1/2", 3/4" or 1" drive? How many Nm do you actually need? A practical guide to choosing the right impact wrench for tire service, workshop and truck work.
What an impact wrench actually does
An impact wrench combines rotation with rapid hammer blows, delivering short torque spikes that break loose fasteners a hand ratchet cannot touch. That is why breakaway torque figures look huge: a compact gun rated 1,950 Nm is using impact energy, not continuous force.
Choose the drive size first
- 1/2" drive: the universal workshop size. Wheel bolts, suspension work, general mechanics. If you buy one gun, buy this.
- 3/4" drive: vans, light trucks, agricultural equipment and rusted fasteners that laugh at a 1/2" gun.
- 1" drive: trucks, buses and heavy plant. Look for ultra-light designs if you use it daily, your wrists will thank you.
How much torque do you need?
Car wheel bolts tighten to 110 to 150 Nm, but a fastener that has seen five winters of salt can need three times its tightening torque to break loose. As a rule of thumb: 1,000+ Nm breakaway for car service, 1,800+ Nm for vans and 4x4s, 2,300+ Nm for trucks. Remember that final tightening should always be done with a torque wrench, never with the gun.
Air or cordless?
Pneumatic guns are lighter, cheaper for the same power and never wait for a charger, but they chain you to the compressor. Cordless guns win for mobile service and roadside work. A busy shop usually ends up with both: air at the bench, battery in the van.
Do not forget impact sockets
Standard chrome sockets can crack and shatter on an impact gun. Use impact-rated sockets (the black ones) and check our socket sets for 6-point metric sets that grip flanks instead of corners.
