MF275 live PTO cannot be shifted on

[Jim.ME]

Have you checked with your feeler gauges to see what the current gaps are? It would be interesting to know what they are now, to see if we are giving you correct directions.

Adjusting the PTO bolts with the tractor assembled is a pain as you are finding out. You may end up with several modified wrenches before you get them all adjusted.

This won't help you at this point but may help someone researching because they are looking at doing a clutch job in the future. It is too late now in your situation; but you are seeing why adjusting the pressure plate fingers and the PTO release bolts are important steps to be done while the tractor is split. In fact, those adjustments can be done on the bench while the tractor is split by pulling the flywheel and mounting the clutch assembly to it on the bench. It should be noted that most manuals call for a new traction disc to be used when adjusting the pressure plate finger height, even if the old disc is being re-used at the time of final assembly.

 

[Herb40]

Have you checked with your feeler gauges to see what the current gaps are? It would be interesting to know what they are now, to see if we are giving you correct directions.

Adjusting the PTO bolts with the tractor assembled is a pain as you are finding out. You may end up with several modified wrenches before you get them all adjusted.

This won't help you at this point but may help someone researching because they are looking at doing a clutch job in the future. It is too late now in your situation; but you are seeing why adjusting the pressure plate fingers and the PTO release bolts are important steps to be done while the tractor is split. In fact, those adjustments can be done on the bench while the tractor is split by pulling the flywheel and mounting the clutch assembly to it on the bench. It should be noted that most manuals call for a new traction disc to be used when adjusting the pressure plate finger height, even if the old disc is being re-used at the time of final assembly.

So far, I only know that one of the gaps is over 0.09 and two are less than my nickel (0.07). I need to get better organized, mark all three pressure plate finger arms to uniquely identify each bolt, and measure all three gaps.

When the pressure plate is rotated so that the current bolt of interest is in the desired position, the bolt head is readily visible (as if visibility were the only requirement to adjust them!)

The lock nuts are not as accessible as the bolt heads. Unfortunately, the arms (pressure plate fingers) that the bolts fasten down curve out in the wrong direction (for me), reduce the usable space, and help hide the lock nuts. But the lock nuts are at least partially visible in most situations and fully visible in others, increasing my opinion that I will eventually be able to adjust them.

Seeing the difficulty of the project, my current plan is to reduce the big gap down to 0.07 and test to see if that works. Reducing the big gap means that both the lock nut and the bolt have to move in the same direction, and the lock nut must be backed off only slightly to begin.

At first, I thought that longer wrenches were part of the solution, but the two I ordered are actually too long, although only 9 or so inches long. But with the wrench at a bolt head, the other end bumps into the side of the access opening. Shortening them to 7 or 8 inches will be necessary. One tool I have found to be very useful is the good old Vise Grip. I have a small one that I can easily attach to my feeler gauge frame, or to the end of a wrench, or in other situations where a strong length-extender is required.

 

[Jim.ME]

You are on the right track. the three adjusting bolt gaps should be even. get the wide one down to .070 and try it.

If you can see the finger adjusting bolts look to see that they all have about the same gap between the bolt and throw out bearing. If they are close you should be ok without adjusting those for now. if one has a much large gap than the others that might be part of the problem.

 

[Herb40]

You are on the right track. the three adjusting bolt gaps should be even. get the wide one down to .070 and try it.

If you can see the finger adjusting bolts look to see that they all have about the same gap between the bolt and throw out bearing. If they are close you should be ok without adjusting those for now. if one has a much large gap than the others that might be part of the problem.

I apologize, but I am confused. Am I supposed to be working on "Release Lever Height Adjustment" or "Secondary Pressure Plate Adjustment?" Or both? Both are described on the same page of my Jensales Service Manual in a section labelled "ADJUSTING DUAL CLUTCH."

I thought it was Release Lever Height Adjustment, although that is not the terminology being used in this thread. I've been trying to adjust the gaps between each of the three Release Levers ("fingers") and the adjacent plate, near the central clutch shaft. When the clutch is on the workbench, special tool 6179 is used to set these gaps, and the correct gaps apparently are whatever the tool causes them to be. No gap widths such as 0.80 are suggested. My manual does not state that these can be adjusted through the inspection opening.

In your reply above, you ask "If you can see the finger adjusting bolts..." Since I've been trying to adjust those bolts, I do see them. Unfortunately, I do not know what the "throw out bearing" is.

While trying to do the above (with very little progress), I noticed, several inches back along the clutch, a large rectangular block that appears to slide along through an opening, with two large springs nearby on each side, such as shown in a figure in my manual labelled "Checking Secondary Pressure Plate Clearance." Special tool MFN 354 is used to adjust the clearance here to 0.080. This adjustment is what the manual states can be made through the inspection opening. For the one movable block I see, there is a large gap between the block and the end of the opening it slides in, and what could be an adjusting bolt is nearby. Am I supposed to be working on these gaps?

I apologize again for my confusion here. Please point me in the right direction.

 

[Jim.ME]

The throw out bearing (I think this is what you are calling a large block) is moved by a fork attached to the clutch operating shaft the outside arm is mounted on. The throw out bearing slides on a tube that is on the front of the transmission, the PTO input shaft is inside that tube, and the transmission input shaft is inside the PTO input shaft. When the pedal is pushed the throw out bearing moves toward the engine, and pushed the fingers forward releasing first, the transmission disc. Pushing it further down the PTO disc is released.

With the pedal free play adjusted the clearance between the finger adjusting bolts and throw out bearing should be even. I would expect up to 1/8" clearance. The key thing is there is clearance and it is even at all three fingers, so the throw out bearing is not running on the fingers when the pedal is not being pushed to disengage the clutch. This is where the tool 6179 is used to check/set the fingers after the clutch is assembled on the flywheel and before the two halves of the tractor are put back together. The manual doesn't mention adjusting the fingers in place as the expectation was it would be done during assembly with the gauge. As I posted earlier at this point you just need to make the clearance between each finger and the throw out bearing is the same, so the release of the disc is even.

The tool MFN 354 is the one for setting the Secondary Pressure Plate Clearance, the three release bolts are tucked inside the pressure plate between the springs. That is where you reduce the .080" gap to .070", or less, to change the release point of the PTO clutch disc.

The cut away drawing below, of a dual stage clutch (this one is in a John Deere, I haven't found a good one for a MF), is a bit different than your clutch but the arrangement of things is similar. It will show you the major components and their locations. The picture is of the two-stage clutch pressure plate in my MF 245. One of the adjusting bolts is shown inside the yellow rectangle, there is supposed .080" between the head of that bolt and the plate above it. Reducing that dimension will reduce the pedal travel needed to release the PTO clutch disc.



Hope this helps.

 

[Herb40]

The throw out bearing (I think this is what you are calling a large block) is moved by a fork attached to the clutch operating shaft the outside arm is mounted on. The throw out bearing slides on a tube that is on the front of the transmission, the PTO input shaft is inside that tube, and the transmission input shaft is inside the PTO input shaft. When the pedal is pushed the throw out bearing moves toward the engine, and pushed the fingers forward releasing first, the transmission disc. Pushing it further down the PTO disc is released.

With the pedal free play adjusted the clearance between the finger adjusting bolts and throw out bearing should be even. I would expect up to 1/8" clearance. The key thing is there is clearance and it is even at all three fingers, so the throw out bearing is not running on the fingers when the pedal is not being pushed to disengage the clutch. This is where the tool 6179 is used to check/set the fingers after the clutch is assembled on the flywheel and before the two halves of the tractor are put back together. The manual doesn't mention adjusting the fingers in place as the expectation was it would be done during assembly with the gauge. As I posted earlier at this point you just need to make the clearance between each finger and the throw out bearing is the same, so the release of the disc is even.

The tool MFN 354 is the one for setting the Secondary Pressure Plate Clearance, the three release bolts are tucked inside the pressure plate between the springs. That is where you reduce the .080" gap to .070", or less, to change the release point of the PTO clutch disc.

The cut away drawing below, of a dual stage clutch (this one is in a John Deere, I haven't found a good one for a MF), is a bit different than your clutch but the arrangement of things is similar. It will show you the major components and their locations. The picture is of the two-stage clutch pressure plate in my MF 245. One of the adjusting bolts is shown inside the yellow rectangle, there is supposed .080" between the head of that bolt and the plate above it. Reducing that dimension will reduce the pedal travel needed to release the PTO clutch disc.

View attachment 153614 View attachment 153615

Hope this helps.

Thanks for sticking with me and for this new information. I am finally becoming more familiar with some parts of the dual clutch.

Now back to the release levers whose adjustment is supposed to be made while the clutch is on the workbench (and supposedly cannot be made through the inspection port after the clutch is installed). Do you know of anyone who has claimed to have adjusted these three bolts? (I have noticed that no other member of this forum has entered the discussion and said "This is how I did it.")

All the gap sizes I have stated previously are for the release lever bolts. I have always assumed that the wrench size needed to adjust these bolts is 1/2" since that size was stated earlier in this thread. I realize now that the 1/2" size could have been in reference to adjusting the secondary pressure plate clearance. After much effort, I have never been able to get my especially-modified 1/2" wrench to fit over the head of any release lever bolt. I gave up on that and finally decided that the problem wasn't that my wrench was too bulky but that those bolts had heads that were larger than 1/2". The bolts and nuts are shown in my Jensales parts manual for dual clutch. The bolt is part 1 853 164 M1 and the nut is part 353 430 X1. Both are available online and appear to be 3/8" bolts whose heads would be 9/16" instead of 1/2". So I will move up to 9/16 and see how it goes.

For the secondary pressure plate adjustments, do you know the size of the bolt heads there? I have not found a special tool MFN 354 online and will have to use a wrench and feeler gauge instead.

Thanks again for your help.

 

[Jim.ME]

T

Thanks for sticking with me and for this new information. I am finally becoming more familiar with some parts of the dual clutch.

Now back to the release levers whose adjustment is supposed to be made while the clutch is on the workbench (and supposedly cannot be made through the inspection port after the clutch is installed). Do you know of anyone who has claimed to have adjusted these three bolts? (I have noticed that no other member of this forum has entered the discussion and said "This is how I did it.")

All the gap sizes I have stated previously are for the release lever bolts. I have always assumed that the wrench size needed to adjust these bolts is 1/2" since that size was stated earlier in this thread. I realize now that the 1/2" size could have been in reference to adjusting the secondary pressure plate clearance. After much effort, I have never been able to get my especially-modified 1/2" wrench to fit over the head of any release lever bolt. I gave up on that and finally decided that the problem wasn't that my wrench was too bulky but that those bolts had heads that were larger than 1/2". The bolts and nuts are shown in my Jensales parts manual for dual clutch. The bolt is part 1 853 164 M1 and the nut is part 353 430 X1. Both are available online and appear to be 3/8" bolts whose heads would be 9/16" instead of 1/2". So I will move up to 9/16 and see how it goes.

For the secondary pressure plate adjustments, do you know the size of the bolt heads there? I have not found a special tool MFN 354 online and will have to use a wrench and feeler gauge instead.

Thanks again for your help.

I have not worked on a 275 clutch but have worked on some like it. I managed to replace a finger bolt that came out of one clutch. I released the arm on the clutch shaft and moved the throw out bearing as far back towards the front of the transmission. Without seeing inside your 275, I can't say for certain that would work on yours. The finger adjusting bolts should be 3/8" NF x 20.5mm long from checking the part number at various vendors.

I believe the MFN354 tool is basically a special thick feeler gauge .080". Based on one used on a similar clutch the picture below is what it would look like. Your plan of using a nickel should work fine. Using the part number in a search those bolts should be 5/16" fine thread x 1" long. Your 1/2" wrenches should fit those bolts and nuts.

 

[Bob NY]

Just for clarification, The bolts in the clutch release fingers are supposed to be adjusted with the complete clutch assembly mounted on the flywheel but BEFORE the halves of the tractor are put back together. I have never tried to adjust them through the inspection hole, and expect it would be very difficult if not impossible. The second stage bolts require 1/2 inch wrenches. I have done that job from under the tractor using standard wrenches.

 

[Jim.ME]

Just for clarification, The bolts in the clutch release fingers are supposed to be adjusted with the complete clutch assembly mounted on the flywheel but BEFORE the halves of the tractor are put back together. I have never tried to adjust them through the inspection hole, and expect it would be very difficult if not impossible. The second stage bolts require 1/2 inch wrenches. I have done that job from under the tractor using standard wrenches.

I do not disagree. As I posted (post #25), finger adjustment is supposed to be done assembled on the flywheel either on the bench or on the tractor while split. Years ago, I managed to replace a finger adjusting bolt in a MF dual stage clutch finger. It was not a fun undertaking. After I got the new bolt in, adjusting it to make it hit the throw out bearing the same as the others was about the only adjustment available with the tractor together.

 

[Herb40]

As I stated previously in #26 about the finger adjustment bolts, the bolt is part 1 853 164 M1 and the nut is part 353 430 X1. Both are available online and appear to be 3/8 bolts whose heads would be normally be 9/16 instead of 1/2. But when I tried a 9/16 wrench, the "fit" was much too loose; even if the wrench could have made the bolt turn, the slack would have consumed too much of the available space for the wrench handle to move. With no normal SAE wrench size between 1/2 and 9/16, I decided to try metric. A 9/16 wrench is 14.2875mm. The next smaller metric wrench size is 14mm; my 14mm wrench fit nicely; so my wrench size problem has been solved.

 

[Ron(Ont)]

There are 17/32" wrenches available.

 

[Herb40]

There are 17/32" wrenches available.

True, but not normally available where we live. I searched for one in my aged tool box, but to no avail. A 14 mm wrench was right there in my metric wrench collection, so I tried it and it fit nicely.

I have been working on this clutch problem for several weeks and don't mind spending a few dollars here and there to solve it. I could tell just by looking up there from under the tractor that these bolts were "different" with their domed heads, apparently intended to minimize the contact area with the pressure plate. The size of the MF bolt is not stated in my parts manual, so I ordered some several weeks ago (minimum order 12; shipping cost more than the bolts). They just now arrived. The head size is about 13.8 mm, confirming my 14 mm wrench choice.

A 17/32" wrench is 0.53125" or just about 13.5 mm, so it would be too small for the 13.8 mm bolts.

 

[Jim.ME]

Just to help you with how it operates. The throw out bearing (not the pressure plate) is what contacts the domed heads of the pressure plate finger adjusting bolts, when the clutch pedal is pushed to disengage the clutches. There should be some clearance between the heads and the throw out bearing face when the pedal is not pushed, you do not want the throw out bearing constantly spinning when the tractor is running.

 

[Herb40]

The clearance between each of the adjusting bolts and the secondary pressure plate were all measured today. It was a hot, exhausting afternoon with me being both the guy underneath the tractor trying to do the measurements and the one behind the tractor trying to turn the PTO shaft. Multiple trips back and forth were required in order to get each target bolt to appear in a measurable position through the inspection port.

The measurements were 0.042", 0.045", and 0.054". I assume that the recommendation would be to adjust all three of them to about 0.070".
Please advise.

 

[Jim.ME]

The less the gap, the quicker the PTO disc should be releasing. That is the purpose of reducing the manual recommended setting of .080" down to 070". It will disengage better.

Just asking this to confirm your linkage adjusting procedure. When you adjusted the rod and set the 5/32 free play clearance of the external linkage did you do the steps of releasing the clamp bolt and rotating the shaft until you felt the resistance of the bearing contacting the pressure plate fingers, then setting the 5/32" clearance? I ask as I don't see you mentioned that step.

If the linkage adjustments are correct and the gaps of the PTO release bolts are that small; @Dieseltech, or others, may have other thoughts; but I suspect you may have issues inside the clutch if it is not releasing. You are approaching the point of having to split the tractor to access the clutch to find the problem. There could be an issue with the PTO disc or pressure plate related to its operation.

 

[Dieseltech]

If all three release lever bolts are evenly set, and all three PTO release gaps are at .070 and you still can't stop/start the PTO rotation with the clutch pedal, then I suspect the PTO PRESSURE PLATE is cracked. Years ago I had a 265 model act the same way, I even set the PTO gaps to .050 and it would still would not work right. After splitting the tractor and tearing the clutch apart I found the PTO pressure plate was cracked, it would flex enough during release attempts it would still cause the PTO disc to drag. Replacing the plate and resetting all the linkage got it going right again.

 

[Jim.ME]

If all three release lever bolts are evenly set, and all three PTO release gaps are at .070 and you still can't stop/start the PTO rotation with the clutch pedal, then I suspect the PTO PRESSURE PLATE is cracked. Years ago I had a 265 model act the same way, I even set the PTO gaps to .050 and it would still would not work right. After splitting the tractor and tearing the clutch apart I found the PTO pressure plate was cracked, it would flex enough during release attempts it would still cause the PTO disc to drag. Replacing the plate and resetting all the linkage got it going right again.

I just re-read his first post in the thread. He does say in that that he had the engine overhauled at a shop. He says the mechanic overhauled the clutch at that time. He also says it worked fine before and has not since. It appears he has checked/adjusted all he can with the tractor assembled. I would say at this point either something was missed during the clutch rebuild or was assembled wrong.

It looks to me that we agree splitting the tractor to access the clutch is required to find the issue, at this point.

 

[Herb40]

The less the gap, the quicker the PTO disc should be releasing. That is the purpose of reducing the manual recommended setting of .080" down to 070". It will disengage better.

Just asking this to confirm your linkage adjusting procedure. When you adjusted the rod and set the 5/32 free play clearance of the external linkage did you do the steps of releasing the clamp bolt and rotating the shaft until you felt the resistance of the bearing contacting the pressure plate fingers, then setting the 5/32" clearance? I ask as I don't see you mentioned that step.

If the linkage adjustments are correct and the gaps of the PTO release bolts are that small; @Dieseltech, or others, may have other thoughts; but I suspect you may have issues inside the clutch if it is not releasing. You are approaching the point of having to split the tractor to access the clutch to find the problem. There could be an issue with the PTO disc or pressure plate related to its operation.

Yes, when I adjusted the rod and set the 5/32 free play, I did all the steps you listed. In #1above, I stated:

"I adjusted the clutch linkage according to the MF maintenance manual, although I was never able to feel the second stage pedal point at which the PTO could be shifted. After multiple linkage adjustments suggested by various sources, I was never able to find one that allowed live PTO to be shifted on."

I had completely rebuilt the clutch pedal assembly because the existing pedal support bracket was badly bent in three dimensions. The short "stop" arm was bent upward and backward and prevented full depression of the pedal. The entire bracket was bent outward, causing the inner side of the pedal to almost reach the sheet metal.

The rebuild removed these problems, of course. I did notice (without saying here) that in following the MF instruction to set the linkage rod length to 11-5/8", the adjusting rod is now screwed in about 1/2" less than before, whereas the rod had been screwed in "all the way." I attributed this difference to the need to make corrections required by the badly bent pedal support bracket.

I do not know what the pedal free play was before this PTO problem showed up.

 

[Herb40]

I would make sure the clutch pedal linkage is set in the correct position for PTO operation. If the pedal seems to be annoyingly high, it is likely in the correct position. Tractors used primarily as loader tractors often have the clutch pedal set in the low position. Remove the bottom cover and adjust the release bolts to .060 inch making sure they are even. Also check to make sure your mechanic didn't damage the extensions on the release plate. Improper disassembly of the PTO clutch can break the extensions. Sometimes to get proper release of a two stage clutch they need to be forced to slip under load. Get your chipper running under heavy load and depress the clutch attempting to release the PTO.

Thanks for your suggestion to try to make the two stage clutch slip under load. As you suggested, the engine was started with the chipper attached and the PTO engaged, and then revved up to normal PTO speed (around 1700 rpm) which brings the PTO up to about 540 rpm and the big chipper drum up to its normal full speed of over 1500 rpm. I then fully depressed the clutch pedal and with some effort shifted the PTO out of gear. I stopped the engine and repeated this entire process three times, without success. I realize now that shifting the PTO out of gear was not required and would have allowed much more exercising of the clutch.

The tractor sat unused for over eight months, which would have allowed corrosion to occur within the clutch mechanisms, so this test sounds like a good one to try. I apologize for not trying it sooner, but I was off on another tangent back then.

 

[Jim.ME]

Thanks for your suggestion to try to make the two stage clutch slip under load. As you suggested, the engine was started with the chipper attached and the PTO engaged, and then revved up to normal PTO speed (around 1700 rpm) which brings the PTO up to about 540 rpm and the big chipper drum up to its normal full speed of over 1500 rpm. I then fully depressed the clutch pedal and with some effort shifted the PTO out of gear. I stopped the engine and repeated this entire process three times, without success. I realize now that shifting the PTO out of gear was not required and would have allowed much more exercising of the clutch.

The tractor sat unused for over eight months, which would have allowed corrosion to occur within the clutch mechanisms, so this test sounds like a good one to try. I apologize for not trying it sooner, but I was off on another tangent back then.

I think to slip the PTO clutch as miangus suggested you would need help. I envision the tractor running the chipper with the clutch pedal held fully down while the chipper was fed wood enough to really load the tractor engine down. The chipper just running at speed is not much load.