Do you
want your racecar to be faster? Do you want your
car to be more consistent on those long runs?
Getting the ballast located correctly is a key
component for a faster racecar. Proper placement
of the ballast is actually a free speed secret.
These simple tips will allow you to go faster
around the turns and provide more grip in your
car.
First
and foremost you should be very weight conscious
when constructing your car. You would be amazed
at how all of those little things add up to
extra weight. Be sure to look for any weight
savings. It is very difficult to find weight
savings in five-pound blocks. Look for quarter
pounds! Those little things will add up if you
pay close attention. Strive to build a car that
is as lightweight as possible. Never compromise
safety for weight savings. There are plenty of
places that you can save weight but safety
should always be the paramount concern. We race
for fun, make sure that you build a safe
racecar.
Now that
you have a good lightweight car you will need to
add ballast to get the car up to the minimum
standards set by your sanctioning body. Check
your rulebook for the maximum left side weight
allowed. You will want to be as close to the
maximum left side weight allowed as possible
while maintaining the minimum total weight.
Never run your car heavy for the sake of more
left side weight.
Next,
check with your car builder for his
recommendation on front to rear weight
percentages. Verify that your car is "race
ready" excluding the ballast operation. Now
that you know what you want for rear weight you
can begin finding a home for the ballast.
You need
to locate the ballast as close to the Center of
Gravity of the car and as low as possible while
maintaining the minimum total weight rule,
maximum left side weight rule and car builder
recommended rear weight. In other words, you
want the ballast to be located in the smallest
area possible. Insure that you properly attach
any ballast to the car. Do it right to insure
safety.
For
example, lets assume that your car weighs 2500
pounds race ready but without any ballast. Lets
also assume that you have a 200 lb driver, your
minimum weight allowed is 2900 pounds, your
maximum left side is 56% and your recommended
rear weight is 50%. With these assumptions you
will need to add 200 pounds to get up to the
minimum weight. Lets also assume that your car
has 50% rear weight without any ballast
installed.
We now
need to mount the ballast to our hypothetical
car. Since we are starting with a rear weight
percentage that matches our car builder's
recommendation we need to add ballast and reach
our goal of 50% rear weight at the rules
mandated 2900 pounds. When mounting the ballast
we want to concentrate the ballast in the
smallest possible area. To illustrate the point,
we would want the 200 pounds of ballast to be
mounted in a concentrated area within the car to
meet our target. We would want to avoid placing
100 pounds near the front of the car and the
other 100 pounds near the rear of the car.
By
concentrating the ballast into a small area
versus spreading it out your car will go faster.
The same idea holds true for the left to right
weight distribution as well. You want to mount
the ballast in a small area rather than taking
the easy route and placing some ballast in the
left side frame rail and some ballast way out on
the right side frame rail.
Take the
extra time to build proper ballast brackets
between the frame rails to attain the desired
left side weight. Avoid placing ballast (or
anything heavy) to the right of the Center of
Gravity. You will see that your static weight
numbers can be the same whether you mount the
ballast in a concentrated area or if you spread
out a 100 pound block on the left rail and the
other 100 pound block on the right rail.
Statically this will look fine on the scales but
dynamically the spread out scenario will slow
your car down and wear out your tires faster.
The same
idea applies to front to rear weight. Avoid
placing some ballast in the front of the frame
rail and then another amount of ballast at the
rear of the rail with an air space in between.
Slide the two chunks of ballast together. Focus
on concentrating the ballast into the smallest
possible area and spend the time building
brackets to meet the goal.
Why will
the spread out ballast placement slow you down?
Lets picture a simple example. Picture a
playground teeter-totter. The teeter-totter
pivots in the middle. The pivot is compared to
the Center of Gravity in your racecar. Now
picture 500 pounds of weight on both seats of
the teeter-totter. The seats compare to the left
and right frame rails. You can see that in the
static position that the 500 pound weights would
balance out. However, when you put the
teeter-totter in motion that much weight would
require much effort to get started and even more
effort to stop once it got moving. If the
teeter-totter were moving fast you would be
crushed trying to stop the movement with 500
pounds out on each end. Your springs and shocks
would have to control all this dynamically
moving weight that is rocking back and forth.
Front to rear movements would have to be
controlled as well.
Now
picture the same example with one revision.
Instead of having 500 pounds on each seat with a
balanced teeter-totter, lets move the 500 pounds
in from each seat until we end up with 1000
pounds directly over the pivot point (this would
be the same as our CG in our racecar). You would
notice that the teeter-totter is still balanced.
The weight would be carried directly at the CG
or pivot point. Once the teeter-totter were put
into motion it would be much easier to control
compared to the spread out version that had the
500 pound weights clear out on the seats. Just
think of how much easier this situation is on
your springs and shocks!
By
concentrating the ballast into the smallest
possible area you reduce the amount of weight
that has to be controlled once the car is in
motion. You reduce the amount of back and forth
motion in the turns and front to rear weight
transitions under braking. Weight transfers
occur in more controllable amounts, which will
result in a more efficient, and stable handling
racecar.
Another
way to think of it is using your own body as an
example. When you carry heavy items you hold
them as close to the centerline of your body as
possible. Typically you hold heavy items against
your chest. With the weight against your chest
you can carry the weight with less effort and
you have more control once you begin moving.
Most people do not carry their groceries into
the house with a bag in each hand and their arms
fully extended. Obviously with the weight
extended way out at the end of your extended
arms the groceries would be difficult to control
and you could be thrown off balance very easily.
Keeping the weight closer to your body or CG is
much more efficient.
Now that
you understand this principle lets take it
another step forward. When building your car you
should strive to keep all support items as close
to the CG as possible. Avoid mounting the
battery out on the right frame rail. Batteries
are heavy and need to be located just like
ballast. Try to mount all of your tanks,
electrical items, fuel filters, hoses, drink
bottles, radio boxes, or any support items to
the left of the CG. Avoid mounting anything to
the right of the CG whenever possible. Using
this strategy will allow you to place more
ballast in a concentrated area.
Simply
by planning your mounting locations you can make
your car faster by properly placing the ballast
and support items. It may require more initial
effort but the cost is effectively zero and the
benefit keeps giving throughout the life of you
racecar.
If you
are conscientious mounting all of your racing
components you will be able to place your
ballast closer to the CG and low to the ground
while still maintaining your maximum left side
weight and desired rear weight. The result of
placing the ballast in a concentrated area is a
racecar that is more nimble. The car will change
directions much quicker. The racecar will be
more responsive. Tire temperatures will be
reduced, tire wear improved, lap times will go
down, your car will have more grip, be more
consistent and your chance for victories will
rise.