What is the best tool for loosening tight header bolts in a truck with a big-block Chevy? I would reach for the Monster MST7125A mini impact wrench. Typically, the answer would be to grab a combo-wrench and do some good ol’ knuckle-busting, but we’re smarter now. Right?! Yes, we should be wearing gloves, but it would be shameful to get those camo-pattern gloves in your toolbox dirty.

Mini or small factor impact wrenches in the past just didn’t seem to have the guts to do the hard work. It never proved worth it to pull the old impact out of the drawer, because it was just a wasted effort. It’s not like that anymore. The new Monster MST7125A pneumatic (air) impact packs more punch than many full size pneumatic impact wrenches.

Monster MST7125A Mini Impact

At a depth, from anvil to back plate, of only 4 1/4”, the Monster MST7125A mini impact wrench is the smallest ½” impact on the market. Even with a 15mm impact socket attached, the depth was still less than five (5) inches. Overall height of the MST7125A is only 7 ½” with the width being 2 ½”. This is truly a mini impact wrench, in terms of size.

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Features

Weighing in at only 3.64 lbs., the MST7125A is comparatively very light as well. With the weight, size and form factor, the tool fits very well in the hand. The finish is a matte black wrinkle, so it can be easily handled. A soft black rubber grip with a satin feel adorns the handle, hence comfortable to grasp.

The 1/2” hog-ring anvil does its job of keeping sockets attached yet still easy enough to remove. Air is exhausted out the bottom of the handle away from the operator. On the rear plate is a switch that allows switching between speeds. The technician can choose between one speed Reverse and three (3) Forward speeds. This switch is in close reach of the technician’s thumb, so one-hand operation is easily achieved.

In Use

We put the Monster MST7125A mini impact wrench to good use and tried it in a multitude of situations. As previously mentioned it was great for zipping out the header bolts on the big block Chevy. We did have to use a universal on some of the header bolts, but the MST7125A still fit where other impacts would not.

While doing a brake job on a Cadillac Escalade, the MST7125A was used to remove the lugnuts. It was a little slower than some larger impacts that we have, but it did remove them without fail. Again it proved its worth by removing hydraulic pump bolts hidden in a recessed area on a bucket truck. It was great to be able to just stick the mini impact in there and pull the trigger. The alternative would have been to stand on my head and turn a wrench 1/8^th turn each time.

Specifications

• Anvil: 1/2″ hog-ring
• Power: Pneumatic (Air)
• Impact type: Durable jumbo hammer
• Torque (@90psi): 500 ft-lbs
• Weight: 3.64 lbs
• RPM: 9,500
• Dimensions: 7-1/2” H, 2-1/2” W, 4-1/2” Deep
• Input: ¼” NPT
• MSRP: $199.90

Wrapping Up

We use air impacts every day, so they’re not anything foreign to this crowd. Cordless impacts are becoming the norm as well. Still, even the best cordless models are not the best fit for certain areas, such as tight spaces.

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Sure, there are pneumatic (air) impacts that are stronger than this, but that’s not the target that Monster was shooting for. The MST7125A “Mini” design allows the technician greater access to tight spaces, and this is something the normal impact can’t do. I really like the size of the Monster MST7125A and the power it provides in such a small package.

If you find yourself working in confined areas, then I would highly recommend the Monster MST7125A mini impact wrench. At a MSRP of just $199.90 and a 1-year guarantee, there is not much in the market with that value.

To learn more about the Monster MST7125A mini impact wrench, please click here.