Team owner and driver Troy...
Team owner and driver Troy Loomis recommends always returning your race car back to your baseline setup at the shop each week. This can help you see how any handling changes you made at the track have affected measurements in other areas.
Based on the IMCA-style Mods, Dirt Modified racing is one of the more inexpensive ways to get into full-scale circle track racing. The class seems like it has been around forever, and it's still going strong all across the country because the general recipe keeps the cars simple, easy to work on and fix, and (relatively speaking) inexpensive. We call it the IMCA-style Dirt Mod because that's the sanctioning body that is most widely known for these cars, and probably sanctions more races at this level than anyone else, but numerous racing organizations and tracks host this style of racing, so we're definitely not talking specifically about IMCA alone.
One of the key features of what we'll call the IMCA-style Dirt Modified is the stock front clip. Although the rest of the car can be constructed from scratch from steel tubing, the front clip, including the front suspension mounting locations, must come from an OEM vehicle. By far the vast majority of race car builders go with a Chevrolet Chevelle front clip, but there are others out there.
Theoretically, the stock front clip rule is designed to slow the advancement of technology, thereby making working with the cars simpler and cheaper. If it's kept stock, the conventional wisdom says that there will be fewer tuning options and that essentially translates into fewer choices for the racer to make.
The signature feature of IMCA-style...
The signature feature of IMCA-style Dirt Modifieds is a stock front clip, which also requires stock suspension mounting points. This means most handling changes will take place at the rear of the car with the exception of spring and shock changes.
However, over the past years we have stressed maintaining a correct front end geometry layout, including the bumpsteer, Ackermann, and roll center characteristics regardless of whether or not you have a stock front clip or a tube frame car. Make sure your car is correct for front geometry issues. You can refer to the numerous Circle Track articles already written on these subjects.
If you do your homework, you will benefit by having a car that turns much better allowing more turn speed and better bite off the corners.
With that said, we will make an assumption that your front end geometry is good to go. As a result, you will notice that a lot of the handling adjustments recommended here will be located at the rear of the car where making adjustments with the precision necessary for racing is much easier.
To find out more, we travelled to the race shop of Troy Loomis, a Dirt Modified racer located in Sherrils Ford, North Carolina. Interestingly, Loomis' day job is the shop manager for Michael Waltrip Racing's Nationwide Series race shop. Loomis began his racing career in the Northeast before moving to the South to work in NASCAR. He took several years off while concentrating on MWR's racing programs, but a few years ago he decided to get back behind the wheel himself and chose Dirt Mod racing as a good way to break back into racing. In 2009, he won the track championship at Wytheville (Va.) Raceway.
At the rear end, a four-bar...
At the rear end, a four-bar suspension like you see here is by far the most popular option on cars these days. Adjusting the four bars (two on each side) gives you a lot of options but how each change affects the car can be confusing to drivers who are new to this particular design.
We chose to work with Loomis because he offered to share everything he knew with us to help other racers go faster and be more consistent. You might think with his resources and contacts with a top-level NASCAR Sprint Cup and Nationwide Series organization, Loomis' car would be a piece of engineering art constructed in the MWR shops with Cup tricks that the average racer could not hope to have the engineering or financial resources to match.
Actually, nothing could be farther from the truth. Loomis races a BMS chassis (www.bmsmods.com) which he purchased from Close Racing Supply (www.closeracingsupply), which sells chassis to racers all across the country. Loomis' chassis is also not the freshest off the jig. It is, in fact, a few years old. Loomis says he plans to replace it eventually but it is still working so well for him that he hates to get rid of it.
"I started from ground zero when I got back into racing," Loomis says. "People think I had all the answers when it comes to setups because of my job, but this chassis and the racing is so different, it really doesn't translate. And it had been so long since I had last raced, all that knowledge was dated too.
"So I don't think I was that different than most racers when they are getting into this class. And the thing I did that helped me progress the fastest so that I was able to win the track championship-and a lot of people aren't going to want to believe this-is I purchased a chassis that is basically mass produced. Not because the chassis is anything magic, although it is a good chassis, but because of the knowledge that goes with it."