As we all know, there are many different designs of race tracks, and Eldora is only one. But the lessons learned here can be applied to any of the other race tracks whether flat and slick or high banked and tight. The three areas we wanted to improve on were: 1) Making the car turn well in the middle of the turns, 2) finding more forward bite off the corners, and 3) being consistent in lap times and performance.

The companies and individuals who put together their resources to make this test happen were DeWayne Ragland representing Bilstein Shocks, Kelly Falls with Hypercoil springs, Mike O’Gara of Pi Research, as well as myself and Chassis R&D software products. The drivers in attendance were Billy Moyer along with his GVS Racing crew and Kevin Weaver and the Eaglin Motorsports Racing team.

Both of these drivers have impressive racing careers and are two of the hottest race drivers in the sport of dirt late model racing with more than 560 career wins between them. Did the teams learn anything here that would help them win? You bet they did, and you too can benefit from the results of this test.

The first thing you need to know is that there were no "trick" components or special equipment used at this test. All of the parts and "tools" are available to every racer. The only new components were the Pi Research Data Acquisition equipment to monitor and record the performance of the cars and a new design of "Pull Bar" spring/hydraulic upper link (more about that later). In the end, it was the correct application of all of the available components in a combined package that would work together to make the cars go faster.

The test ran from 2:30 in the afternoon until 11:00 that night. The track surface was extremely consistent throughout the day and night. This aspect of the Eldora track on that day was very important so that the test results were comparable. Each driver took turns running 5 to 10 lap sessions and after each run we compared the data recorded by the onboard equipment which was collected by the PI Research team of three technicians.

The first objective was to try to make the cars turn well. Time is usually lost having to slide the rear around to point the car in order to get around the turns. Each team was made aware of the importance of correct roll center location and proper spring selection. We wanted the front and rear of the car to work and roll together. The Chassis R&D software programs were used to calculate the roll center locations and compare spring rates so that the combination that would best help the car to turn could be found.

Shock selection was also very important. Not only did we need to control the wheel travel over the rough portions of the track, but we also wanted to control the entry and exit attitude of the cars. Each team had a good idea of what shock rates would be needed for this track to suit their driver and his style of driving. The Bilstein gas pressure shocks which each team uses week in and week out provided consistent control of the wheel movements and weight transitions.

Once this combination of roll centers, springs and shocks was applied, the cars were faster and smoother through the middle of the turns. The lap times showed more consistency and the attitude of the cars was more "straight ahead" and less sideways. Most of us will agree that this really is the quickest way around a race track, and the trick here is to make the car turn well. The combination of good chassis design, proper selection of springs (quality and rates), and shocks that will perform consistently without fading all together proved to make the cars much faster.

The Pi System consisted of electronic recording of various aspects of the cars. We were able to monitor lap times both in segments as well as whole lap times. We could graph the shock travel and velocities, throttle input, brake application, wheel speed differentials (RF to RR), as well as G-Forces. Data from previous runs could be compared with new data simply by overlaying the graphs. Positive or negative results were easy to see. Throughout the test, team members could be seen crowded around the computer after each run. They would read over the graphs and charts trying to interpret each change and its affect on the performance of the race car. For a group that rarely uses computers for racing, they seemed to catch on fast. It was easy to see the improvements in turn speeds by comparison of the turn segment times. As changes were made and the cars ran smoother through the turns, it was immediately reflected in the segment times as well as the total lap times.

For example, we tested different length springs to determine if length alone affected the setup. We first installed a twelve inch spring and made a run. Then we installed a ten inch spring with the same rate and made a backup run. There was no measurable difference in travel or performance between the two lengths. While some drivers report a different feel between two different sizes of same-rate springs, we felt that with excess spring travel using a shorter spring, there may be some coil bind taking place. This would increase the spring rate by reducing the number of useable coils. If that were true, the driver would definitely notice a difference in the feel of the setup. The trouble is not with the spring design, but rather involves improper installation of a short spring in a suspension corner which has a lot of movement and therefore requires a longer spring to match the greater amount of travel.

Shock travel data confirmed that the selection of springs and shocks was indeed making all four tires work. Analysis of the throttle movement and the application of the brakes showed improved consistency as changes were made throughout the test. After the adjustments for the handling of the cars was completed, the next step was to try to get all of the horsepower converted into forward thrust.

There were basically three areas to work on to try to improve forward bite. The first was to try to reduce the "shocking" effect to the tires caused by sudden application of power. A motion sensor was installed which measured the amount and speed of the rotation of the rear end as the car was accelerated off the turns. The teams had installed a new design of upper link called a "Pull bar". It is designed with a special spring and hydraulic combination and it smoothes out the transition of power to the rear wheels while also applying more direct downforce to the rear wheels. We could monitor the rotational speed and total travel of this bar with the sensor. The use of the bar allowed the tires to "hook up" better and therefore reduced the amount of tire spin under acceleration. As you might imagine, this new design of bar has only recently become available and is fast becoming one of the most sought after items in dirt racing. Installing this bar alone accounted for an honest two tenths of a second lower lap times with both cars.

The second area to explore was to study the effect of rear steer to increase forward bite. We wanted to steer the rear end more to the left to gain bite and to allow the forward thrust to be pointed more straight ahead. If your car already has trouble turning, you could not use this effect. But remember, we designed our cars to turn well, so we can now utilize this method. The way to accomplish this is to let the movement of the rear trailing arms, as the car rolls, create rear steer in the direction we want. Most cars will steer the rear end to the right to help them get around the turn. This is especially helpful if the front of the car will not turn. But when the rear end of the car is steered to the right, it will have less forward bite on acceleration off of the corner.

On a three link car we can lower the front mounting points of the outer trailing arms to create more rear steer to the left. On a four link system, the upper bars are usually angled upward going forward from the rear end. By decreasing this angle, you can reduce the tendency of the rear end to steer to the right and therefore increase forward bite. Less angle in the upper bars will also help eliminate excessive rear bump steer as the car encounters ruts and holes in the race track. This is just what we did in the test with the some positive results. But remember, if the car doesn’t want to turn well, these methods will make for a very tight race car on exit. Make the car turn by having the correct roll center location and spring selection before trying this.

The third way in which we increased forward bite during this test was through the use of what is called a Spring Rod. This unit replaces the right lower control arm on a four link, or the right control arm on a three link system. This bar is a slider with a spring and a special built shock absorber attached which will compress on acceleration to allow the right side of the rear end to move forward. This causes the rear end to steer more to the left and therefore increases forward bite off the corner. The shock dampens the movement back to the original position as the driver backs off the throttle and the car enters the next turn. Again, the car must already turn well when using this devise or it will be very tight on exit.

Much of the experimentation the crews did during this test resulted in setups that were smooth on entry, fast and consistent through the middle of the turns, and provided a lot of bite on exit. Overall, everyone was very pleased with the results. Both teams had definitely learned some things that would improve their performance.

This test proved that anyone can go consistently faster by following basic rules. If we can apply simple proven methods in a package that will work together, we will see positive results. In our test, the increased performance we saw was a direct result of being able to design the correct roll center locations and install the correct spring rates and shocks in combination. That created fast turn speeds which then allowed us to tune the chassis for maximum forward bite off the corners. How fast did we go? On a surface that all agreed was no better than the last race’s conditions, we recorded lap times consistently a half a second faster than the leader of the last race run at Eldora.