Basic Oval Track Setup Building for DW12

Building a competitive setup requires a great deal of trial and error testing.  While one could start from scratch for each track, each season, it is often time efficient to build on already existing setups.

iRacing provides “fixed” setups for every oval track. Each of these are thoroughly tested by some unknown person or persons to be “competitive” and are almost always a bit under-steery or “tight”. On most ovals, it is useful to take this fixed set and modify it.

First, run the fixed set for 10 laps and get a baseline set of lap times.

One modification is called “fixing the toes”.   Essentially, using the toe in/out settings to make the front and rear wheels “steer” into the turn.  The system will generally only allow -2 on the right rear (toe out) and +2 on the left rear (toe in).  At the same time, generally the front is set with -1 on the left front and +1 on the right front.   There are many theories of why this works.  The most plausible is that the car essentially travels in a “crab” orientation creating some aerodynamic assist in turning but it is also correct to note that this adjustment changes the location of the turning radius center. The driver needs to adjust his sense of attitude (loose vs tight) as the car may seem loose, even though the tires’ slip angles may not be materially different.

The next modification is to adjust the radiator inlet—changing to 1/3 blocked for racing and 2/3 blocked for qualifying. Most fixed sets run the radiator Open.

After making these two modifications, run another 10 laps and compare lap times and handling to the baseline. Also view the tire temps and wear. 

Generally the car will be “tight” or under-steery.  This is usually the result of excessive Relative Rear Downforce and will also be signaled by higher front tire temps compared to the rear.

IMPORTANT TERM:   A Balanced Race Car is one where the right front and the right rear tires are close to the same temperature and wear---this is the goal. With the correct driving line, you will “feel” this with the car not being loose or tight.

Note the % Front Downforce.  Reduce the rear wing downforce slightly as well as reducing the lower beam wicker to ¼”

IMPORTANT TERM:  Best Camber for Racing Grip is the setting that produces nearly equal tire wear from left to right of each tire. (This may not be the best setting for qualifying, but for racing it produces the setting that will provide the best lap times for long runs.) See Figures below. On an oval track, negative camber on the right side and positive camber on the left is essentially creating a "camber angle" and "camber thrust" on both left and right tires. (Forces on both tires to the left to make the car turn left.)

Note the Cross Weight (Left Front +/- Weight). Adjust the left side to less positive camber (often to the least allowed by iRacing). Adjust the right side as required to achieve Best Camber for Racing Grip. ( See figure above--You are compromising maximum lateral grip when cold for better tire performance when tires are hot as well as maximizing the usable tire surface for longest life.) Adjust ride height to restore the original Cross Weight. 

Run another 10 laps and compare lap times and handling. Note tire wear. Repeat with additional changes to wing aero until a Balanced Race Car is achieved.

Once a Balanced Race Car is achieved by adjusting wings, note the Front Downforce %. Reduce front and rear wing as needed to reduce total downforce while maintaining the Front Downforce %.  At some point, reduction in downforce will expose poor handling. The car will be too tight or too loose.

Before making any further adjustments, using ALT L, and some form of telemetry software analysis, note the ride heights on all four corners.  If the car is hitting the track during corners, then ride height needs to be increased. Generally, at corner entry and mid corner, the optimum ride height on the right side would be not be much more than 0.3 inches—often this requires you to lower the car.  On the straights, it is generally good for the rear ride height to be 0.3 inches higher in the rear than the front. (You can tell if the car is too low without telemetry--top speed will be hurt and if you watch carefully in the replay, you can see sparks.)

Having noted these ride heights, make adjustments as needed while maintaining the Cross Weight. Run another 10 laps and compare lap times and handling. Note tire wear.

You will now start making adjustments to remedy the handling issues you observe without adjusting wings.

If the car is tight, adjust ride heights to put more weight on the left front tire. If the car is loose, adjust ride heights to take weight off of the left front tire. (By taking weight off the left front, you are essentially reducing the right rear tire weight at the same time. Most times the loose condition will be reduced by reducing the right rear tire load.)

Run another 10 laps and compare lap times and handling. Note tire wear.

If the car exhibits a tendency to snap oversteer on exit, increase left rear spring or decrease right rear spring. This is called adding "bite". (Alternately try reducing left front spring.) At the same time, reduce rebound dampening on the left rear and reduce compression dampening on the right rear and  try increasing the front ARB. Reduce caster settings. (Higher caster makes the car looser when turning.)  If the car exhibits a tendency to be tight in mid corner and/or exit, do the opposite, plus reduce rebound dampening on the left front.  

The figure above gives a bit of insight about the high and low speed damper settings.The low speed settings affect the damper when moving at 1-2 inches per second. The high speed settings affect the damper when moving faster than that. The rate of damping force increase relative to speed is different for high speed movement vs. low speed. Rebound damping is higher than compression damping because the spring is acting to accelerate the damper's movement.

The challenge here is that each track has a different “Ribbon Banking Transition”. Think of the track as a ribbon of pavement that is twisted as it transitions from higher banking in the turns to less banking on the straights. The shape of that “ribbon” will change the “dynamic” handling characteristics of the car.  As a car comes off the steeply banked turn, the reduced banking on the front straight requires the inside of the track to RISE, placing more force on the left front tire and less force on the left rear momentarily—the car will be loose.  As a car enters a steeply banked turn, the inside of the track will FALL, placing less force on the left front tire and more force on the left rear momentarily—the car will be tight. (Many times this “tight on entry” will not be noticed and will extend to turn exit where the driver will input too much steering to correct for it—causing a loose on exit problem. ) Each track and each corner “twists the ribbon” differently. Adjusting the Cross Weight and relative spring and damper settings for each corner is generally how this dynamic handling is optimized. (This issue is the reason you will often find that the best setup requires a weaker spring on the left front.)

Run another 10 laps and compare lap times and handling. Note tire temps and wear. Keep in mind the important goal of maintaining a Balanced Race Car. (97% RF; 97% RR is good for example.)

Now, experiment with increasing downforce AND decreasing downforce to achieve faster laps. (Keep in mind the goal is to improve or optimize the Downforce to Drag ratio when making changes, if possible.)  Experiment with different tire pressures. Experiment with changing "rake" of the difference between front and rear ride heights--more rake with rear higher than the front will increase downforce and drag. (This requires lots of trial and error testing.)  Be sure to run a full fuel run on what you think is your best setup. On hot tracks, most setups will require adjustments to weight jacker and/or ARB during a full fuel run.

The choice of settings for the various aerodynamic devices on the Indycar is not simple. One confusing aspect is that "negative" wing angles can still produce downforce.  In iRacing, one simple help is clicking the right side box increases downforce.  Generally, the wing is more efficient with a small wicker or Gurney Flap--the theory being there is less turbulence. (Reducing turbulence is a good thing in aerodynamics and in addition to making your car faster---less turbulence creates less draft and makes it harder for your opponent to pass.)

Negative weight jacker takes weight off of the left front, making the car less loose. Positive weight jacker puts more weight on the left front and right rear, making the car more loose. When thinking of the weight jacker, think LOOSE----Negative=MINUS or LESS LOOSE; Positive=PLUS or MORE LOOSE. Adding front ARB will tighten the car. Reducing front ARB will loosen the car. When thinking about the Front ARB, think TIGHT---More Front ARB=MORE TIGHT; Less Front ARB=LESS TIGHT.

Check top speed at the end of straights--adjust gearing as needed. Generally you want 5th gear max to be 3-5 mph higher than your top speed. 6th gear should have enough more max speed to allow for added speed in the draft. Set 4th about 10 mph lower than 5th so that it can be used in corners during the race----in traffic near the end of the race.

Be sure RACE setups do not use Qualifying Boost.  (Do be sure to use Qualifying Boost for running Qualifying setups in Practice.)

For qualifying, generally, you change the radiator inlet to 2/3 blocked, and reduce fuel to 2 gallons. Since the car is lighter, adjust the ride heights to compensate while maintaining Cross Weight. Then, experiment with reducing rear wing and increasing all springs by 50 or 100 # to make the car more stiff. (Tires will have maximum grip and stiffer springs can be faster.)  You may find increasing weight on the left front, i.e. changing Cross Weight may be faster. For qualifying you want a SLIGHTLY UNBALANCED setup with a tendency to be a little loose. (This usually is indicated by rear tire temps about 5-10 degrees higher than the front.) You may also find that increasing camber and caster settings make the car faster. Be careful as the car may become “edgy”.  On some tracks, the second lap of qualifying is slower because during the first lap, you abused the tires to get maximum speed.

Colder temps generally allow less wing and more weight on the left front. Hotter temps generally require more wing (downforce) and less weight on the left front. Remember that the underwing is the most efficient so be sure to maximize available downforce with strakes and ¾ wicker before adding front or rear wings.

Some drivers use the weight jacker in between corners to make the car better suited for each corner. Some actually do this DURING the corner to change the handling between mid corner and exit!

A loose race car is very hard to drive in traffic, so for extra hot conditions, generally the car will need to have more rear downforce and sometimes a stronger left rear spring. (Or weaker right rear.)  A loose condition usually requires a reduction in throttle which causes a weight transfer from rear to front which may make it more difficult and may take more time to stabilize the car where an understeery condition can often be quickly remedied by a slight reduction in throttle.

Often, it will require 6 to 8 different setups to cover the range of temperatures for qualifying and racing.

This is by no means a complete instruction. There are many other adjustments that can be made and vehicle dynamics are complicated. These “more advanced” settings (like choice of wheelbase and assymetrical caster settings or moving weight forward/rearward as well as tire pressures) should be attempted to further optimize your lap times but will require additional time consuming testing. And, remember that driving lines and throttle modulation are part of how best lap times are achieved. 

Note 1: The choice of spring rate for each corner is "relative" to the spring rates on the other corners. The choice of the average spring rate depends on three factors--bumps ride height, and grip. Choosing a higher spring rate will reduce the chassis deflection at high speed from aero downforce--this is good. Choosing a higher spring rate will increase the speed that weight transfers in turns and when grip is lower--this can be bad. Most times the best setting is the result of trial and error testing. Tire pressures change the effective "spring rate" of the tire and tend to produce a similar result as a change in spring rate for that corner--think of the tire and spring as two springs connected in "series".

Note 2: There is an advanced topic regarding the use of significant added weight (100-250#) to the left front tire. In NASCAR this is called Negative Cross or Negative Wedge. In IndyCar it is EXTREME ADDED LEFT FRONT weight. It is a very odd setup that only works on some tracks, at lower temps. The added weight to the left front keeps the front “planted” and extra high rear downforce is used to keep the rear “planted”. The extra drag from the extra rear wing is less than the reduction in scrubbing/friction drag from the front steering tires.  When it works, the car can be an order of magnitude quicker.  Often it works on a cold track (like Iowa at night) but it seldom works on a hot track. The effectiveness depends on the relative temperature vs. grip curves of the front and rear tires.