Spa-Francorchamps is one of Formula 1's undisputed legendary circuits. The Belgian track is situated deep in the Ardennes Forest and has a unique microclimate as a result. Therefore, rain is common and you'll have to adapt your dry setup to one that's better suited for wet conditions.
We've got the setup you need to succeed for when the heavens open in F1 2021!
Low aero is usually the way to go in Belgium, as it allows you to overtake through the near flat-out first and final sectors. You'll have to go a little higher to 5 on both the front and rear of the car in the wet though. This is to help prevent understeer and keep the rear tyres planted to the tarmac.
You'll need an open differential to avoid spinning the car round in traction zones in the wet. The transmission should be set to 62% for on-throttle and 55% off throttle. This allows you a good amount of grip, but also keeps the transition to on-throttle a smooth one.
The wet tyres are extremely durable in Spa, so you can go aggressive your toe and camber values. The higher the camber and the lower the toe, the more mechanical grip you get from the tyres, but the higher the tyre wear is also.
We opted for -2.50 for the front camber and -1.60 for the rear. We also went with full left toe, 0.05 on the front and 0.20 on the rear.
With the notable exception of the front springs, your suspension should be fairly middle of the road in Spa for a good compromise. The springs should be set to 1 at the front and 6 on the rear to allow for a smooth ride. The anti-roll bar is best at around 6 on the front and 7 on the rear, as this allows for good direction changes without risks spinning off.
Finally, the ride height needs to be a little higher than usual at 5 on the front and 7 on the rear axle. This is thanks to Spa's massive inclines and declines, particularly that at Eau Rouge. This ride height also allows you to run over the kerbs without fear of spinning off.
There are some massive stops around Spa, so your brake pressure needs to be very high. In the wet, you can't go further than 95% brake pressure though, as you'll be locking the fronts up into the bus stop and Les Combes.
The brake bias is an interesting one, as you need to go more to the front than usual. 59% usually does the trick, but go up even further if you're locking the rears into La Source.
As the gaps between corners and braking zones can be long, your tyre pressures need to be higher than normal. This is to help retain the heat within the rubber between these events. 22.2 psi on the fronts and 23.5 psi on the rears is usually ideal. If you find that your rears are getting too hot though, turn this pressure down.