Craftsman 42 tractor mower cuts deep in center

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Old 09-15-08, 06:13 PM
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Craftsman 42 tractor mower cuts deep in center

Having a problem with a 42" Craftsman tractor mower. It cuts deeper in the center (possibly a little off center) and scalps the grass, even at highest settings. Checked mower deck level, has new blades, new belt. Any idea what is causing this?
 
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Old 09-15-08, 10:44 PM
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Check the aluminum mandrel housings. Often, one or two of the mounting legs break and cause the entire assembly to lean when the belt is tightened, and cut unlevel.
 
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Old 09-18-08, 08:51 PM
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The mandrels appear to be solid. However, in looking under the mower deck it has become apparant that the one blade on the right side is slanted and rotates about 2 inches lower in the middle than on the outer side. The blade is not bent. We took it off and the blade is fine, it's the mounting that seems to be on an angle. Any thoughts on how this would suddenly become a problem?
 
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Old 09-18-08, 11:51 PM
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Generally this is caused by one of the mounting legs on the mandrel being broken. Have you looked at all 3 mounts of the mandrel housing up close and from the underside?
 
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Old 09-19-08, 03:19 AM
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Follow Cheese's advice and ensure neither of the mandrels are broke. If they're not, the next thing that could have happened is the deck portion that the mandrels are bolted to is distorted. Put a straight edge on top of mandrel pulleys, if the deck is not bent, the straightedge will touch both sides of both pulleys.
My experience with Craftsman decks is that when someone hits something solid, e.g., short stump or rock, the tension of the belt will help distort the deck/mandrel inward.
Another clue is, with deck off and standing on it's edge, see how the blade tips match up when they are at their closest point together.
I've never had both distorted, I beat the underside of the deck with a big hammer to get it back in position.
hope this helps,
thanks,
 
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Old 09-21-08, 07:32 AM
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Will try this again.

It is only one side that does this and it seems to be a problem no matter what height the deck is positioned and is worse if not on a flat surface. For example in the back yard there is a slight hill and when I turn on the hill it will leave "crop circles" from the right blade as it scalps the grass and digs in the dirt. You can see the ridges of the blade turns as the mower moved away from that spot.

The mandrells will not budge. They are solid on the deck. Will try the straight edge and see what happens.
 
  #7  
Old 09-27-08, 10:29 PM
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Cool Try the straightedge trick

Greetings,

Try the straightedge tip, it might make it easier to visualize the problem. The deck is pretty rigid, so my money is on a broken mandrel leg or two. If the mandrel pulls inward (due to the tension of the belt) then the blade tip WILL be lowered on the inside (or "the middle between the two blades" if you prefer.) The 'outside' edge will be raised and may actually grind against the deck, so check for damage there too.

Just today I broke one mandrel leg on my Craftsman 42". Visual inspection while the deck was still on the mower didn't show any obvious damage but the blade wouldn't spin.

I pulled the deck and only then could I determine that the mandrel was canted inwards about 6 degrees. I first thought 'bent deck' also, but veeerrrry careful inspection uncovered the broken mandrel leg. Seriously, a broken leg can be hard to spot, especially if you don't pull the deck off first.

And trust me, the cast aluminum mandrel will break long before the steel deck deforms. Probably a design feature to keep the deck from deforming! This is my third mandrel replacement in about 12 years. :-)

Good luck! I hope this resolves your scalping problem.
 

Last edited by Bubba Beernut; 09-27-08 at 10:36 PM. Reason: Clarity
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