Most "four link" rear suspensions...
Most "four link" rear suspensions have adjustment of the control links using a series of holes like the new CT Mastersbilt car. We will adjust our car so that we can utilize the correct amount of rear steer depending on the conditions we will be racing. Note the high angles (the car is resting on a stand) of the links. This causes the axle on this side to roll forward and down loading the left rear tire under acceleration.
By that time, we had Scott Bloomquist, Shannon Babb, Donny O'neal, and a few others on the setup. Bloomer set fast time the first round (out of 247 cars) and was disallowed when his car weighed too light. He went back out the second round and set fast time again. He would have done well in the race but a right rear tire separated early on dropping him out.
Are you starting to get the picture here? We were having a lot of success with a process and methods that were all-new and winning is the best measure I know of to gauge how well your ideas fit, no matter which type of race car. There was a measure of validation in the way things were going.
The Third Clue
Fast forward to 2007 and a dirt test we ran at Magnolia Speedway in Mississippi with Dewayne and Jay Dickens. In that test we changed everything you could change on a Dirt Late Model car and the very last thing was to run the J-bar to the right side of the chassis. The track had medium bite, not too dry slick and not at all tacky or black.
This car is equipped with...
This car is equipped with sliding clamps mounted on square tubing. Adjustments to the link angles and J-bar heights can be made quickly and infinitely with this design. When changes are made, the rear axle must be repositioned for proper squaring.
The car laid down on the right side much like an asphalt car and the right rear tire was biting so hard that it looked like a drag slick with wrinkles in the sidewall. The lap times were no slower or quicker than any other laps we had run during the entire test, but the car was more consistent and easier to drive according to the driver (read the full article in the May '07 Circle Track).
It has long been a theory of mine that you don't need to have the fastest car to win on dirt. Many times the winner is the one who makes the fewest mistakes. A car that is hard to drive causes more mistakes and loses more time during those missteps. They don't call Billy Moyer "Mr. Smooth" for nothing and he continues to win a large percentage of the races he runs out of shear consistency.
Today, we see teams and car builders designing their moment centers more carefully and running setups where the left front tire is mostly in contact with the track surface.
In other words, the car is set up with a more balanced dynamic. What we get is not only speed, but consistency and the top teams know that is the way to Victory Lane. Here are ten things you can do this season to be more consistent and give yourself a better chance at winning.
1. Front End Geometry
The mounting of weight including...
The mounting of weight including the battery should be well thought out to gain maximum benefit for load distribution. There are times we need our weight high and to the right for dry slick track surfaces and low and left for tacky conditions.
For any race car with a double A-arm front suspension, we always start with an analysis of the frontend geometry. If the moment center (roll center) design on your car is not right, then the whole car will suffer, no matter what setup you have in it. This we have established as a fact.
The dirt car moment center design is different than that of an asphalt car. On dirt, the average g-force is much less than on asphalt because the track just does not provide as much grip. So, the MC needs to be located farther to the left in order for the car to work well.
2. Rear Geometry
The dirt car rear geometry layouts are varied and usually highly adjustable. Each car needs to be evaluated for where it is to be raced and then set correctly. The trailing arm angles affect the rear steer and bite and the pull bar or lift arm can redistribute load upon acceleration and deceleration.
Many teams will tell you that there is a need for rear end steer to the right at times when the car is tight and you need to get it pointed in order to exit the corner. During tight and tacky conditions, a slight amount of rear steer to the left would probably improve lap times, but only if the car turns well. The use of rear steer to the left must only occur on acceleration and not at mid-turn. This is a possibility with certain designs.