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Discussion Starter #1
Hello all I hit a stump that was covered by leaves, I knew it was there but I had one of those moments anyway after I hit it had a vibration in the mower deck cut the pto off no vibration with pto on vibration back. I took the deck off and examined the blades and I cant see any bend but one of the blades does have a little more shine in a small part. Cant see any bend when spinning. Just wonder if even a small bend could cause the vibration , it is an L130 with 48 inch deck Also to my eye when I put the blades on top of one another I cant really see any real difference. Thanks for any help. The stump was an old dogwood stump pretty tough.
 

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With the deck off, check the play of the blades attached to the spindles as you may have damaged the spindle. The blades should rotate smoothly with zero up and down movement and should be no rough spots as you rotate.
 

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This is also a good time to fill the spindles with grease. Check the sheaves on top of the spindles for tightness.
 

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You probably bent the spindle that the blade is bolted to and the blade now wobbles up and down as it rotates. The eyes alone are not enough to judge a wobble when looking down on a rotating blade.

Flip the deck upside down and tape a laser pointer to the outer end of the blade and observe the dot on the inside of the deck walls as the blade rotates. It should be a consistent distance from the bottom of the deck all the way around. Variation means that the deck that the spindle housing is bolted to is bent (no vibration), or the spindle itself is bent (vibration).

As proof, flip the deck back right side up and lay a straight edge across the two spindle pulleys.

- If the deck is bent, any gap under the straight edge should be consistent in the same position on the straight edge as the blade is rotated a full 360°.

- If the spindle is bent, the position of the gap will move from one edge of the pulley to the other and back as the blade is rotated 360°.

- If the gap varies during rotation, but one edge of the pulley is constantly touching the same spot on the straight edge, both problems are involved.

The cures:

- Buy a new spindle and housing complete if the spindle is bent.

- Shim between the deck and the housing to compensate for a bent deck.
 

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Discussion Starter #8
this is a 3 blade deck I have an old set of blades I might just put them on and see if vibration goes away then I will know if it is the blades being a 3 blade deck hard to tell which spindle could be bent
 

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I hit a steel pipe the other year and had immediate vibration. Once I got the deck off and flipped over I could see it was a cracked spindle and not the blade. It was less $s than I guessed to get the replacement and an easy fix.
 

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You can also flip the deck over and rotate each blade so that its tip is opposite the tip of the next blade. Then rotate one of them to see if they are still lined up. Then rotate the other one to once again see if they are still in alignment. Then move to the next pair of blades and do the same thing. This will tell you if one of the blades is out of the horizontal plane that they should all be in. Most of the ones I have had have been the spindle mount that got warped not the blades.
 

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I hit a hidden stump last summer and ended up replacing all 3 blades and spindles. After that it still didn't cut right. I didn't think I could fix the deck. If I had seen Tudors post maybe I could have.
 

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+1 on what inspectorudy said.
Need to take the mower belt off so you can move the blades independently and check at tips.

Also check for pulley runout on the top of the deck.
I have seen cases where the splines in the (stamped steel) pulleys got stripped out.
 

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You can also flip the deck over and rotate each blade so that its tip is opposite the tip of the next blade. Then rotate one of them to see if they are still lined up. Then rotate the other one to once again see if they are still in alignment. Then move to the next pair of blades and do the same thing. This will tell you if one of the blades is out of the horizontal plane that they should all be in. Most of the ones I have had have been the spindle mount that got warped not the blades.
This is the method that I usually use, but it always leaves me wondering if the spindle is bent. A bent spindle will cause a blade to wobble, but the wobble crosses the horizontal plane at two points, 180° apart. If those points also match the blade on the next spindle you just don't know if the wobble is there or not. A laser pointer will prove the situation, one way or the other.

It will also take the guesswork out if there are 3 blades since a laser on the blade of a straight spindle will hit both of the other spindles in the same place, no matter how far offset they are in relation to each other.
 

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Discussion Starter #15
I ended up putting new blades on they were about due, and I had a spare spindle from other work I had done. The pully on top of the spindle was shifted about an 1/8 off the shaft. So between the new blades spare used but good spindle running great again.

Thanks again for all the help !
 

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Sounds good, jkw123! Have to really watch out for them stumps as they love to hide then jump out when you least expect it.
 
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