The Brazilian Grand Prix is the penultimate race in the Formula 1 Championship, making it an important race to get right if you want to claim the title. It is also a difficult track to get right, with a lengthy pit straight that requires high top speed but also a remarkably twisty, hilly, middle sector with a lot of quick changes of direction that require a responsive, well-balanced setup to maximise your speed.
This circuit is unique due to the changes in camber and elevation throughout. The first corner has a downhill braking zone which sweeps you into the Senna Esses. You need to get out of the Esses well because the Reta Oposta is the second-longest acceleration zone of the lap and the first DRS spot. Turn 4 is an excellent overtaking spot, but the circuit quickly narrows as you head back up the hill around a long, tricky turn 6 and really hit the slow part of the track.
The turn 8 and turn 11 hairpins have multiple racing lines, making them sneaky overtaking spots in F1 2018, and turn 9, Pinheirinho, is so slow and long that it is an easy place to get impatient and lose time. The sweep down from turn 11 around Mergulho takes you to the final braking zone at turn 12, Junction, which is vital to get right as you are then accelerating all the way back up and around the hill to the start/finish line.
You need to be smooth in Interlagos, because the surface and the kerbs are not, and to find time around this circuit you need to take to the kerbs a lot.
You can't trim too much wing around Interlagos despite the two long flat-out sections. You need good front wing angle to create the front downforce so you can turn in well, and the rear is needed as you will be accelerating and turning frequently. In this setup we have taken down the rear wing just a touch to help with straight line speed.
We need to lock up the 'on throttle' differential a little so we can get good traction out of turn 3 and turn 12. It will also help gain ground into the two hairpins where you can make a move on an unsuspecting foe. However, unlocking the 'off throttle' differential a little to help the car roll through the corners. Unlocking the 'off throttle' will also help with tyre wear.
This is a drive-specific part of the setup, so while it works for my style on the throttle it may not suit you. If you are getting too much oversteer then lock up the differentials a little more, and if you are under-steering, open them up.
Suspension geometry can be one of the more complicated parts of car setup. It is all about how the tyres are aligned to the body of the car. All F1 cars start with negative camber on their tyres, meaning the top of the tyre is closer to the body than the bottom. This creates more grip when cornering.
At Interlagos there are a lot of slower corners where we are not carrying much speed at all, therefore we don't need as much camber on our tyres. Straighten up the rear tyres as much as possible to aid straight line speed. Take a little off the front so you can still lean on the tyres around the acceleration zones of the curved start/finish straight and carry nice speed up the hill as we turn toward the first hairpin.
Toe describes how the tyres are aligned compared to each other. The front tyres are set in a toe out position, so the front of the tyres are further away from each other than the back. This is to help with turn-in responsiveness. Don't want to play around with this too much at Interlagos, as you need the responsiveness for the tight corners, but adding more toe-out will reduce straight line speed. We can add a little speed by turning the rear tyres inward a touch more. The lack of high-speed corners and the short track length means tyre wear isn't too big a problem, so we can accept a little more wear on the rears.
Interlagos is not kind to F1 cars. The old nature of the circuit and the hills that flow create bumps, and the corners require you to take a lot of kerb due to the narrow track and the tightness of some. As a result you should soften your suspension fairly considerably. By making the rear suspension even softer than the front you allow the weight to shift back under acceleration, aiding traction even more.
What this track does require though, is responsiveness on turn-in, and that is why the anti-roll bars are made firmer. It reduces body roll through corners and allows all four wheels to act in the corners. It helps us get into corners more effectively, but it will increase tyre wear. This isn't too much of a problem around Interlagos as I said, and with the Senna Esses and snaking middle sector we make more time with a responsive car than we would by saving more tyre life.
Because of the bumpy, kerb-happy, nature of the circuit we can't drop the ride height too much at all. At a flat power circuit like Monza you could trim ride height to 3, but at 5 so we can get slippy in a straight line but not bottom out on the kerbs as you dart through the corners.
The different angles of braking zones at Interlagos make it tough to push brake pressures too high. You need good stopping power for turn one and turn four, hence knocking the pressures up to 85%, but any more and you risk locking up into the Senna Esses and ruining a lap before it has even started. You will also struggle for stopping power in the bumpier parts of the circuit if the pressure is too high.
Move the brake bias back a touch just to help create a little oversteer to get the nose into the corners. There aren't too many tricky braking zones so the compromise in stability under braking that this set up change makes is fine.
The only change we make to the tyre pressures is in the rear, where we take a little air out just to increase surface area and traction. We need the front tyres responsive, but creating big differences in pressure will result in uneven wear so we leave them alone and just drop the rear pressure slightly.
Do not touch the ballast that evens out weight distribution. Moving the ballast forward will increase understeer and reduce traction, with moving it backward having the opposite affect. This is an easy way to make minor adjustments to the setup without playing with the suspension too much. If you are breezing through the middle sector but struggling to keep up down the straights, then shifting the ballast back can help you see if it just a minor adjustment that needs to be made or if your driving style means you should trim more wing and adjust the suspension more.
There it is, our setup for the Brazilian Grand Prix. It is a nicely balanced, and doesn't go too extreme anywhere except for rear camber. It should be a good starting point for new drivers to try to tweak to their own style. See you on the time sheets!