Rain can fall quick and hard at Spa and will ruin your race weekend if you aren't prepared for the changing conditions.
The parc fermé rules mean that once qualifying starts you can only change a few parts of your setup, so keeping an eye on the weather forecast for the race is key to deciding which setup to use, but if the rain is pouring all weekend then don't worry, we have a setup for you.
The Beligian Grand Prix, held at the wonderful Spa-Francorchamps circuit, can often fall foul of the weather despite being held in August, and online races love to throw rain at you, which can ruin your ranking if you aren't ready.
So how should you set up your car for when the rain pours at Spa?
This setup is radically different from our dry one for Spa. When the rain comes down a lot of the flatout sections become tricky, and the racing line moves a lot. You go from leaning on mechanical grip to requiring a lot more aerodynamic performance.
We have gone with a 6-8 setting here to provide a lot more bite and stability. This is needed through corners like Eau Rouge and Pouhon that become a lot more challenging in the wet. This setting keeps you competitive up the Kemmel straight and the run through the final sector too.
Unlocking the differential is vital to stability in the wet. It stops a singular puddle from throwing you off, and the grip difference between wet asphalt and wet kerb/grass is even more stark and dangerous.
As a result we have fully unlocked the on-throttle differential to 50% to allow the rear tyres to rotate more independently as grip levels change.
The off-throttle differential is set at 70% which keeps the rears relatively close as you brake, making it more stable when you do put your foot on the loud pedal again.
Thanks to the rain we don't really have to worry about tyres overheating. With Spa not testing the rubber too much anyway we can go to the most optimum geometry setting. That is a front camber of -2.50, a rear camber of -1.00, a front toe of 0.05 and a rear toe of 0.20.
This keeps cornering performance high, crucial in the middle sector, and with the long straights you can cool off the rubber. This will massively increase wear when the rain stops though, so be ready to change tyres quickly.
The suspension settings are always key to overall performance. Here we have gone with a 2-2 setting as we should be avoiding the kerbs a little in the rain and the slightly stiffer springs than normal do help with aerodynamic stability.
The anti-roll bars are set to 4-5. This keeps the rear more responsive and stops it rolling out on you as you put the power down.
Ride height is set to 8-11. This is perhaps the most dramatic change due to the weather. More ground clearance allows you to clear water better, but also means you can create an even bigger rake which makes the front end more responsive. If you have a race that is expected to see dry tyre use at some point then reducing the ride height is the best way to compromise.
The temptation is always to up the stopping power in the rain, but you shouldn't. You need to feather the brake pedal more in the rain, and squeeze them a touch between corners where you wouldn't normally. As a result, the best brake pressure around Spa is 84%.
Brake bias is set to 56%. This keeps the front responsive when on the brake pedal, but it is moveable during the race so you can find which one suits you. When making a pass you will absolutely want to move it forward a bit.
Tyre pressures directly impact contact patch with the tarmac. We have left the fronts at 23.0 psi to allow them to cut through the water and keep the car settled. The rears are at 21.1 psi to aid traction. Any lower and the temperatures risk dropping so much that the rubber doesn't do its job properly.
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So that's our setup for a wet Belgian Grand Prix. Racing in the rain is always tricky but this setup provides consistency and stability. It is one that you can grow in confidence with and feel relatively secure in. The circuit does bite more in the rain, especially Eau Rouge/Raidillon, but plotting your way around is a lot easier with this dedicated wet setup.