.
I have a manual for all the Deere x70 and 790 tractors. I'm at work right now, but will look up the adjustment procedure tonight.

BTW, this manual is from Deere and is on CD-ROM. It's $48 (was when I got it, anyway) and is a very worthwhile investment if you intend to keep that 970 (fine tractor...wish I had one!)

 

[rojo]

Gentlemen, the tractor is a JD 970. I have a John Deere Technical manual and it shows how to adjust to clutch. There is only one adjustment and it does both the main clutch and the pto clutch (I think). I have not had time to do this yet and hope to get to it on Sunday. I was just wondering if anyone had seen this problem before because it doesn't seem as the main clutch really needs adjustment. But maybe a little adjustment will do alot. I will let you know. The CD-Rom you where talking about is the same as this tech. manual or no?

 

[JC-jetro]

Gentlemen, the tractor is a JD 970. I have a John Deere Technical manual and it shows how to adjust to clutch. There is only one adjustment and it does both the main clutch and the pto clutch (I think). I have not had time to do this yet and hope to get to it on Sunday. I was just wondering if anyone had seen this problem before because it doesn't seem as the main clutch really needs adjustment. But maybe a little adjustment will do alot. I will let you know. The CD-Rom you where talking about is the same as this tech. manual or no?

Rojo,

The procedure is the same with either 970 or 790. I have done the procedure for single clutch only but studied the dual clutch system also. There are two things to consider. One is the distance between the release fork and the spring loaded finger on the pressure plate . Basically enough distance is maintained between the release fork and fingers so they don't touch but close enough. The second is the spring adjustment between pto clutch disk and it's pressure plate. On 1700 with dual clutch yo can tighten or loosen the spring action. What I also would do is to mark all my adjustment nuts and what have you with a chalk, paint or soap stone to know the before condition.


good luck,
JC,

 

[Keoke]

Hi Rojo, there is a very good chance that the PTO clutch is stuck (rusted) to it's pressure plate. This is a common occurrence, especially on clutch disk's that utilize metallic linings. This condition usually occurs when tractor sits for a long time in humid or wet conditions. Some manufactures recommend blocking down clutch pedal when tractor is going to sit for a long while.
You can try breaking the disk loose by engaging the pto and then locking the out shaft from turning (lock drive shaft after shear bolt on rotary mower with pipe wrench, etc.) and then bumping the starter with ignition off. Have a helper hold clutch pedal fully down while you bump the starter. You will have to go directly to starter solenoid to do this since engaging pto will open starter circuit at safety switch and ignition will be off.
Keep in mind that this procedure will put some strain on starter drive gear so go easy.


lot's of luck,
keoke

 

[rdln]

I can say that while at my local dealer about a year ago, a used 1070 caught my eye, a fellow traded it in, it needed a clutch. I asked the dealer how to tell and he said that the pto will stop engaging b4 the trans stops.

 

[RoyJackson]

Gentlemen, the tractor is a JD 970. I have a John Deere Technical manual and it shows how to adjust to clutch. There is only one adjustment and it does both the main clutch and the pto clutch (I think). I have not had time to do this yet and hope to get to it on Sunday. I was just wondering if anyone had seen this problem before because it doesn't seem as the main clutch really needs adjustment. But maybe a little adjustment will do alot. I will let you know. The CD-Rom you where talking about is the same as this tech. manual or no?

Yep, it's the same...CD-ROM is cheaper, that's all.

I had a 670 (basically the same as the 790, but less power and smaller tires) that I had always thought had a single stage clutch. When I traded it off for my 790, the dealer told me it was actually a 2-stage that required adjustment. I don't know if it took splitting the tractor to do this, but they had it squared away within a week since they sold that machine in a week.

I've adjusted the clutch pedal free play, but never had to go any deeper. However, I'd talk to a dealer tech before I'd try breaking a frozen clutch loose. If it were a single stage clutch, I'd have no qualms about popping the clutch. But messing around with the PTO could do some serious damage to the PTO gearing or even worse if your helper doesn't hold that clutch all the way down.

 

[Keoke]

Roy, one would think that if the pto drive train is strong enough to snap a 1/2 inch shear bolt repeatably it should be able to handle what ever torque a starter motor can come up with.
Rojo, for added safety while trying to brake clutch plate loose you could put a shear bolt on the rotary mower that is half the size of the OEM bolt.

take care,
keoke

 

[RoyJackson]

Roy, one would think that if the pto drive train is strong enough to snap a 1/2 inch shear bolt repeatably it should be able to handle what ever torque a starter motor can come up with.
Rojo, for added safety while trying to brake clutch plate loose you could put a shear bolt on the rotary mower that is half the size of the OEM bolt.

take care,
keoke

I'd be more leery of trying to hold that PTO from turning with a pipe wrench. I'm sure you didn't mean for someone to hold it...but that PTO puts out a lot of torque (as you know).
Guess I am a safety freak!

 

[JC-jetro]

Rojo,

With the engine OFF, pto coupler (lever) engaged along with clutch pedal fully pushed in all the way, then one can try to loosen the pto stuck clutch by getting a pipe wrench on the pto shaft and rotating it back and forth. in condition above the pto shaft should not rotate if clutch is stuck.

Again I emphasize " engine off" ..I never touch any part of PTO with the engine on other than engaging it from the tractor seat.

JC,

 

[Keoke]

JC, the pto drive line is designed to free-wheel when driven from the pto end in one direction. This is to prevent mower blade inertia from driving the engine rpm when slowing down engine. Also, turning pto shaft while engaged will simply turn the engine over and is not likely to break loose a frozen up clutch disc unless you find some way to lock engine flywheel or crankshaft up while turning shaft.

take care,
keoke

 

[RoyJackson]

It's possible rigging a cutter to the machine and popping the clutch (tranny in neutral) might do something. That's pretty safe and it might be enough of a shock load to break the plates free. If you try this, just let that cutter stop rotating (betwen the times the clutch is popped) for maximum effect.
I'm suggesting using a cutter as those heavy blades will provide the most inertia of any PTO driven implement I can think of.
Good luck!

 

[zzvyb6]

When this happened on my 1070, I put the 8' mower on and drove into a thick clump of grass + anthill. With the clutch in, it didn't take very long to overload the clutch rust.

This means you have to start the machine + mower combo together, but I'm sure you can figure it out....

 

[Keoke]

ZZvy, very good idea for heavy loading and breaking free the frozen pto clutch plate.
Roy, the pto drive line has a "sprag" unit built in. This allows the engine to turn the pto shaft but does not allow the pto shaft to turn the engine.
This the same sort of unit (over-running clutch) that you find in starter drive gears (eg. starter can turn engine but engine can't turn starter).

take care,

 

[JC-jetro]

JC, the pto drive line is designed to free-wheel when driven from the pto end in one direction. This is to prevent mower blade inertia from driving the engine rpm when slowing down engine. Also, turning pto shaft while engaged will simply turn the engine over and is not likely to break loose a frozen up clutch disc unless you find some way to lock engine flywheel or crankshaft up while turning shaft.

take care,

keoke

Keoke,

Yes.. I do realize the one way clutch operation. I was hoping in one direction the force to break sticking plate loose is less than torque required to turn the engine and if the engine turned!! so be it as long as the gear is in neutral as Roy suggested. I don't think you can turn the flywheel fast enough to get the engine started. Using a brush hug is a good idea too.. I would make sure to disengage the pto coupler, hook on a brush hog, start the engine and raise the the implement, go where I want to test the procedure, lower the brush hog on some stand/logs or what ever, turn the engine off, engage the pto coupler and start the tractor. At that point I start the tractor and brush hog at the same time. I then move to a safe place and lower the brush hog on to some bush or low sapling hoping for the shock load the break the disk free while pushing the clutch plate all the way down. Wouldn't you think that may work?

JC<

 

[rojo]

I tried adjusting the clutch and that did not help. Next I tried the pipe wrench on the PTO shaft Like JC suggested and that did not help either. I was thinking I would hook up the brush hog and go cut brush, but I ran out of time. When I got in, I see the same suggestion was made here so next weekend I will be trying that. Thanks for all the help, will let you know what happens next.

 

[zzvyb6]

You don't want a shock load to break a clutch free. That may break the clutch material. All you want to do is gradually overload the friction surfaces that are engaged. Its not the entire clutch pack. Probably just a few square inches or less of surface. Then you want to feather the clutch when it cuts loose so you don't rip up the clutch plates or scratch the metal surface(s).

 

[rojo]

I tried brush hogging today and several times I backed into heavy brush with the clutch pushed all the way down and it never released. So I guess I will have to break the tractor in half and see what is going on. Probly will wait a little while longer and maybe try using the post hole auger first.

 

[Keoke]

Rojo, there is a lot of kinetic energy (inertia) stored in those rotating Bush Hog blades. Soo, in heavy brush, try bringing the engine speed down to idle and while going forward (down-hill) into the heavy stuff, with clutch fully down, run the engine up to full throttle real quick. This should put a accelerative sheer load on the pto clutch.
Let's hope you get lucky. Hey' it's no fun splitting that tractor.

take care,