General Set-up Tips For Carpet Oval Racing

Listed in order of importance

TIRES—From my experience racing, foam tires work the best for racing on the carpet surfaces.  If you are not familiar with foam tires, they are rated according to their traction and wear characteristics. 

  Here is a brief chart of the different types of tires that I have used.

  The Green and Blue tire compounds are lower in price, and the White, Pink and Purple tires are a little more expensive.  This is a situation where you get what you pay for.  For example, on my NASCAR, I run Purple front tires.  The Purple tires have about the same traction as the Blue tires, but they will last almost twice as long.

  A general rule that I follow when selecting tires, is to have a little harder tire toward the front of the car compared to the rear of the car.  If you have too much traction in the front, and not enough in the rear, your car will always want to spin out on you in the corners.  Another reason is because the tires in the front of the car tend to wear faster, so having a tire that is harder will extend the life of the tire.

  Car balance is also an issue to think about when selecting tires.  If your car always has a tendency to push(won’t turn very well) in a corner, you can compensate for that by adjusting spring tension and shock mounting positions.  However, if you have to make major adjustments to make the car turn left better, you are also taking away your car’s ability to make right hand corners.  This actually is what we are after in oval racing, to be able to make your car turn left only.  But lets not forget all of the other drivers on the track.  It is very seldom that you make lap after lap only turning left.  There are many times that you are required to make right turns to avoid an accident, or get the proper position to make the next corner.  So what I am getting at is, if your car has a push(won’t turn very well), instead of making major adjustments with spring tension and shock position, try a little softer tire in the front to help keep the right and left turning balance of the car more equal.

  The last thing that I want to mention about foam tires is Traction Compound.  Traction Compound is almost always necessary to help the foam tires get traction on the carpet.  When using traction compound, I coat all of the tires all of the way around.  Some people only put traction compound on the inner parts of the tires, but I feel that in order to keep a consistent amount of traction from one run to another, you are best off putting the traction compound on the entire surface of the tires.  Apply the traction compound a minimum of 5 minutes before your race to let it soak in a little.  Then wipe off your tires with a rag (Not the Carpet), and make a lap or two to make sure that it is soaked in properly.

  RIDE HEIGHT—I can not stress the importance of ride height enough.  The lower to the ground that your car is, the better it will handle.  Most of my cars are set up with 1/8” to 1/4” ride height.  You can adjust the ride height by lowering your springs, using shorter springs, adjusting shock positions, or putting shock travel limiters inside your shocks.  Another thing that you have to consider with ride height is not only the height of the chassis from the ground, but the height of your body in respect with the chassis.  On the NASCAR’s, if the body is only 1/2” higher, it will really change the cornering characteristics of the car and make it want to roll over at every corner.

  Keep in mind that when you are running your car a lot lower to the track, that you will need to have a heavier spring installed to keep it from bottoming out.

  SPRING SELECTION AND SHOCK POSITIONS—When racing on an oval such as we are, usually the stiffer the suspension is, the better.  Most of the R/C kits that are being used to race on our track were not designed for a track such as ours.  Therefore, most of the springs and shock settings that are recommended as the base setup are not the best for our track.  Usually a stiffer spring, along with some thicker shock oil (or shock dampers with smaller holes) will help give you a stiffer setup.  This is only part of the solution.  By placing the shocks in different holes on the shock tower, and suspension arms you will be getting different leverage action on the shock.  The closer the shock is to the center of the chassis, the softer the suspension will appear.  Placing the shock in the holes toward the outside of the car will make the suspension stiffer.

  A rule of thumb to follow with shocks and springs is that stiffer springs will give you less traction, and softer springs will give you more.  With foam tires, there is plenty of traction available, so don’t feel that you will be losing traction and sliding all over the place.  What you will gain with a stiffer suspension is a car that will be a lot more stable on all parts of the track.  

Use the above picture to make sure that you understand which spring or shock I am referring to.

    The term Tweak is used to describe the difference in weight between the left and right sides of the car.  For example, if you put more spring tension on the left front you will not only increase the weight on that tire, but the tire kitty-corner from it as well.  In this case it would be the right rear.  Because we are turning left most of the time, adjusting the spring tension on the right front and the right rear will make the biggest difference in handling.

     If your car has a tendency to spin out when you enter a corner, you can fix it by applying more spring tension to the right front, or by removing tension from the right rear.  Applying more spring tension to the left rear, or less tension on the left front will also have the same effect, but to a lesser extent.  Keep in mind that you want to keep your car as close to level as possible.  If your car spins out, and the front of the car is already higher than the rear, it would only make sense to add more tension to the left rear to level out the car, instead of adding tension to the right front.

    If your car has a tendency to push in a corner(not turning very well) you can fix that by increasing the tension of the right rear spring, or decreasing tension on the right front.  The same goes here as well, you want to make your adjustments to help keep the car level.  

    A quick overview of spring tensions 

If your car spins out in the corners you can fix it by:  increasing tension on the right front and left rear, or by decreasing tension on the right rear and left front

If your does not turn very well in the corner you can fix it by:  increasing tension on the right rear and left front, or by decreasing tension on the right front and the left rear.

  GEAR RATIO—Selecting the proper gear ratio can be very frustrating.  The best way to determine the proper gear ratio is by trial and error.  The second best way is to ask someone who already has the same car with the same size of tires what they are running.  The gear ratio is determined by the amount of teeth on the spur(plastic gear on the transmission) divided by the number of teeth on the pinion(metal gear on the motor).

  A LOWER gear ratio is one that will allow for faster acceleration, and a lower top end speed.  A HIGHER gear ratio is one that will have slower acceleration, but will yield a higher top end speed.  If your gear ratio is too low, you will not be able to go fast enough to compete.  If it is too high, you will not be able to accelerate off of the corners very fast, and you will cause your motor and batteries to get hot, and you will lose run time.

  If the spur gear is 100 teeth, and the pinion is 25, you will have a gear ratio of 4.00 to 1.  If the spur gear is 100 teeth and the pinion is 20, you will have a gear ratio of 5.00 to 1.  100/25=4 and 100/20=5 respectively.  5.00 to 1 is a LOWER gear ratio than 4.00 to 1.  I know that it seems backwards, but that is the way that it is so learn it, it is important.   It is always best to start with a lower gear ratio at first, and keep gearing up one or two teeth on the pinion at a time until you feel that you are hitting top speed about ½ to ¾ of the way down the straight aways.  If you are geared too high(too big of a pinion) you will never reach top speed on the short straight aways.

    BATTERIES--Right now, there are many different types of batteries to choose from, and if you read this 2 months from now, it will most likely change again.  There are different capacities available from 2000's all the way up to 3600's and different types, either NiCd or NiMH.  The numbers refers to the milli-amp rating of the battery, or how long they will last on a charge and the type is just the chemical materials inside. So, which ones are the best is a good question. Typically, the NiCd cells are better for bashing around and daily use. They seem to stand up to daily use better than the NiMH cells. The NiCd cells are still good for racing, I have several 2400 packs that I use each week for racing. The NiMH cells are more suited for racing applications and require a little more care when charging and discharging. From what I have read, the NiMH packs don't have the same lifespan as the NiCd packs. The NiMH packs seem to have more overall voltage than the NiCd packs, but it is minimal and for daily use or bashing around, I would recommend NiCd packs.

Batteries are always changing, as well as charger technology. Really the best way to keep current is to check web forums, such as http://www.rctech.net and see what the latest battery and charger technology is.