Pull-rod gamble pays off for Ferrari: aerodynamics and mechanics improve, according to Haas technical director

With the exception of Williams, Scuderia Ferrari remained the only one to bet on the pull-rod scheme for the rear suspension, consequently affecting its client team, Haas. The presentation of the SF-24 had raised some skepticism among the audience, surprised not to see the Scuderia conforming to the now-dominant push-rod suspension, considered better in terms of aerodynamic interaction with the underbody side pods. However, in continuing with the pull-rod suspension, Ferrari did not just employ the pull-rod of past seasons but rather developed a new concept. What initially appeared as a conservative choice now seems to be a step forward from the past, noticed also by the client team Haas.

Tighter gearbox
The Italian-American team buys both the front and rear suspension from Ferrari, as well as the gearbox around which it is built. Interviewed by Racecar Engineering magazine, Haas’s new Technical Director Andrea De Zordo spoke about the new rear end developed in Maranello: “It’s much tighter at the bottom. It gives you more freedom in designing the diffuser. It’s also better for all the aerodynamic appendages around the brake ducts.”

From the outside, it’s noticeable how the suspension rod has been moved back compared to 2023, indicating a different housing for the internal spring-damper unit, as well as a different aerodynamic interaction with the flows collected by the underbody side pods. According to De Zordo, however, the most important change is hidden in the lower part of the car. The transmission has been further streamlined, offering the team more freedom to shape the diffuser ramp, thus ensuring direct aerodynamic benefits from the floor.

The rearrangement of the external arms also defines a different kinematics of the suspension, but not only that. Moving the attachment points on the wheel side benefits the aerodynamics of the flaps and deflectors attached to the brake cooling ducts. In addition to increasing local aerodynamic load, the change improves the management of local vortices, exploited to enhance the efficiency of the diffuser, once again benefiting the car’s aerodynamics.

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Optimal compromise
According to Andrea De Zordo, the new Ferrari rear end ensures aerodynamic benefits without sacrificing improvements in the kinematics of the suspension, i.e., its purely mechanical behavior. “In terms of how it works mechanically, it takes into account the behavior of the suspension more,” explains the Technical Director. “You can get something more from the aerodynamics, but at the same time also from the mechanics. It’s all welcome.”

At the presentation of the SF-24, Ferrari Technical Director Enrico Cardile explained how updating the pull-rod scheme compared to a push-rod suspension ensured a better overall balance between aerodynamics and mechanics: “We have seen good aerodynamic results moving in this direction. Switching from pull-rod to push-rod, on the other hand, we did not notice advantages enough to justify the compromise in terms of weight and compliance.”

In addition to the external innovations, changes in Ferrari and Haas also include the layout of the internal spring-damper unit, completing a deep restructuring. “The mechanics of the rear suspension are located differently inside the transmission box,” Enrico Cardile pointed out. “It’s a new concept, for us it’s an innovation, because it’s a different way of managing the suspension compared to what was done in the past.”