McLaren had a significant upgrade fitted to its car in Barcelona, featuring a new floor and subtly different front wing. The outer end of the wing’s mainplane has been raised slightly, giving a greater ‘throat’ area beneath, while the gap between the mainplane and the first flap has been widened. Both these changes suggest McLaren is seeking to make the car less pitch-sensitive. With the previous smaller throat area, the gap between the wing’s underside and the ground at that outboard end would be very small as the car dives under braking, enough to generate significant ground effect. As the surface gets closer to the ground the downforce increases exponentially. If this ramp-up on downforce is too sudden it can make the car nervous and induce rear instability.
This is generally a more likely problem to encounter with the 2021 generation of cars because of the reduced rear downforce from the trimmed floor and other aero restrictions at the rear around the diffuser and brake ducts. One of the rebalancing processes that teams are going through is to make the front downforce less aggressive as the car dives, simply because the rear can no longer withstand such sudden increases in load.
Ideally, they would wish to retain the extra front downforce by boosting that at the rear – but this is a long process. McLaren’s new floor is part of that process. This means the team has joined the ‘Z-floor’ club, popularised by Mercedes and Aston Martin with the 2021 cars. With McLaren now adopting it, only Alfa-Romeo and Haas remain with what was the conventional diagonal floor edge.