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Toyota Introduces New Diff Hardware in “Major Change”

Toyota “jumping in the unknown” with new differential hardware starting at Monza..

Photo: Toyota Gazoo Racing

Toyota has installed new differentials in its LMH cars ahead of the 6 Hours of Monza, in what is a “major change” according to the manufacturer’s technical head Pascal Vasselon.

Coinciding with the debut of the Peugeot 9X8, the pair of four-wheel-drive Toyota GR010 Hybrids are running with completely new differential hardware for the rest of the FIA World Endurance Championship season.

Vasselon said that Toyota only briefly tested the fresh components before last month’s 24 Hours of Le Mans, giving the Monza event an air of “jumping in the unknown”.

Sportscar365 understands that Toyota, the FIA and ACO agreed at the start of the year to run the new differentials when Peugeot arrived, to assess how they work ahead of their mandatory use next season as part of the balancing act between LMH and LMDh.

The Toyota GR010 Hybrids have previously competed with mechanical locking differentials, but they have been replaced with open differentials as required in the terms for LMH-LMDh convergence that were announced one year ago on Saturday.

A differential stabilizes the wheels on either side of a car when they are rotating at different speeds, for example when braking for a corner.

In March, ACO competition director Thierry Bouvet explained that the differential values should be the same for both four-wheel-drive and rear-wheel-drive cars.

Toyota views its change as a performance hit as the four-wheel-drive nature of its car, which can only use its front-mounted electric motor at 190 km/h, is further constrained.

“For the first time, we are running different differentials,” Vasselon told Sportscar365.

“For us and for Peugeot, the differential regulation is changing here. It means that, on top of the BoP adjustment, there is another major change or hit for us.

“It’s that we cannot run the differentials we had before. We now have to run differentials with much less torque transfer.

“This is to anticipate the convergence with LMDh next year, to somehow make four-wheel-drive cars two-wheel-drive cars.”

Toyota, which is returning to action after claiming its fifth consecutive 24 Hours of Le Mans win last month, expects the differential change to give newcomer Peugeot an advantage in one department at Monza.

It is understood that Peugeot has been running with the open differential technology for most of its track testing program, whereas Toyota only just getting started.

“We have very shortly tested them and we need to discover quite a lot of things,” Vasselon said, declining to specify where the test with the new system took place.

“Here it’s clearly one area where Peugeot are probably ahead of us. We have known since a long time that we had to race with the other hardware.

“Peugeot have been testing in the last months with this configuration.

“So we could say that we are on the back foot compared to Peugeot because we have to set up the car and the controls with this new situation.”

Vasselon explained that the installation of a new differential has required other adjustments in the GR010 Hybrid to ensure the car does not encounter any problems.

“On top of that, we have to respect very hard limits… the hardware will give you some things that can be quite noisy,” he said.

“We have the change of hardware, which will reduce the torque transfer left to right, and on top of that we need to add controls to the front motor to ensure that we don’t have issues.

“Here the change is quite big: a change of hardware front and rear, change of controls and change of regulation.

“For us, it’s a major change on top of the power and weight adjustments which are not very big.”

In the Hypercar BoP for Monza, Toyota has been handed a 7 kW power increase and a 1 kg weight increase, bringing its cars to 513 kW (688 hp) and 1071 kg respectively.

Daniel Lloyd is a UK-based reporter for Sportscar365, covering the FIA World Endurance Championship, Fanatec GT World Challenge Europe powered by AWS and the IMSA WeatherTech SportsCar Championship, among other series.

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