Aston Martin has got to the bottom of its troubled Brazilian Grand Prix that left Lance Stroll out on the formation lap and Fernando Alonso battling extreme bouncing.
The Silverstone-based team endured a hugely challenging race afternoon at Interlagos as Stroll spun into the wall on the formation lap after his rears unexpectedly locked, before he managed to beach himself in the gravel.
Then Alonso struggled throughout with similar rear locking issues plus excessive porpoising that left him struggling with back pain at the end, but he was determined to push on and see the chequered flag.
Speaking on the team radio at the time, Alonso, who finished 14th, admitted that something unusual was happening. “This bouncing is not normal,” he said.
With no immediate explanation for what happened on both cars, Aston Martin has spent some time since returning to its factory trying to get a better comprehension of the factors at play.
It now suspects that the problems on both cars were triggered by a super nervous rear-end characteristic that had been introduced as a result of car changes made following the qualifying crashes the team suffered on Sunday morning.
Both Stroll and Alonso had hit the barriers in the wet qualifying session, damaging the Suzuka-concept specification floors the team had intended to run for the Interlagos event.
With no spares of that specification available, Aston Martin had to revert to a previous floor version – which was the one it first introduced at the Hungarian GP.
Normally teams cannot change specs between qualifying and the race, as that is a breach of parc ferme regulations and mandates a pitlane start.
However, things are different on a sprint race weekend when allowances are made if there is a shortage of spare parts.
Article 40.4 says at sprint weekends teams can change specification if they can “demonstrate there is a shortage of parts, and provided that the replacement part is of a specification that has been previously used in a qualifying session or a race".
It was this rule that Mercedes used at the United States GP to allow George Russell to go back to an older specification of floor following his qualifying crash.
The complication for Aston Martin, however, was that the change of floor had to be made without it being able to alter the mechanical set-up around it – as suspension settings are totally fixed in parc ferme.
So on a weekend where teams were battling the problems of excessive bumps on the Interlagos track, plus tricky weather conditions, the end result was a car whose aero platform and mechanical settings did not match up.
Speaking about what Aston Martin has found out since Brazil, team principal Mike Krack thinks a combination of elements came together to leave both its drivers with a car that was ultra nervous.
“It was clear that both drivers were battling a car that was incredibly difficult to drive during Sunday's race," he said. "Our post-weekend analysis has highlighted several factors that explain this.
“Following both car’s accidents in qualifying, we had to replace a lot of components with a different specification due to availabilities at the end of a triple-header. This is allowed by the Sprint Event regulations, and you declare your shortages and replacement options to the FIA before the event.
“[But] you aren’t allowed to change the mechanical set-up of the cars. This meant we could neither check nor adjust the set-up of the cars, which negatively affected aerodynamic behaviour and performance.
“Add in treacherous wet conditions, along with an incredibly bumpy track, and you begin to understand that both drivers had the odds stacked against them.
“Both cars were highly susceptible to wheel-locking, and we can see in the data that this is what caused the issues for both Lance and Fernando."
Aston Martin has been experimenting with its floor choices in recent races, with an upgrade it delivered for Austin not delivering the step forward hoped for.
It reverted to the Suzuka spec from Mexico, and may commit to the Budapest version for the next high-speed races in Las Vegas and Qatar.
