Waving the Checkers: Breaking axles

Jimmie Johnson and Brian Vickers didn’t do anything wrong Sunday night at Atlanta, except they were aggressive. And on bigger tracks, that comes with risk.

Broken axles happen because drivers are nearly perfect in anticipating the left-side tire change being complete. That’s right – they are penalized for being on top of their game, so to speak.

Drivers are aware that how quickly they get on and off pit road contributes to the overall speed of a pit stop, and part of this includes leaving the pit box.

When the right-side tire change is complete and the jack drops, the driver shifts from neutral to first gear. While the left side is in the air and tires are being replaced, the driver sits with the clutch in waiting for his signal to leave. That signal comes as the jack is being dropped. Anticipating it and actually releasing the clutch as the car is dropping to the ground would qualify as perfect, saving perhaps a few valuable tenths or even a full second, which translates to valuable spots on the track.

Problem is, if you release the clutch and accelerate with roughly 900 horsepower just as the weight of the car presses on the tires, you risk a mechanical failure.

The frustrating part for the driver is understanding what they did wrong, because the one time an axel breaks will seem no different than when you executed 99 stops before this failure.

The risk of axles breaking decreases when competing at smaller tracks, because the lower rear-gear ratio helps get the car rolling. Let me use a 10-speed bicycle as an example.

If you take off in first gear, it’s easy to get started. First gear would be like a Martinsville ratio. But if you attempt to take off in 10th gear (equivalent to a Daytona or Talladega gear ratio), it takes a lot more energy and is quite a strain on your legs.

The gear used this weekend would be somewhere around eighth gear on the bike. But remember, they are using nearly twice the leverage or horsepower because Daytona and Talladega use restrictor plates.

Next time you ride that bike, try taking off in a higher gear and you’ll have a better understanding of the strain being placed on a race car’s drive train.

Sunday, Jimmie Johnson and Brian Vickers didn’t do anything different than what they’ve done for years, except this time it bit them.

It’s really no different than what they do every time they come on pit road. You can flirt with trying to gain speed on pit-road entry, and you probably won’t get a lot of credit for the times you do it really well. But you will get a ton of attention when you mess it up.

These are intangible things drivers think about and train for, but don’t get much attention for being good at until something fails.

Although it cost Jimmie Johnson and Brian Vickers – and what Brian Vickers’ crew did, getting him back on the track without losing a single lap, was phenomenal – neither did anything wrong other than being aggressive.

I’m sure today the guys at the race shop responsible for the drive trains are telling them to be a little less aggressive, which Johnson and Vickers may do for a stop or two. But they will soon dismiss it, because when you can get away with it more often than not, it’s a risk worth taking.