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I need to add a cordless impact wrench to my toolset do some exhaust work (loosen some really tight bolts, basically). I also plant to use it for CV joint-related work.

They seem to be kind of pricey, so I can only get either a 1/2" or 3/8" drive right now. Which is more versatile?

If I get the 1/2" one, are there any adapters like in regular hand ratchets to downgrade from 1/2" to 3/8"? Or are these impact guns fixed and you must have both?

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up vote 3 down vote accepted

The 1/2"-drive can withstand more torque than its 3/8" sibling (due to its larger moment of area). Since the question clearly states that this is needed to undo really tight or stuck bolts, the 1/2"-drive impact wrench makes more sense.

As for recommendations, there will always be someone recommending Brand A over Brand B and vice versa. That said, I'm looking to pick up something like the one in this video if the price is right.

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I have only ever had/used 1/2" drive air impact guns. The reason is simple: I can produce as much/more torque with a 1/2" breaker bar than a 3/8" impact drive can produce. If I need to use an impact wrench (which usually works really well on rusty bolts), I'll grab the 1/2" drive and have at it. For me, there usually is no reason for a 3/8" impact drive, so why have/use one.

As for electric impact drives, I understand the newer battery operated ones are very nice to have. I believe most of these are 3/8" drive. For this reason alone, I may have change of heart. Having to not haul a hose around plus the ability to remotely carry it to where I need it would be a great bonus.

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1/2" drive is the way to go, the only advantage to the 3/8" is it's going to be smaller and lighter. With the major disadvantage of much less torque.

are there any adapters like in regular hand ratchets to downgrade from 1/2" to 3/8"?


1/2" to 3/8" adapters are readily available on all the tool trucks, and most other places that sell tools.

Here's a few examples, not only are the readily available they make them for impact wrenches.

Snap on Adaptor, 3/8" Internal drive x 1/2" External drive, 1 5/16"

Bottom right of this page in the Snap on Catolog

Again this one is made to be used with an impact wrench.

The ones pictured below are NOT for impact wrenches

enter image description here

Craftsman 4 pc. Adapter Set

While this one is for use with impact wrenches.

enter image description here

Craftsman 1/2 in. to 3/8 in. Impact Socket Adapter

It's is important that you use impact sockets as non-impact sockets can shatter when used on an impact wrench.

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