The drop snout design was perfect for the older and stiffer spring setups where we rolled more and dove less. This design allowed a consistent moment center design and very little camber change at the right front wheel. Now with setups that dive more and roll less, we don't need, or can use, the dropped snouts and resulting higher upper control arm angles.
Moment center control is still a desire and we have to live with the camber change issues. Rules changes that limit and/or disallow running on coil bind or bumpstops are a good way to go. It's sad when the track officials and promoters are smarter than the racers. In this case, I think they are.
IMCA Mod Bar Lengths
I have a couple of questions. First of all, we race IMCA Modifieds and I would like to know about four-bar lengths. I've heard that there are guys running bar lengths as short as 10 inches; we are currently running 14 inches on the lowers and 16 inches on the uppers. We are running the four-bar on both sides. Is there an advantage to the shorter bar and what length upper bars do you use?
Running shorter bar lengths allows more cockpit space for the driver for taller drivers. You can move the 'cage back several inches while keeping the same wheelbase. Geometrically, shorter bars react more to vertical motion in changes to front and rear motion of the rear end.
Both short and long lengths can be made to steer the same within certain ranges and be made to create zero rear steer also within a range of vertical motion. I suggest that you support the car and move each rear wheel vertically so determine rear steer characteristics. Measure horizontally from a fixed point to each wheel rim across the center of the wheel and when you move the wheel vertically, note the change in fore and aft movement of the wheel.
Plan out how your wheels will move in the turns and recreate that movement. Then you will know if and how much rear steer you have. If it's not what you want, make changes to the bar angles to create what you desire. The tendency now is for less rear steer and a more straight ahead attitude going through the turns.
Dirt LM Body
Thanks for a great magazine. We read Circle Track religiously. I was reading an old article titled "Dirt Late Model Panels-Hang Tight" by Jeff Huneycutt. I was wondering if you could steer me toward an article that I missed or a company that would sell me the patterns for the panels?
We are pretty handy and have the equipment to make the panels ourselves but do not have a pattern. We are moving to the Dirt Late Model for the 2010 season so I don't have an existing one to copy. Any advice would be greatly appreciated.
Most teams will buy a new body and then make their own templates if they intend to cut their own panels in the future. Some special tools will be needed to create beads and bent edges for radiuses. A good, long sheetmetal brake is also a good idea. And don't forget a pneumatic rivet gun, it will pay for itself many times over. All of these items can be purchased at any race parts outlet store.
Metric Part Numbers
On the metric Monte Carlo, to get the moment center where it needs to be, what exact spindles, A-arms, ball joints, and other modifications do you guys recommend? Any part numbers and manufacturers would be most helpful. I am new to dirt racing, and am building a new car. I subscribe to your magazine and read all the articles relating to metric Montes, but a lot of it is over my head tech-wise.