I read one of the other posts about mower shear pins and was a bit surprised. I've never heard of Grade 2 bolts nor Grade 10 for that matter. Anyway, I have a five foot wide bush hog that I've been using 3/8"x3" Grade 5 bolts in as the shear pin. I doubt the deck would even spin up with a Grade 2, lol. The problem is that I break bolts constantly, maybe four or five per hour. Now I'm not hitting rocks or otherwise stalling the blades from an impact as such. One of two things will break the bolt: heavy grass/weeds or a small sapling (3/4-1.5 inch dia.). The little saplings, what usually happens is I hear the bang as the mower cuts the tree off and the bolt breaks at the same time. The blades are still spinning after the bolt breaks, but it's irrelevant at that point.
The heavy grass/brush is the most annoying, at least with the little trees I can see them coming and raise the deck a bit. Yesterday I broke a two Grade 5's in twenty minutes, with the deck 9-14 inches off the ground mowing 4 foot high grass and whatnot, no dogwood or anything. I've tried Grade 8's in the past and they aren't much better, they are a little tougher, but they still snap on the little saplings and they are a d@mn sight more expensive.
I was about to replace the bolt with a plain steel rod, hammered over at the ends to keep it from falling out when I saw the post about Grade 10's, and the different sizes. It also occurred to me that maybe the cheap steel rods they sell here are no tougher than a Grade 5 bolt. Anyway, I've always used 3/8" carriage bolts because that's what this ancient deck came with, but given how loose they fit, a larger bolt might fit, so I bought some 7/16 and 1/2 inch bolts to try, and I have Grade 8's of both coming tomorrow. I'm sure the 7/16" will fit, less sure about the half-inch.
I'm using a 1970 (I think) IH 444 diesel to run the deck. I'm not too worried about stripping the gears out of, if it dies, it dies. I generally mow in 2 low, revs at near max. I can't tell you what that is, because the tach has been broken since I bought the tractor 27 years ago. 1 low is just too slow, and 3 low is too much for the heavy stuff, but it's fine for normal mowing. If I'm working near the treeline and the bush is all dogwoods and crap, then I'll shift to 1-Low, the tractor has to work pretty hard in that stuff.
So how much tougher is a Grade 10 bolt ? I was thinking of getting a skinny drawbar pin that would fit through the bolthole, I'm pretty sure that thing won't break even if I hit an anthill. Any other suggestions as to what else might not break as a shear pin ? I haven't yet looked into where to buy Grade 10 bolts, I'm hoping a fatter bolt will help.
The heavy grass/brush is the most annoying, at least with the little trees I can see them coming and raise the deck a bit. Yesterday I broke a two Grade 5's in twenty minutes, with the deck 9-14 inches off the ground mowing 4 foot high grass and whatnot, no dogwood or anything. I've tried Grade 8's in the past and they aren't much better, they are a little tougher, but they still snap on the little saplings and they are a d@mn sight more expensive.
I was about to replace the bolt with a plain steel rod, hammered over at the ends to keep it from falling out when I saw the post about Grade 10's, and the different sizes. It also occurred to me that maybe the cheap steel rods they sell here are no tougher than a Grade 5 bolt. Anyway, I've always used 3/8" carriage bolts because that's what this ancient deck came with, but given how loose they fit, a larger bolt might fit, so I bought some 7/16 and 1/2 inch bolts to try, and I have Grade 8's of both coming tomorrow. I'm sure the 7/16" will fit, less sure about the half-inch.
I'm using a 1970 (I think) IH 444 diesel to run the deck. I'm not too worried about stripping the gears out of, if it dies, it dies. I generally mow in 2 low, revs at near max. I can't tell you what that is, because the tach has been broken since I bought the tractor 27 years ago. 1 low is just too slow, and 3 low is too much for the heavy stuff, but it's fine for normal mowing. If I'm working near the treeline and the bush is all dogwoods and crap, then I'll shift to 1-Low, the tractor has to work pretty hard in that stuff.
So how much tougher is a Grade 10 bolt ? I was thinking of getting a skinny drawbar pin that would fit through the bolthole, I'm pretty sure that thing won't break even if I hit an anthill. Any other suggestions as to what else might not break as a shear pin ? I haven't yet looked into where to buy Grade 10 bolts, I'm hoping a fatter bolt will help.
