Why did I choose the Chicago Pneumatic 3/8 stubby impact?
I recently welcomed a Chicago Pneumatic 3/8 stubby impact wrench to my toolbox. I wanted something smaller and lighter than my Ingersoll Rand 231GXP 1/2 inch air impact, which was too big and powerful for many of the jobs I encountered. Things like removing brake pad carriers, removing engine mount or gearbox bolts in confined spaces.
My research led me to the Chicago Pneumatic CP7731 3/8 air impact. I liked the position of the controls (immediately behind the trigger), so they could be reached with one hand whilst holding the tool. I also noticed that the bigger 1/2″ version (CP7732) of this tool had come closest to it’s claimed maximum torque in a head to head test against competitors from Ingersoll Rand, Astro and M7.
Unboxing the Chicago Pneumatic 3/8 Stubby Impact
There isn’t much in the box apart from the wrench itself. It comes with a detachable hook. At first I thought this might be useful, but quickly realised it wasn’t. I can see why some would like it, but for me it just got in the way. I never hang my air tools up anyway. Apart from the hook, it’s just the manuals and parts diagram.
There is no fitting included, so I added a PCL XF fitting. This is my preferred connector for tools requiring high air flow, and I use them on all my air tools to avoid having 2 different types of connector in play. I use gas grade PTFE tape to make an airtight connection.
This Chicago Pneumatic 3/8 stubby wrench has 3 torque settings, both in forward and reverse. These are set using a dial behind the trigger. The torque selector moves with the forward/reverse selector, so the torque setting remains unchanged when changing between forward and reverse.
As with most air impacts, the ‘undoing’ torque figure is higher than the tightening torque. The maximum undoing torque is 415 Nm (306 ft⋅lb) and the tightening torque 96 – 328 Nm (71-242 ft⋅lb).
2.1 litres per second (4.5 cfm). Needs a minimum 10 mm (3/8″) inlet air hose size.
These are my own measurements.
120 mm (4.72″) front to back (with a 14mm short socket mounted). This is the most important one for me.
58 mm (2.28″) wide.
200 mm (7.87″) top to bottom (including the fitting).
Chicago Pneumatic list the weight as 1.3 kg (2.9 lbs).
The true test of build quality will be to look back in 10 years’ time and see if it’s still going strong. But I can’t do that right now! The build quality feels good. It feels well made, with aluminium body and steel front and back plates. The trigger, direction selector and torque dial are plastic, but feel solid enough.
First test of the Chicago Pneumatic 3/8 Stubby Impact
The first job for the new impact wrench was to remove a bull bar from a Mazda Bongo. If you know these vehicles, you’ll know how much they love to rust. The bull bar mounting bolts were no exception, but no trouble at all for the CP7731.
Next were some brake pad carrier bolts. So much easier and quicker with an impact than with a breaker bar. My 1/2″ Ingersoll Rand was sometimes too big to be useful for these, so it was great to have something more compact to use. Despite it’s size, it has more than enough power to undo bolts like this.
I’m really pleased with my Chicago Pneumatic 3/8 stubby impact! I use it a lot and find it really helps me get things done. It’s had plenty of torque for everything I’ve asked it to do so far and feels well built. It can also get to places that bigger impacts couldn’t reach.
Here is a video review if you like that sort of thing!