On many two-stage snowblowers, the auger is held to its shaft by shear pins or bolts. They are designed to break when the auger hits something solid, like a newspaper, chunk of ice or landscape rock, so the gearbox and auger are not damaged. This page covers the pins and the auger area. For general fall prep of the whole machine, see the snowblower winter prep page.
Signs a shear pin has broken
- The engine runs and the impeller throws a little snow, but one or both auger halves do not turn.
- A loud bang followed by the auger stopping after hitting something.
- One side of the auger spins freely by hand when the machine is off.
Replacing a pin safely
Shut the engine off, remove the key and disconnect the spark plug wire before reaching anywhere near the auger or chute. Never clear a clog with your hand; use a clearing tool. Replace the broken pin with the correct part for your machine, not a standard bolt, which may not break when it should and can lead to gearbox damage.
Shear pin and auger checklist
- Find the part number in your manual and keep a few correct spares plus the matching nuts or cotter pins.
- Store spares on the machine if it has a holder, or in a labeled bag in the garage.
- Inspect the pins in the fall for cracks or bending.
- Lubricate the auger shaft where the manual calls for it so the auger can turn on the shaft when a pin breaks.
- Check the gearbox lubricant on machines that have a fill plug, using the type the manual specifies.
- Walk the area before the first snow and pick up rocks, cords, papers and toys.
- Protect bare metal on the auger housing from salt and moisture.
Frequently asked questions
Can I use a regular hardware bolt instead of a shear pin?
It is not recommended. A standard bolt may be stronger than the designed pin, so the next impact can damage the gearbox or auger instead.
Why does the auger need lubrication at the shaft?
On many designs the auger is meant to spin on the shaft once the pin shears. If it is rusted to the shaft, the protection does not work as intended.
How many spare pins should I keep?
Enough to replace a full set at least once, plus matching hardware. Storms rarely happen when stores are open.
AMSOIL products for this job
- AMSOIL Synthetic Water-Resistant Grease. AMSOIL says: “Specially formulated for wet-duty performance”; “Excellent water-washout resistance to stay in place longer”.
- AMSOIL Spray Grease. AMSOIL says: “White lithium grease protects against wear and corrosion”; “Quick, convenient spray gets into hard-to-reach places”.
- AMSOIL Heavy-Duty Metal Protector. AMSOIL says: “Protects against the effects of salt, moisture and chemical corrosion”; “Leaves a long-lasting (up to several years), protective, wax-like, amber coating”.
Product wording above is quoted or summarized from amsoil.com. Read each product’s label and data sheet for directions.
Use AMSOIL’s official lookup guide to see what is listed for your vehicle or equipment, then order online whenever it suits you.