Haas tried Carbone Industrie (CI) material in free practice ahead of the Russian Grand Prix, following a successful post-Bahrain GP test, but reverted to Brembo after struggling to cool the CI brakes sufficiently at the Sochi circuit.

The American team planned post-race wind tunnel tests to find solutions for the disc cooling problems it suffered with CI brakes in Russia, but team boss Gunther Steiner said "as things stand" Haas would stick with Brembo brakes for the forthcoming Spanish GP.

"To figure out how we can fix the problem will take a bit, but we will get there," said Steiner. "It isn't an easy problem to solve. Everybody needs to understand that this is a very sophisticated brake system.

"We know what we've got after our Bahrain test with CI brakes, and after Sochi in FP1 and FP2, [but] as it stands now we will race Brembo in Barcelona.

"Romain [Grosjean] was pretty happy with the latest iteration of Brembo; Kevin [Magnussen] liked the CI better because the bite is better - he just has a better feeling with the CI brakes.

"Now we need to get the CI working and see where we stand before coming to the absolute conclusion. I'll be happy when we can check this off our list."

Grosjean complained regularly about the inadequacies of the Brembo brakes on the Haas car throughout last season, and Steiner says the lack of in-season testing in modern Formula 1, coupled with the complexity of the braking systems on current F1 cars, means finding a final resolution is taking much longer than expected.

"The obvious question, and rightly people ask, is that it cannot be this difficult to fix a brake," Steiner added. "It actually is. It isn't easy. This is because they're highly complicated technologies.

"When you change from one to the other, you encounter issues you're not aware of until you try it properly.

"Without testing during the season, you need to do it in FP1 and FP2 - you always have to wait two weeks to do something, so you can never go and do a proper test and do modifications.

"It compromises your testing, and that's why it takes so long. It's not that we're not working hard. Our people are very competent and can do this, it just takes time."