Hobbywing XR10 Justock G3S ESC + G2.1 25.5T Motor Combo – HW38020374 (JS7)

Overview

The Hobbywing XR10 Justock G3S ESC paired with the G2.1 25.5T fixed-timing motor (HW38020374) represents the pinnacle of competitive RC electronics for serious racers in the UK. This complete combo is engineered specifically for zero-timing specification racing, delivering consistent, fair performance across 1/10 and 1/12 scale on-road and off-road club competitions. Whether you're competing in touring car championships, drifting events, buggy racing, or short-course truck competitions, this is a battle-tested platform trusted by competitors who demand nothing less than precision and reliability.

The XR10 Justock G3S ESC brings cutting-edge brushless speed control technology to stock class racing. Unlike standard ESCs, this unit is meticulously calibrated for zero-timing applications, which means the motor timing is locked at a competition-legal fixed position. This standardised approach levels the playing field in spec racing formats, ensuring that driver skill and chassis setup determine the outcome, not electronic tricks. The G2.1 25.5T motor is perfectly matched to this ESC, offering a smooth, controllable power delivery of 1600kV that makes it ideal for rock crawlers, low-speed technical courses, and drivers who prefer maximum torque and control over outright top-end speed.

For UK RC enthusiasts seeking a ready-to-race brushless combo that complies with major racing specifications including IFMAR and ROAR, this HW38020374 package delivers everything you need in a single, coordinated system. The integration between ESC and motor ensures optimal performance, safety features, and the flexibility to program your setup to match local competition regulations.

Key Features

• Zero-Timing Preset Configuration — The motor timing is fixed at the competition-legal zero-timing position, eliminating timing adjustments and ensuring fair racing across all competitors using the same spec equipment. This is essential for stock class and sport class racing where all drivers must use identical settings.
• Intelligent Fan Control with Automatic Start and Stop — The ESC includes a sophisticated thermal management system that monitors temperature continuously. The cooling fan remains off during low-temperature operation, reducing noise and power consumption during cooler racing sessions. Once the ESC reaches its preset temperature threshold, the fan automatically activates to keep electronics within optimal operating range, ensuring consistent performance throughout extended race meetings without unnecessary noise pollution.
• Freewheeling Function for Advanced Throttle Control — When enabled, the freewheeling feature allows the motor to spin freely when you release the throttle, rather than being held by electronic braking. This results in faster deceleration when cornering, improved handling characteristics around turns, lower ESC temperatures during racing, and more responsive, predictable vehicle behaviour that rewards smooth driving technique.
• Multi-Position RPM Limiter with 79 Selectable Settings — The ESC supports 79 different RPM limit settings ranging from 10,000 to 88,000 RPM, allowing you to fine-tune maximum speed to match specific competition class requirements or track conditions. These limits can be programmed quickly through the optional LCD programming box or via the OTA wireless module using the HW Link mobile app, making it simple to adjust between different racing formats without physical modifications.
• Built-in Polarity Protection — One of the most valuable safety features, polarity protection guards against accidental damage caused by reversed battery connections or short circuits. This prevents catastrophic ESC failure if you make a momentary wiring mistake during track setup or maintenance, saving expensive repair costs and keeping you racing instead of troubleshooting.
• Integrated Capacitor Module with Optimised Circuit Layout — Rather than requiring external capacitors that clutter your chassis and add weight, this ESC incorporates the capacitor module directly into the PCB. The optimised internal layout improves electrical efficiency, reduces voltage spicer ripple, and eliminates the need for additional wiring and components, resulting in a cleaner installation and more reliable operation under high current demands.
• Adjustable Built-in BEC with Dual Voltage Output — The integrated Battery Elimination Circuit (BEC) supplies power directly to your receiver and servos without requiring a separate battery pack. With a maximum output of 8 amps at selectable 6V or 7.4V, it can support even the latest high-torque digital servos used in modern competition vehicles, ensuring your steering servo receives consistent, clean power for precise control throughout the race.
• Built-in Data Logging and Real-Time Telemetry — The ESC records critical performance data including minimum voltage, maximum temperature, maximum current draw, maximum motor temperature, and peak RPM. When paired with the optional OTA Bluetooth module and HW Link mobile app, you can monitor real-time telemetry data such as throttle input, voltage, current, temperature, and speed from up to 5 metres away, allowing engineers and drivers to analyse performance and make informed setup changes between heats.
• Advanced Motor Design with Hall Effect Sensor — The included G2.1 25.5T motor features a built-in Hall sensor and non-adjustable end bell, delivering smooth, linear power delivery and consistent RPM stability across the throttle range. The sensor electronics are permanently sealed into the motor can, protecting them from track debris and moisture while guaranteeing reliable sensored brushless operation lap after lap.
• Reinforced Construction with Heat-Resistant Magnet — The motor incorporates a heat-resistant magnet attached to an aluminium case, double-insulated copper windings, high-precision ball bearings, and a robust rotor structure designed to withstand the demands of competitive racing. This engineering guarantees outstanding performance and exceptional durability, with the motor able to deliver consistent power even during extended high-speed running sessions.
• Silicon O-Ring Seal for Dust and Heat Protection — The sealed joint between the end bell and stator not only prevents dust and debris from contaminating the Hall sensor assembly, but also conducts internal heat outward to the motor case for improved thermal management. This design feature significantly extends motor life and maintains electrical consistency even in dusty, outdoor racing environments common to UK club events.
• Detachable Motor Structure for Easy Maintenance — The motor design allows straightforward disassembly for cleaning and bearing maintenance, which effectively extends service life and maintains peak efficiency over an entire racing season. Regular maintenance becomes quick and simple, keeping your motor running smoothly without expensive factory servicing.
• Firmware Upgrade Capability — Should Hobbywing release firmware updates to add new features, improve performance, or correct bugs, you can upgrade your ESC without sending it away or replacing it. This future-proofs your investment and ensures you always have the latest technology available.
• IFMAR and ROAR Compliant Design — This motor and ESC combo meets the stringent specifications established by the International Federation of Model Auto Racing (IFMAR) and the Radio Operated Auto Racing (ROAR) organisation, confirming its legality for virtually all major competitive racing formats worldwide, including UK national championships.

Technical Performance

The Hobbywing XR10 Justock G3S ESC delivers 60 amps of continuous current with a peak rating of 380 amps, providing exceptional power delivery and response to throttle inputs. The ESC is rated for 2-3S LiPo batteries (up to 7.4V nominal) or 4-9 cell NiMH packs, making it compatible with both modern lithium and traditional nickel-metal hydride battery chemistry. The compact dimensions of just 40.9 × 33.9 × 32.1 mm combined with a weight of only 75.4 grams (including pre-installed wires) means installation into even tight engine bays is straightforward, whilst the light weight contributes to better overall vehicle handling and battery efficiency. The included wires feature heavy-duty 14 AWG gauge in both black and red, with 200mm lengths providing flexibility in routing through your chassis.

The paired G2.1 25.5T motor is a 540-size brushless unit (the standard size for 1/10 and 1/12 touring cars and buggies in the UK RC scene) with a 3.2mm bore that accepts standard 3.17mm motor shafts. The 25.5-turn winding delivers an equivalent KV rating of 1600, meaning approximately 1600 RPM per volt of battery voltage applied. On a 2S LiPo battery (7.4V nominal), this translates to roughly 11,840 RPM, providing controlled, manageable power ideal for technical courses where traction and precision matter more than raw speed. The motor can operate on batteries from 2-3S LiPo (7.4-11.1V nominal), giving you flexibility to adjust power levels for different track conditions or competition classes. Motor dimensions are approximately 35.9mm diameter and 52.5mm in length, with a weight of approximately 173 grams. The sensored brushless design delivers smooth, predictable acceleration without cogging or hesitation, essential for maintaining consistent lap times and smooth steering control during precise cornering manoeuvres.

This complete combo is specifically engineered for competitive 1/10 and 1/12 scale on-road racing (touring cars, drift cars, F1 mini cars) and off-road racing (buggies, 2WD short-course trucks) in both club competition and normal training environments. The zero-timing specification makes it legal for stock class racing where equipment is standardised, and the 25.5T motor option is also approved for rock crawling applications where extremely low speed control and high torque are required. The combination of fixed timing, sensored motor operation, and precisely calibrated ESC parameters ensures repeatable, fair performance that allows driver skill to be the determining factor in competition outcomes.

What's in the Box

• XR10 Justock G3S Brushless ESC with pre-soldered wires (14 AWG black and red, 200mm lengths)
• G2.1 25.5T Fixed-Timing Brushless Motor with Hall sensor
• Motor mounting hardware and documentation

What You Need to Complete

• RC car suitable for 1/10 or 1/12 scale (touring car, buggy, or short-course truck)
• LiPo battery pack (2S or 3S recommended) or NiMH equivalent with appropriate connectors — you may wish to add bullet connectors such as 4mm or 5mm for ease of connection
• LiPo battery charger rated for your chosen battery type
• Radio system receiver (compatible with your transmitter)
• Digital or analogue servo for steering
• Battery connector (Deans, XT90, or bullet connectors — optional upgrade connectors are available to order)
• Optional: Hobbywing LCD Program Box Pro for advanced ESC programming without mobile app
• Optional: Hobbywing OTA Programmer module for wireless real-time telemetry and data logging via the HW Link mobile application

Frequently Asked Questions

• Is the Hobbywing XR10 Justock G3S ESC legal for UK racing competitions? — Yes, this ESC is legal for STOCK and SPORT class racing in 1/10 and 1/12 scale on-road and off-road competitions recognised by IFMAR and ROAR. However, it is not BRCA legal for 2024 Nationals in the 17.5T control or FWD class; for those specific formats you would need alternative controllers such as the HW30112003, HW38020321, or HW30408011. Always check your local racing organisation's technical regulations before racing, as some clubs may have specific equipment lists.
• What does zero-timing mean and why is it important for competitive racing? — Zero-timing refers to a fixed motor timing position that cannot be adjusted by the driver or ESC. In competitive racing, standardised zero-timing rules ensure that all competitors using the same spec equipment have identical electronic characteristics, meaning victories are decided by driver skill, chassis setup, and track performance rather than by who has the most advanced electronic tuning. This creates fair, balanced competition where everyone is on an even playing field.
• What battery does the XR10 Justock G3S ESC require? — The ESC supports 2-3S LiPo batteries (nominal 7.4V to 11.1V) or equivalent 4-9 cell NiMH packs. For stock class racing with the 25.5T motor, a 2S LiPo (7.4V, approximately 5000-7000mAh capacity) is the most common choice, delivering smooth power and manageable top speed. A 3S LiPo (11.1V) will increase speed and acceleration but may be too powerful for tight technical courses. Always select a battery with a discharge rating (C-rating) of at least 50C to support the 60-amp continuous current draw of this ESC.
• Can I use this ESC and motor in an off-road buggy or short-course truck? — Yes, absolutely. The G2.1 25.5T motor and XR10 Justock G3S ESC are designed to work in 1/10 scale off-road buggies and 2WD short-course trucks, as well as on-road touring cars. The 1600kV motor delivers the torque and control needed for off-road racing, and the sensored brushless design provides smooth acceleration suitable for loose or technical terrain. The combo is equally at home in club off-road racing as it is in touring car events.
• Is this combo suitable for beginners or only experienced racers? — Whilst this is a professional-grade spec racing combo designed for competitive use, it is absolutely suitable for beginners and intermediate racers. The 25.5T motor is one of the lower-KV options available, meaning it delivers manageable power and torque that is easier to control than higher-speed options. The built-in safety features such as polarity protection and thermal management make it very user-friendly. However, beginners should budget for the optional LCD Program Box or OTA module if they wish to adjust RPM limits or monitor performance data, as this adds to the overall cost.
• What is the difference between the G2.1 25.5T motor and other Justock motor options like 21.5T or 17.5T? — The number refers to the winding turns; more turns equals lower KV and more torque at lower speed. The 25.5T (1600kV) delivers maximum torque and minimum top speed, making it ideal for rock crawlers and technical tracks. The 21.5T (2050kV) offers a balance of torque and speed, suitable for mixed terrain. The 17.5T (2450kV) and 13.5T (2800kV) provide progressively higher top speeds for faster, more open tracks. Choose based on your track layout and driving style: lower turn counts for speed, higher turn counts for control and torque.
• Can I upgrade the firmware on this ESC? — Yes, the XR10 Justock G3S supports firmware upgrades via connection to the OTA Bluetooth programmer module. This allows Hobbywing to add features, improve performance, or fix bugs without you needing to purchase new hardware. You simply connect the OTA module to the ESC and use the HW Link mobile app on your smartphone to initiate the upgrade.
• How does the intelligent fan cooling system work and why is it better than a constantly-running fan? — The ESC continuously monitors its internal temperature. When the ESC is cool during normal operation or low-current draws, the fan remains off, reducing noise and power consumption. As the ESC works harder and temperature rises above a preset threshold, the fan automatically activates to cool the components. This smart approach means you only use power for cooling when absolutely necessary, extends the life of the fan, reduces noise during practice sessions, and ensures the ESC stays within optimal temperature range during intense racing.
• What is the maximum current draw of the built-in BEC and can it power modern high-torque servos? — The integrated BEC can supply up to 8 amps at either 6V or 7.4V output, which is more than sufficient to power even the latest high-torque digital servos including those with metal gears and fast response times. The selectable voltage output means you can choose the setting that best matches your servo's specifications, ensuring consistent performance and protecting your servo from overvoltage.
• Does this ESC have waterproofing, and can I use it in wet weather or in wet grass? — The XR10 Justock G3S is not rated as waterproof or sealed. Whilst the connectors and wiring can tolerate light moisture and wet grass typical of UK club racing venues, you should avoid immersing the ESC in water or exposing it to heavy rain or water spray. If racing in damp conditions, keep the ESC as dry as possible and allow it to dry completely after use.
• What connectors are included with this combo, and can I upgrade to Deans or 4mm bullets? — The motor and ESC in this combo ship with no factory connectors installed (bare wire ends). This gives you complete flexibility to choose the connector type that matches your vehicle and battery setup. You can upgrade this combo with optional connectors including Deans and 3.5mm motor bullets, Deans and 4mm motor bullets, or various 4mm and 5mm bullet combinations, all available as paid add-ons at checkout.

Why Buy from RC Model Shop?

RC Model Shop is a trusted UK RC retailer and authorised dealer for all the brands we stock, including Traxxas, ARRMA, Losi, FTX, Hobbywing, Spektrum and more. Based in Walsall, we have a physical store where customers are welcome to come in, view products and purchase in store. Whether you are a seasoned competitor, a weekend basher, or just discovering the world of RC for the first time, our team of experienced RC enthusiasts is here to help you find the perfect setup and provide ongoing support. Order the Hobbywing XR10 Justock G3S ESC + G2.1 25.5T Motor Combo – HW38020374 (JS7) today with confidence, knowing you are buying from an authorised retailer with genuine products, expert knowledge and a commitment to customer satisfaction. Shop online or visit us in Walsall — we look forward to helping you get the most out of your RC experience.