Cordless Impact Wrench Won’t Shift It? Torque Figures Explained

The box says 550Nm, yet the wheel nut or hub nut still won’t move. Or you’re wondering whether cordless can replace an air gun without a compressor.

Read the right torque figure, pick a sensible power source and battery, and finish wheel nuts with a torque wrench. PartsForMachines stocks 40 products from Sealey, Draper, Chicago Pneumatic and Abracs in its impact wrench range: cordless, 230V and air impact wrenches, plus cordless ratchet wrenches.

Rated 550Nm but the Nut Won’t Budge: What Does the Torque Figure Mean?

On many tools the headline figure is the breakaway torque, for undoing, and the figure for doing nuts up is lower. The CP400LI 18V 1/2in impact wrench, for example, gives 550Nm breakaway and 420Nm fastening. The gap can be far wider: the CP8854 lists 120Nm working torque forward but 1050Nm in reverse.

So compare breakaway with breakaway between tools, and leave plenty in hand: a nut that has sat for years can corrode onto its thread and take more to undo than it was tightened to.

Corded, Cordless or Air: Which Makes Sense Without a Compressor?

Without a compressor, the real choice is cordless or a 230V corded wrench; air makes most sense where a big enough compressor is already running. Cordless needs no hose or cable. A corded tool never runs flat but needs a socket within reach: the 82994 230V impact wrench kit gives 480Nm (±10%) on a 6m rubber cable, with 17, 19, 21 and 23mm impact sockets in the case.

A corded wrench can be the heavier tool: the 82994 weighs 3.67kg, while a 1/2in cordless body such as the 86928 is 1.1kg before the battery. If you already run air tools, the 65017 1/2in air wrench is rated at 340Nm at 90psi and weighs 1.8kg.

Will a Bigger Battery Give More Power, or Just Longer Runtime?

Mostly longer runtime: amp-hours describe how much energy the pack stores, while voltage is the better guide to power. A 4Ah pack on the same tool should keep going longer than a 2Ah one rather than hit harder. More important is staying on one platform, because packs are made for their own series: D20 batteries work across D20 tools, but Storm Force 20V packs won’t suit Storm Force 10.8V tools.

Starting from scratch? Buy a kit: the 04791 D20 20V brushless mid-torque impact wrench kit comes with two 3.0Ah batteries, a charger and ten metric deep impact sockets from 10 to 27mm.

Do Torque Presets Make a Cordless Wrench Safe for Wheel Nuts?

They help, but they don’t replace a torque wrench: spin the nuts on at a low preset, then finish with a torque wrench set to the vehicle maker’s figure, in a star or cross pattern. For running nuts down, the CP8849-2 impact wrench (8941088499) has two forward shut-off positions, at about 4–5Nm and 70Nm, to avoid over-tightening, and the 04791 has five presets from 100 to 400Nm.

A cordless wrench at full power can’t hold an exact torque, and uneven tightening can stress the brake disc enough to cause judder.

What Should I Check Before I Buy?

both torque figures, breakaway and fastening, against the job: hub nuts, wheel nuts or smaller fixings
the drive: on most wrenches here, 3/8in on the compact 10.8V and 12V models and 1/2in on the 18V and 20V ones
the battery platform you already own, and whether “body only” means you still need a battery and charger
speed settings or shut-off positions, if you’ll also run nuts on with it
impact-rated sockets in the sizes you need

Browse the impact wrench range, or contact the PartsForMachines team by WhatsApp, telephone or email with the job and your battery platform.

Product options, delivery options and returns terms are shown on each product page. A 30-day return policy applies to eligible items.

Frequently Asked Questions

What is the difference between a cordless ratchet wrench and an impact wrench?

An impact wrench hammers tight fasteners loose; a cordless ratchet runs nuts on and off at low torque in tight spots. The CP20VRWKIT1 20V 3/8in ratchet wrench kit gives 60Nm, so crack stubborn fasteners free first.

Is a compact 10.8V or 12V impact wrench enough for engine-bay jobs?

Often, for small and mid-size fasteners. The CP108VCIW gives 220Nm breakaway and 155Nm fastening, and the 27859 is a 250Nm 3/8in tool. For wheels and suspension, a higher-rated 1/2in wrench, such as the 550Nm CP400LI, gives more in reserve.

What does “body only” mean?

The tool comes without a battery or charger. SV20 impact wrench bodies such as the CP20VIWX, for example, take 20V packs from 2Ah to 6Ah, bought separately. If you own no compatible batteries yet, a kit includes them.

Can I use batteries from another brand or series?

Don’t count on it. Packs are built for one series, so check the series name and voltage printed on your current battery, then choose a tool from the same series. Our team can confirm a match from a photo.

Is a brushless impact wrench better than a brushed one?

Often, by the makers’ account. Sealey says the brushless motor in the CP20VIWX improves performance and needs less maintenance than a brushed one, and Draper says the brushless 27859 gives more power and longer battery life.

Why use an impact wrench instead of a long breaker bar?

Speed. The wrench delivers short, sharp blows many times a second, so it can shift a tight nut without you heaving on a long bar. A breaker bar remains the fallback when a nut beats the tool’s rating.

Will one battery do a full wheel change?

It depends on the pack and how tight the nuts are, because runtime drops as the work gets harder. For several wheels or seized nuts, keep a second charged battery; kits such as the 55343 come with two 2.0Ah packs.

Can a 1/2in cordless wrench undo truck or tractor wheel nuts?

Sometimes. Check its breakaway figure against the vehicle maker’s tightening torque, with room to spare, because nuts left on for years can take more to undo than they were tightened to. The CP650LI, for example, is rated at 650Nm breakaway.

Does a cordless impact wrench work in cold weather?

Within limits. The CP8849-2, for example, is rated to work from -18°C to 50°C, but its battery should be charged between 10°C and 38°C. In winter, bring packs indoors to charge.