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Discussion Starter · #1 · (Edited)
Hi all,

I have a GT262 that I bought about 6 months ago that has been mowing great until a couple weeks ago. I am having a problem with the bolt that holds the PTO on shearing off.

The first time it happened I had mowed for about 20 minutes before the blades stopped spinning (which was my clue that something was wrong). I found the bolt about 10' behind me laying in the grass. I figured out what part needed replaced, ordered a new one, and bolted it back on. I took it out a few days ago after getting it buttoned back up for a test run and it seemed to be working great, except the clutch wouldn't fully disengage, leaving the mower going forward at a crawl with the pedal pushed down. I had to replace the transmission drive belt underneath and got the tension too tight. When I put the PTO bolt in, I turned it until the whole clutch was turning. I am not sure if I am supposed to find a way to get the motor to hold still so I can get the bolt to hold the PTO tighter.

Anyhow, today I took it out and started the 3 hours chore of cutting the grass. I stopped the mower but left it running so that I could rake up a few small piles of grass before I mowed over that area. When I came back to the mower I climbed on and pulled the PTO switch to resume cutting but nothing happened. I tried all sorts of things before getting off of it to look underneath and see what was wrong. I found the sheared off bolt laying on the front deck rollers (melted a nice little gouge in them as well). The PTO was pulled back at an angle (as pictured) but went straight once I took off the tension from the deck drive belt. Shortly after I released the tension, the PTO dropped off the bottom of the mower and landed on the front deck rollers. I grabbed it before anything else could melt and set it on the floor. It appears to have just let go; doesn't look like anything broke, aside from the bolt.

I haven't changed anything on the mower since I got it. I have just been using it every couple weeks for about 3 hours to cut my grass. I am at a loss as to why the bolts keep shearing. The only thing I can think of is that the deck drive belt is too tight, essentially pulling the PTO back and putting stress on the bolt, causing it to shear.

Anybody have any ideas?



These pictures were taken after the bolt came out. It was not tilted like this when I "fixed" it.



 

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Are you starting and stopping the deck at wide open throttle? If so that maybe the issue. You should start and stop the deck at the lowest RPM possible. The shock load is quite high other wise.

The other thought I had is the pulley is not on the shaft correctly or the wrong grade of bolt was used when you replaced it.
 

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Discussion Starter · #3 ·
Are you starting and stopping the deck at wide open throttle? If so that maybe the issue. You should start and stop the deck at the lowest RPM possible. The shock load is quite high other wise.

The other thought I had is the pulley is not on the shaft correctly or the wrong grade of bolt was used when you replaced it.
I will double check the pulley once the PTO cools down. As to your other comment, that is exactly what I have been doing. This is my first rider and I didn't get much guidance as far as technique goes from the former owner. I will get a new bolt and give it another shot, making sure not to pull the knob at WOT.

Is there a certain torque I should shoot for when I put it back on? I was trying to get 40 lb/ft but the clutch started turning before the wrench clicked.
 

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Is the bolt shearing off or just loosening and backing out.The bolt looks like it has never seize on it,it should have lock tight on the thread so it doesn't loosen up.They two different types you want the red.As long as its off inspect the pto for worn bearings.If that bolt is getting that hot your bearing could be getting hot loosing the bolt and out it comes.
 
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Make sure that the threads in the end of the crank shaft are good. You may have to remove the deck to get your head in there for a good look. If any are missing or stripped out the bolt will never stay in.
If all looks good clean out the hole with brake clean and compressed air. Any kind of dirt or oil will keep the thread locker from working. Then use high strength as stated above.

I'd just replace the PTO assembly & bolt with a brand new parts. Once you get it to stay on you want to be good for several years. The internall bearing might be going bad.

There should also be some kind of pin that keeps the PTO from spinning with the crank shaft. Make sure it's engaging the PTO correctly.
 
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Discussion Starter · #6 ·
Is the bolt shearing off or just loosening and backing out.The bolt looks like it has never seize on it,it should have lock tight on the thread so it doesn't loosen up.They two different types you want the red.As long as its off inspect the pto for worn bearings.If that bolt is getting that hot your bearing could be getting hot loosing the bolt and out it comes.
The bolt is definitely shearing. The old one had some blue threadlocker on it and the new one, which I got from JD, had a white substance, which I assumed would serve the same function. I will stick some new stuff on it once I get a new bolt. It seems like the entire assembly gets extremely hot when the mower runs (PTO, bolt, etc.) so I am not sure if it is excessive or if that is just how it is.

Make sure that the threads in the end of the crank shaft are good. You may have to remove the deck to get your head in there for a good look. If any are missing or stripped out the bolt will never stay in.
If all looks good clean out the hole with brake clean and compressed air. Any kind of dirt or oil will keep the thread locker from working. Then use high strength as stated above.

I'd just replace the PTO assembly & bolt with a brand new parts. Once you get it to stay on you want to be good for several years. The internall bearing might be going bad.

There should also be some kind of pin that keeps the PTO from spinning with the crank shaft. Make sure it's engaging the PTO correctly.
I will clean the threads out when I get the broken off bolt out. I thought I did that last time but I will make sure to pay extra attention this next time around.

Are you saying to replace the entire PTO, or just get a new bolt and try again? Is there a way to check if the bearings are going bad? I had the mower in neutral while I put the PTO bolt back on this time. Would that keep me from getting it as tight as it should be (should I leave it in gear so that the clutch doesn't spin while I am tightening the bolt)? Is there a torque value that I should shoot for during reassembly?

I appreciate the help that you guys have given me so far.
 

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You may want to get the tech manual for your tractor. The cd version is going to be cheaper than doing parts swaps. It will have things like the torque spec for the bolt, though 40ft/lbs sounds reasonable, dealer should be able to look it up also. But it will also have things like clutch adjustment. The air gap on the clutch may be out of spec causing it to slip and over heat.
 

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Discussion Starter · #8 ·
You may want to get the tech manual for your tractor. The cd version is going to be cheaper than doing parts swaps. It will have things like the torque spec for the bolt, though 40ft/lbs sounds reasonable, dealer should be able to look it up also. But it will also have things like clutch adjustment. The air gap on the clutch may be out of spec causing it to slip and over heat.
Where would I obtain the cd tech manual? I think for now I'm going to ask th dealer and see what they say. Can't really afford to throw a bunch of money at this right now. Just need to get it back in service.

Thank you for your help.
 

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Where would I obtain the cd tech manual? I think for now I'm going to ask th dealer and see what they say. Can't really afford to throw a bunch of money at this right now. Just need to get it back in service.

Thank you for your help.
This is the hard cover, some older models are not on cd or hard to find.John Deere Technical Service Manual - TM1582
 
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Where would I obtain the cd tech manual? I think for now I'm going to ask th dealer and see what they say. Can't really afford to throw a bunch of money at this right now. Just need to get it back in service.

Thank you for your help.

https://techpubs.deere.com/Products/ProductSearch.aspx

Part number TM1582 for printed and TM1582CD for digital. if the link doesn't take you there

Looks like it is about $50 bucks for the digital.
 

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In addition to what the others have said, make sure the bevel washer under the head of the bolt is oriented correctly. The "dish", concave, should be against the clutch.
I would remove the clutch completely and check the bearings very closely.

Sent from my XT1080 using Tapatalk
 

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The bolt is definitely shearing. The old one had some blue threadlocker on it and the new one, which I got from JD, had a white substance, which I assumed would serve the same function. I will stick some new stuff on it once I get a new bolt. It seems like the entire assembly gets extremely hot when the mower runs (PTO, bolt, etc.) so I am not sure if it is excessive or if that is just how it is.



I will clean the threads out when I get the broken off bolt out. I thought I did that last time but I will make sure to pay extra attention this next time around.

Are you saying to replace the entire PTO, or just get a new bolt and try again? Is there a way to check if the bearings are going bad? I had the mower in neutral while I put the PTO bolt back on this time. Would that keep me from getting it as tight as it should be (should I leave it in gear so that the clutch doesn't spin while I am tightening the bolt)? Is there a torque value that I should shoot for during reassembly

Yes replace the PTO with a new bolt. No way to check sealed bearings except turning it by hand. Feel for rough spots or slop/looseness. Seeing the unit gets so hot & snapping the bolt is what makes me think a bearing is going bad.

The PTO works like an air conditioning clutch on a car. An electric current energizes a magnet behind the pulley. This draws the outer clutch part into the pulley making it turn with the belt. Over the years the clutch wears out increasing the gap between the pulley & clutch. Eventually the clutch will start slipping causing even more heat. This is usually the kiss of death that finishes it off. Any excess heat can also melt the windings inside the electromagnet. A weak magnet will also cause the clutch to slip & cause further damage.

Yes you will need to hold the crank shaft stationary while you torque the bold. The dealer should be able tell the specification & the best way to keep the crank from turning.

While the drive belt is off inspect the other pulleys & linkage for any obvious problems. I'd also replace the belt at this point. They get nicked, cut & burnt whenever you have a pulley problem.
 
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I also would recommend removing the clutch for inspection of the bearings, spring "fingers", and the sleeve that goes through the bearings. The sleeve may be broken. It seems like the drive pulley is tilting way more than I thought it could with the bolt out and belt tension still on. I could be wrong.

Auto part Axle part Clutch part Automotive engine part Automotive alternator


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Discussion Starter · #14 ·
In addition to what the others have said, make sure the bevel washer under the head of the bolt is oriented correctly. The "dish", concave, should be against the clutch.
I would remove the clutch completely and check the bearings very closely.

Sent from my XT1080 using Tapatalk
Got the washer figured out when I installed the replacement. The bolt isn't long enough the other way. Thanks for the heads up though.

I will give the clutch a good once over to see if I can identify anything that might be out. If I end up needing a new PTO, what do you think about this one: PTO Clutch for John Deere for 260 265 285 AM119536 High Torque Upgrade | eBay ?
 

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Discussion Starter · #15 ·
The bolt is definitely shearing. The old one had some blue threadlocker on it and the new one, which I got from JD, had a white substance, which I assumed would serve the same function. I will stick some new stuff on it once I get a new bolt. It seems like the entire assembly gets extremely hot when the mower runs (PTO, bolt, etc.) so I am not sure if it is excessive or if that is just how it is.



I will clean the threads out when I get the broken off bolt out. I thought I did that last time but I will make sure to pay extra attention this next time around.

Are you saying to replace the entire PTO, or just get a new bolt and try again? Is there a way to check if the bearings are going bad? I had the mower in neutral while I put the PTO bolt back on this time. Would that keep me from getting it as tight as it should be (should I leave it in gear so that the clutch doesn't spin while I am tightening the bolt)? Is there a torque value that I should shoot for during reassembly

Yes replace the PTO with a new bolt. No way to check sealed bearings except turning it by hand. Feel for rough spots or slop/looseness. Seeing the unit gets so hot & snapping the bolt is what makes me think a bearing is going bad.

The PTO works like an air conditioning clutch on a car. An electric current energizes a magnet behind the pulley. This draws the outer clutch part into the pulley making it turn with the belt. Over the years the clutch wears out increasing the gap between the pulley & clutch. Eventually the clutch will start slipping causing even more heat. This is usually the kiss of death that finishes it off. Any excess heat can also melt the windings inside the electromagnet. A weak magnet will also cause the clutch to slip & cause further damage.

Yes you will need to hold the crank shaft stationary while you torque the bold. The dealer should be able tell the specification & the best way to keep the crank from turning.

While the drive belt is off inspect the other pulleys & linkage for any obvious problems. I'd also replace the belt at this point. They get nicked, cut & burnt whenever you have a pulley problem.
That's great info. I will make sure to get that done correctly this time. I feel like maybe the bolt not being in all the way allowed the clutch room to move, along with my engaging the PTO at WOT, caused it to snap well before the old one did.

I should have time this week to check out the PTO bearings for condition. I appreciate the feedback and answering my questions.
 

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Discussion Starter · #16 ·
I also would recommend removing the clutch for inspection of the bearings, spring "fingers", and the sleeve that goes through the bearings. The sleeve may be broken. It seems like the drive pulley is tilting way more than I thought it could with the bolt out and belt tension still on. I could be wrong.

View attachment 210089

tommyhawk
I thought it was tilting a lot too, but with the belt tension off, the pulley goes back straight. I will see if I can identify a failure of the sleeve during my inspection. It does seem like it is tilting pretty far back but this is all new to me and I have no idea what these parts are capable of.
 

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It may take two people, I am thinking to hold the crank when tightening the PTO bolt. Remove the top screen and have someone hold the flywheel nut on the top end of the crank. I am not sure if a wrench or socket would work best. :dunno: The other trick is remove a spark plug and fill the cylinder with as much nylon rope as you can stuff in. Goes without saying leave some rope coming out to pull the rope out after you finish tightening the PTO bolt.

If the Tech Manual does not give a torque spec, go by the size and grade of the bolt. Owner's Manual and Tech Manual should have a table of torque specs for bolt sizes and grades.
 

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Discussion Starter · #18 ·
It may take two people, I am thinking to hold the crank when tightening the PTO bolt. Remove the top screen and have someone hold the flywheel nut on the top end of the crank. I am not sure if a wrench or socket would work best. :dunno: The other trick is remove a spark plug and fill the cylinder with as much nylon rope as you can stuff in. Goes without saying leave some rope coming out to pull the rope out after you finish tightening the PTO bolt.

If the Tech Manual does not give a torque spec, go by the size and grade of the bolt. Owner's Manual and Tech Manual should have a table of torque specs for bolt sizes and grades.
That's a good idea. I wouldn't have thought of holding it from the top side; I would have searched for a way to clamp it from below while I torqued the bolt.

I have seen a service manual and a technical manual for the mower. What is the difference? I want to make sure I get the correct one.
 

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Well from my experience books come in the following.

Owners manual; the book you normally get when you purchase a new piece of equipment. Ex, 2014 JD X540. Then you have others for almost every attachment you add to it. Ex, 48" front plow, 42" lawn sweeper, rear bagger etc.
This will show you how to setup, operate & do minor repairs/adjustments to it.

Service manual; this is the book that your local dealer has for the repair techs use. This will brake down the different systems on the tractor or piece of equipment. They usually have diagnostic flow charts for checking components of said systems. Also how to R&R (remove & replace) the problem part.

Parts manual; this book will be used to identify the parts that make up the systems. It's usually with pictures, arrows and part numbers.

Electronic diagnostic manual; some machines with a lot of electrical parts & computers will have another book to diagnose and repair them.
 

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I too have used the nut on the flywheel to hold the crank from turning while torquing the PTO bolt. A word of caution about that, especially if the flywheel is also held by a bolt. Check the torque value for the flywheel first. If it is less than the PTO torque value, you risk over torquing the flywheel and cracking it.
I've used the rope in the cylinder method on old flathead style engines with no problems. I have not done this with the newer, overhead valve engines though. I fear the possibility of bending one of those small, delicate valves. It should work just fine if you make sure both valves are closed before the rope is compressed against them.

tommyhawk
 
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