Oval Car Setup Tips

January 12, 2011 in iRacing by slowry

With the old iRacing forums going offline at the end of this season, I recalled a thread with some absolute jems of information on setting up the top 3 iRacing Oval cars.

Dale Earnhardt Jr was kind enough to allow me to post it. Enjoy!

SETUP TIPS

Setup Tips by Dale Jr

Heres some interesting real world info vs iracing.

Car: Cot

Track: Charlotte

Real world right side air pressure baseline
Race: RF 60 RR 58
Qual: RF 75 RR 70

What many used in the WDC Charlotte race last week
Race: RF 56 RR 56
Qual: RF 61 RR 58

Blowing up your right side tires to go fast is common knowledge in the real world. It appears that in this one case the real world pressures are even higher than what many used in one of the top series in Iracing.

I would expect that higher air pressure would be quicker, but I would be surprised if someone is running these types of pressures online for the entire duration of an event.

Left side air at Charlotte this week is about 2-4 pounds higher than in Iracing in race trim.

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I would be surprised if anyone can make a setup in iRacing at Charlotte for example with over 65 pounds in the right sides that would be real competitive over a full fuel run.

My method to getting the cambers and tire temps is this. It’s quite simple.

Get a baseline on the front springs. Get a baseline on the chassis heights.

Go run some laps. Stop, look at temps, adjust cambers to even out the inside and outside temps. Also adjust air pressure to bring the center temp to within a few pounds of the outer temps. Reset heights throughout this process.

Go run some laps and repeat this process. After a 10 lap run I want to see all the temps on the right front tire to be as close as possible.

The left front tire will most likely perform the best with a little more camber which will produce more temp on the outside edge of the tire. Any where from -5 to -7 degrees.

Air pressures in the left are different for each track, I just run laps and find a setting that gives me the best grip for the exit.
I don’t run the trucks enough to know. But in the NW and COT…I run the nose as low as you can. I run the springs as soft as you can. My front heights are consistent in these two cars from track to track. The front springs are always very soft, usually in the 350 to 600 pound range. On smoother tracks I can run softer, but on a track with bumps like Vegas I may need a bit more spring.

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From my experience I choose the LR spring by how the car gets forward bite on exit.

I choose the RR spring that helps the car rotate in the center without making it over rotate. Also adding RR spring will sometimes make the car aero tight on entrance at a track like Michigan so when I get that feeling I can either back off the RR spring or take out some nose weight.

We are able to run about the same springs in the NW car here and IRL.

In the COT we are able to run a little softer than what is currently common IRL.

That doesn’t mean its wrong or unrealistic. What we lack in the COT on Iracing is the ability to adjust the bump stop compliance and the bump stop gap. So I would assume that with those two settings currently in their fixed state on iRacing in the COT, we are limited in our ability to be more creative with our choices in optimal front spring settings. I’m sure one day we will be able to adjust the bump stop gap and the compliance. That will open up the range of springs you would put in the front and the choices there would be closer to IRL.

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Something that I have learned about the garage over the last several builds. I will credit Chris Shearburn for pointing this out to me.

Looking at the COT garage you’ll see two pieces of information:

Shock deflection
Spring deflection

To my knowledge, this is what this information is telling you.

If your looking at your right front and your shock deflection is 3.45″ of 5.75″…
That means you have 2.30″ inches of travel before you will engage the bumpstop.

You do the same math with your spring deflection. If its 2.80″ of 6.10″…..
That means you have 3.30″ of travel in the spring before it will begin to coil bind.

With these two settings, you will engage the bumpstop 1″ before the spring will coil bind. In the COT this is usually the best approach. (the bumpstop engaging before the spring is fully collapsed)

If your keeping your front heights the same while adjusting your setup (you should do this always)….your shock deflection will not change. This means that the bumpstop on the shock is in a fixed position and we are not currently allowed to change its position.

Now its different with the front springs. You can change the spring deflection. You can make it less by running a softer spring that will coil bind sooner, or you can make it more by running a heavier spring that will travel more before coil binding. You can also make the difference between your two front spring perch offsets larger and allow for more or less travel in the front springs.

What you want to do is basically run springs that are as soft as possible on ovals. We know the shock deflection is fixed. But keep an eye on the spring deflection. I like to keep my left front and right front spring deflection very close. I get this by moving the front spring perches. From my experience, having the left front spring more likely to coil bind before the right front helps me turn better but that’s just my preference.

On the NW car, you do not have a bumpstop to use. So if you are running soft springs, paying attention to the spring deflection can be very helpful. Try left front coil binding there as well. Different drivers like different things. But having a large difference in the two front spring deflections (more than 2″) will more than likely cause a large balance shift during the duration of a fuel run. Left front coil bind will help your rotate better, and right front coil bind will help keep the cross in the car throughout the corner toward exit.

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But with my experience in IRacing so far, I have had better wear and tire performance by evening the temps on the right front through camber adjustments and tire pressures.

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I know your are asking about left side pressures.

First I want to add that I run excessive left front camber to help me turn on entrance and exit. This is common IRL as we run upwards of +8 degrees on most tracks like Charlotte and Michigan. I just run enough to help it turn in, but I have to be careful because it will decrease the cross in the car on exit as the nose starts to come out of travel. So if can make you loose off if your not careful.

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On to the left side pressures. Its not as critical to get even temps on your left side tires. As I noted with the left front camber, you can run very hot on the outside edge and get away with it because the other three tires are wearing considerably more during a run. With the LR, I usually just run enough to hook up the back of the car while in the throttle toward exit. You will notice that as you get higher in LR pressure the car can become more unstable through the tri ovals. It may appear on new tires or could show itself on the long run. As Im testing a track throughout the week, I keep adjusting the LR if and when the car needs to gain or loose grip in the back while applying throttle toward the exit. I don’t recall every running more than 30 pounds at any track in the past several seasons online.

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But stop after ten laps or so and don’t slide your tires when you do. Check the garage and look at your middle tire temps. Make sure that they have not exceeded the outer temps. Keep adjusting them back down to where they match across the tire as close as possible after a ten lap run. Over inflating the tire will cause you to loose traction on the long run, while yes it may feel good for the short term.

Setup Tip from others

protip – calibrate your wheel to the left about 15 degrees

Blow your right side tires on the COT or B all the way up to maximum. Then lower the RR a bit to get the blade out of the air. After you do that, start moving the cross weight down and freeing up the car. The tire temps all read way sub optimal, the contact patch is obviously wrong, but once you get it right you’ll pick up 2 to 3 tenths a lap.

are you talking about the shock settings that has been going around for a while to exploit the tire model?

the 032 032 320 3232

The A-B Impala’s aero performance will benefit when you run your shocks at maximum rebound + minimum bump for the front end and maximum bump + minimum rebound for the rear end. I think it helps to keep the nose down bum up angle of attack that improves downforce.

Remember that setting a shock in iRacing to 0 doesn’t mean you are running no shock at all. It means you are running the softest option available in iRacing.