HKS 24999-AT003 Fine Tune Timing Belt for Toyota 1JZ-GTE 1JZ-GE Supra JZX Soarer

Vehicle Fitment

• 1990-1993 Toyota Supra JZA70 (1JZ-GTE, DOHC 24V Twin-Turbo I6)
• 1991-2000 Toyota Soarer JZZ30 (1JZ-GTE, DOHC 24V Twin-Turbo I6)
• 1990-1992 Toyota Mark II JZX80 / Chaser JZX80 / Cresta JZX80 (1JZ-GTE)
• 1992-1996 Toyota Mark II JZX90 / Chaser JZX90 / Cresta JZX90 (1JZ-GTE)
• 1996-2000 Toyota Mark II JZX100 / Chaser JZX100 / Cresta JZX100 (1JZ-GTE)
• 2000-2007 Toyota Mark II JZX110 / Verossa JZX110 (1JZ-GTE)
• 1990-1999 Toyota Crown JZS131 / JZS141 / JZS151 (1JZ-GE)
• 1999-2003 Toyota Crown JZS170 / JZS171 (1JZ-GTE / 1JZ-GE)

Fitment Notes

• Fits both 1JZ-GTE (twin-turbo) and 1JZ-GE (naturally aspirated) variants of the Toyota 1JZ inline-6 engine - both share the same timing belt specification (belt size 137Y25.4) and OEM belt part number 13568-49065
• Replaces OEM Toyota timing belt part number 13568-49065 - direct OEM-spec replacement dimensions
• Highly recommended for use with HKS Slide Cam Pulleys - the Fine Tune belt is specifically designed to work with adjustable cam gears under high torque and high-RPM conditions where OEM or standard replacement belts may skip or stretch
• Suitable as both a maintenance replacement belt and as a performance upgrade for modified 1JZ-G(T)E builds
• All fitments listed are JDM-market vehicles - verify engine code on export or grey-market versions before ordering

Features

• Aramid fiber + nylon fiber tooth construction - aramid (Kevlar-type) fibers provide exceptional tensile strength and heat resistance in the tooth body, while nylon reduces friction and surface wear against the sprocket teeth
• H-NBR (Hydrogenated Nitrile Butadiene Rubber) tooth rubber - H-NBR offers significantly higher resistance to heat, oil, and ozone degradation compared to standard NBR, extending belt service life in the demanding thermal environment of a turbocharged inline-6 engine
• Heatproof, waterproof, and high-strength core wire - the longitudinal tensile cords that determine belt stretch resistance are engineered for sustained high-load performance in a hot, humid engine environment
• Novel tooth moulding process - traditional timing belt manufacturing forms teeth by pressing from the outside, which stretches and weakens the tooth material. HKS pre-forms the tooth cavity in the mould to the correct shape, allowing teeth to be formed without external pressure and preserving the full structural integrity of the tooth. This approach reduces the risk of tooth stripping or belt skip under high-torque, high-RPM conditions
• Belt tension remains stable through heat expansion cycles - the materials and construction are selected specifically to maintain consistent tooth engagement as the engine heats up and components expand
• Purple backside color - identifies the belt as an HKS Fine Tune unit at a glance during inspection and provides the distinctive HKS engine bay aesthetic
• Optimized strength profile for the 1JZ-G(T)E application - HKS calibrates belt strength per engine type rather than using a generic specification, resulting in a belt that matches the torque characteristics and thermal demands of this specific engine family
• Engineered and manufactured by HKS in Japan

Specifications

• Part Number: 24999-AT003
• Product Type: Fine Tune Timing Belt
• Compatible Engine: Toyota 1JZ-GTE, 1JZ-GE (DOHC, 24V, 2.5L inline-6)
• Belt Size: 137Y25.4
• Tooth Material: Aramid Fiber + Nylon Fiber
• Tooth Rubber: H-NBR (Hydrogenated Nitrile Butadiene Rubber)
• Core Wire: Heatproof / Waterproof / High Strength
• Back Color: Purple
• Replaces OEM Part Number: Toyota 13568-49065

Included Components

• 1x HKS Fine Tune Timing Belt (24999-AT003)

Product Description

The HKS 24999-AT003 is a Fine Tune Timing Belt for the Toyota 1JZ-G(T)E inline-6 engine family, covering both the 1JZ-GTE twin-turbo and 1JZ-GE naturally aspirated variants across the full run of JZA70 Supra, JZZ30 Soarer, and JZX80/90/100/110 Mark II, Chaser, Cresta, and Verossa platforms, as well as Toyota Crown applications using the 1JZ. The belt uses the same dimensional specification (137Y25.4) and replaces OEM Toyota part number 13568-49065, making it a direct fitment upgrade over the factory belt. Its primary performance advantage lies in the tooth construction: while standard timing belts - including most OEM replacement belts - are formed by pressing material into a tooth shape from the outside, which creates internal stress in the tooth body, HKS pre-shapes the tooth cavity in the mould itself, forming the tooth without external compression. The result is a tooth structure with significantly more intact material integrity, better able to resist skip and stripping at high torque or when used with aftermarket cam gears that alter belt tension dynamics.

The tooth compound is built from aramid and nylon fibers in an H-NBR rubber matrix. Aramid (Kevlar-type) fibers deliver high tensile strength and heat resistance within each tooth, while the H-NBR rubber - a hydrogenated upgrade over standard NBR - resists heat, oil, and ozone degradation far more effectively, keeping the tooth material pliable and strong across the wide temperature range of a turbocharged engine under hard use. The core wire is engineered specifically for heatproof and waterproof performance, maintaining consistent belt tension and resistance to stretch even as the engine cycles through sustained high-RPM and high-temperature operation. Together, these materials produce a belt that provides stable tooth engagement with the cam and crank sprockets across all conditions, including the elevated loads imposed by high-boost 1JZ builds, racing applications, and extended track sessions.

This belt is HKS's first-choice recommendation for any 1JZ-G(T)E equipped with HKS Slide Cam Pulleys (adjustable cam gears), as the modified belt routing geometry and increased sprocket surface loads that come with cam timing adjustment require a belt with more robust tooth strength than the OEM unit. It is equally well suited as a straightforward high-quality maintenance replacement for street-driven 1JZ vehicles where longevity and reliability are priorities. The distinctive purple backside provides easy visual identification during inspection.