This tough steel 21T MOD0.5 Pinion Gear provides a direct replacement for your kit item.
Features
- Strong and durable steel for long-lasting performance in extreme RC conditions
- Precision manufactured tooth profile for smooth operation
- Precision manufactured set screw hole
- For 2.3mm motor shaft
Includes
1 x 21T Mod 0.5 Pinion Gear
1 x M3 x 4mm Set Screw
- Manufacturer: ARRMA
- Model Number: Z-ARA311207
- EAN: 5052127047463
- Product Type: Pinion Gear
- Number of Teeth: 21 to 22 teeth
- Gear Pitch: MOD 0.5 (0.5 modulus)
- Bore Size: 2.3mm
- Material: Hardened steel
- Manufacturing Process: CNC machined for precision
- Tooth Profile: Precision manufactured for smooth operation
- Set Screw Hole: Precision manufactured
- Fastener Included: 1 x M3 x 4mm set screw
- Motor Shaft Compatibility: 2.3mm ARRMA MEGA 380 brushed motor shafts
- Compatible Vehicle Models: ARRMA MOJAVE GROM MEGA 380 Brushed 4x4 (C-ARA2104T1, C-ARA2104T2), ARRMA MOJAVE GROM 1/16 RTA (C-ARA2104KT1), ARRMA TYPHON GROM MEGA 380 Brushed 4x4 1/14 (C-ARA2106T1, C-ARA2106T1U1, C-ARA2106T2)
- Included Quantity: 1 pinion gear + 1 set screw
Overview
The ARRMA Pinion Gear 21T 0.5 MOD CNC 2.3mm Bore is a precision-engineered replacement gear designed specifically for ARRMA's compact RC models, including the popular MOJAVE GROM and TYPHON GROM ranges. Whether you're a dedicated RC enthusiast in the UK looking to maintain your small-scale desert truck or buggy, or you need a direct replacement after intensive bashers, this pinion gear delivers the performance and reliability you expect from ARRMA's engineering heritage. This tough steel component is built to withstand the extreme demands of RC racing and recreational driving, making it an essential spare part for any RC model shop customer who wants to keep their vehicles running at peak performance.
As one of the most recognisable names in electric RC vehicles, ARRMA has earned a reputation for producing hard-wearing components that perform under pressure. This 21-tooth pinion gear is no exception. Whether you're driving an RC car in the UK or abroad, you'll appreciate how ARRMA's precision manufacturing ensures consistent performance and smooth meshing with your spur gear. The CNC machining process guarantees that every tooth is cut to exact tolerances, eliminating the inconsistencies that can occur with less precise manufacturing methods. This is the kind of component that separates genuine, lasting performance from budget alternatives.
When you invest in replacing your pinion gear with an ARRMA original, you're not just buying a spare part—you're investing in the longevity and reliability of your RC vehicle. The 21-tooth configuration offers a specific gear ratio suited to the GROM models, balancing acceleration with top-end speed for both racing circuits and open-field bashing. This is genuine ARRMA kit equipment, designed to work seamlessly with your existing drivetrain.
Key Features
- Strong and durable steel construction — The pinion gear is manufactured from hardened steel that resists wear and deformation even during the most demanding RC conditions, ensuring your replacement gear will outlast cheaper alternatives and maintain consistent performance session after session.
- Precision manufactured tooth profile — Every tooth is cut using CNC machinery to exact specifications, creating smooth engagement with your spur gear that minimises noise, reduces drivetrain stress, and extends the life of both components in your RC transmission system.
- Precision manufactured set screw hole — The mounting hole for the set screw is machined to exacting tolerances, ensuring a secure fit on your motor shaft with no play or slippage that could cause performance issues or unsafe operation.
- Optimised for 2.3mm motor shaft — This gear is engineered to fit standard ARRMA MEGA 380 brushed motor shafts found in the GROM models, providing a perfect mechanical fit without requiring modification or shimming.
- 21-tooth configuration — With 21 teeth, this pinion gear provides the ideal balance of acceleration and speed for the smaller GROM-scale chassis, delivering responsive handling and competitive performance on track or rough terrain.
- MOD 0.5 pitch specification — The 0.5 modulus rating matches perfectly with ARRMA's spur gears designed for GROM models, ensuring proper meshing geometry and preventing issues like binding or excessive backlash.
- Includes mounting hardware — The gear comes complete with an M3 x 4mm set screw, eliminating the need to hunt for the correct fastener and ensuring you have everything needed for immediate installation.
Technical Performance
The ARRMA Pinion Gear 21T 0.5 MOD represents the pinnacle of small-scale RC drivetrain engineering. This component is specifically engineered for use with ARRMA's MEGA 380 brushed electric motor system, which powers the MOJAVE GROM and TYPHON GROM small-scale RC vehicles. The 21-tooth count provides a specific gear ratio that has been tuned by ARRMA's engineers for optimal performance on these chassis types, delivering responsive acceleration whilst maintaining sufficient top-end speed for competitive racing or high-speed bashing. The CNC manufacturing process ensures that every tooth maintains consistent geometry and surface finish, which is critical for smooth power transmission and minimal drivetrain noise. The hardened steel material provides exceptional durability under the high rotational forces and impact loads typical of RC vehicle operation, making this a genuine wear part that will perform reliably for hundreds of running hours. For builders and racers in the UK who demand precision engineering and proven reliability, this ARRMA original pinion gear is the correct choice for maintaining your GROM-series RC vehicle at factory specifications.
What's in the Box
- 1 x 21T MOD 0.5 Pinion Gear (steel, CNC machined, 2.3mm bore)
- 1 x M3 x 4mm Set Screw (for securing the gear to motor shaft)
Compatibility
- ARRMA MOJAVE GROM MEGA 380 Brushed 4x4 Small Scale Desert Truck RTR (Red variant C-ARA2104T1)
- ARRMA MOJAVE GROM MEGA 380 Brushed 4x4 Small Scale Desert Truck RTR (Blue variant C-ARA2104T2)
- ARRMA 1/16 MOJAVE GROM 4x4 RTA Race Kit (C-ARA2104KT1)
- ARRMA 1/14 TYPHON GROM MEGA 380 Brushed 4x4 Buggy RTR (Blue/Silver variant C-ARA2106T1)
- ARRMA 1/14 TYPHON GROM MEGA 380 Brushed 4x4 Buggy RTR (Pre-Owned variant C-ARA2106T1U1)
- ARRMA 1/14 TYPHON GROM MEGA 380 Brushed 4x4 Buggy RTR (Red/White variant C-ARA2106T2)
Frequently Asked Questions
- Is the ARRMA 21T Pinion Gear compatible with other RC car brands? — No, this gear is specifically engineered for ARRMA GROM models with 2.3mm motor shafts and MOD 0.5 spur gears. Using it on other brands' vehicles may result in improper meshing, noise, and accelerated wear. Always match your pinion and spur gears for proper drivetrain function.
- How do I know when I need to replace my pinion gear? — Signs of wear include increased drivetrain noise, difficulty starting, visible damage to the teeth, or slipping under load. If you notice any of these symptoms in your RC car UK setup, it's time to replace the pinion gear with this genuine ARRMA replacement.
- What is the difference between this 21T gear and other tooth counts? — The number of teeth directly affects your vehicle's gear ratio. A 21-tooth pinion is factory-spec for GROM models and provides the optimal balance for these chassis. Fewer teeth increase top speed but sacrifice acceleration, whilst more teeth improve acceleration but reduce maximum speed. Stick with 21T for the performance your GROM was designed to deliver.
- Will this gear work with my brushless motor conversion? — This pinion gear is designed for ARRMA's MEGA 380 brushed motors found in standard GROM kits. If you've upgraded to a brushless system, you may need a different pinion configuration—check with your brushless motor specifications to confirm compatibility.
- How difficult is it to install this pinion gear? — Installation is straightforward for anyone with basic RC mechanical experience. Remove the motor from the chassis, slide off the old pinion gear, slide on the new one, and secure it with the included M3 x 4mm set screw. The entire process takes just a few minutes with standard hex tools.
- Do I need to replace the spur gear at the same time? — Not necessarily, but it's good practice to inspect your spur gear when replacing the pinion. If both gears show significant wear, replacing them together ensures optimal meshing and extends the life of your drivetrain components.
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 ARRMA Pinion Gear 21T 0.5 MOD CNC 2.3mm Bore Z-ARA311207 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.
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