Toro Rosso Honda had a nightmare end to their Formula 1 Russian Grand Prix as both the cars were forced to retire after just six laps in the race at Sochi.

A strategic induction of fresh Honda engines saw them start from the back of the grid even though they did not use the new spec in the grand prix in Russia. However, it wasn’t a straightforward run for both Pierre Gasly and Brendon Hartley.

The Kiwi pitted early to switch on to the soft tyre and run through the race but he suffered a brake failure after his pit stop at the same time when Gasly also had a spin due to the same problem few corners ahead.

The car was brought in then to retire in a big blow as they are only three points ahead of Sauber. Team principal Franz Tost was confused with the issue on both the cars as they didn’t change anything as it was under parc ferme conditions.

Explaining the issue, Tost revealed that a piston got stuck in the calipers which then overheated the brake fluid to cause the long pedal and the resultant spins for both Gasly and Hartley. Further investigation will continue by Toro Rosso before Suzuka.

“It was a frustrating Sunday for Toro Rosso as both cars had to retire,” he said. “For whatever reason we ended up with very hot front brakes and one piston in the calipers got stuck. This caused the overheating of the brake fluid and a long pedal.

“Therefore, we called the drivers to come to the garage. Obviously, being in Parc Fermé conditions, we didn’t change anything from yesterday, so we need to investigate further what the reason is.

“The positive side of this weekend is Honda’s new upgraded engine which is a big improvement. Now we are focussing on preparing everything for Suzuka where we hopefully will have a much better race.”

Post race, Hartley spilled an interesting note from the race where he was due to run on the soft tyre from Lap 6 until the end of the race as he said his long run pace and degradation was enough for him to see-through the whole race on one set of compound.

“I had a good start and passed Pierre before Turn 5, I was attacking the McLaren when the brake pedal went long,” said Hartley. “I reported it on the radio and then made our planned pit stop.

“We were going to try and be a bit cheeky with the strategy and do almost a full race on the Softs, we had great tyre life and pace and think it would have worked. However, once I left the pits the pedal went completely to the floor, the rears locked and the car spun.”

Meanwhile, his teammate Gasly was involved in another incident where a carbon piece from Red Bull Racing’s Daniel Ricciardo flew into his cockpit under the Halo and hit his visor before he could pick it up and throw it out of the car.