When building a new car, creating a Center of Gravity that is lower than your current car will allow for more speed. Physics demands that a lower Center of Gravity will create more grip on an object (racecar) that is going fast in a straight line and then, for reasons that are obvious to drivers, the object (still a racecar) suddenly needs to move violently left.
If you had material that was extremely dense and heavy such as a tiny chunk from the marble like object that created everything, you could use this heavy material to make your car consistently faster. Lead is commonly used to balance out racecars because it is dense, melts easily and is relatively inexpensive. The melting point of lead is a mere 621.5 Degrees F and it well suited for molding to nearly any shape.
Lead is less than healthy though and fumes, grindings and over handling should be avoided. Food while working with lead is forbidden. Researching the web for proper lead handling is a great idea. After finishing your lead handling research, and fitting lead for your application, it is easy to add a quick paint job to your completed lead blocks to assist in reducing unwanted exposure.
Lead costs less than 2 bucks per pound. 1 Cubic Centimeter of lead weighs in at 11.35 grams and steel comes in at 7.85. In a perfect world, you could use tungsten for your car ballast which weighs in at 19.35 grams per Cubic Centimeter and is very safe to handle. Too bad tungsten has one of the highest melting points on earth at about 6170 degrees F. Tungsten costs about $13.00 per pound or more. Regardless of your ballast material, the earth element lesson is utilized to help illustrate a point. Tungsten weighs about 1.7 times as much as lead which means you could take up almost half the space with Tungsten ballast as compared to lead. The smaller mass allows you to build in more adjustability. A small sliver from the big bang marble of the universe would be really efficient – let me know when you find a supplier for the mythical and magical material.
While safe, tungsten is one of the hardest materials on earth making it difficult to work with. Maybe you can find usable chunks at a discount from a surplus company. If you have some Osmium or Iridium laying about this would make excellent racecar ballast – of course finding these elements might prove to be very hard and very expensive. Guys in black suits would probably fly in from Area 51 to see what is going on in your race garage.
The point we are making is that we want our racecar ballast to be located in the smallest area possible verses being spread about the car. We work hard and spend big bucks on light weight materials for our cars so that we can add ballast for adjustability. It pays to locate car batteries low and left. Dry sump tanks are best mounted far to the left. Anything that is required in the car should be mounted in the lowest possible position and as far left as you can get away with.
Example 1: Side Weight - The example above shows two hunks of lead on the left frame rail and 2 equal chunks on the right frame rail. Locating lead in this fashion might show desired weights statically on the scales but when you put the car in motion this car will be slower than a clone car that has lead located in a centralized fashion.
Super Modifieds take the low and left thought to an extreme and their Indy Car looks are only given away by the giant V-8 engine that hangs completely outside the car to the extreme left. Super Modifieds are very fast and they are incredibly lightweight, have a very low CG, have a ton of left side weight and have massive horsepower. The only thing holding them to the ground is the giant wing that controls corner entry and down force.
When mounting lead in your stock car you always want it low. Your goal is to reach the maximum left side weight allowed by your rules with the lead in a compact area. By placing the lead in a compact area your car can handle the weight with more efficiency.
If you place lead in the left frame rail and another chunk on the right rail then the car will not be as efficient and on paper it will be slower than the same car with the ballast placed in the ideal location. With improper positioning of the ballast the tires will wear faster, the shocks will get hotter and the maximum car speed will be less than if you placed the lead in a compact area. You may need to manufacture your lead in shapes to fit in the ideal spot between your frame rails.
Example 2: Center Weight - Our hypothetical car shows the lead from Example 1 moved to the center of the car. In Example 2 we have the exact same amount of weight and are at the legal minimum and the maximum left side percentage. The shocks, springs and tires are much more efficient due to the proper location and centralized layout.
Your goal is to have the lead low and built for adjustability. Filling the left rail and then filling the right rail gives you the static numbers on your scales that might allow you to write down the set up numbers aimed for. The trouble occurs when you put the car into motion. Having lead on the left and right rails creates a situation the motion is harder to control than if the lead centralized. The lead on opposite sides of the car creates a back and forth rocking force that must be controlled by the springs and shocks. Located properly, the back and forth motion is reduced as the lead is centralized and supported between the springs and shocks for efficiency.
To illustrate further, school has started and many of you are loading your children up with books, computers, lunches, IPODS and cell phones. All of these items go in their backpack which is centered between their two tiny legs. The weight is carried so that the mechanical leverage of the human body can most effectively hold the weight while utilizing the least amount of energy. To improve conditions for your kids, making the back pack lighter is the best option. I am certain that parents would not load their kids down with extra weight and then make them carry the weight outside of their body center line. Kids wouldn’t be asked to carry two backpacks with their left and right hands extended out away from their body center line. I doubt parents would feel the need to add weight to one back pack in an effort to make the back packs the same weight and increasing the overall load of their little ones.
Our racecars (babies!) feel the same extra work when ballast is spread out with some lead on the left rail and some on the right. Ballast needs to be centralized so that the suspension can manage the inertia and centrifugal force efficiently.
Example 3: Rear Weight - Placing lead behind the rear axle might read the correct percentage on your scales but placing lead behind the axle is not recommended. Weight mounted behind the rear axle will cause the rear tires to overheat quickly and the car will be difficult to control. Ballast should always be mounted between the axle center lines for maximum potential speed and efficient control by your springs and shocks.
Less weight is always the better answer for your racecar and extra weight should never be added to gain more left side weight percentage or rear weight percentage at the expense of the overall total. In other words, you should never run over the legal minimum weight to get up to the maximum left side weight or any other number for that matter. Run as light as the rules allow and if your car is below the maximum left side allowable weight then find something in the car to move left but never add weight above the legal minimum.
Locating components in your car properly can help you to maximize weight distribution for ultimate potential speed. the clamp mounts on this radiator mounting system allow you to slide the radiator as far to the left as your frame allows. This mount also adjusts up and down ensuring your radiator is fit properly in the car. Creatively planning the low and left mounting goal of all of your required car components will help your car get through the corners efficiently.
The minimum legal overall weight is always the most important number otherwise our babies (racecars) will get tired by the end of the race. Shocks will overheat and tires will give up - just like kids that are carrying back packs with too much improperly placed junk in them. For your car to go faster, less weight is always the correct choice. The weight you add in ballast form should be concentrated in one area to allow your car the most control over the entire race distance. Your frame rails are much smaller than the universe and it only takes a little pre-planning to properly place ballast keeping your team from being in outer space.
Go Forward – Move Ahead
Jeff Butcher
09/1/10
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