HRP High-Speed idler gear 28T (48P) - GRK5-R

TheR31S130 HRP High-Speed Idler Gear 28T fromR31 House is a reinforced idler gear designed for the transmissions of theGRK5-R / GRK-R motor unit, with a focus onstability, smoothness, and management of high rotational speeds.

Developed under the supervision ofHayato Yoshiba, this model benefits from a complete optimization of theresin material as well as the manufacturing process, delivering an excellent balance oflightness, strength, and mechanical efficiency.

The bearing housing has been specifically adjusted to anticipatethermal expansion, ensuring consistent operation even during long sessions with high temperatures.

This28T version changes the transmission behavior compared to the 24T by promoting a different management of the internal ratio, allowing you to fine-tune themotor feel and drift progression.

Used in competition, particularly inSDC, this gear has contributed to top-level performance

• Brand:R31 House

• Reference:R31S130

• Type:reinforced idler gear (intermediate gear)

• Number of teeth:28T

• Pitch:48P

• Material:optimized high-performance resin

• Development supervised byHayato Yoshiba

• Precise bearing seat fitment (thermal management)

• Compatible with:GRK5-R / GRK-R motor unit

• Optimized fordrivetrain stability and consistency

• 1 × 28T idler gear

👉 Key difference vs 24T:

• 24T → more responsive, quicker response

• 28T → smoother, better torque management