A new brake package developed by Spark for Formula E’s second season has been shelved, according to the company’s head of engineering, Theo Gouzin. The Frenchman also confirmed to Current E that most of the rear suspension is open to manufacturers, including wishbones, dampers and springs.

“As you know, we did some testing for the brake package, changing the specification of the discs to maintain heat,” Gouzin told Current E today, in the build up to the Moscow race.

All 40 Spark-Renault cars run carbon fibre discs without shrouds, which can make it difficult for drivers to get them up to the temperatures required to work properly at the Formula E street circuits.

Braking is also provided when the cars capture energy through a process known as regenerative braking, which means the interaction between the powertrain and the mechanical brakes can be complex and can require a lot of fiddling with throughout the race by the drivers.

While Spark has developed a solution that it believes will work well for all teams, cost has now ruled it out. “It was a bit expensive so we had to withdraw this proposal,” says Gouzin. “We’ll test another disc in two weeks’ time. We’re still pushing to develop an improved specification for season two. Development for the second season is mainly about brakes, although we’ve also changed the driver seat bulkhead to make it a little more rigid, at the request of the teams. The suspension is sorted.”

To test season two powertrains, manufacturers have each bought a fifth chassis from Spark, built to the same specification as the cars on track (with the exception of some of the uprated suspension components).

“We delivered them at the beginning of May,” says Gauzin. “We supplied everyone at the same time, and with complete body and battery. The car has the new lower wishbones but not the upper ones, so it’s a sort of hybrid, but it will never race. Teams are allowed to use them until 1 Aug, and then from 1 Jan to 1 Aug next year to develop the powertrain for season three.”

Season two manufacturers have free reign to change the rear suspension, Gauzin explains: “Some manufacturers will have one motor, some will have two motors, so they will need different suspension components. If you are Sauber and you purchase a Ferrari engine, you will not have a Mercedes suspension. So those guys can change almost everything, including wishbones, dampers and springs. They have to carry over the uprights and associated parts, such as the wheel hub and, of course, brakes.”