mower blade torque

Bob_Trevithick · May 20, 2002

A buddy has an old wheelhorse with MMM, and we used my new air impact wrench to remove and replace his mower blades the other day. My wrench claims to be good for 230 ft/lbs.. should that be enough?

I would have thought it would be more than enough, but he says the first time he tried the deck after the blade switch it made loud clanking noises. We're going to look at it tonight and see if we can figure out what's wrong.

He normally used a very long wrench with a "cheater bar" and gave it everything he had to tighten the blades. I'm thinking that my air wrench probably got them just as tight, and even if it didn't, the problem wouldn't show up immediately, would it? Wouldn't it take at least a few minutes to loosen up enough to make loud noises?

I'll look at my rear finish mower manual when I get home, and see what torque values they recommend for those blades. That should at least get us in the ballpark? Anybody know what typical values are for smaller lawn tractor type mowers?

Any thoughts appreciated!

s1120 · May 20, 2002

Your gun should have tightend them well. I don't know what the value should be, but I dont think over 100-150ftlbs.The bolts are not that big.

Argee · May 20, 2002

Check the length of the blades. If the new ones are longer, then the tips of the blades are hitting. I put a new set on mine a year or so back and they were an 1/8" longer. Looked like I had the clearance. Boy was I wrong,/w3tcompact/icons/blush.gif made a hell of a clatter when I fired her up./w3tcompact/icons/shocked.gif Ground both ends of the center one and was back in business./w3tcompact/icons/smile.gif Just have to remember which one goes in the center when I sharpen them/w3tcompact/icons/hmm.gif I just tighten them by hand to what I think is right. They have lock washers on them. I think they're only 5/16" bolts.

s1120 · May 20, 2002

Ahhh, What size deck do you have? The 48" deck has two diferent size blades. The center is about an inch shorter.

Bob_Trevithick · May 20, 2002

I'll bet you guys are right about getting the blades in the wrong position! We'll be working on it in about 20 minutes.. and this is the first thing we will check!

Yes, I think he said it was the 48" deck!

Thanks!! You guys are super!!

s1120 · May 21, 2002

Sorry to mis lead you Bob, but I mis spoke. Argee was talking about having one blade to long, and I know he has Case tractors, but I see from his profile he has a 42"deck. As far as I know, only the Cases have the one short blade, and only on the 48"deck. But I could be wrong. I hope you find the problem.

Bob_Trevithick · May 21, 2002

Well, it turned out that what had really happened was that we got two washers under one of the blades and none under another. /w3tcompact/icons/blush.gif I guess we were so impressed with the air wrench that we just kind of rushed the job and didn't pay enough attention. He's back up and running now with no problems.

Funny, you could spin the blades by hand and no sign of anything wrong, but spin them up with the engine and she made a terrible clatter.

Anyway, problem solved.. thanks for the assist!! As always, I learned a lot just by the conversation.

Bob

Argee · May 21, 2002

I've got a 44" deck. Bought a set of generic blades at the local hardware who carried quite a few different blade sizes. The guy I bought them from owns a Case also. He said they would work. He's the one who ground the center blade down. For free I might add.

s1120 · May 21, 2002

<font color=red>Bought a set of generic blades at the local hardware who carried quite a few different blade sizes. </font color=red>

?? I did not know you could get aftermarket blades for these. Being reverce rotation, I thought no one made them. Now if I gould just get some mulching blades.