Car setup solver 3 steps
To get this to work for every car, you need to start with Arnout’s preset.
I use a % of the sliders instead of the values, like for instance mm or KN.
To get the preset:
Step 1
Rear wing setting.
First, set a wing setting for your car. Go on the straight of a track, try to get the best exit possible, and see how fast you are on that straight. Determine from other drivers or previous experience in races if your top speed isn’t too low.
Low top speed is super painful in races.
If you figured this out, I suggest you stay away from this rear wing setting.
Step 2
Rear ride height.
The next thing we need to figure out is how your ride is behaving with this wing setting. Let's assume we have 50% of the wing setting.
Front ride height I push on 0% of the slider to start. Why? The lower the car, the more downforce we have. We only increase the front when we bottom out, meaning the floor of the car hits curbs or the road surface.
The rear ride height I use to find balance. So you have your wing on 50%, you drive laps. Do you feel understeer? The car isn’t turning with the steering wheel enough? Increase the rear ride height by 10% and try again.
As you gain more experience, you’ll find you can maybe change 20% if you feel the car is super understeery.
When the car is oversteering, then you want to drop the rear ride height by 10%. If you are at the lowest ride height and you still are super oversteering, you might want to increase the rear wing setting as you are on the limit of your car and setup combination.
If you absolutely want to keep the wing setting, move to the mechanical grip section.
Step 3
Mechanical grip section.
You are using Arnout's preset, so you have margin on changing the sliders up and down.
A corner has an entry, mid, and exit. This setup solver doesn’t work if we brake on exit and throttle on entry. So we can never change brake bias to manipulate car balance on exit.
Example: Lamborghini Huracán Evo2
You got 50% rear wing setting and 20% rear ride height:
You found an overall balance, but there are some issues with how the car behaves.
You can have the following understeer issues:
Understeer on entry
Understeer on exit
Understeer off throttle
Understeer while braking
And the following oversteer issues:
Oversteer on entry
Oversteer on exit
Oversteer off throttle
Oversteer while braking
These situations you can have in fast, mid, and slow corners. I’m skipping the mid-section of the corner because I believe you should have fixed this with the wing and rear ride height settings.
Example: Your Lambo oversteers when you exit the corner. You want to apply throttle, but the back end of the car doesn’t have the grip, and the rear is sliding whenever you apply throttle.
How to fix this?
You've never seen this before this way:
To create balance in your car, you can do 2 setup changes:
Remove tire grip efficiency
Add tire grip efficiency
We are going to work with front and rear grip efficiency and start counting points.
We have the max efficiency points when:
Lowest wheel rates
Lowest bump stop rates
Lowest anti-roll bar setting
Highest bump stop ranges
The opposite is going to be lowest points of front and rear grip efficiency:
Lowest efficiency points when:
Highest wheel rates
Highest bump stop rates
Highest anti-roll bar setting
Lowest bump stop range
Now we still have brake bias and preload differential settings.
The brake bias changes the car balance for braking.
Differential settings changes car behavior on and off throttle.
We have a tire grip efficiency issue on the exit, so we are going to increase the grip efficiency on the back.
Bump stop range and wheel rates can influence the car everywhere, so if you find this problem on a lot of corners, you want to increase the rear bump stop range. The back of the car will be allowed to drop when on throttle and at higher speeds, and the range will also create more stability on the back.
But if you have balance in fast corners, you want to decrease the anti-roll bar on the back; this will not influence the aero balance.
Solutions
A: Decrease rear anti-roll bar by 10 or 20%
B: Decrease diff preload by 20%
C: Increase rear bump stop range by 10%
D: When only in fast corners, lower the rear bump stop rates by 10%
My advice is to do 10 or 20%, then move to changes B,C and D start over.
The rear anti-roll bar setting is your best friend in creating grip on the back when on throttle. Take note: Low anti-roll bar settings can make your car unresponsive and sluggish. Example: You’ll find that when your car oversteers when pushing over the limit, it can be harder to save your car when oversteering. (It doesn’t stop sliding.)
The lower preload makes sure the back of the car will lose rotation on throttle; this can also greatly benefit your balance when hitting throttle, but this does however create oversteer off throttle.
Great, it reduced the sliding on exit when on throttle, but I have some understeer now on the entry of slow corners:
When decelerating, the weight of the car is moving forward, and there might be an issue that the front tires don’t get the efficiency and dominance to force the car into the corner.
Solution:
Lower the front wheel rates
This allows the front of the car to dive more easily, creating more balance to the front when the weight goes forward when coasting and braking.
If this solution gives you oversteer everywhere, you need to increase the brake bias or/and decrease the bump stop range on the front.
The low wheel rates make your car dive when braking or coasting, but the lower bump stop range prevents the dive from going too deeply. Lower wheel rates add efficiency in slow corners, lower bump stop ranges remove efficiency in fast situations.
So here is what we have done so far as an example:
You got 50% rear wing setting and 20% rear ride height (overall balance).
You lowered the rear anti-roll bar by 20% (reduced oversteer on exit).
You increased the rear bump stop ranges by 10% (reduced oversteer on exit).
You decreased the wheel rates on the front by 10% (understeer on slow entry).
You decreased the brake bias (understeer while braking).
All these changes affect the car in multiple ways, but this is just an example of how I would do it.
Now I know that a Lambo will always have oversteer on throttle in slow corners, and that is just a characteristic of this car. Car setups will not solve everything, but it is a great way to change things up a bit.
Now I spoke about car setup solver system A, but I found there are more ways to change them up completely . I will get into those later.
I’ve been driving the Audi R8 LMS Evo2 the last weeks, and that car really opened my eyes on how car setups can be approached from different angles.
take note, this newsletter is also a learning tool for myself. i’m learning this is public feel free to comment in my patreon or discord to add info or if you have other ideas about this subject, the end goal is to create a setup solver that everybody will understand
Cheers,
Arnout