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Discussion Starter #1
I have an STX38 and the clutch is gone in it...according to the JD dealer. I was thinking about replacing it myself and saving $200. The only way I can figure out to get to the clutch is to take the deck off, then use my chain hoist to haul the front end up in the air so the tractor is balanced on it's rear end. Then I can see what I'm doing.

I'm a strong do-it-yourselfer, but I don't work on tractors, cars, etc. so I don't have the "feel" you need for that kind of work. Does anyone have some suggestions of what to do?

I have both STX manuals, and tried to read through the clutch part but it was just too tough. Couldn't make sense of it.
 

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If the clutch on your tractor is attached the same way as clutches on larger GTs with vertical shaft engines and its not rusted on, it's a piece of cake... just remove the bolt and it'll slip off easily. I once replaced the clutch on my old 265 and it came right off with no difficulty. Last fall I had to remove the clutch on my 335 and that was a different matter... it was frozen on solid and no amount of PB Blaster would free it up. This clutch was still in good shape and I ended up destroying it getting it off.

My suggestion to you is that if you plan on keeping your tractor for a while, get some antiseize compound and apply it to the crankshaft before putting the new clutch on... it'll make it much easier to remove it later on.
 

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looking at the exploded parts diagram, just what part of your clutch is gone? It looks to me to be a mechanical pedal to idler wheel setup. No clutch plates or anything to break say the drive belt. What is it not doing, if it isn't re-engaging then likely just a weak return spring or an adjustment.
 

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Discussion Starter #4
It wouldn't start so I took it in to the dealer. The starting problem was that the spark plug cable wasn't completely seated. But he also found that an idler was bad and a couple bearings were bad plus the clutch was going out.

I don't have a job and since he got the mower started, I thought I'd just keep mowing with it and put off spending the money. Well, I mowed over a small, low stump I've mowed over before without any trouble, but this time the blade caught and stalled the motor.

When I got it started and back into gear, it made a really funny noise and wouldn't drive very well. Now, if the motor is off and it's in gear I can push it around. Before, being in gear would lock it if the motor was off.

The clutch part number the dealer gave me shows a completely contained unit if you search on the JD website.

What's the easiest way to remove the clutch? Do I just haul the mower vertical on my hoist like I mentioned or is there a better way? I'm assuming the stump just finished the clutch off.
 

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OK, I'm looking at this and thinking we're talking different tractors. Here is the drivebelt/clutch diagram. Looks like pulley (#29) moves back to release (clutch) the drive. I've seen a number of posts about this setup and most recommend to lift the tractor up to work on it.

 

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I think he may be talking about the PTO clutch. Not sure though.
 

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I wasn't sure exactly that's why I posted the diagram, but that makes more sense! I'll have to go back through the sections to see if I can find the PTO.
 

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Here is the PTO looks like you should be able to remove and open to see if it can be fixed. Most PTO's, Part # 7,5, and 4, have a snap ring on the upper side, remove it an then you should be able open to see the field coil and magnets. I know one forum member, a machinist, had one with scratches in it and took it to work put it on a lathe and cleaned it up. Said it worked perfectly after he put it back on and gapped it!

 

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The pto clutch has nothing to do whatsoever with the tranny or drive wheels. It is for the mowing deck only.
 

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The pto clutch has nothing to do whatsoever with the tranny or drive wheels. It is for the mowing deck only.
True. But there's also no clutch per se in the driveline, just a tensioner pulley on the drive belt. Hence the confusion.
 

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if he is talking about the pto "clutch"-

and assuming replacement with a new one, it is a simple task if it takes more than 30 mins something is wrong

I just did the STX38 recently.

Remove the mower deck
Remove the gas from the tank
Push the mower over on its side
Remove the spark plug
put some nylon rope into the spark plug hole (use a LONG piece)
rotate the shaft until the rope is compresssed
now turn the crankshaft bolt and it will come loose
disconnect wire from above deck
clutch will come right off

push wire through deck
install new, tighten bolt!
done

REMOVE NYLON ROPE BEFORE TRYING TO START

(after turning mower upright, let it sit for 10 mins or so to be sure all oil returns to the bottom of the motor)

REPAIR
the pto "clutch" is just a big electromagnet, you can test it by putting 12Vdc across the two wires. With no voltage, the two parts should spin independantly, with voltage applied the two parts are pulled together and will NOT spin seperatly)

It also has an adjustable gap to allow it to "slip" when non powered. I believe the correct gap is .012 you use those three spring loaded nuts to set the gap.

your dealer said it was gone? I would ask what GONE actually means? is an actual metal part broken??, a bushing shot?, or maybe one of the windings in the magnet bad??

often a take apart and a good cleaning and re-gapping is all that is needed! :trink40:

ask if more questions-
 

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Remove the spark plug
put some nylon rope into the spark plug hole (use a LONG piece)
rotate the shaft until the rope is compresssed
now turn the crankshaft bolt and it will come loose
While this method may work I would not recommend it. There is a risk of valve damage when you compress the rope with the piston, particularly if you happen to be on the exhaust stroke. The OEM recommendation is to remove the top engine cover and access the flywheel bolt to hold the crankshaft from moving and counter the torque required to break the PTO bolt free. If you have access to an impact wrench neither method is necessary and you are done in about 30 seconds.
 

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While this method may work I would not recommend it. There is a risk of valve damage when you compress the rope with the piston, particularly if you happen to be on the exhaust stroke. The OEM recommendation is to remove the top engine cover and access the flywheel bolt to hold the crankshaft from moving and counter the torque required to break the PTO bolt free. If you have access to an impact wrench neither method is necessary and you are done in about 30 seconds.
been doing this a real long time and have NEVER seen damage, 2-stroke, 4-stroke, over and under cams, etc. while I would agree it is "possible" to do damage it is HIGHLY unlikely, but if a black cloud seems to follow you maybe try another tactic...

I would also agree if you have an impact wrench use it and if really fearful HODs sugesstion will work very well, might take two people too, but for the do it yourselfer on a budget, fill it with nylon... and never look back :thThumbsU
 

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Discussion Starter #16
I have several older impact wrenches so that option is available. Not sure how big my black cloud is...I'll have to check on the day I do the mower work. :)

1) Either push it over on it's side or haul it vertical with a chain hoist....is pushing it over better for any reason?

2) Does the fact I can push it around while in gear with the motor off confirm the PTO clutch needs replaced/fixed?

3) Where is the PTO clutch? Sorry, I'm such a greenhorn on fixing tractors.

4) The part number the JD dealer gave me on the repair estimate took me to something on the JD website that looked just like the PTO clutch above. So that must be what the dealer was talking about.
 

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I'm not an expert on your tractor, but I believe (pretty sure) that this will be under the tractor since it comes off the engine shaft. It should be a double pulley setup with the PTO on the bottom (not so sure about this). I've never heard of an electric PTO "locking" a tractor up. If something goes wrong with them normally when the electric is turned off they will release! I would haul it up vertical not push it over. The PTO clutch should not affect your ability to push it around!
 

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..I have also probs with my pto on the STX38, black mower deck. Export Version.
My PTO is frozen and it wont disengaged it is also locked if the engine is not running.
I´ve an impact wrench and will remove the pto soon.

But I have a guestion.

Has the pto bolt left hand thread or is it normal right hand thread?

thanks

joe
 
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