Ingersoll Rand 231C 1/2 in Air Impact Wrench 600 ft-lbs

The Ingersoll Rand 231C is the 1/2-inch pneumatic impact wrench most transmission benches end up owning. It makes 600 ft-lbs of maximum reverse torque through a twin hammer mechanism at 8,000 rpm free speed, which is the range you actually need for bellhousing bolts, crossmember bolts, driveshaft straps, and the flexplate-to-converter bolts you reach through the inspection cover.

It runs on a 1/2-inch square drive with a standard 1/4-inch NPT air inlet and wants about 90 psi. The four-position power regulator on the back lets you dial it down for pan bolts and aluminum cases and back up for rusted subframe and crossmember hardware, so one gun covers the whole R and R instead of forcing you to swap tools. Pressure-feed lubrication keeps the motor oiled in normal shop use.

The two-piece housing is the reason this model has stayed in production: the motor and hammer case separate for service, so when the vanes or the hammer dogs finally wear you rebuild it instead of replacing it. At 5.8 lbs and 7.3 inches long it still fits over a transmission on a jack without fighting the tunnel. Ships fully lubricated and ready to hook to the line.