Overview
The ARRMA 21T 0.8Mod Safe-D5 Pinion Gear (Z-ARA311004) is an essential replacement and upgrade component for RC enthusiasts who demand reliability and precision in their electric RC cars and trucks. This tough steel pinion gear is engineered to deliver consistent performance in extreme RC racing conditions, whether you're running competitive heats or weekend bashing sessions. As a trusted spare part for ARRMA vehicles, this pinion gear is the perfect addition to carry in your RC tool box, ensuring you're always prepared for maintenance, repairs, or performance tuning on the track or at the bash spot.
Designed with the RC racer and hobbyist in mind, the 21T configuration offers an excellent balance of acceleration and top speed control for 5mm motor shaft applications. The precision-manufactured steel construction ensures durability through countless runs, whilst the innovative Safe-D profile eliminates the frustration of losing drive and braking power if your set-screw backs out during intense driving. This is the kind of thoughtful engineering that separates quality RC components from budget alternatives, and it's why ARRMA has become a recognised leader in the UK RC hobby market for dependable drivetrain components.
Whether you're setting up a new ARRMA RC car, replacing a worn pinion, or exploring different gearing options to fine-tune your vehicle's performance characteristics, the ARRMA 21T 0.8Mod Safe-D5 Pinion Gear delivers the precision and reliability that competitive RC drivers and casual hobbyists expect. Available now from RC Model Shop, this is genuine ARRMA equipment that meets exacting manufacturing standards.
Key Features
- Strong and Durable Steel Construction — The pinion gear is manufactured from tough steel that withstands the extreme stresses of competitive RC driving and aggressive bashing, providing long-lasting performance that won't strip or fail prematurely under load.
- Precision Manufactured Wide Tooth Profile — The carefully engineered wide tooth profile ensures smooth, quiet operation and consistent power delivery to your spur gear, reducing noise and vibration whilst maximising gear mesh efficiency for reliable acceleration and braking.
- Safe-D5 Profile Design — The distinctive 'D' shaped bore matches your motor shaft profile precisely, preventing drive and brake loss if the set-screw backs out during intense driving sessions, giving you peace of mind and eliminating unexpected drivetrain failures mid-race.
- 5mm Motor Shaft Compatibility — Designed to fit 5mm diameter motor shafts, this pinion gear is compatible with a wide range of ARRMA electric motors and aftermarket brushless motors commonly used in 1/10 scale and smaller RC vehicles.
- Precision Manufactured Threaded Set-Screw Hole — The set-screw hole is machined to exacting tolerances, ensuring secure fastening and consistent clamping force that keeps your pinion gear locked in position without slipping or rotating on the shaft.
- E-Clip Retention System Included — The supplied 3.2mm E-clip provides additional security to the motor shaft pinion retention, creating a belt-and-braces approach to gear security that prevents accidental removal during transport or extreme driving conditions.
Technical Performance
At the heart of this component lies genuine ARRMA engineering excellence. The 21-tooth configuration combined with the 0.8 Module pitch delivers a proven gear ratio suitable for a wide variety of RC driving styles and terrain conditions. The steel material selection provides superior strength compared to plastic or aluminium alternatives, resisting the shearing forces that develop during acceleration, deceleration, and cornering. The precision-manufactured wide tooth profile distributes load evenly across multiple teeth simultaneously, reducing peak stress concentrations and extending component lifespan significantly. The Safe-D5 bore profile is a standout feature that addresses a real-world problem in RC driving: the frustration of set-screws backing out due to vibration and shock loads. By incorporating a D-shaped profile that matches the motor shaft, the gear maintains positive drive even if fastening becomes slightly loose. This design philosophy reflects ARRMA's commitment to building RC components that perform reliably in the chaos of real-world driving rather than just in laboratory conditions. The inclusion of both an M4 x 4mm set-screw and a 3.2mm E-clip demonstrates attention to detail and provides a complete drivetrain security solution. Whether you're running a brushless 5mm motor in a competitive circuit racing setup or a casual basher RC car, this pinion gear delivers the performance and reliability expected from a major manufacturer in the UK RC hobby market.
What's in the Box
- 1 x 21T 0.8 Module Safe-D5 Pinion Gear
- 1 x Set Screw M4 x 4mm
- 1 x E-Clip 3.2mm
Frequently Asked Questions
- What is the 0.8 Module pitch and why does it matter for my RC car? — Module is a measurement of gear tooth size and spacing. The 0.8 Module specification indicates this pinion gear is designed to mesh perfectly with spur gears of the same module pitch. Using matched module gears ensures smooth, efficient power transfer from your brushless motor to the spur gear and differential, which is essential for fast acceleration and reliable performance. Mismatched modules cause poor mesh contact, noise, vibration, and premature wear.
- Is the Safe-D5 pinion gear suitable for beginners? — Yes, absolutely. In fact, beginners benefit significantly from the Safe-D5 design because it prevents a common frustration: losing drive power when the set-screw backs out during driving. This is especially valuable if you're still learning proper maintenance routines. The precision manufacturing and included fasteners mean you can install this pinion gear confidently and enjoy reliable performance without worrying about drivetrain failures.
- What motor shaft size does this pinion gear fit? — This pinion gear is designed specifically for 5mm diameter motor shafts, which is the standard shaft size found on most small brushless motors used in 1/10 scale and smaller RC cars, buggies, and trucks. Before purchase, verify that your motor has a 5mm shaft diameter.
- Why is the E-clip included if the set-screw already secures the pinion? — The E-clip provides redundant security by creating a mechanical stop that prevents the pinion gear from sliding along the shaft, even if the set-screw becomes loose. This dual-fastening approach is industry best practice for competitive RC vehicles and aggressive bashers where vibration and shock loads are constant stresses.
- How do I know if I need to replace my pinion gear? — Signs that a pinion gear needs replacement include visible tooth damage or chipping, excessive noise or grinding sounds during acceleration, difficulty shifting or inconsistent power delivery, or if you've had the set-screw back out repeatedly. Regular inspection during maintenance helps catch wear early.
- What's the difference between the Safe-D5 and a standard pinion gear? — The Safe-D5 features a D-shaped bore that matches the motor shaft profile, whereas standard pinion gears typically use a round hole with only a set-screw for retention. If the set-screw backs out on a standard gear, you lose drive and braking power immediately. The Safe-D5 design eliminates this risk, making it far more reliable for demanding RC applications.
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 21T 0.8Mod Safe-D5 Pinion Gear Z-ARA311004 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.
We want to make sure your delivery goes smoothly, so here are some important details about our service:
- For orders above £120, we offer delivery to most mainland UK addresses. For orders under £120, we can still deliver to Northern Ireland and the outlying isles, as long as the item can be sent by Royal Mail, weighs less than 30kg, and fits within 61cm × 46cm × 46cm. Some highland and remote areas may carry an extra delivery charge as couriers often apply surcharges in these locations. If you live in one of these areas, feel free to contact us before ordering so we can confirm the delivery options and costs for you.
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