# Shear pins or bolts



## sboricic (Jan 18, 2011)

I was just wondering if you would recommend using the correct shear pin or just a bolt and nut for the auger on a snowblower when it breaks.


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## Shryp (Jan 1, 2011)

You should use the correct shear bolts or pins because if you use a generic nut and bolt they might be stronger than what the manufacturer intended to be there. If the bolts are too strong the gears inside the gearbox will break instead of the shear pins.


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## bwdbrn1 (Nov 24, 2010)

Shear pin for sure! Too many horror stories popping up lately about folks finding out the hard way about substituting them with regular bolts.


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## sboricic (Jan 18, 2011)

Good to know. I have a snowblower that was given to me by a friend that I'll have to put proper shear pins on then.


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## uhall (Dec 17, 2012)

Also, and I forgot who posted it, but they said not to tighten the shear bolt tight to the auger. You should be able to move the shear bolt a little, there should be some play between the auger and bolt.


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## GT14 (Feb 12, 2011)

Shear pin!


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## sscotsman (Dec 8, 2010)

The terms "shear pin" and "shear bolt" are used interchangeably, to refer to the same thing..I dont believe one or the other is "official" in any way.

logically, using "shear pin" might be better, because it avoids the use of the word "bolt" alltogether..so people might be less likely to confuse them with *regular* bolts!

The manufacturers themselves usually say "shear bolt" however, in owners manuals..so that is probably the most common term..but either is fine and acceptable.

Ariens manual from 1966:
http://apache.ariens.com/manuals/SSA-66.pdf
note the use of "shear bolt", not shear pin.

Different manufacturers have probably used different terms, or have probably used both terms at different times..In my experience, "shear bolt" is the more widely used term, and probably the most commonly used term overall.

and technically, they *are* bolts! in the sense that they are threaded, and take a nut.
But the important word here is not "bolt" or "pin"..the important word is *shear*! 
Just always make sure you an *actual* shear bolt, or shear pin..and not a "regular" bolt! 

Scot


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## uhall (Dec 17, 2012)

I remember back in the 70's when my dad had a Bolens garden tractor with a PTO. This thing had every accessory known to man. All the accessories, especially the tiller, needed shear pins. The shear pins were a smooth metal bolt (no threads) that had a hole towards the end, that accepted a cotter pin. That's what I always picture when I hear of shear pins, but I understand we all use pins and bolts in the same way. And like Scot said, just as long as it has "shear" in it, you're fine.


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## sscotsman (Dec 8, 2010)

uhall said:


> I remember back in the 70's when my dad had a Bolens garden tractor with a PTO. This thing had every accessory known to man. All the accessories, especially the tiller, needed shear pins. The shear pins were a smooth metal bolt (no threads) that had a hole towards the end, that accepted a cotter pin. That's what I always picture when I hear of shear pins, but I understand we all use pins and bolts in the same way. And like Scot said, just as long as it has "shear" in it, you're fine.


Interesting! shear pins without threads! never heard of those before, but it makes sense both types would exist (threaded and non-threaded).. well that is clearly the origin of the two terms then, "shear pin" and "shear bolt"..both are correct! for one type or the other..

technically both terms would not be correct for both types though! 
because a non-threaded "shear pin" wouldnt technically be a "shear bolt"..and vice-versa..but its too late to change that now..the terms have been intertwined for 50 years at least..maybe 100 years for all we know..too late to change it now! 

Scot


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## uhall (Dec 17, 2012)

sscotsman said:


> Interesting! shear pins without threads! never heard of those before, but it makes sense both types would exist (threaded and non-threaded).. well that is clearly the origin of the two terms then, "shear pin" and "shear bolt"..both are correct! for one type or the other..
> 
> technically both terms would not be correct for both types though!
> because a non-threaded "shear pin" wouldnt technically be a "shear bolt"..and vice-versa..but its too late to change that now..the terms have been intertwined for 50 years at least..maybe 100 years for all we know..too late to change it now!
> ...


Cub Cadet CUB SHEAR BOLT 2 Snow Blower Shear Pin (Two Stage 900 Series 3 Pack) Cilck on this link. They were like this, but maybe a little thicker and bigger


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## Blaine B. (Aug 29, 2014)

So should you leave the shear pins loose, or tighten them up snug with the auger?

The Ariens style pins have lock nuts, so I suppose you could leave them slightly loose and they won't back off on you.

The Troy Bilt shear pins are actually pins with clips - no threads or nuts.


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## Shryp (Jan 1, 2011)

Some owners manuals say to snug them up, but most people say leave them a bit loose so that you can spin them by hand. If you tighten them too much you can have 2 issues. With weaker augers you can actually clamp them to the auger shaft. This will pinch the auger to the shaft and kind of defeats the purpose of the shear pin. The other thing I can imagine happening is tightening them too much can stretch the pins and start to shear them and you will be going through a lot of them.


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## Blaine B. (Aug 29, 2014)

In that case, I will have to slightly loosen my pins.

The one that was intact didn't have any play, so I snugged up the one I replaced. I wouldn't say I tightened it....but, it's hard to say exactly.


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## Sid (Jan 31, 2014)

I first heard of shear pins on outboards, they were usually brass, no threads sized for the horsepower of the engine. The Murray that I restored, had full threaded 1/4" mild steel bolts for shear bolts, if you think about it, a 1/4 20 thread doesn't leave much metal left, so it should shear pretty quick.
Sid


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## Shryp (Jan 1, 2011)

Most shear pins don't have any thread inside the auger. They are shoulder bolts.


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## Sid (Jan 31, 2014)

Yes, Shryp your right, and they have a grove at each end where the axel and the auger tube meet. Sometimes I noticed that the newer ones are just cut part way at the meeting point. But it's the same as with the outboards were "don't leave home without a spare".
Sid


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## Blaine B. (Aug 29, 2014)

I can see how having the pins too tight would somewhat reduce their purpose.

I loosened my pins to the point where there is a bit of slop between the auger, the shaft, and the pin. I would imagine they would shear easier in this slightly loose configuration, which is a good thing.


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## 1952Mekanic (2 mo ago)

Another bonus to being loose is they can move in the shaft making it less likely they will seize into the shaft. I just had to remove a broken MTD blower shear pin this evening - I had to heat it red hot several times, soaking it with PB50 penetrant between heats - and pound the crap out od it with a pin punch and BFH. When I got it out I decided it was going to be easier to remove the other one before it broke - heated it and tried to get it to turn after loosening the nut. Snapped the head off, then took the air hammer to the other end with the nut backed odd about 3 threads and managed to get it to move with the air hammer - then after heating and soaking it again was able to drift it out with the hammer and punch. I will clean up the hole with a 3/8" drill bit in the morning and replace the pins, slathered with anti-seize and about 1 thread loose


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## 1952Mekanic (2 mo ago)

1952Mekanic said:


> Another bonus to being loose is they can move in the shaft making it less likely they will seize into the shaft. I just had to remove a broken MTD blower shear pin this evening - I had to heat it red hot several times, soaking it with PB50 penetrant between heats - and pound the crap out od it with a pin punch and BFH. When I got it out I decided it was going to be easier to remove the other one before it broke - heated it and tried to get it to turn after loosening the nut. Snapped the head off, then took the air hammer to the other end with the nut backed odd about 3 threads and managed to get it to move with the air hammer - then after heating and soaking it again was able to drift it out with the hammer and punch. I will clean up the hole with a 3/8" drill bit in the morning and replace the pins, slathered with anti-seize and about 1 thread loose


- sorry - 5/16" bit - 3/8 would be overkill!!!!


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## orangputeh (Nov 24, 2016)

Too bad too much bad info in this thread.


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## Oneacer (Jan 3, 2011)

@1952, 

That is why I instruct everyone to pull the shear pins/bolts at least once a season, inspect them and lube and spin the augers.


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## KJSeller (Nov 3, 2021)

Oneacer said:


> @1952,
> 
> That is why I instruct everyone to pull the shear pins/bolts at least once a season, inspect them and lube and spin the augers.


That's the best thing to do yearly!


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