Twisting and Turning Straight to the Point

Dec. 28, 2009
Wireless indictators and data collection make measuring torsioinal stiffness simpler and more accurate for one NASCAR race team.
To test chassis stiffness, Joe Gibbs Racing technicians lock each car into place and locate indicators at designated positions. Then, a load is placed on the car and measurements are taken from the indicators. This procedure is repeated 12 times with different loads and different chassis configurations.

In NASCAR racing, torsional stiffness of a car chassis is one of thousands of critical details that must be executed reliably, and Joe Gibbs Racing (JGR) takes no chances. To test chassis stiffness, technicians at JGR will lock down the car structure and place indicators at eight designated positions. Then, a load is manually placed on the car, and the measurements are taken from the indicators. This procedure is repeated 12 times with different loads and different chassis configurations, for a total of 96 measurements.

It used to be necessary for a technician to walk around the chassis and write down each measurement after each setup and load placement. Also, the dial indicators used in this step would be upside down (positive and negative readings) and, because the car would be rising on one side and declining on the other, half of the dials would turn in the opposite direction. The process was time-consuming and error prone.

Joe Gibbs Racing needed a faster — and more accurate — process. They approached The L.S. Starrett Co., a company well known to JGR through sponsorship agreements.

With the goal of automating the data-collection process, JGR recently replaced the dial indicators that had been used on the chassis twist rig with new Starrett wireless indicators and a DataSure wireless data collection system. Each indicator has an accompanying DataSure end node, and a DataSure Gateway attached to a PC records the data.

The new package improves data gathering in several important ways. Rather than positioning himself awkwardly around the twisting chassis, taking a reading and recording it, the technician now simply pushes the DataSure end node "send" button.

Also, the prior procedure required another step: the technician had to enter the measurement data into an Excel spreadsheet, which added time and potential errors to the process. With DataSure, captured data is entered directly once it’s sent from the end node for 100% error elimination.

At first, JGR expected that the indicators and DataSure would only save process time, but it became clear that they were also saving effort. While most of the time spent twisting a chassis is devoted to setup, which has nothing to do with the indicators, quite a bit of time is saved in post processing.

For now, the load is still applied manually, which means that at each load setting, technicians can take eight measurements with the click of a button. Data- Sure and WinWedge serial data-collection software ensure that all of the data is written directly into a prepared Excel worksheet. This eliminates any post processing and saves 15 to 20 minutes worth of extra work.

Starrett wireless indicators and DataSure have been a welcome addition to the chassis twisting rig. As documented in the table, DataSure and the wireless indicators have made a chassis twist take almost 30 percent less time than using conventional dial indicators. The process is easier for the technician and more reliable for Joe Gibbs Racing.