Stripped pullies

MC-ProfessorJune 7, 2013

I have a Craftsman YS4500 rider, which I use to mow 1 1/2 of my 2 1/2 acres. Every year I have to replace the blade drive pulleys a couple of times and the mandrels at least once because they strip out due to poor design.

Does anybody make an aftermarket mandrel/pulley system for model 917.276180?

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You can Google-
AYP part#
and see what's available out there.

    Bookmark   June 7, 2013 at 6:25PM
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Loktite on new ones??

    Bookmark   June 8, 2013 at 7:04AM
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The design of the pulley/mandrel splines on the YS4500 has been used for quite some time by a number of mower manufacturers. Murray was using identical drive splines 10 or more years ago. The pulleys are die-stamped with the hole configuration. The shafts are hot rolled with the spline configuration. Both are low cost production techniques.
Better designs exist, such as keyed shafts and pulleys. But they require more room and cost considerably more. They may not exist as off-the-shelf parts for your specific mower.

This post was edited by bus_driver on Sat, Jun 8, 13 at 9:19

    Bookmark   June 8, 2013 at 7:19AM
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Strange. Something else must be afoot here. I see hundreds of these spindle pulleys a year and replace maybe 20 pulleys a year. These are almost always from a situation where the blades have been where they didn't belong. In most cases where you replace a spindle with a broken housing- the spline is still good and if the pulley isn't tweaked- it goes back on. Would an out of balance blade loosen the lock nut enough to cause this condition- possibly.

    Bookmark   June 8, 2013 at 10:53AM
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I would hazard to guess that perhaps insufficient torque is being used to tighten the pulley retention nut.
The splines (or key and keyways on others) serve as just "a portion" of power transmission in and of themselves.
It is absolutely necessary that the pulleys be clamped down into position as tightly as the design and materials permit in order to assure that the pulley does not develop any slop between it and the spindle shaft.
Any rotational slop or slipping of the pulley will lead to the spline contact surfaces slamming against one another in operation...........with hammer-like force...........and that is what ultimately wipes out the splines.
Maybe want to review exactly HOW the pulley is being tightened to the spindle (work methods).
If you are doing the actual replacing of the parts (instead of farming it to a pro shop), how are you holding the spindle from turning and how are you applying tightening torque to the pulley nut?
Knowing exactly how the pulleys are being dealt with might reveal a problem (and provide a solution).

    Bookmark   June 8, 2013 at 12:21PM
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When repairing a mandrel I always block the rotation and use a torque wrench on the pulley nut and the blade nut and then peen them with a center punch.

When replacing a mandrel assembly I do the same regardless of where the part came from.

Questioning the pros(?) in the area they are all in love with their air impacts and then charge the customer for the repair when the new mandrel fails a year or so later.

I've never had to replace a mandrel that I had previously installed.

    Bookmark   June 8, 2013 at 12:58PM
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I have been using commercial automotive type anti-seize on rotary mower clamp bolts for many years, and never has the blade come loose or required re-tightening. I don't use a torque wrench, but I do reef on the bolt hard enough to exceed 50 foot-pounds.

    Bookmark   June 8, 2013 at 4:20PM
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Replaced a bent spindle/mandrel on a Craftsman mower today. The left side of the deck. It is not necessary to remove the deck. Disengage the deck drive clutch so that the belt will be slack.With heavy shoes, put left foot against the blade to prevent rotation and 7/8 wrench on the pulley nut. Yes it is very tight, but removable with ordinary wrench. Splines are quite tight on this one -fortunately. Spray splines with penetrant, tap pulley light with with hammer. When the pulley moves, wiggle it up and down and off the spindle, remove the belt. Remove the old spindle assembly, install the new. You know the rest. Really tighten the pulley nut.

    Bookmark   June 8, 2013 at 8:19PM
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I've used my 1/2" air impact on all mower decks, both pulley nuts and blade bolts or nuts, for yrs and haven't a spline or key failure yet.

This post was edited by mla2ofus on Sat, Jun 8, 13 at 23:25

    Bookmark   June 8, 2013 at 11:24PM
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Had to chuckle on lurkers post. Not so much on the mechanical content of it. I do think sometimes people get to aggressive w/ an impact. The fact that he's never had to replace a spindle he had replaced before. I seem to much of the time. especially used to be w/ the old 3 leg spindles. But not because of bearing or pulley failure- but because they keep hitting that same root or the stupid things the kids leave in the yard or... :0

    Bookmark   June 10, 2013 at 2:20AM
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Yes Tom. I think someone on this forum once said, "Stupidity is doing the exact same thing over and over again, but expecting the outcome to be different" (or something like that).

    Bookmark   June 10, 2013 at 10:44AM
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It was Albert Einstein who said "Insanity is doing the same thing over and over again and expecting different results."


Some people learn from their mistakes and some just get tired of spending money on the same repair again and again and some don't.

I don't fix Riders for a living and my repair count is low mostly helping friends and neighbors in the area. Far less riders around here than subcuts, cuts, and full size.

    Bookmark   June 10, 2013 at 11:22AM
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Thanks JAL. I knew I had seen something like that before.

    Bookmark   June 10, 2013 at 12:55PM
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Until recently, I always thought Einstein said it. Although commonly attributed to him, It's very doubtful that it was Einstein. It has been attributed to Ben Franklin amongst others and that is also unlikely. The earliest report of the quote occured in the 70's or 80's. if memory serves me, it was in a text on drug addiction. It has never been documented that Einstein or Ben Franklin ever said it.

    Bookmark   June 10, 2013 at 9:29PM
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The uncertainty of the origin of the statement does not diminish its content in the least.

    Bookmark   June 10, 2013 at 10:47PM
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Didn't say it did, so, I was kinda wondering why you felt it necessary to clarify mownie's statement with the inaccurate attribution. Regurgitating an incorrect attribution just promotes falsehoods (urgan legends) for others to pass on. Then again, inaccuracies are your bailiwick. Once again I've encroached on an area of your expertise-when will I learn?.

    Bookmark   June 10, 2013 at 11:24PM
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Well grass... Google the statement and you find about 858,000 hits and quite a few at the top seem to attribute that saying to Einstein.

If all you've got to do is troll here on the forum insulting and demeaning people then you are a legend in your own mind.

I must remember to âÂÂNever argue with an idiot. They will only bring you down to their level and beat you with experience.âÂÂ
â George Carlin

And you grass, are the most experienced idiot on the forum.

    Bookmark   June 10, 2013 at 11:48PM
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JAL- I neither have the time nor the inclination to teach you how to research factually. It doesn't matter how many "googles" show Einstein as the author--it's never been documented. The fact that you are one amongst many in error doesn't make the error anything more than urban legend::

Despite your constant insistance otherwise, Opinion isn't Fact and Fact is not determined by the consensus of the masses.
Here is an actual Einstein quote for you:

"In order to be a perfect member of a flock of sheep, one has to be, foremost, a sheep."
-Einstein's Essays presented to Leo Brock. (1954)

    Bookmark   June 11, 2013 at 8:13AM
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You are a man who holds his own and your ability to type without missing a stroke is impressive.

This post was edited by justalurker on Tue, Jun 11, 13 at 10:11

    Bookmark   June 11, 2013 at 10:10AM
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I wonder if the original poster who started this thread has learned anything from the suggestions/examples offered by us.
Or you thinks we might have hit upon his problem, but he he is unwilling to respond (embarrassed, confounded, bewildered, in denial)?
Oh well!

    Bookmark   June 11, 2013 at 11:19AM
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JAL, I'm a man of many typos, misspellings and more than my share of misconceptions, but I enjoy reading this forum and learning everything I can from you tractor gurus.

mownie, I can take a subtle hint. I'll shut my mouth now.

    Bookmark   June 11, 2013 at 11:46AM
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No, no. I wasn't hinting at anyone, except the original poster.
I just wondered if MC-Professor was going to be one of those "one hit wonders" who never come back to acknowledge that anyone tried to help and/or discuss the issue (in the interest of furthering information to all parties).
You guys can go back to being the Hatfields & McCoys now :^)

    Bookmark   June 11, 2013 at 11:58AM
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No longer do I have access to a metal hardness tester. It would be interesting to test the hardness of original part and compare to the typical aftermarket part. Soft parts will fail sooner for this application.
I have an idea for a "farmer fix" for this . But it is only a concept at the moment and needs implementation and testing before posting. Perhaps later.
A "farmer fix" is a way to quickly get something functioning again after a fashion when time is of the essence. Often the term is used derisively but if the baler breaks and rain is expected within the next two hours, one does all the improvising possible to get the hay into the barn.

    Bookmark   June 11, 2013 at 5:25PM
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Time has not yet permitted testing my concept. One farmer fix for stripped pulley splines would be to weld the pulley directly to the shaft. But that has potential problems. While concentricity should be OK, the pulley is likely to wobble in the horizontal plane with vibration and other problems. It would have to be cut off to replace the spindle, bearings or the housing. The heat of welding so near the bearing is not good at all.
If a nut was welded to the stripped pulley, it would tighten as the blade encounters resistance while cutting-- on the AYP mowers, at least.
So my plan is to use a 5/8 lockwasher on top of the pulley and under the nut, tighten the nut as outlined above. Use the original nut-- it has a counterbore to fit over the splines. Then weld with MIG to secure the lockwasher to the pulley and the lower flange of the nut to the lockwasher. No welding on the wrench flats on the nut. Continuous welding is not necessary. About 3 good tacks should do the job. This places the welds out on a larger circle than does welding the shaft directly to the pulley, keeps the welding heat much farther from the bearing, leaves the weld accessible so that the nut can be later separated by grinding off the tacks. Pulley removal is by just using the 7/8 wrench to unscrew the nut ( and pulley) .
If the splines are not stripped, grinding the welds is required for removal.
Obviously, the shop equipment available to each of us will vary.

    Bookmark   June 13, 2013 at 7:47AM
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First, not all YS45000 are identical. They have a number of different engines and cutting widths.
Today I did my pulley "repair as noted above.
It worked just as expected. Be sure to tighten the nut with a long wrench before use. Letting the running of the blade tighten the nut may overstress the threads.
I have not disassembled any of the aftermarket spindle/mandrel assemblies. But I strongly suspect that those with a grease fitting in the top end of the spindle have bearings without seal or shield on the interior of the spindle housing. And suspect that they are shipped with no grease. This means quick failure if one neglects to grease generously before the initial use. And that could contribute to pulley spline failure because of the extreme load caused by a bad bearing. So grease with several pumps of the gun before use. Don't be stingy with the grease before the first use. .

    Bookmark   June 20, 2013 at 5:52PM
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