Index Home About Blog
From: John De Armond
Subject: Re: Air tools questions
Date: Tue, 30 Jan 2001 06:47:28 -0500

jj3000 wrote:

> I have just got an air compressor (CH Oilless and some CH tools) I know
> they are not that good, but it fit my budget and usage: I don't work on
> my car very much, but when I do I want to get it done quickly, thus the
> need for air tools.
> Anyways I have some questions:
> 1) Is it possible to loosen lug nuts while the car in the air with a
> air impact wrench?

Yep.  It's the impact torque that does the work.  The inertia of the
wheel will hold it still.

>Is it advisble to use impact wrench on the special
> lock pattern lug nuts?

I've gotten away with it a couple of times but I'd not recommend
it.  Far too easy to have the "key" cam out of the lug nut and
booger up things.  When you become very skilled with the air wrench
AND you're prepared to toss the anti-theft lug in the garbage
without remorse, then give it a try.

> 2) Is there a kind of air ratchet that can tighten things to a torque I
> specify, thus replace the use of a hand torque wrench?

Nothing that you would want to pay for.  There ARE precision torque
limited wrenches available for assembly line and aerospace use but
they are $$$$ and rather fragile.  Plus they're usually custom
configured by the tool mfr for one specific job.

>I notice some
> of the expensive air ratchet.. Like Chicago Pneumatic for like $130,
> has a rating of 10ft.lbs - 140ft.lbs for example, does that mean it is
> adjustable and can be used to tighten to a torque spec?

That's just an air valve that limits the air flow.  Really coarse
adjustment.  I consider the valve to have two positions, "weak" and
"wide open".

> 3) Are impact sockets really necessary?

No, but be prepared to break sockets every so often.  I use
Craftsman sockets precisely because Sears will replace an
impact-wrenched socket with no hassles.  The problem with impact
sockets is they are heavy and thick.  They frequently won't fit in
the pockets milled in things where the nuts or bolts are.  I have a
set of impact wrenches and use 'em when I can.  But I don't give it
a second thought to toss a regular socket on the wrench when called
for.  Another disadvantage with using non-impact sockets is that
once the drive square is wallowed out a little, much of the wrench's
impact energy is used taking up the slop between the wrench nose and
the socket.  Impact sockets typically fit very tightly on the nose
for that reason.

> 4) Are CH air tools bad?  Are Central Pneumatic sold by harbor freight
> tools also bad?  They are both made in Taiwan. is the name "Central
> Pneumatic" to confuse customers with "Chicago Pneumatic".  Because I
> notice harbor freight also carry a brand called "Chicago Electric".
> What is up with that?

I consider all of them to be second tier tools.  CH probably has a
bit better QC/QA than the rest but they're all about the same as far
as fit and finish.  The difference in fit and finish between these
and say, a CP is remarkable.  Even though I now wrench at the level
of a very serious hobbyist, I still buy the best.  An air wrench is
a lifetime purchase so the cost difference is insignificant in the
long term.  I still have my first impact wrench I bought in 1970.
Still running strong and has never been touched.

Awhile back I had misplaced my 1/2" CP impact wrench, so after
looking for awhile, I borrowed an off-brand from the mechanic next
door.  I was trying to remove the crankshaft bolt from a Toyota
Camry engine so I could change the harmonic balancer.  I had done
this same job before with my wrench and the large bolt (28 mm if my
memory serves) sailed right out.  With his wrench, it would not
budge, even with 175 psi air pressure.  I ended up walking to the
tool rental place a block away and renting a 3/4" off-brand wrench.
IT had to struggle before the bolt came loose.  Now my CP and the
off-brand 1/2" wrench look the same on the outside.  But the
performance is like the difference between night and day.

> 5) Any other tips?  So far I have upgraded the wimpy 1/4" I.D fittings
> to 3/8" I.D Automotive fittings so I could get the tools to work closer
> to specs.

Set the pressure switch as high as you can and not trip the motor or
lift the safety.  Power goes up with the square of the pressure so a
little helps a lot.  If you're going to do much work with air
wrenches, consider trading the compressor for a small 2 stage unit
that can make 150-175 psi.  A single stage compressor is OK for
spray painting, filling tires and even running a speed ratchet.  But
to get the tough work done, high air pressure is the ticket.  Yeah,
I know the mfr says not to use more than 100 PSI.  Probably a combo
of their lawyers and their warranty managers talking.  I've never
been in a pro shop that DIDN'T have high pressure air.  My tools
have been working well for 30+ years.

Inspect your fittings for the internal bore diameter.  Many cheap
fittings have surprisingly small holes in them.

Install good brand name (Milton, snap on, matco, etc) whips on your
wrenches.  These little 3 ft hunks of very flexible air hose makes
the tool much easier to use by putting flex hose up next to the
handle and by getting the coupler mass away from the wrench.

Get some of that "dip a handle" liquid plastic tool dip, take your
female couplings, stopper both holes and dip.  The rubber sheath
will protect your paint when you drop the hose against the car.

Use Marvel Mystery oil in your tools.  Much better than regular
oil.  CP packages a private label bottle of MMO with their tools and
recommends it.  I don't like in-line oil misters.  The oil tends to
degrade the hose plus the oil slobbers out of the tool.  Oil the
tool in the air inlet every so often, then operate it unloaded for a
few seconds to blow out the excess.

Use real rubber (usually red) hose instead of this cheap import PVC
stuff that everyone seems to have today.  The real rubber is much
more flexible, especially when cold and it will last longer.  I'm
fond of the brand names like Goodyear or Gates.  I have mine made up
at a local machine shop supply company.  Milton hoses are also
rubber and are better than PVC but they tend to suffer ozone
cracking pretty quickly, especially if you live in a large city with
crappy air.

Bleed the water out of your tank every time you use the system.
Make that a part of the same routine that has you turn on your shop
lights.  Water is bad for the tools plus standing water will
eventually rust through the tank from the inside out.


Index Home About Blog