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We got about 12" of snow today and my snow blower lasted only 30 minutes before shearing off one of the 1/4" bolts that holds the rotary blade in place. This is the second time this has happened in as many snow blowing adventures.

What is the right kind of bolt to use for such demanding snow removal?

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    What does the manual say? It should specify the bolt size and grade. Grade 2 will snap/break a lot faster than grade 5, but other stuff might break before grade 5. 12" is quite a lot, so maybe just need to slow way down in speed.
    – crip659
    Feb 24 at 21:54
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    Remember those bolts/shear pins are used to prevent expensive parts from breaking. Might also be trying to tell you a bearing is wearing out or some parts need grease/oiling.
    – crip659
    Feb 24 at 22:16
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    Check the manual for your blower. If it tells you that the bolt is a shear bolt, then replacing it with a stronger bolt will only result in you damaging the machine somewhere else more expensive or harder to repair.
    – brhans
    Feb 24 at 22:40
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    It's not unusual for shear pins to break, especially if you have a gravel driveway. They're doing their job when they break. IIRC, my record is three in a single session (granted, my driveway is 500'). If you're breaking them "too" frequently, you may be trying to use a machine that is under-powered for your needs. BTW, warranty won't cover these, as they are "normal wear and tear" (same for the snow thrower's shoes). Also, is your drive gravel or paved/concrete?
    – Matthew
    Feb 25 at 16:09
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    @Mazura - next time I'll be sure to get up at 3:00am when only 6 inches have accumulated to do that first run :).
    – forrest
    Feb 28 at 2:22

2 Answers 2

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The "right kind of bolt" is a shear bolt.

Specifically, the shear bolt your snowblower manufacturer specifies for that location, since not all shear bolts are the same.

It is deliberately designed to break easily. It's a mechanical fuse. It costs a small amount and prevents breaking other parts that cost a large amount. It is sacrificial protection.

To prevent breakage of the shear bolts, you stop overloading the blower (go slower, take less of a bite, avoid blowing rocks), or you do the classic "replace the shear bolts with regular bolts" and instead of breaking the shear bolts as designed, you break some other more expensive part of the snowblower that the shear bolts were protecting by breaking first.

As mentioned in comments, you might also be seeing a need for lubrication (or adjustments,) lack of which is causing loss of performance and abetting the overload condition. It's also possible (but not the most likely option) that your shear bolts were replaced with incorrect ones that were actually weaker than the correct ones.

Buy lots of shear bolts when buying more. Many recent blowers actually have spots to hold 5-6 spares right on the blower itself - they are meant to be easily replaced. You may have some of the right ones sitting in a bag of maintenance parts included with the blower when you purchased it.

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  • All bases covered, OP should accept this answer.
    – Solar Mike
    Feb 25 at 10:00
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    @jwh20 While such will prevent shearing, stating something like that here is counterproductive, particularly without clearly indicating it's sarcasm and something which will probably cause more harm. Yes, hopefully anyone who is reading has read the answer and translated that into an understanding that what you're saying is exactly what this answer is saying is a bad idea. However, we all know that people actually understanding the answer and translating that into sufficient understanding to recognize such sarcasm doesn't always happen, particularly when just learning.
    – Makyen
    Feb 25 at 14:35
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    Grade 8 bolts would be VERY unlikely to shear. That would solve the problem. It would, obviously, create other problems that will be a LOT more expensive. Yes, it was sarcasm.
    – jwh20
    Feb 25 at 15:02
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    Thank you for a response that puts it all into perspective. Despite 6+ years of snow blowing experience, this is the insight I needed to understand it.
    – forrest
    Feb 28 at 2:24
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I have had a few different snow blowers over the past 40+ years and have only broken 6-8 shear bolts. Every time a bolt broke it was from a stone or a piece of hard ice getting stuck in the 1st stage rotor. If you are breaking shear pins and are sure it is not from something getting into the 1st stage rotor then I would try to find a local dealer to have it serviced.

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