Toyota's Process for Manufacturing the GR Corolla and GR Yaris

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【Summary】Toyota's performance and motorsports division, Gazoo Racing, has implemented unique manufacturing methods to produce the GR Corolla and GR Yaris. The assembly line at the Motomachi factory in Japan is designed to minimize uneven loads on the suspension bushings, improving chassis adjustments. The GR Corolla, with all-wheel drive and a 300-hp turbo inline-three, is a larger version of the GR Yaris, which is the basis for Gazoo's WRC race car.

FutureCar Staff    Nov 05, 2023 5:16 AM PT
Toyota's Process for Manufacturing the GR Corolla and GR Yaris

In the November 2023 issue of Car and Driver, it was reported that Toyota's factory in Motomachi, Japan, has a unique procedure for producing the GR Corolla and GR Yaris. These high-performance hatchbacks are redirected onto a turntable, eliminating the need to turn their steering wheels. This procedure helps minimize uneven loads on the suspension bushings, improving the precision of final chassis adjustments. It is impressive to see such attention to detail from a major manufacturer for these racing-inspired driver's cars.

The GR Corolla, introduced in the 2023 model year, was created by Toyota's performance and motorsports division, Gazoo Racing. With all-wheel drive, a 300-hp turbo inline-three engine, and a close-ratio six-speed manual transmission, this sport compact is a larger version of the GR Yaris, which is used in the World Rally Championship. The GR Corolla has received critical acclaim and earned a 10Best award, solidifying its position as one of Toyota's best performance machines. Both the GR Corolla and GR Yaris are produced at the same facility that previously built the Lexus LFA.

The Gazoo Racing factory has a daily output of only 49 GR Corollas, eight GR Yarises, and four track-focused GRMN Yaris models. This low-volume operation requires a high level of specialization. The GR workstations are arranged in semipermanent cells, combining multiple production steps into one. Electric power tools are used instead of compressed air to lift and locate heavier subassemblies, reducing costs and complexity. Autonomous tugs help shuttle partial vehicles from station to station, replacing bulky conveyor systems. Workers manually check the machines' output and push body shells around on dollies.

The structure of the GR Corolla is reinforced with additional adhesive and spot welds compared to its mass-produced siblings. The body shell is assembled on a single jig, which tightens its tolerances. The suspension mounting points are scanned and measured, allowing individual components to be matched with complementary variances. This attention to detail is influenced by Gazoo's race car construction methods. Toyota's chairman, Akio Toyoda, has emphasized the importance of making GR models fit for the racetrack right off the showroom floor.

The development of the GR Corolla involved engineers functioning as a race team, overcoming challenges together and accelerating the process. The goal was to create a car that not only performs well but also brings joy to the driver. The chassis components of the GR Corolla are carefully measured and matched for optimal balance. The brake calipers are tested for efficiency and paired up accordingly. The alignment of bolt holes and wheel-angle variances are more precise compared to regular Toyota models.

The GR Corolla's refinement process included testing at Toyota's proving ground outside Nagoya. The facility's handling course helped the GR team fine-tune the car's performance. The chassis was further improved, and more power was squeezed out of the turbocharged 1.6-liter three-cylinder engine. The production process for the GR Corolla involves combining the working bits with the painted bodies. Unlike regular models, the GR models have their bodies lowered onto stationary underpinnings, creating a stronger connection and reducing stresses on the car's skeletons.

Gazoo Racing plans to continue building future GR models with the same level of attention to detail. Former GR boss Koji Sato, who is now Toyota's CEO, ensures that the GR ethos will be upheld. The GR Corolla will also continue to be developed, with feedback from racers being analyzed. Gazoo Racing will offer aftermarket performance parts and support its cars throughout their life cycles. While electric models may join the GR lineup in the future, they present challenges in terms of developing their driving characteristics.

The term "Gazoo" originated from a photo-centric Toyota used-car website in the 1990s. It has evolved to mean "garage," representing a place where engineers focus on a car's details.

The assembled GR Corollas undergo rigorous verification steps inspired by motorsports. Weighted bags are added to simulate passengers and fuel, ensuring accurate steering feel. Rear-axle alignment is checked and adjusted before making any tweaks to the front end. The brake pedal is verified for pressure and progression, followed by additional chassis and suspension measurements. If any figures fall out of tolerance, new components are fitted, and the finishing process starts again. Only after passing these tests is a car taken for a test drive and prepared for shipping.

The GR Corolla is not only a dream car for many but also a testament to the teachings of the Gazoo team. Toyota engineers have learned to push the limits and break cars during development, thanks to the perspective change brought about by Akio Toyoda. The result is the GR Corolla and GR Yaris, which embody the spirit of carbuilding.

In terms of the engine, the GR Corolla and GR Yaris are powered by a turbocharged three-cylinder engine that produces 300 horsepower and 295 pound-feet of torque. The engine is assembled with performance-focused attention, including matching the cast-aluminum pistons by weight. This 1.6-liter three-cylinder was chosen for its favorable torque curve and reduced exhaust back pressure compared to an inline-four. It is eligible for the WRC2 class, and a Rally2-spec customer race car is currently being developed.

The Toyota Technical Center Shimoyama played a significant role in the development of the GR Corolla. This facility, located near Toyota City, features various test tracks, including a country-road handling course inspired by the Nürburgring Nordschleife. The course is challenging, with elevation changes and sharp corners, allowing chassis engineers to fine-tune the car's performance. Safety measures, such as towering catch fences, are in place to protect drivers and the surrounding environment.

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