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We recently bought a Husqvarna M ZT-52 zero-turn lawn mower. It's been working wonderfully, except yesterday, the center blade and retaining bolt fell shot off while I was mowing.

We flipped the deck, and removed the two remaining blades and bolts, and reattached them all, torquing to what was listed in the manual (55 Ft-lbs). Thinking all was well, I started mowing again today, and the left-hand blade shot off after about six hundred feet.

Now I'm not opposed to getting my hands dirty, but this is a new machine (13 engine hours clocked), and having to halt everything to reattach these stupid blades is getting old pretty quickly.

What can I do to keep these dang blades and retaining bolts under the cutting deck where they belong?

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Since the blade is balanced you probably don't want to use lock washers, but you can get away with LockTite or some othe thread lockers. Just be sure that the one you use is reversible. Some will make it so the blade never comes off, even when you want it too. Generally speaking LockTite Red is the permanent kind. You want blue, or purple LockTite. There are other brands as well but that's the one I'm familiar with.

Thinking more about it, putting lock washers on the bolts would probably work as well since the weight you're adding is evenly distributed around the rotation of the blade (both retaining bolts are the same distance from the hub). Not to mention they are likely close to the hub, and the weight of the washers is really small. So they should work, but the thread locker will certainly keep the bolts from separating from the nut or whatever they are threaded into.

I hope that helps!

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  • I'm a little leery about thread lockers, as even the temporary ones have caused problems for me when removing screws and the like. I'll definitely try the lock washers though, thanks for the suggestion. I'll comment again and let you know how it shakes down. – Gabe Evans Jun 22 '16 at 18:34
  • Trying to think of other ways to do this. A castleated nut would retrain the nut, but now you have a pair of cotter pins rattling and spinning at a high rate. I'm really surprised that a drop or two of purple or blue LockTite cause you problems removing the bolt. I've never seeen it, and it just seems really odd. How much torque did you apply trying to remove the bolt that was stuck? Was it a 6 or 12 point socket? – cdunn Jun 22 '16 at 19:20
  • It was a Phillips head screw, and I was twisting hard enough to cam the head out entirely. I don't know if that makes a difference. – Gabe Evans Jun 22 '16 at 19:23
  • Philips to retain the blade? Ok that just seems odd.. Can you replace the Philips head screw with a hex head or a cap screw? The hex head will keep you out of trouble with the thread locker tna then that solves your problem.. – cdunn Jun 22 '16 at 19:37
  • No no no. The phillips head screw was an unrelated incident. The bolt holding the blades in is an 11/16 inch 6-point hex... I think – Gabe Evans Jun 22 '16 at 19:40

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