Learn me: proper use of air tools: Grassroots Motorsports forum: Grassroots Motorsports Magazine

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May 6, 2011 7:20 p.m. peter Reader

Due to my own stupidity, I need to pull the engine out of my new-to-me WRX. The good news is that I will be doing this in a full on garage-mahal, so air tools will be available.

I've used air impacts before, but mostly for stubborn suspension bolts. This job seems a bit different.

Since everything looks like a nail to a man with a hammer, what are the proper places to use air tools (and the proper tools) when removing an engine?

Do you try hand tools first, then pull out the impact when that doesn't work?

Is an air ratchet good for anything?

What's the deal with "butterfly" impacts (not sure if the garage has one).
May 6, 2011 7:26 p.m. internetautomart SuperDork

for disassembly of high torque bolts use an impact.
for reassembly use the air ratchet.
that's my .02. take it for what it is worth.
May 6, 2011 7:32 p.m. Curmudgeon SuperDork

Okey doke. Pulling stuff apart with air tools is fine regardless of what it's holding or its thread diameter. Common sense does come into play, I use an air impact on big stuff and an air ratchet on the small stuff. That way you are less likey to accidentally round/snap something if it's corroded, etc. Butterflies are great for disassembling small stuff.

Going back together: big stuff like tranny to engine bolts, etc are generally OK to air impact. My personal limit is it needs to be 10mm or bigger thread. Head bolts, main cap bolts etc are exempt from this, hand tools only.

Intake exhaust etc is usually 8mm, there's where the air ratchet and butterfly come in. There's a whole bunch of that stuff on the average car. Here's the secret: don't 'stall' the air ratchet or butterfly when doing this! They can make enough torque to break an 8mm. Run it down till it bottoms then stop immediately.

6mm or below, I like hand tools. Takes more time, but I'd rather spend, say, 30 seconds spinning a bolt in by hand than 5 seconds breaking it with an air tool and then 2 hours digging the busted bolt out.

My #1 rule (learned the hard way): no power tool disassembly of anything held together with Allen or Phillips screws! A butterfly will 'cam out' of a Phillips before you can blink, leading to MUCH aggravation. The absolute best tool for that is a hand held impact driver.
May 6, 2011 7:33 p.m. TRoglodyte Reader

I like air rachets much better than an impact wrench, I get a much better "feel" for what the fastener is doing. Less rounded off stripped out inertia welded fasteners with a rachet. 3/8" rachet is most useful but I use a 1/4" because the size is easier to manipulate in tight spots. YMMV.
May 6, 2011 7:37 p.m. Toyman01 SuperDork

What Curmudgeon said. Though I have a 1/4 air ratchet I'll use on anything. It doesn't have enough torque to twist off a wet noodle.
May 6, 2011 7:49 p.m. peter Reader

Thanks for the quick input!

Regarding the air ratchet and disassembly - since it doesn't hammer, isn't it just going to spin my hands into the nearest, sharpest object if the fastener is the least bit stuck?
May 6, 2011 7:52 p.m. fasted58 Reader

Use the air ratchet (as you would manual ) to break free, then spin 'er off
May 6, 2011 7:54 p.m. peter Reader

Also, an old hand once taught me to approach stuck fasteners slowly when using the impact. His impact had a few torque settings in the reverse direction - he'd start off on the lowest setting, just hammering away, then move up one at a time. Using his technique on my suspension bolts, I rarely made it to the highest setting and didn't break a single fastener.

The impact at this garage has a bunch of settings in forward, but not reverse. Am I missing out?
May 6, 2011 7:55 p.m. Toyman01 SuperDork

You can actually stall one without too much trouble, but a curmudgeon said smaller fasteners it can and will snap.
May 6, 2011 8:32 p.m. Dr. Hess SuperDork

Personally, my philosophy is all air tools are fine on all disassembly. Except for special cases of very large bolts/nuts, which I use the impact set on a low air setting, I use the air ratchet for assembly and stop before it gets tight, then manually tighten it. Newbies helping out, even on their own E36 M3, are not allowed to use any air tool for reassembly. If I'm not in a hurry, Iwon't use the air ratchet at all for reassembly, except for those few nuts or bolts that have to go in like 35 turns or something.
May 6, 2011 9:34 p.m. jimbbski Reader

While i don't always do it I know that there are bolts that I should remove using a an air wrench and not a breaker bar. I have snapped more bolts with a breaker bar then i have ever with an air wrench.

A few weeks back I did struts on my sisters Taurus. The rear pinch bolts on the struts were rusted in badly. I had to run the bolt in and out dozens of times. Each time trying to get the bolt to come out a bit more. If I had tried to use the brute force of a breaker bar I would have snapped the bolts for sure. With the air wrench the bolts finally did come out. I just needed to re- tap the threads to clean out the rust and install new bolts.
May 6, 2011 10:01 p.m. Timeormoney Reader

from the Doh files: double check lefty loosey. Its pretty easy to reverse it on some guns. BTW, you can always turn the air down on the compressor for lower torque.
May 6, 2011 10:57 p.m. KATYB Reader

impacts are perfect for dissasembly. actually less chance of snapping a bolt with an impact than with hand tools. personally in my tool box i have 1/2 impact gun 3/4 impact gun. 1/2 butterfly impact 3/8 impact gun 3/8 butterfly 1/4 inch air ratchet 3/8 airratchet electric 1/2 impact and electric 3/8 impact.
May 7, 2011 6:18 a.m. SVreX SuperDork

If the air ratchet is in your hand and does not have enough torque to bust it loose, use it like a manual wrench. Usually works (except for big high-torque bolts).