Nascar Intern Engineers Seeking Advice

Tech Tales helps improve function and reliability

By Tony Green
Jameco Technical Support

Nascar I took a conference call from a group of young automotive engineers interning at NASCAR seeking assistance on their project to improve function and reliability of remotely operated track bar positioning system in NASCAR Sprint Cup cars.

Driver control of the track bar position has been problematic so far, the current system(s) is not optimal. I had been hearing of trouble with the track bars during this year’s racing season, everything from poor feedback, out of control track bar controllers to weak systems failing for a variety of reasons. Of course, drivers make mistakes, too.

The track bar is located underneath the rear of the car, one end connected to the rear axle, the other to the frame. By raising or lowering the right side of the bar, it alters the position of the rear axle in relation to the car's centerline. Any changes affect the weight distribution of the car and how it moves through the corners. The team of NASCAR engineering interns were seeking to build a robust, infinitely adjustable track bar positioner with very clear driver feedback.

The track bar (also called a Panhard bar or Panhard rod) is a suspension link that provides lateral location of the axle in reference to the frame. Invented by the French Panhard automobile company in the early twentieth century, this device has been widely used ever since on solid rear axle suspensions. Track bars and traction bars are not the same.

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The red bar that crosses in back of the black differential pan is the track bar.

Changes to the track bar can tighten or loosen a car. Too loose, the car is unstable, too tight, the car doesn't want to turn. In the endless contest between handling and speed, with track and tire performance changing during the race, any advantage is time sensitive and usually temporary. Giving the drivers control of the track bar is new this year. Previously the track bar could only be changed during pit stops with a long shaft wrench through a hole in the rear window.

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It seemed to me their existing system was fragile and unreliable. They didn't want to share much about that, which is understandable, for this is a fiercely competitive sport. In qualifying, it's not unusual for the lap time difference between fastest and slowest car to be 1/200th of a second!

Automotive is an extremely harsh environment to design and build for. Although NASCAR is easier in some ways (no rain, snow, ice, mud, hail, etc.) it is the worst in others. Eight or nine hundred horsepower cars are driven flat out for hours, cockpit temperatures easily reach 140°F, sometimes (many times?) disc brake rotors are glowing red hot. Each car is specifically designed and tuned to keep air from getting under the car. Where the track bar is. All the way in the back of the car.

We talked about this and it seemed like they had a revelation. I suspect the motors or solenoids being used were being heat killed. I suggested they get some fans down there and switch to gear-head motors. Since the gear-head motor only has to survive one race we decided Jameco gear-head motors were a go.

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Feedback for the driver has also been a problem. Since NASCAR has switched to "glass displays" I would have programmed it there, but maybe they can't. It sounded like they were using either analog gauges or LCD displays, but I couldn't be sure. I suggested they switch to LED bar graphs as they are easy to see, very clear as a status indicator and pretty darn robust. They went with that also.

Another problem is the driver control interface. Some are on the steering wheel (rocker button), others on the dash (toggle switch) or the side of the driver's seat (joy stick). We talked about many options on this but couldn't reach a consensus. Since this seemed to be the least serious problem, it was deferred until they have a working system to test.

Jameco is always happy to offer our two cents to assist customers identify the right component and design strategy for a project. If you get a moment, drop us a note at [email protected], and we'll do our best to help.
Tony Green majored in Aeronautics and Aerospace Design at San Mateo Community College. Before coming to Jameco in 2011, he was an Electronics Technician / Automation Engineer at Genentech, Inc., in the engineering and product development divisions, supporting drug manufacturing and development. He was also an Electronics Technician at B. Braun AG, in West Germany. His hobbies are restoring classic Corvettes and relentlessly spoiling his grandkids.