McLaren’s 2026 rear brake duct asymmetry and thermal management

Lando Norris experienced sudden brake temperature increases during the Japanese Grand Prix. A piece of Charles Leclerc’s front wing end plate, which shed after a first lap incident with Max Verstappen, entered the right-front brake duct of the McLaren. This debris caused the brake temperature to rise through the roof, which forced the car into the pits to clean the components. Andreas Seidl stated that the end plate exploded and became trapped in the duct, which ended the points chance for Norris. Leclerc received a 10-second time penalty for running with an unsafe car, which caused him to drop from sixth to seventh place.

The 2026 ban on asymmetric braking torques

The 2026 technical regulations forbid any system or mechanism that produces systematically or intentionally asymmetric braking torques for a given axle. This rule targets torque steer, which allows for a difference in clamping force on each brake disc across an axle. A team could use a one-way flow restrictor to slow the release of brake pressure on one side, which creates drag to help the car rotate. Such a system would help the car during the turn-in phase, especially for ground-effect cars prone to understeer in slow corners. While teams could use lateral force to identify turn direction, the new regulations prevent such asymmetric pressure from being used to manipulate car rotation. The FIA introduced this wording to close a loophole that could allow teams to influence car balance through braking.

Detailed airflow and cooling channel management

Thermal management requires controlling the heat path from the brake discs to the wheel rim and tyres. Brakes often reach temperatures between 600 and 800 degrees Celsius. McLaren utilizes specific flow routes from the brake ducts to manage this. A yellow channel feeds air to the inner side of the brake disc, while a light blue channel feeds air to the low-slung caliper. A dark blue channel feeds air to the outer side of the brake disc. Surrounding these is a green layer of cool air that envelopes the components to minimize heat transfer. Teams attempt to isolate heat from the brake discs and calipers to prevent it from reaching the wheel rims and tyres. This process remains a primary challenge because engineers must use the minimum amount of air to cool the brakes while using as much as possible to cool the rest of the assembly.

Phase change materials and the tyre window

Maintaining tyre temperatures within a 10 to 15 degree Celsius window provides the grip needed for performance. McLaren uses phase change materials in the wheel drums to act as thermal buffers. These materials absorb thermal energy when they change state from solid to liquid. As the material reaches its melting point, it absorbs heat without the material itself increasing in temperature. This allows teams to select specific transition temperatures, such as 80 degrees Celsius or 120 degrees Celsius, to suit different compounds. When the brakes cool, the material solidifies and releases the stored heat. If you are a racing driver, you know that getting this window wrong results in sliding or a lack of grip. This technology acts as a magic temperature sponge to prevent excessive heat from reaching the rubber.

MGU-K, weight, and energy depletion

The 2026 MGU-K provides 350kW of power, which is three times the power of the previous generation. This increased power makes traction loss more severe. Drivers must conserve electrical power to avoid clipping, where the battery depletes and the power cuts out. When clipping occurs, the car must exit low-drag X mode and transition to high-drag Z mode to conserve energy. At the 2026 Australian Grand Prix, Lando Norris experienced this clipping, which caused him to lose 0.9 seconds per lap compared to George Russell. The increased mass of the 2026 cars also requires more electrical power from the MGU-K, which exacerbates battery drainage and forces the car to exit low-drag modes earlier than intended during the race.

Drivetrain vibrations and pressure imbalances

Effective cooling depends on creating a low pressure exit to pull airflow through the system. McLaren has previously faced issues where pressure within the duct exceeded the inflow, which caused the system to stall or reverse flow. To prevent this, teams use sensors to monitor outer airflow. This ensures that hot air exits the brakes rather than staying inside. Additionally, teams must manage drivetrain vibrations. Aston Martin reported issues where the Energy Store (ES) and Control Electronics (CE) butt up against the Internal Combustion Engine (ICE). This proximity allows vibrations to transmit through the chassis, which potentially affects the gearbox or half-shafts.

Technical specifications of the power unit

The 2026 power units utilize a 1.6 litre six-cylinder engine with a 90 degree vee angle. The internal combustion engine uses high-pressure direct injection with a maximum of 350 bar. A single-stage compressor and exhaust turbine operate on a common shaft, with the exhaust turbine reaching 150,000rpm. The energy recovery system uses a crankshaft coupled electrical MGU-K to provide 350kW of power. The lithium-ion battery solution has a minimum regulation weight of 35kg. This system allows for a maximum energy storage of 4 MJ per lap and a maximum energy recovery and deployment of 9MJ per lap. These systems must work together to prevent the clipping issues that hinder performance on long straights.

The verdict on McLaren’s thermal strategy

The McLaren cooling strategy relies on managing heat flux through advanced airflow channels and phase change materials to keep tyres in the optimal temperature window. While the 2026 asymmetric braking ban prevents the use of torque steer to aid rotation, the team’s focus on thermal isolation remains a significant advantage. The effectiveness of these systems depends on the car’s ability to manage energy deployment and avoid the heavy drag of Z mode during MGU-K clipping. Will the FIA eventually scrutinize the use of phase change materials as a form of active thermal management?