The test and tune was great fun and very helpful in
providing valuable knowledge that would normally require several disappointing races to realize. For example, my Ninco Le
Mans car was faster without weight added while testing alone, but very vulnerable to any side contact from another car causing
it to de-slot. I added a bit of weight and it became much more stable in competition albeit a tad slower. I was also able
to determine that I was giving up about one car length to average cars in each straight and that I need to work on that. Here
are the rest of my thoughts after testing my cars and observing others:
Weight tuned classes
1. The thin weight sheets from Victory Station are
the best. The adhesive is reliable even in hard crashes yet removable with some effort without ANY damage to the chassis whatsoever
and the thinness prevents contact with the track.
2. Optimal weight for our cars is between 75 and 90
grams total and weight should be placed under the chassis in front of the rear axle and extend to approximately half way between the motor and the guide. Realizing
that I fine tuned the weights on my cars during the test & tune day, I used a slipknot string to check them afterwards and discovered some
things I find very interesting. Distance from guide pivot measured to rear axle divided by distance from horizontal CG (slipknot
location when car is dangling perfectly balanced front to rear) measured to rear axle, multiplied by 100, equals the weight
bias percentage. N :- N = A x 100 =% Vertical CG is determined by where the slipknot location when the car is dangling on
its side with the chassis perfectly vertical from side to side. By day's end I had added weight to the Saleen, added more
weight to the rear of the Cobra, and shifted some weight from front to rear on the RS200, all based solely on handling characteristics.
Despite the fact that each car is very different, the horizontal weight balance is now very much the same for all three at
approximately 35% front and 65% rear + - 1mm measuring tolerance from the rear axle to the guide pivot and the CG is also
nearly identical at approximately 3mm above the rear axle for the Saleen and 2 mm for both the RS200and Cobra. Interesting
isn't it? Of course, the optimal balance will vary depending on traction and track conditions.
3. All the tips that Stephen posted at last year’s
test and tune and on the website (such as slightly loose screws, etc.) really work and cars should be properly tuned and adjusted
BEFORE attempting to weight tune.
4. With everything set up properly such as tire truing
and sizes, front axle movement, braids, and etc. then front to rear weight balance will affect whether the car's handling
is loose (tail happy) or tight (front end rolls out of the slot in the turns).
All classes except 4W/D
1. Front axle movement: Rules dictate that front tires
MUST touch the track and roll when the car moves but it is legal and advisable to true the front tires so that some of the
car's front end weight rests on the guide. (with Ninco cars for example, you should be able to move the front tires up and
down about 1/16th" with the car sitting in the slot).
All classes
2. It's much easier to eliminate drag than to find
an especially good motor. Carefully oil the motor and axle bearings and use plastic-friendly light grease on the gears. Check
cars carefully to be certain that everything moves smoothly and freely.
3. "Running-in" a car really works to make them smoother,
quieter, and faster. If you have a "rolling road", great, but if not you can lay the car on its roof and use 2 to 4 volts
for about an hour to gain noticeable improvements (I use a mobile phone charger rated at 3.7 volts and nowadays one can find
low voltage transformers just laying around since they've become so common). Keep close watch on it, stop and check everything
if anything seems wrong such as rubbing, binding, or excessive heat in the motor.
4. Braids can cause cars to run slower even when they
may not hesitate or stop and they can also cause them to deslot more easily. Take the time to fray the ends slightly; make
certain they are smooth and straight with enough pressure for good contact but not so much that they keep the guide from resting
all the way into the slot. I'm amazed out how ignorant I was about this early on and further amazed by how many poorly adjusted
braids I saw at the test & tune.
5. Plastic molded wheels and tires are seriously out
of round so it pays to check them carefully and realize that they may need more than a little sanding on the truing block.
The test & tune provided a rare opportunity for me to stalk other cars to see where I was faster and what might help the
slower cars. Most are very loose and based on my personal experience I believe that proper truing and freeing up the chassis
makes a huge difference. René taught me this when he fixed my Minardi from sloppy loose into one of the faster cars in the
class.
I’m sharing something special that I’ve
been doing that I believe helps my cars to be faster because they’re less tail happy but I must disclaim that it requires
a more careful driving style as they can sometimes de-slot before sliding out. I true my rear tires to have a very slight
taper from inside to outside so that when the rear axle tips ever so slightly in the turns (they all do this) the outside
tire’s contact patch is flat on the track and the inside tire touches only on its inside edge. Moreover, I taper the
front tires for the opposite effect so that the outside tire touches only on it’s outer most edge in the corners. Of
course, I could be wrong so consider my thoughts with a grain of salt so to speak and be amused at least.
