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obviously the auger vibrates and moves a lot and you would want to use lock nuts so the nut doesn't fall off followed by the pin. Unless it's a cotter pin style bolt which is the same purpose though.

But all I'm seeing on ebay are people selling these with regular non lock nuts. And it's not as if the bolts/pins are 'cheap ebay crap' because they are just like 30 cents cheaper for OEM from a parts website. They're like $1.25 plus shipping pretty much everywhere.

I google stuff like 'snowblower shear pin nut came loose off' etc but surprisingly didn't read any posts or anything.

for like 20 cents, I'll put lock nuts on, but figured I'd bring this to peoples' attention and see if anyone confirms that these often fall off with using regular nuts?
Could probably use a lock washer also or some thread locker but I don't have faith in those holding up on an auger.

And this guy says you shouldn't tighten the nut down all the way because you might pinch the outer pipe onto the inner pipe and thus defeat some of the purpose of the shear pins, which you can't do with a non lock nut. A regular nut you'd have to tighten down all the way or it will very easily come off.


 

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Interesting question...You got me wondering.

Obviously, some auger bolt nuts have a nylon inner piece that locks them..
Husqvarna 580 79 04-01 Snow Blower Shear Bolts, 6-Pack

But I just checked mine in the garage and they don't have that. However, they almost feel as if they are "cross threaded" . In other words the nut doesn't thread smoothly onto the bolt.. it feels stiff as if it's chewing its way down the threads and tightening as it goes. Don't know if that's by design or not. Could they be tapered perhaps?

Let's see what folks have to say.
 

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Locknuts come in a few different flavors, some of which can be tough to identify in a photo or video.

For example, most of the ones on my Ariens are like this:

There's no nylon piece, just a dimple in the side (sometimes just one, sometimes more). That's done to deform the threads a little in that one area, which makes the nut a tight fit.
 

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I've been using shear pins w no locknuts since 1994. I use a dab of blue Loctite, and have never had one fall off. I do keep a couple of locknuts in case I need to change a pin in the middle of a job. Thread lockers need to dry.
 

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Shear pins are not to be tightened down or they will defeat their own purpose which is they are to "shear" if there is an obstruction that stops the auger from spinning and doing possible damage to the gears. Because of this loose installation they need to have lock nuts . Elaw's pic shows the most common type of locknut but there are a few different types including the nylon/poly types too. Some are simply pins with a cotter pin retainer.
The very worst thing you can do is to use regular nuts and torquing them down so they'll stay on. Be prepared to spend some $$ on major repairs.
 

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As was pointed out about, most of the nuts are crimped so they get forced on when you screw them down.
 

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... they almost feel as if they are "cross threaded" . In other words the nut doesn't thread smoothly onto the bolt.. it feels stiff as if it's chewing its way down the threads and tightening as it goes....
FWIW I took photos of my shear bolt nuts. They do indeed have two dimples on them which probably explains why they feel "cross threaded".
My eyes can't see the non-circular thread, but I certainly can feel it.

Photos: Arrows point to the two "dimples" on the nut
https://goo.gl/photos/SeLmK3QcH3Jrj4Gr8
 

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Thanks for that information stuart80112! You helped me figure out exactly what I needed to order for my machine.

Dave
 
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