IndyCar mandates new rear suspension components for Indy 500

The NTT IndyCar Series and official chassis partner Dallara have informed its teams of new rear suspension uprights the Italian firm has in production that will become mandatory for all teams to use on ovals starting in April at the Indy Open test, and then in competition beginning at May’s Indianapolis 500.

The redesigned rear uprights, which attach to the suspension A-arms and carry wheel bearings, axles, brakes, and the hubs which spin in the bearing and connect the transmission’s axles to the wheels, are stronger than those currently in use.

The new rear upright, above right, will be mandatory on ovals starting from the Open Test at IMS in May, while the new front retaining nut, above left, will be deployed on all ovals in 2024, and on all tracks from 2025.

The updated design comes in response to the crash last May when Felix Rosenqvist’s Arrow McLaren car struck Kyle Kirkwood’s Andretti Global entry and ripped the hub and wheel assembly from the left-rear upright, which went sailing over the fence at Turn 2.

Following an investigation of the incident by IndyCar and Dallara, the failure was determined to be in the retaining nut that holds the hub within the wheel bearing and upright. A new retaining nut with a larger flange was designed and mandated by the series as a preventative measure.

Further evaluation led to the creation of the new rear uprights, and the call for the same kind of new and larger retaining nuts has been made for the front uprights.

According to the bulletin distributed to the paddock, the new front retaining nuts are required for all ovals in 2024 and all races starting in 2025.