The 2026 F1 rulebook promises cleaner power, lighter cars, and a big push toward electrification. But in the garages, engineers are already concerned about something important: braking.
With the removal of the MGU-H and the heavy reliance on the MGU-K, the way F1 cars slow down is about to change, and some teams are worried that what looks clever in theory could become tricky in practice.
Engine Braking Is About to Change in F1
In modern F1, when a driver lifts off the throttle and hits the brake pedal, the car slows through a combination of mechanical braking and electrical harvesting as the hybrid system recovers energy, with the traditional brake discs taking over the rest.
From 2026, the MGU-K will take center stage, and with the MGU-H gone, all energy recovery will come from braking, and the MGU-K will be responsible for harvesting up to 350 kW of power, which is roughly 475 horsepower during braking.
That is a massive amount of stopping power handled electrically. However, there is a catch: if the MGU-K is doing most of the work, the rear mechanical brakes are doing less, and brakes that are not used enough tend to cool down, which can be very dangerous.
In 2026, the batteries will also be bigger as teams will be able to recover up to 8.5 megajoules per lap, with a total state of charge window of 4 megajoules. That means the cars will be constantly charging and discharging. Under medium and light braking zones, the MGU-K alone may be enough to slow the vehicle.
That sounds fine until the driver arrives at a heavy braking zone, and if the discs are cold, the response can be poor. In the worst-case scenario, mistakes can occur.
This is where engine braking becomes a balancing act, as the brake-by-wire system must determine how much braking is performed electronically and how much is accomplished mechanically. The goal will be to keep the rear brakes in a safe temperature window, even if the MGU-K could handle most of the deceleration.
The Delicate Balance F1 Teams Must Find
Much of this will be determined by software, as the electronics must balance the battery state, temperature limits, driver input, and track layout. Additionally, if the battery is full, the MGU-K cannot harvest any more energy. In that case, the mechanical brakes must take over. If the battery is empty, the system will try to recover as much as possible.
Teams will also have to consider circuits as tracks with many medium-speed corners, where braking demands are lower; the MGU-K could handle most of the work. However, when a big stoppage arrives, the driver may not get the response they expect.
To counter this, teams may choose to use the mechanical brakes more than strictly necessary, simply to maintain temperature balance in the system, which is not ideal for energy recovery, but it may be safer.
This is why some F1 engineers believe that the most significant gains in 2026 will not only come from engines or aerodynamics, but also from how well teams manage this energy and braking challenge. A team that can keep its brakes in the right window while still harvesting maximum energy will have a clear advantage.
There is also the human side as drivers rely on feel. If the brake pedal response changes lap to lap because the system is switching between electric and mechanical braking, confidence can suffer.
The new rules are opening a fresh chapter for F1, bringing new challenges along with them. How teams handle this hidden brake issue will be one of the more interesting stories to watch as the season gets closer.