Race Car Chassis - Race Car Design Basics

What I find from talking to hundreds of teams throughout the season is that many racers know more about his/her chassis and how it's built than ever before. That is because the competition has moved ahead in its knowledge. Just to keep up, let alone pass the winners, in any class be it Dirt or Asphalt, we need to have knowledge.

The beginning of your success starts with knowing all of the technical details about your chassis. This is true for all stock cars no matter what class or racing surface you run on.

Let's compare your chassis to your motor. If you have the luxury of having a good engine man tuning your motors, you will know that he/she is aware of every detail of how that motor is built, the components installed, and what is important to have for maximum power output.

In stark contrast to engine knowledge, most teams know very little about their chassis construction. That situation is rapidly changing whereby many top- and midlevel teams and more and more car builders are aware of the critical components and design issues that must be incorporated into the chassis.

Just a few years ago, if you visited most chassis shops and asked where their moment center (roll center) was located, they would either tell you it wasn't important or that they didn't know and didn't care. There was a very good reason for that. At that time, no one, including myself, knew what the MC did, much less where it should be located. Things have changed dramatically.

The MC syndrome is just one example of how technology has rapidly advanced over the past few years to where we can now define many important design issues related to the race car chassis. If we can define those areas, then we can make changes to our chassis to make them better. The chassis builders too can incorporate the proper design into the new chassis they build. And believe me, they are doing just that across the board, for Dirt and Asphalt chassis.

It's a wonderful time to go racing when, given the right knowledge, we can properly set up our cars to be competitive right from the start. In the past, it could take several months or years to find the sweet spot for our setup and some teams have never found it. Let's take a look at the most important aspects of chassis design and why they affect our handling and performance so much.

Moment Center Design
I don't care if you race on dirt or asphalt or ice for that matter, the front moment center design is the most important aspect of performance in your chassis. Sure, it's not the only aspect, just the most important. Up front is where it all begins.

Do you want to know how I know that? I know that because I continually hear from racers from all walks of racing say the same thing over and over again. When they took charge of their frontend design and corrected any deficiencies in the design, the car literally came alive. Once the car turns well, all of the other important aspects of setup can be properly dealt with.

The MC must be in a certain location for each type of racing and racetrack. The two most important considerations are camber change for both front wheels and MC static and dynamic location. We must develop a frontend design that will offer the least camber change while also positioning the MC where it will do the most good to promote the proper dynamics for the frontend.

With the softer spring setups, we will have a greater degree of camber change, but we can still minimize it to a certain extent. Frontend design is much different for those setups than with more conventional setups. That is why you can't successfully change from one to the other without a redesign of your front suspension.