Should Snowblower Auger Spin Freely? – Avoid this mistake

By: Author John Cunningham. Published: 2021/06/23 at 11:12 am

Making great progress, and then “bang” – the snowblower stops blowing snow. It’s a startling experience, and at once, you know something up. You are in the right place, alright, I’m a mechanic, and this is a common snowblower issue.

A snowblower auger should not spin freely when the auger control lever is off. A free-spinning auger is a symptom of broken shear pins. Shear pins are a fail-safe feature designed to break when the auger hits a solid object.

In this post, you’ll learn what shear pins are, how to diagnose their failure, and how to fit new ones. I’ll also point out the importance of using the correct shear pins.

What are Snowblower Shear Pins?

Shear pins are also known as shear bolts; they are metal fasteners employed to fix the auger to the auger shaft. Shear pins come in two main flavors: bolts or pins. The bolts are obviously threaded, and the pin variety uses a pin and clip to fasten. Not all snowblower auger shear pins are the same.

What do Snowblower Shear Pins Do?

Shear pins, as you know, fasten the auger to the auger shaft. The auger shaft is powered; without the pins, the auger shaft would simply turn without turning the augers. Not much use for shifting snow.

But the shear pins have another even more important function. They are designed to shear (break) when called upon. An auger in motion carries energy, and when it suddenly stops, that energy must be dissipated. We’ve all done it; we’ve all tried to shred a frozen newspaper or dog toy.

Other common reasons shear pins break include shoes worn out or just set too low, which allows the scraper bar to collect gravel and other hard-to-bend debris.

Yep, you’ll be clearing the yard of rocks, one shear pin at a time.

The shear pins absorb the energy by shearing. If shear pins failed to do their job, the energy would instead be transferred into the gearbox and transmitted to the engine. Often resulting in lots of downtime and many hundreds of dollars in repairs.

How to Diagnose Broken Snowblower Shear Pins

Now you know a sheared auger pin is a good thing. Otherwise, you could be fixing a gearbox or worse.

Your auger assembly has, as you know, a separate auger on each side with its own shear pin. Breaking both shear pins at the same time is unusual but not impossible.

If you can spin it, your shear pin has sheared.

Symptoms of broken shear pins include:

• Auger spins freely
• Snowblower not blowing snow far
• One auger not moving when auger lever engaged
• Snowblower not moving snow as before

How To Fit New Snowblower Shear Pins

Fitting is one of the easiest jobs you can do on a snowblower. Frankly, I’m a little jealous; in my workshop, I only ever seem to get the really tough jobs.

Anyhow, it is super important that we disable your snowblower before working on the business end.

Tools you’ll need

To make the job move like butter, you’ll need the following tools:

Replacement Shear Pins

I can’t emphasize enough how important it is to fit the correct shear pins. Sure, shear pins might look like a nut and bolt, but they are chosen to suit your machine. Meaning the metal is sufficiently soft so as to shear (break not bend) long before kinetic energy grenades the gearbox.

Bolts are identified by their tensile strength, the maximum force they can withstand before fracturing.

Fitting bolts you may have lying around the garage is not cool. I’d be very disappointed as that would mean I didn’t do my job very well.

Order new pins, they are cheap when compared to a new auger transmission, order as per your manufacturers’ specs; shear pins are not all the same. I have included many of the more common types, together with the tools you may need to fit them, here on the “Snowblower maintenance tools page.”

Shear Pin replacement as follows:

It’s important the shear bolt type isn’t tightened to the auger too tightly; just snug them up. Overtightened shear bolts won’t allow them to shear and could cost you a gearbox or, worse, an engine.

Now get out there and start moving snow!