I use an impact all the time, and have never damaged a coupler. Couplers get damaged from long-term wear, and are designed to absorb instant shock. Now think about how that nut tightens. By the time it'* nearly snugged down, the SC is already spinning. There'* no shock to speak of.

If you have an impact, use it. This prevents possible damage to the pulley while holding it.

I change pulleys between the two cars and my stack of extras VERY often, and always use an impact off and on.

Ok I was Simply Advised not to by someone else... All be it it was on a different car. Wasn't trying to argue just share what I was told before using an impact would be easier lol

What is the maximum torque rating on the impact being used in your case?

Max rating doesn't really matter, Bill. There is no resistance. The nut is a nylock. Self-locking nylon insert. When it'* tight, the supercharger is spinning, and it can't tighten any more.

I usually have my impact set to 2 if I'm using my big 500ft/lb (3 forward settings), or 3 on my smaller impact (out of 4 settings). Again, it can't over-tighten it, because by the time it gets there, the rotors are already spinning, providing no resistance to the impact.

(oops, willwren, you got here first. But I'll leave my post as is, ignorance and all )

That'* a great question, Bill(boost). It'* a little like the discussions previously on torque wrenches. If you don't pay attention to, or don't understand the ratings of these kind of tools, you can certainly cause some damage.

On the other hand (I think), an experienced "wrench" (not me though) with a good touch and a light rachet impact (edited) wrench could probably use one daily and go a lifetime without a hitch.

(BTW ....I've had in the back of my mind to start a thread on torque tools [in a large part to help me use them], but I haven't felt competent enough to lead it off :? )

Then why would the settings matter if your using one impact from the other?

I believe that the max torque information was being requested so that if it was too high, it could then be adjusted so that no damage would occur when that nut finally tightens and snaps up on the coupler.

In Wrens case, if the settings are properly set, then yes, the coupler is probably already spinning by the time the nut is being snugged down and no damage occurs.

/2cents

I set them to what my experience tells me it takes to fully seat the nut and pulley. The impact wrench doesn't fully transfer it'* energy into seating the nut because the supercharger is spinning as well. For that reason, you have to 'amp up' the impact a bit to overcome the fact that the SC wants to spin and resist the nut tightening.

When the pulley fully seats and the nut stops turning, the supercharger is already spinning, so the impact to the coupler is GREATLY reduced.

There are several dynamic motions going on simultaneously that all need to be accounted for. It may be difficult to imagine it all until you actually do it for yourself. I'd be willing to demonstrate this with a video for those that would like to see it.

My reasoning for asking was to ensure that you weren't suggesting someone pick up their buddies gun of 600 ft lbs and squeeze fully to seat the pulley on a nut that is torqued to approximately 20-30ft lbs.

The instructions given were
That leaves a large area for error. Many mechanics or shops will tighten lug nuts in the same manner to at least 100ft lbs with the tire spinning. It would be a shame if someone nailed their SC with 500 ft lbs of torque and the nut stripped or coupler broke.

Also remembering that an impact gun is a lot of quick hits, it is not a smooth motion like a drill. If someone ever took an impact gun to my supercharger, they'd be buying me a new one.

Okay. I was just wondering because not everyone has this experience.

I think that this would definately benefit the original poster of this thread along with anyone else who might perform this task down the road.

Let me repeat......even my big gun at max won't damage the charger or coupler. You're not hitting something that can't move. The rotors are already spinning before the nut fully seats.

I'll vid a demo tonight. It'll be alot easier to see. In a nutshell, this is VERY different than impacting on a lugnut, which could shear the stud if overdone, and even very much different than a HB bolt, as the engine has alot more rotating mass to resist with.

This is a much smaller assembly that spins easily, and is already in motion by the time the pulley and nut seat.