We will modify this system...
We will modify this system to include a new pull bar, and the elimination of the lift arm which was probably used with the previous four-link rear.
Initially, we had to move some weight to the front to get a better front-to-rear percent, to around 52-53 percent rear, so we moved a 30 pound piece of lead from the back of the car to a point at mid-chassis and at around shoulder height next to the driver. This piece came from the rear bumper and should not have been located there for reasons of negative polar moment tendencies. We will talk more about that later.
5. Safety is a concern in any racecar, and we are doing an evaluation of this car along those lines. Bobby had a hard crash last season where he contacted the outside wall hitting on the driver's side. We are installing a better seat (his bent severely in the crash) and moving it farther to the right. We will install racing-quality padding on the roll bars, around the steering column, and beside his legs. He has also just purchased a new racing-approved Simpson helmet.
Note the different mounting...
Note the different mounting heights for the shocks and the pull bar. The low mount of the pull bar would mean a lot of force on the bar causing it to move quickly and probably spring bind early on in the process of acceleration. We will install a multi-spring pull bar and change the location of the rearend mount to a higher position. The shocks are OK where they are.
An up-to-date fire suppression system will be a part of our safety package too, along with making sure Bobby has properly dated approved seat belts, a sufficiently effective firesuit with racing shoes, and gloves.
As we go along, we will be reporting on our progress and providing details on what we do to the car and why. We will give you exact setup parameters as well as any decisions we make as to setup changes for track conditions. This will not be a generalized reporting, but rather one that tells all. Again, these setups and designs might not work for your car, but the directions we go will demonstrate how successful teams think and act.
We don't expect to always be right in our decisions. We will tell you when we do something that is not in the right direction. We all learn as much from our mistakes as we do from our successes. A change that does not produce the desired results still teaches us something.
We noticed when we inspected...
We noticed when we inspected the rear birdcages that the location of the front end of the upper link was not near the radius of the adjustment mounting holes in the chassis. Therefore, when the link was moved from hole to hole, the rear alignment changed. This is not desirable at all. We will find a mounting point that is very near the radius of the adjustment holes.
From historical feedback over the past ten years, we have heard that the swing-arm cars, either Dirt Late Models or Dirt Modifieds, are usually very good on the tight and heavy tracks, but do not work as well on the dry slick tracks. We are going to see if we can design this car to work well under both conditions. Only after testing and racing will we really know if that is possible.
We will experiment with different components and spring combinations to try to compensate for changing conditions as we race at different tracks. We will develop a definitive plan of attack to meet the challenge of going from a wet and tacky track to one that is either sandy-dry slick or black-dry slick. We're going to tell you exactly what that plan is and why we are following it. Any changes we make to the plan will be documented and presented.
Along the way, we want your input, too. As we move through this project, please send along any comments and/or suggestions to us here at Circle Track. By the next issue, we should have the car all ready to race. We can't wait.
This view is staged to simulate...
This view is staged to simulate the position of the rearend in relation to the chassis at ride height. Note the severe angles of the links on this left side view. We will reduce the angle of the forward link to around 5 degrees (forward high) and the rear link to approximately 10 degrees (rear high). This reduces the amount of rear steer to almost zero. We will still have adjustments to where we can introduce limited rear steer if we want to.
The battery location in this...
The battery location in this car was excellent. It is mounted high and to the right side in front of the fuel cell. Our driver weighs around 300 pounds, so right side weight is not a problem. We actually need to create more right side weight to reduce left side percent. Note also the lead bolted to the chassis just in front of the battery.
The lift arm system that is...
The lift arm system that is now in the car was probably installed with the four-link conversion in the past. We will remove the arm and all associated hardware to save weight and then use the new pull bar to control axle wrapup. We will be mounting a 30 pound chunk of lead to the chassis rail just in front of the oil filter to get weight up in the car and to reduce the rear percent.