SHIBATA tests GRK prototypes without telling the drivers what changed

Saturday's session was at Dayz, with the GRK Chukyo team drivers SHIBATA names as Shinichi and Kagawa. He describes the work there as secret testing and reports that good data came off the P-tile surface. P-tile is the Japanese vinyl floor tile many drift tracks run on, and a surface change is a setup change, so the venue matters to what that data is worth.

Sunday moved to the Tamtam Nagoya store's drift course, which the post describes as nearly full. Drivers had traveled from Kanto, Chugoku and Kansai to practice for the GRK decider. SHIBATA names GRK advisor Makkachin and DR-GRK driver Sekiya from Kanto, GRK advisor TKO and DR-GRK driver TakaC from Kansai, and GRK advisor Ruri with DR-GRK driver Yokota representing Chukyo. He writes that it is a rare chance to have them all in one place and that the advisors spent the day exchanging information with one another while he continued prototype testing, this time with the whole group evaluating the test car.

The post does not say what the prototype is — chassis, body or component — and that absence is the point of the method he describes.

The one car SHIBATA breaks down is Makkachin's GRK5-R in RR spec, which he says was running the GRK decider layout hard on Tamtam's asphalt. Both Makkachin and Sekiya had the new GRK aluminum spur gear holder plate fitted — a part SHIBATA says was developed from Makkachin's own proposal.

His description of its effect, as published: the throttle feel as the motor spins down is easier to read in the hand, which widens the range of control and makes it easier to carry into traction. That is the maker's account of his own part, and the post gives no comparative data behind it.

The rear end is listed as dampers with helper springs and Hyper Spring 6, wound left and right, and a 14T bevel. SHIBATA hedges on the gearing himself, writing that he thinks the gear ratio is around 8.

What he singles out about the car is handling rather than pace: despite the RR layout, he writes, there is no sense of the rear being thrown around, and the impression is of the front biting while the car turns in strongly. He attributes part of that to the electronics layout, without detailing it.

SHIBATA closes by noting that the number of people coming to practice is growing day by day and inviting readers to the Tamtam Nagoya store's drift course. That is an invitation from a maker's blog on a specific weekend, not a confirmed schedule: opening hours, entry conditions and whether the layout stays as built for the decider are not in the post.

For a newcomer reading this from outside Japan, the useful part is less the spring numbers than the structure behind them. A regional advisor network, drivers from three regions sharing a floor before a title event, and a maker running prototypes past them without saying what they are — that is a development loop running in public, credited to the people in it.