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Developers driven by harsh reviews from professional drivers.

In fact, the GR-DAT, which is installed in the GR Yaris and GR Corolla, was developed focusing on an ultra-fast shift speed and a direct feel based on the 8-speed AT so that it can also be used in motorsport.

The GR-DAT no longer works quietly in the background. It orchestrates its own driving. The development team’s commitment is evident in every aspect of the product.

While the traditional AT development approach focused on the performance, such as smoothness (reduced shift shock) and fuel efficiency (improved transmission efficiency), the development concept for the GR-DAT was “an AT that stands toe-to-toe with an MT.”

Mr. Masanori Manabe (left in the photo), Project Manager, 1st Group, Design Section 1, T/M Engineering Department, talks about the ideas realized in the GR-DAT. During the visit, the author was also able to interview Mr. Tsutomu Suga (right in the photo), Chief of the group, and Mr. Shinji Sawaguchi (center in the photo), Team Leader, 1st Group, 2nd Casing Design Section, Component Engineering Department

That is, the AT must be operable at will, at a level equivalent to that of an MT, and must be durable and reliable to withstand even more severe motorsport conditions.

The key to sporty driving is responsiveness at the driver’s command. Toughness is also required to withstand continuous driving under extreme conditions. The GR-DAT was developed as a transmission to win in races, breaking away from conventional wisdom of ATs focused on smoothness and fuel efficiency.

Various media outlets have reported that the GR Yaris has been developed using unconventional techniques and technologies.

Yamamoto: You sometimes defy the conventional approach and take a disruptive move to undertake custom development when existing products do not meet expectations. What approach did you take for the GR-DAT?

Mr. Masanori Manabe, Chief Engineer of Group 1, T/M Design Office 1, T/M Technology Dept., Powertrain Products Headquarters, AISIN Product Development Center, said:

The development team members showed a mix of confidence and humility on their faces. They talked about next-generation ATs with AISIN’s legacy at heart.

Mr. Manabe: Actually, we did not make major changes to the hardware. Given our track record, we were confident in terms of durability and reliability.

The development team had absolute confidence in the durability of the baseline hardware. However, there were many challenges in adapting it for sporty driving.

Meanwhile, the development team received mixed feedback regarding the competitiveness of the performance versus an MT. In the early stage of development, they asked professional drivers to drive a test car equipped with an unmodified DAT. There were harsh reviews for the long shift time, lack of a direct feel, and a wide gear ratio range, which prioritized fuel efficiency.

Control at will:　What is the mechanism behind the highly responsive shifting?

Yamamoto: What technologies did you incorporate in response to such harsh reviews?

Mr. Manabe: Regarding shift responsiveness, we used quick‑response, compact linear solenoids to minimize the lag from the input of electrical signals (shift action) to hydraulic control. The design also aimed to minimize the piston stroke to disengage and engage the clutch after hydraulic pressure is applied. As a result, the GR-DAT achieves world-class shifting performance for an AT, with the shift responsiveness improved by more than 50% compared to conventional models.

The vertically stacked cylindrical objects in the center of the photo are quick‑response, compact linear solenoids. They enable crisp shifting with the shift time reduced by more than 50% compared to conventional ATs.

Yamamoto: What about the direct feel, which is a crucial factor in sporty driving?　There were some ATs that highlighted such feature, but the performance was not necessarily satisfactory for ATs.

Mr. Manabe: In conventional ATs, the torque converter is locked up (namely, directly connected) in almost the entire range, except when starting. In the GR-DAT, the torque converter damper has been reinforced to further expand the lock-up range, achieving a direct feel similar to that of MT cars.

Yamamoto: What about the wide gear ratio range, which professional drivers found unfavorable?

Mr. Manabe: While MTs are 6-speed, the GR-DAT is an 8-speed. By taking full advantage of this feature, the gear ratios are kept closely spaced to constantly keep the engine in the power band.

This minimizes the drop in engine speed during shifts, enabling continuous acceleration and reducing a drop in torque after an upshift. Acceleration is possible with a sharp response from any speed range.

Obviously, the close-ratio setup increases the shift frequency, but the strength is optimized to prevent gear breakage and wear even under frequent hard acceleration and deceleration by incorporating AISIN’s expertise.

The GR-DAT is an 8-speed, surpassing 6-speed MTs. The increase in the number of gears is the key to the sharp response while keeping the engine in the power band.

Yamamoto: Fully automatic gear shifting in the D range is one of the features of the GR-DAT. It goes beyond mere automatic gear shifting. Control logic is incorporated to anticipate the driver’s intentions. What are your thoughts on this?

Mr. Manabe: Toyota is in charge of software. We are confident that the GR-DAT faithfully reproduces the complex and elaborate control logic and that the hardware executes the driver’s intended actions. AISIN’s strength lies in its ability to further advance its proprietary hardware technology and deliver value in line with increasingly sophisticated software.

Designed to withstand heat without compromise. Reintroduction of the traditional 100% inspection

Here, Mr. Shinji Sawaguchi, Group 1 Team Leader of Casing Design Office 2, Component Engineering Dept., Elemental Products Headquarters, and Mr. Tsutomu Suga, Chief of the same group with which Mr. Masanori Manabe (Chief Engineer) is affiliated, answer questions.

Yamamoto: I imagine that the thermal conditions are extremely severe due to the improved shift responsiveness and a close-ratio gear setup. What measures did you implement?

Mr. Sawaguchi: First, the friction material (clutch plate) was redesigned to be highly heat-resistant. In addition, a cooling fin was newly added to the bottom of the transmission case. The structure is designed to dissipate heat by actively utilizing the airflow generated while driving. In addition, two ATF coolers are installed to reduce the rise in oil temperature even at low speeds and under high load.

Cooling performance has been improved by installing two ATF coolers. This sports-car-specific design prioritizes maintaining performance over fuel efficiency.

That is, the structure and configuration prioritize dissipating heat and maintaining performance over fuel efficiency.

That said, the team encountered significant heat-related issues during development. I also experienced such issues when I previously had opportunities to drive a test car under development.

The GR-DAT was developed for extreme conditions, including rally environments where the shifting is harsh and the transmission recieves less airflow while driving. Rigorous evaluation patterns far exceeding the standard were introduced. Professional drivers conducted real-world driving tests by pushing the car to its limits to thoroughly address weaknesses and enhance reliability.

 Yamamoto: AISIN is committed to quality for all its products. Are there any initiatives specific to the GR-DAT?

 Mr. Suga: We implement tighter control over variations during assembly. The GR-DAT is designed to maintain stable performance even under demanding driving conditions, such as those encountered in motorsport.

Through the interviews about the GR-DAT, the author felt that the enthusiasm to “make the technology proprietary” from the founding period has been shared among engineers.

The GR-DAT is manufactured on an advanced automated line. In the inspection process, inspectors listen to sounds through microphones to detect even the slightest abnormal noise from gear meshing and bearings. 100% inspection is carried out by checking against digital data.

Upon learning about 100% inspection, I recognized that the GR-DAT embodies the same spirit as the AT designed in-house by AISIN in 1972. It reminded me that AISIN-ism has remained unchanged over time.

The GR-DAT still evolving into an even better product based on refinement through motorsport.

AISIN has been working to deliver even better ATs    upon completion of development of the GR-DAT. One example is its participation in the Japanese Rally Championship as AISIN’s own team named AISIN RALLY TEAM with LUCK.

A rally-type GR Yaris appeared on the test course. It features a rally-spec GR-DAT with modified gear ratios and improved lubrication of friction materials, but it is basically the same as the mass-produced model.

The DAT installed in the car underwent minor modifications, including a change in gear ratios (a setting that eliminates the use of first gear), but it is basically the same as the mass-produced model. In other words, they are gathering insights for the next-generation sport AT by continuing to test under more rigorous conditions.

The author rode along with Mr. Hiroaki Sakakibara, chief mechanic of the AISIN rally team. How was the ride quality?

Incidentally, the GR-DAT is completely disassembled after each rally to check for deterioration and defects. That is, they continue to refine the GR-DAT that they developed.

The rally car’s steering wheel featured a single paddle, which instantaneously enables harsh shift changes of the DAT from any steering angle.

I was given the opportunity to ride in the passenger seat of the car. It was obvious that the body, suspension, and controls were modified as a full-fledged rally car, but the crisp upshifts and downshifts of the transmission and the direct feel were the same as those of the GR-DAT of my well-loved car! It made me grin. This experience reminded me that the AT performs well both on regular roads and in competitions.

Through the visit, I learned that the GR-DAT possesses the hidden, understated potential to orchestrate its own driving, though ATs should work quietly in the background.

The visit was worthwhile to capture the spirit of engineers. Conventional wisdom of ATs was overturned by the DAT. The visit ended with the smiles of members who underpinned the innovation.

It occurs to me that the engineers, who challenged the latent consensus that “ATs are boring” and created an exciting product that gives them driving pleasure, radiated confidence.

So, I want the users of the GR-DAT, which is installed in the GR Yaris and GR Corolla, to know that the transmission was developed by a group of engineers at AISIN.

[Text: Shinya Yamamoto, photos: Ryosuke Doi]