Jumping the (Air) Gun

(Air) Gun Control

A lot’s changed on Pit Road this year. In addition to cutting the over-the-wall crew to five people, NASCAR decided (by majority vote of the Team Owners’ Council) that they would provide air guns to all teams. Not everyone was in favor of this.

Rob Kauffman tweeted that Chip Ganassi Racing voted against the plan and Nate Ryan reported that Joe Gibbs Racing was also not in favor of moving control of the pit guns to NASCAR. Ryan also point out that JGR had made a seven-figure investment in research, development and building of air guns.

As seems to be the trend, the teams who could afford that kind of money asked NASCAR to save them from themselves and the teams that couldn’t afford to play that game asked for a level playing field


The specifics of the new rules:

  • The air guns are provided by Paoli, an Italian company that supplies racing series from F1 to V8-Supercar to NASCAR
  • Both XFINITY and the Cup Series use the mandated air guns
  • Teams are assigned air guns using a random lottery like the one used to assign restrictor plates.
  • Teams are provided three air guns: front, back and spare. The gun has to be used for the end of the car it’s labeled for.
  • The air guns must be returned within an hour of the race ending.
  • Teams can make some very minor modifications, like adding grip tape, but they aren’t allowed to do anything else, including removing the socket.
  • Some parts of the gun are sealed so that any tampering would be evident.
  • NASCAR also provides the hoses and air pressure regulators
  • Air pressures are mandated by NASCAR and the equipment for controlling them is part of what is issued to the teams

And How’s That Workin’ for Ya?

Air guns have been a major news topic this year.

My frustration is that in absolutely no other professional sport does the league give you faulty equipment to play with and that’s what we have here.

— Denny Hamlin, after Bristol (via NBC Sports)

I think in theory, I think the pit gun idea is a good idea. I just don’t think at this particular point it’s being executed to the point where it’s fair for the race teams and safe. It’s becoming a safety issue.

— Kevin Harvick, after Texas  (via NBC Sports)

The loose wheels, at some point we got to get these guns better. I’ve bit my lip all year about this stuff and I’m tired of biting my lip about it.

— Rodney Childers, Kevin Harvick’s Crew Chief during Texas (via Fox Sports)

Mine worked, so we’re happy. If it didn’t work, we wouldn’t be happy.”

— Denny Hamlin, after Atlanta (via NBC Sports)

I have to be honest, the people that took that (providing pit guns) on have really done an outstanding job. There’s no way I could sit up here and complain about anything they’ve done because I can’t imagine taking that on during the winter, and what they did over a two-month span or a three-month span trying to get all that stuff ready for the teams. My opinion is we’re going to go through ups and downs and we need to go through them together and learn together, and [having problems is] part of it.”

— Rodney Childers, Kevin Harvick’s Crew Chief after winning Atlanta (via racer.com)

They’re pieces of sh*t

— Cold Pearn, Martin Truex’s Crew Chief, after Atlanta (also via NBC Sports)

Two Type of Problems

You can actually divide the types of problems we’ve seen into two groups: obvious failures in which the evidence is the gun; and less-obvious failures in which the evidence is a wheel left loose.

Obvious Issues

In Atlanta, Harvick’s team had an air hose detach from the gun. He still managed to win that race. NASCAR responded immediately by adding a whip hose in Las Vegas to provide stress relief.

The problem was that, before the whip hose, the tire changers were basically pulling the hose with the gun, which puts a lot of stress on the connector (the silver angled piece coming out of the handle in the photo above). This fix seems to have solved that problem.

Also in Atlanta, the Furniture Row team had an air gun that wouldn’t switch directions (from tightening to loosening).

At Martinsville, Daniel Suzárez’s team had an air gun snap in half.


Time. I must disagree with the Rolling Stones. Time is not on anyone’s side and it wasn’t not on NASCAR’s side. The decision that NASCAR would providing guns happened in the October/November time frame last year, which left only a few months for NASCAR to find a provider, have all the guns made, and get a program in place. Dale Jarrett said on NASCAR America that the prudent thing would have been to test the process for a full season in XFINITY because trying it at the Cup level.

NASCAR has had a lot of success with their on-track experiments lately, so I can’t blame them for feeling like they could pull it off. Dale Jarrett was right, but how much money would have been spent during this year had the change been delayed a year? You could argue that the teams might have turned down their R&D efforts knowing they would be obviated in a year, but somehow, I doubt that would happen.

The Guns are Sh*t. Numerous commentators have noted that race car drivers (and Crew Chiefs) are in a no-win situation when a microphone is shoved in their face immediately after getting out of the car (or during the race for the Crew Chiefs)


Paoli has a long history in motorsport. Take a look at who uses their guns:

There’s very little difference between single-lug-nut models and multi-lug-nut models. If there were a systemic problem with the guns (e.g. production was rushed; a design flaw), we’d be seeing a lot more issues than we have.

Sharing. Each team gets three guns, so we’re talking 40 teams x 3 air guns = 120 air guns. But NASCAR is doing this for both the XFINITY and the Cup Series. They’re using the same guns. That means that if an XFINITY crew member drops a gun or jams it up, a Cup team could get a problem air gun. The time between the races is so short that I don’t see how they could do a thorough inspection of the guns between XFINITY and Cup races. Remember this point, too: It will be important later.

Less-Obvious Issues

In the last few races, the primary complaints about air guns have been after drivers left pit stops with loose wheels and had to come in to have the wheel re-tightened. These are slightly harder to diagnose. Teams blame the air guns, but NASCAR has come back in recent weeks to point out that loose wheels have been a persistent problem in the sport and suggests that teams are jumping to the conclusion that the air gun was at fault.

To understand why this is an issue, we have to take a quick look at how air guns work.

How Air Guns Work

The air guns used by NASCAR pit crews can also (Wikipedia tells us) be called impact wrenches, impactors, impact guns, air wrenches, air guns, rattle guns, torque guns and windy guns). More important than what they’re called is what they do: they provide higher torque output than you’d get from a continuously rotating source like a drill.

Impact wrenches use a basic principle of physics to accomplish this: energy transfer.

Let’s say you need to hammer in a nail. One way would be to press the hammer against the nail to push it into the wall. Or, you could put all that energy into swinging the hammer and, instead of a continuous force over, say twenty seconds, you exert a one-second blow that contains the same energy. An impact wrench is the same analogy, except we’re talking rotational motion and thus torque instead of force.

Another analogy: You’re changing a tire on the side of the road. You crank on the lug wrench with all you’ve got, but the nut won’t budge.

You stand on the lug wrench. Still nothing.

Now you jump — and the lug nut finally moves. You jump again. A little more. One more time and the nut is finally free enough that you can do the rest of the job without looking silly.

An impact wrench works the same way, but with a motor.

The Hammer/Anvil Mechanism

An impact wrench looks like it’s turning continuously, just like a drill, but an impact wrench sounds much different. The characteristic sound is because most impact wrenches actually only turn twice during each rotation of the motor. The video below (Nick Moore) was taken at 600 frames per second. The first part shows it played back at the same speed, which is what you’d see if you were just looking at it in real time.

Then he plays it back at the normal rate (around 30 frames per second), which means you’re watching it 20 times slower. What looks like a continuous motion is actually a series of discrete turns. (There are two impact wrenches being shown because he’s comparing a really good one with a cheap one that he subsequently takes apart.) Watch this until it reaches the 1:20 mark.

Mr. Moore then cut away part of the the housing so you could see how this works. The next clip was filmed at 1200 frames per second. You can see how the hammer rises to compress a spring. Compressed springs store energy. All that energy goes back into the hammer when it’s released and it delivers a rotational impact to the output shaft. The motor provides the same energy it would if it were used continuously, as a drill, but now that energy is bunched up for a greater impact. Mr. Moore shows you how there are only two impacts per revolution. Watch this one to about 2:58.

The Air Motor

Compressed gas is used to provide the energy on pit road instead of electricity, which means the electric motor shown above is replaced by an air motor. The principle part of the air motor is the air vane, which is the cylindrical piece of steel with slots cut into it. Vanes (usually made from plastic or, in the case of NASCAR air guns, carbon fiber) are fit into the slots and can move in and out.


The compressed air coming into the gun is split into two paths.

  • Part of the air is pushes the vanes outward. As you can see, the housing into which the air vane fits isn’t exactly round, so the vanes on the bottom can expand.
  • The second part of the incoming airstream pushes against the now-extended vanes and turns the motor.

Here the important part: The air pressure determines the motor speed. Higher air pressure means more revolutions per minute — and that’s going to be the crux of the matter currently in debate.

Switching Directions

Changing the direction the air motor rotates changes the air gun from tightening to loosening. You switch direct by switching the air path. One air path through the gun makes the air motor rotate clockwise and the other counterclockwise.

I’ve shown the forward/reverse switch on the photo above, but here’s the Red Devil 2.0, which is the NASCAR-specific air gun Paoli brought on market a couple of years ago.

The FRS on the NASCAR version has a fancy red button, which is an upgraded switch that allows the user to switch directions more quickly.

Regardless of what the outside looks like, the inside is a metal cylinder with a hole and grooves on either side. You can sort-of see it in the exploded view below.

When you move the cylinder, the hole in the center moves to direct the air to the forward or reverse paths. The grooves hold o-rings, which make air-tight seals.

Remember the O-Rings. They’re going to be very important in a moment.

The Air

We talk about the air gun, but it’s actually an entire system. High pressure air is provided by an air compressor — which the teams are still responsible for providing; however, NASCAR provides the hoses, the pressure regulator and the pressure relief valve. The pressure regulator sets how much pressure you can get coming into the gun and the pressure, remember, determines the speed of the motor rotation. (Note that most teams don’t compress air: they use dry nitrogen.)

Just like engines, the faster something rotates, the more expensive it gets. When teams were using their own air guns, they rotated at about 14,000 – 18,000 rpm. This year, that’s down to about 10,000 rpm this year.

There’s also a pressure relief valve so that if there is a blockage in the line (like, say, a 3500-lb car with a tire on it), there is a safe way to release the air. I’ve had an air hose blow up right next to me. I don’t recommend it.

Why All the Loose Wheels?

As I mentioned above, we haven’t had so many of the obvious failure-type problems in the last few weeks, but it seems like the last few races have had a lot of talk about loose wheels, with the teams placing the blame on the air guns.

The Teams’ Argument

You can’t blame a team for complaining when a gun flat-out does work; but that’s not the majority of what we’re hearing at this point in the season. We’re hitting on more subtle issues, most of which revolve around problems with the pressure in the guns.

Gas pressure regulators are fussy and don’t stand up well to any type of abuse. You can’t tell if a regulator is wonky by looking at it.

But there are perils along the entire path the air must travel to get to the output shaft. Here’s a rebuild kit from Paoli for their air guns.

It includes new vanes, gaskets, springs and o-rings, as well as lubricant. The seals (gaskets and o-rings) are especially critical because any leakage in those seals means less pressure and lower rotation speed.

Tony Gibson of Stewart-Haas Racing told Mike Neff of frontstretch.com that they were seeing anywhere from 500 to 3,000 rpm variance between the guns they were assigned. He cited a 500 rpm variance between new seals and used seals.

Decreased the rotational speed not only does this slows you down, it can decrease the amount of torque at the output shaft.

This is a big problem because it means you need to apply the gun longer to loosen or tighten a wheel.

As I mentioned, there isn’t time to rebuild (or even thoroughly inspect) all 120 air guns between XFINITY and Cup races. If you happen to get a gun that was abused (or even just used hard) you might have a problem.

Even longer term, though, there’s an issue. Each tire changer took care of his own air gun. I suspect the relationship is something like the one a soldier has with his or her personal weapon. Your life depends on it and you spend a lot of time ensuring it is in tip top shape and ready to use. Even if NASCAR re-builds the guns every week, even the most conscientious person won’t do as good a job as the guy whose career depends on his air gun.

The User

Here’s where it gets interesting. NASCAR can’t complain when a team has video of an air hose that’s come off an air gun. But they’ve gotten a little more aggressive in the last few weeks in response to team comments (like the ones above)

This isn’t the first time that there’s been a loose wheel on a car. Everybody’s always quick to blame the gun, not saying that it may not have been a gun problem, but we have to look at everything before we can flat out say we had a gun problem.

— Scott Miller, NASCAR Senior VP of Competition (after Texas; via SiriusXM The Morning Drive)

We knew going in, the technology of the guns is not going to be what some of the teams were used to in the past. The hand speed (of pit crew members) is incredible. The talent is incredible. Somewhere in between lies the truth. …Any gun that malfunctions is not acceptable to us, but there are some occasions where someone may be moving a little too fast on a stop as well.

— Steve O’Donnell, NASCAR Senior Executive Vice President

As O’Donnell pointed out, it’s irresponsible for drivers and crew chiefs to immediately blame loose wheels on the air guns immediately after (or during) a race. They simply haven’t had time to investigate the situation.

Drivers on less-well-funded teams pointed out that the problems with loose wheels are all on teams that have pioneered the souping-up of air guns. David Ragan, in particular, on Sirius XM radio, suggested that since their crews were used to slower guns, the change didn’t affect them as much as it did other teams. He suggested that Front Row Motorsports was able to have pit stops competitive with the more-well-funded teams this year.

I attempted to verify this with numbers, but the pit data that is available on www.racing-reference.info for past years isn’t available for 2018 – but that would be a really interesting analysis to do.

I drive a manual transmission car. My husband’s is automatic. And every time I drive his car, my left foot goes for the (non-existent) clutch. It’s the same thing when you get into a rental car and automatically reach for a radio or light or heat button that isn’t there. Or, for you non-drivers, switch to a new keyboard on your computer that is just slightly different than your old one.


It’s possible that the pit crew members who have had problems are just having a hard time adapting to the slower guns. They establish a process — which goes into muscle memory — that is more about the rhythm than it is about waiting to feel whether the nut is tight against the wheel. So it is possible that  whether the that is more muscle memory? That the rhythm they’d gotten used to with the faster guns isn’t allowing enough time for the slower guns to do the job?

How Big a Problem is This?

Despite all the calls for urgent action to ensure that air gun problems don’t taint the championship, I think this is a problem that is going to disappear relatively quickly as NASCAR hones their processes and procedures and tire changers get used to their new tools.


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