Something that could be used to provide a combined effect of an impact wrench and lead hammer is to use an air chisel on the spinner ears. Obviously, you will want to use something to protect the surface of the ears (ie., aluminum, or anything softer than the spinner). I saw a video of someone using one on a rather large (1-7/16”) radiator fan clutch nut (link below). He simply put the chisel head on the edge of one of the flats to sort of push/rotate it around and then pulled the trigger while pressing down to push on that edge. About three half second bursts and it loosened right up. Granted it wasn’t tightened to the same torque as a spinner, but with a spinner you do have the well defined surface of the spinner ear to put the chisel against and provide direct blows.
Although in the video he uses a standard chisel head attachment, it looks like the head in the shape of an inverted “V” would be the preferred attachment here, as the insides of the “V” are not sharp, so it will be providing more of a hammer effect than cutting effect on whatever you are using to protect the ear, and it can straddle the ear to keep it in place. Chisel and attachments < $20 at Harbor Freight.
As a disclaimer, I haven’t done this nor have I seen it done, but the concept of using sudden blows on the ears is essentially the same as with the lead hammer, just a much much faster repetition of blows. Just use the same method as has already been pointed out in other posts on the subject….just a few seconds of taps on each ear, and work your way around, several times if necessary. As with an impact wrench, the vibratory action alone will have a tremendous effect on breaking the molecular bond that gets established between the threads over time.
Use of air chisel is at around 2:20
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