Snow Equipment Owning/Operating Breaking shearbolts

[DHD]

I am guessing your shear bolts are grade 8 and they have a grove cut in the shank of the bolt where that are suppose to break.

I agree with jix about using a cheap grade bolt.
I've even gone with cheap bolts that had threads the full bolt length, so when the bolt broke it would break at a thread part of the bolt rather than at an unthreaded part.
Thinking that the cut of the threads would make the bolt slightly weaker compared to a bolt that is only threaded partially up the bolt shank.
Most carriage bolts I've seen are threaded full length, and I've used carriage bolt for shear bolts, and yes they will break.
Problem with a carriage bolt is that the head of the bolt is round and requires a pair of pliers to grip the head rather than a wrench.
I buy my cheap carriage bolts by the pound at TractorSupplyCompany. I believe they are grade 5.
.

 

[dbuck]

I am guessing your shear bolts are grade 8 and they have a grove cut in the shank of the bolt where that are suppose to break.

I agree with jix about using a cheap grade bolt.
I've even gone with cheap bolts that had threads the full bolt length, so when the bolt broke it would break at a thread part of the bolt rather than at an unthreaded part.
Thinking that the cut of the threads would make the bolt slightly weaker compared to a bolt that is only threaded partially up the bolt shank.
Most carriage bolts I've seen are threaded full length, and I've used carriage bolt for shear bolts, and yes they will break.
Problem with a carriage bolt is that the head of the bolt is round and requires a pair of pliers to grip the head rather than a wrench.
I buy my cheap carriage bolts by the pound at TractorSupplyCompany. I believe they are grade 5.
.

Any reason you wouldn't use a hex bolt? That's what I'm going to try.

 

[lencamp]

My Lorenz 630 3pt blower uses (2) 1/4-20 Grade 5 full thread shear bolts on the PTO drive flange and auger chain sprockets. On a gravel road I break several during the season but nothing else has broken. Easy and cheap.

 

[dsmiley]

That looks like a good idea. The stock ones are a bit inadequate now that you mention it. Thanks very much.

You should also read this thread before using something other than OEM shear bolts. RAD, the Canadian company that built the BX2750D blower did the R&D on the bolts but there are those who think they have a better idea, and who knows, maybe they do, but personally, I don't think you can beat the OEM shear bolts.

 

[jix]

I Use3/4 inch 1/4-20 grade three crap bolts with a hex head and a plain hex nut without a washer. I use a ratchet to torque them up to about 30 Ft Lbs, WHICH SLIGHTLY OVER STRETCHES THEM AND WEAKENS THEM A BIT, so they are sure to break fairly easily. My answer, works for me.

 

[dsmiley]

I Use3/4 inch 1/4-20 grade three crap bolts with a hex head and a plain hex nut without a washer. I use a ratchet to torque them up to about 30 Ft Lbs, WHICH SLIGHTLY OVER STRETCHES THEM AND WEAKENS THEM A BIT, so they are sure to break fairly easily. My answer, works for me.

I think it will be grade 2, 5, or 8. Not grade 3.

 

[DHD]

Any reason you wouldn't use a hex bolt? That's what I'm going to try.

I haven't had much luck in finding fully threaded Grade Five 5/16" hex bolt .
That's why I was using the fully threaded carriage bolts.

 

[dbuck]

Ok so tonight I tried a regular 5/16 hex bolt, and it broke even quicker than the proper shear bolt. Totally frustrated. Taking it to my dealer tomorrow to have them assess things. Maybe there is another reason.

 

[Phil48]

Not normal...

2011 , first year I had my new front snow blower, 5 or 6 shear bolts in a nick of time! The dealer could send a competent mechanic. He isolated one by one every potential source of the problem. He found out a crooked shaft. He swamped the problematic piece on another snow blower, since then, not a single shear bolt was deheaded! There must be something a little off in your setup. Something over tight? Offset?

 

[bigtiller]

Ok so tonight I tried a regular 5/16 hex bolt, and it broke even quicker than the proper shear bolt. Totally frustrated. Taking it to my dealer tomorrow to have them assess things. Maybe there is another reason.

Try an 8mm bolt. It should fit and it is just a hair bigger.