Changing Mower Blades

I've got a John Deere L110 lawn tractor that I want to replace the mower blades on. Today I drove it up onto a set of car ramps and reached up under it to try to remove the two blades. All I managed to accomplish today was refill the tires with air and remove some twine that had wrapped itself tenaciously around the hub of the blade. As for loosening the two end caps that actually hold the blades on: forget it. I couldn't budge any of them.
Looking in the owner's manual says they're supposed to be torqued to 42 ft-lbs. Well, even using a piece of pipe as a cheat, I got nowhere. Are these things reversed threaded? Is there a trick I don't know? I was using a 1/2" socket wrench with a 15mm socket. Maybe I need to move up to a bigger wrench?
I hate to pay for something I should be able to do myself.
Mortimer Schnerd, RN mschnerd at carolina.rr.com
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Mortimer Schnerd wrote:

Reverse threads are not unknown.
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Bob F wrote:

Very true, PLUS, loosening overtightened nuts is often eased by trying to tighten and then loosen. So try it both ways. Something that tight, it's not going to hurt.
Liquid Wrench is often a good idea for such a setup. Follow instructions on cans.
As for which way it's threaded, check the rotation direction of the blades. Tightening direction of the nut will be opposite to the direction of the blade rotation. e.g. if you hit a rock, the blade tries to tighten the nut, not loosen it. Twayne
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Mortimer Schnerd wrote:

You may have to remove the deck so you can adequately hold the jack shaft and blade while you torque the bolts. Try a air wrench if you have one. They should be standard counterclockwise to unscrew. Careful you don't round off the corners of the hex bolts, then you will be in deep poo poo. Put some grease on the threads when before you replace them so you don't go through that again.
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Or, of course, a shot of spray lubricant or Heat with torch and then wrench off. but not both (!)
One of those bound to work.
But, by now, that penetrant worked, right?
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-snip-.

but when I apply heat I like to spray a little PB blaster on to cool -- soak for a bit- re-apply heat and try again.

Patience is a virtue with those buggers. Spray & go do something else. Try again tomorrow.
Jim
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Sometimes if you torch heat, and then spray the oil on the bolt, you can shrink the bolt away from the nut. Helps separate them and loosen. I've used impact wrench on a hot nut, that helps. Heat it up, then slam on the impact gun, and pull the trigger. Removed a trailer hitch off a truck that way, one time. Heat-n-beat.
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Years ago, I decided to try an electric, plug in impact wrench. Bought a Wel Bilt, from Northern. About $70. Used it, and had a lot of fun. Until it broke, two lugs into a brake job. I was about three hours from home, helping a friend. Finished the job with hand wrenches. Caught one at Harbor Freight, on sale. It has served well. Problem with the electrics, they are too big to get into some spaces. So, this year I'm going to clear enough space to buy a little compressor, and a length of air hose, and a smaller impact wrench.
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Mortimer Schnerd wrote: ...

Remember hitting anything?
It's possible you've stretched the bolts which has the effect of locking them in there like the blazes. Managed that w/ the outside blade on the 72" deck last year; took about a 4-ft cheater and initially bent a 1/2" small pry bar had used as the lock through the drive sprocket to hold it. Had to get a stouter stop... :)
Heat/cool can help on this; heat alone only makes this problem worse because it's a mechanical distortion problem and swelling the bolt by heating it only tightens it even further. When it cools after a heat cycle it may help some.
If it is this problem, the only real solution is bigger wrench. As somebody else said, go to a six-point socket to minimize the likelihood of rounding them over 'cause if you do, you're toast.
_IF_ (the proverbial big if) you have a good-size knick in the knives, that'd be a clue--I didn't recall hitting anything I thought was significant enough to have caused the problem but w/ that larger mower, sometimes you don't realize what you've gone over in heavy brush. In that case, you might consider taking it to the JD dealer simply to put the onus on them if twist one off. They're hardened, but I was really beginning to wonder before this one came out finally. It was amazing it could have stretched and distorted the threads so much while in place--never seen it to such a degree before in 60-something years.
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Too late. Sounds like he used heat, and a breaker bar. I like a dab of grease on the threads before I reassemble. Makes dissembly easier, next time.
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Stormin Mormon wrote:

I didn't need a breaker bar or a cheat. I moved up from a 3/8" ratchet to a 1/2" drive, heated the bolts for a bit with a LP torch and just put some oomph on them.
I polished the threads with a scotchbrite pad and put some machine oil on the threads before I put them back in.
I don't believe I fried anything. The bolts screw into a substantial block of metal. That metal block would act as a heat shield before the heat would travel up the shaft to the bearings. When I say I heated them, I don't mean to say they were red hot. I was able to handle them bare handed after removing them from the block.
No screeching metal so far....
Mortimer Schnerd, RN mschnerd at carolina.rr.com
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