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John Deere 21" JA65 Self Propelled Mower- Drive Belt Shredding Itself


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05-13-15, 10:17 PM   #1  
John Deere 21" JA65 Self Propelled Mower- Drive Belt Shredding Itself

Before telling me to take my mower to a professional understand that is what I did last summer after an unrelated problem. In trying to fix that problem the "professional" broke the crankcase of my mower and then lied to me the rest of summer about not being able to get a part per the original agreement to replace the crankshaft. At the end of November he came clean and admitted to what happened. He replaced the engine with a used match.

All seemed OK until at the start of this season on the second mowing the drive belt shredded itself. I replaced the belt and then the spring on the end of the drive cable broke. Before it broke it made an abnormal clattering sound. I suspect two problems.

Since a different used replacement engine was provided I do not know if I have the correct drive pulley on the crankshaft and if so if it is installed correctly. Two questions.

1) Should the crankshaft belt drive pulley be installed with the set screw part of the pulley closer to the bottom of the crankcase or the top of the blade brake clutch? Mine is installed with the set screw closer to the crankcase. I wonder if it is installed upside down.

What does the pulley look like? I may not have right one but don't have a way to know. The online JD parts catalog gives only a rough picture of it.

Related to this, I have noticed that the belt is "burning" a groove in the crankcase. This makes me think the belt is riding too high and that the pulley might be upside down or it is the wrong one.

The other drive belt problem is that the drive belt cable has broken twice and shredded the second time. The blade must have done this. I have noticed that the lever which is attached to the drive belt arm is moving up and down relative to the arm. Is that correct? I would think that the lever should not move relative to the arm. It seems that since the lever is dropping below blade shield it may be causing the cable to being drawn into the turning blade.

If I knew how all these parts look correctly installed, I could fix the current problem. Can anyone help? All info appreciated.

 
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05-14-15, 05:44 AM   #2  
You should be able to get a good Owner's Manual and reference to the schematic in a Repair Manual online . . . . I use Tulsa Equipment Warehouse or Manufacture's Supply; but their is probably a good one dedicated to just John Deere.

What I'm referring to is the Schematic and Parts Diagram so that you can see clearly how the parts, pulleys and belts et cetera should be installed to function together properly.

 
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05-14-15, 10:38 AM   #3  
It does sound like the pulley is on upside down. I don't recall there being a set screw though... it may be a generic pulley that he just put on to get it working. I can't really picture what you're saying about the lever moving and all. I can't recall what this system looks like underneath off the top of my head.


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05-15-15, 10:41 AM   #4  
Thanks for the suggestions. Very frustrating that I cannot find a complete exploded diagram to see if the drive pulley is upside down. The JD parts site shows a partial view of it with respect to the drive system but not how it is attached to the crankshaft.

To change the pulley orientation I will have to pull off the top half of the BBC which is frozen to the crankshaft. Do you recommend a puller to get that done?

 
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06-09-15, 10:07 AM   #5  
The drive belt problem is solved. It turns out there were two problems. The pulley was on upside down. Flipping it has aligned the pulley on the crankshaft better with the drive pulley above the transmission. There as also some wear on the lever by the transmission allowing it to drop down below the blade shield. I fixed that putting a washer between the lever and the arm to move it over to catch onto the stop that keeps it from dropping.

Now I have a new problem. It looks like the shop installed the pulley too high on the crankshaft which is causing the handle of the top half of the blade brake clutch to bind on the bottom of the crankcase. That is preventing the BBC from releasing blade engagement. You would think a John Deere dealer could do a better job putting one of their own mowers back together.

 
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06-09-15, 12:57 PM   #6  
Posted By: rjhdyer ". . . It looks like the shop installed the pulley too high on the crankshaft . . ."
I don't think that is even possible . . . . isn't it bolted right to the very bottom (end) of the crankshaft ?

 
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06-09-15, 04:42 PM   #7  
Vermont, no the pulley goes on the crankshaft first, then the brake portion of the blade brake clutch and then the clutch which is the bottom half of the BBC assembly. It is very clear that the thing the BBC cable attaches to on the brake is binding on the bottom of the engine. But I don't know what sets the position of the brake on crankshaft. I don't think I can lower the pulley because then the drive belt is going to rub on the chassis when it is engaged.

 
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