Haas appear unlikely to complete their brake manufacturer switch ahead of this weekend's Russian Grand Prix.

After complaining throughout 2016 and now into 2017 about the feeling from his Brembo-supplied brakes, Romain Grosjean got to try the equipment of rival manufacturer Carbon Industries at the recent Bahrain test.

It is believed that Haas have been reluctant to make the switch before now, because Brembo is a long-time and trusted partner of the American team's technical partner Ferrari.

"They feel very similar," Grosjean said of the Brembo versus Carbon Industries comparison, according to Auto Motor und Sport.

"But we can see from the telemetry that a few things are already working better. They behave more in the way I like at the end of the braking process."

At the same time, the Frenchman admitted that Brembo has been making recent progress.

"There was an update in China," he said, "and since then it has worked better. We had to wait a year and half to get it."

Switching to Carbon Industries would not be simple for Haas. It is not just the braking material that changes, but also the surrounding equipment and then tuning the complex brake-by-wire and MGU-K integration.

Grosjean admitted: "We should be completely sure that we are improving.

"We cannot sacrifice practice sessions to continue working on brakes."

Brakes aside, Haas are having a good second season to date, even if the high points finishes are not yet consistently flowing.

"Renault is faster than us in qualifying," said Grosjean, "but we have the better race pace."

Haas are currently seventh in the constructors' standings with eight points.