Bush Hog shear pin

[ebeacham]

I have a 6 ft King Kutter BH that came with a grade 2 bolt as the shear pin. Does anyone know wether or not that is the correct hardness for this application? Sure seems like I go through a lot of them.
Thanks,

 

[Rick Jay]

Eric,

I can't answer your question, but I'd like to "tag-a-long" a shear bolt question of my own. With any luck, the wisdom of this board will be able to address both issues at once.

In preparation for winter, I checked the 2 shear bolts on my Woods SS60 snowthrower. I figured it's better to get familiar with them now, before they shear and I have to replace them in the bitter cold. Anyway, the manual specifies them as both being 5/16"x1" long bolts. One of them is on the tractor end of the PTO shaft and the other is on the auger chain sprocket.

I removed them both, and sure enough, they are the size specified. However, the PTO bolt is a grade 8 (6 dashes) and the sprocket bolt is a grade 5 (3 dashes). I was expecting grade 2!

My dealer thought that was a bit odd and was going to look into it. While I had the bolts out, I picked up a couple of grade 2 replacements. I wanted Grade 5, but as is always the case, the hardware store didn't have the Grade 5 bolts in that size.

My question: If I use grade 2, could I cause any damage? By my reasoning, I figure they'll shear before the grade 5's or 8's would. If they shear too easily, then I figured I'd try grade 5's, once I pick some up.
But the grade 2's should work in a pinch.

It sort of defeats the purpose of using the same size shear bolt for both applications if you have to keep two different types (hardnesses) of bolts on hand.

Any comments?

And yes, I know, a new snowblower with plenty of spare shear bolts guarentees that there won't be a flake of snow within our property all winter. /w3tcompact/icons/sad.gif

~Rick

 

[bky]

yes grade 2 are the right bolts to use.
i made the mistake of just throwing any old bolt in my bush hog and then i hit a stump and wam i busted my ptoshaft up inside the tractor.
breaking the shaft wasnt as bad as putting a new one in.
i had to split the tractor to fix it.
so if i was you i would use grade 2 bolts

 

[OverlyRun]

Grade 2 are what are specified for my Land Pride rotary cutter and the bottom of my toolkit is littered with evidence that they shear just fine (well part of the evidence...the rest is in the field somewhere).

 

[mrutkaus]

Just got an SB74-2 blower, posted msg a while ago, seems Woods initially specified a no-name-no-hardness bolt but it has been updated on the parts list to a grade 8 bolt. That's all I know! Maybe a harder bolt fractures more easily? Less easily?

Mike

 

[Poopdeck Pappy]

Just got an SB74-2 blower, posted msg a while ago, seems Woods initially specified a no-name-no-hardness bolt but it has been updated on the parts list to a grade 8 bolt. That's all I know! Maybe a harder bolt fractures more easily? Less easily?

Mike

You are replying to a 12 year old thread, so I suspect he's got his shear pin issues worked out by now.

FYI, I would never use a Grade 8 bolt for a shear bolt. Most manufacturers specify a Grade 2 it seems to me. Grade 8 seems like a good way to negate the whole purpose of the shear bolt setup.

 

[Grant1]

You are replying to a 12 year old thread, so I suspect he's got his shear pin issues worked out by now.

FYI, I would never use a Grade 8 bolt for a shear bolt. Most manufacturers specify a Grade 2 it seems to me. Grade 8 seems like a good way to negate the whole purpose of the shear bolt setup.

I had the same problem with a woods BB60. was shearing grade 2 bolts faster than I could change them. I installed a slip clutch using a grade 5 and solved the problem

 

[Gary Fowler]

I would go to a higher grade if it is shearing bolts for no reason (not hitting anything but grass). My BIL had to go to a grade 5 to keep his Fred Cain BH from shearing when engaging the PTO even at an idle. I have seen it shear a GR.2 bolt when mowing light grass and no obstacles. Some shear bolts are just not the right size/type to begin with. Move up a grade at a time till it only shears when it should, like when you hit a hidden object and not when you just engage the PTO.

 

[JWR]

Maybe this is a timeless topic or maybe all shear bolt issues were solved years ago. Anyway ... using a 4ft John Deere 413 (with no slip clutch) I found the critical factor is the bolt fitting the hole. On my 413 the correct bolt is metric and grade 5 is recommended. When I used an English dimensioned (3/8" or so) bolt that had a little bit of play in the hole it would shear every time I tried to use it. Once I used metric bolts that fit the hole tightly and happened to be grade 5 I have never had a single problem since. I came away with the opinion that a good snug fit in the shear pin hole was at least as important as what grade bolt it was. In my experience only the smaller hogs (being used on smaller tractors) have shear pins instead of slip clutches. I favor using a grade 5 at least if not an 8. However, a grade 2 shear bolt is very cheap. Try it ! If the thing does not become a nuisance by shearing all the time then you have the best protection. If it shears often, go up a grade on bolt hardness but make sure it fits snug first.

 

[Ultradog MN]

It can not be a Bush Hog® if it is a King Kutter.