One area where Fogleman separates himself from a lot of other Saturday night level racers is his understanding of how to set up a race car and drive it when racing "on the bumpstops." Bumpstop racing is essentially a response to get around a common rule stating a minimum ride height while the car goes through inspection. To get around the rule, several years ago NASCAR Sprint Cup teams began using front springs so light that they were only useful for holding the car off the ground while it was sitting still. On the track, aerodynamic downforce and g-forces in the turns pulled the front of the car down until the suspension bottomed out. At that point the only thing holding it up are the hard rubber bumpstops mounted on the shock shafts.
There are several advantages to racing with the front suspension essentially completely collapsed. Most of all, it lowers the car's center of gravity significantly. Racing on the bumpstops also reduces the car's aerodynamic silhouette, meaning less drag, and settling the car right down on the racetrack further reduces the amount of air that gets underneath the car. By keeping stronger springs in the rear, you get more rake in the car which helps keep the rear spoiler in the air for more downforce on the rear as well. And finally, while bumpstops still allow some wheel travel, it is minuscule compared to standard suspension travel. This makes setting the camber and toe easier because the limited amount of wheel movement makes dynamic wheel and toe changes almost nonexistent.
Crew chief Will Brafford prepares the set of shocks to be tested. It's critical that you s
A system of rigid beams slide underneath the scale pads and connect quickly to provide a f
Here, you can see Brafford setting up one of the four actuators that mount on the frame at
But there are also a few drawbacks--namely, that the cars are uncomfortable and often difficult to drive if you aren't familiar with how bumpstops will cause it to react. Finding the best setup with a car designed to run on the bumpstops is also quite different than a traditional chassis package.
"The material used for the bumpstops is slightly flexible so when the car is sitting on the stops, there is still some wheel movement but it is very small," Fogleman explains. "The spring rate really spikes when the car gets down on the bumpstops and that can cause a drastic change in the way the car handles. Plus, in many ways setting up the car is the exact opposite of what you would expect if you have any experience in what we will call the old style with stiffer front springs.
"For example, one situation that often throws a lot of newer drivers is the car will be loose getting into the turn, but as soon as the front end settles down on the bumpstops the wheel rate spikes and the car instantly goes tight. Traditionally, the fix for a tight car is to take some spring out of it, but that's the opposite of the correct move for a car with bumpstops. What you actually want to do is put some more spring in it to keep the car from hitting the bumpstops so hard. Now the wheel rate won't spike so high and the car won't transition from loose to tight so quickly."
This shot provides a better view of the bracket that mounts to the pull-down actuator and
As part of the pull-down rig, Fogleman also uses DRP's Real Square laser alignment system
Fogleman is working with DRP to design measurement fixtures that bolt directly to the shoc
It's safe to say that few people on the Saturday night level have put more effort and time into researching how bumpstops affect handling and performance on Late Model race cars. And besides helping other drivers and crew chiefs, that knowledge has also influenced how Fogleman wanted the chassis he races constructed.
"Over time I found things that I felt just worked better," he says, "and so we would make those modifications to our race cars. I wanted a chassis built to my specifications from scratch but the chassis builders I talked to didn't want to do something that was so different from their standard chassis. So I decided it was time to go out and start building my own."