Any setup for Spa is a compromise between downforce in the 2nd sector and drag in the first and third sectors. This issue is only exacerbated in the rain, as the slippery track calls for higher levels of downforce.
To get the right balance between these two aims, run 3-7 for your front and rear wings respectively.
This will give you plenty of grip through the twists and turns of sector two, and also good rear-end stability in the traction zones.
Getting the aforementioned traction zones right at Spa is crucial to achieving a good lap time.
Another way to help you to nail your acceleration is to run 50% on-throttle differential. This will ensure that the rear of the car doesn’t get too twitch when you lay the power down.
For the off-throttle setting, 60% is what I recommend. This gives you plenty of rotation for the slower corners with bringing on mid-corner instability.
Much like with the wings, finding the right camber settings is a balancing act.
Running a front camber of -2.80 with a rear camber of -1.30 give your car great performance through the higher speed corners while also keeping it planted in such situations.
Going with the minimum toe settings of 0.05 and 0.20 is what I usually recommend, and there’s not reason to do otherwise here. Running low toe helps with the longer corners of the track without any major downside.
For the suspension itself, a softer setup tends to be well suited for the rainy conditions, as it helps your car to deal with the unpredictable track surface.
Therefore, I suggest using 1-3 for your suspension stiffness settings.
The anti-roll bars are another matter. Here, the wet conditions actually require a stiffer setup to prevent the car from sliding. 7-10 works nicely for me.
For the ride height, going up high is best for the rain as it helps to keep the car stable. 8-10 is the lowest I have been able to go without the car beginning to complain.
Everyone has their own preferences when it comes to their braking setups. For me, I like 100% brake pressure and 50% brake bias at pretty much every track.
If you have issues with front locking, running a lower brake pressure is the way to go.
It is always a good idea to run low tyre pressures in the wet conditions.
For your front tyres, I would go with 21.8psi, with 19.5psi for the rears. The low pressure for the rears is especially helpful as it gives you much better traction than a pumped-up tyre would.
A wet race in Spa is a classic test of a Formula 1 driver. Many legends have tried and got it wrong. With this setup, you’ll have the best chance of getting it right instead.