FZCSGRR01

Overview

The FONZON FULL METAL REAR DIFF w/INPUT PINION is a premium upgrade component specifically engineered for the ARRMA GROM series, one of the most popular 1/18 scale RC vehicles available in the UK market today. This all-metal differential represents a significant durability enhancement over standard plastic components, making it an essential upgrade for RC enthusiasts who demand reliability and longevity from their RC car UK setup. Whether you're a weekend basher enjoying outdoor RC action or a dedicated hobbyist pushing your GROM to its limits, this full metal differential delivers the robust power transfer and smooth drivetrain operation that separates quality builds from basic setups.

Designed and manufactured by Method RC with precision engineering, the FONZON differential combines advanced materials science with intelligent design to create a component that performs as well as it protects your investment. The rear differential is the heart of your drivetrain, responsible for distributing engine power to both rear wheels whilst allowing them to rotate at different speeds during cornering. A quality differential like this ensures smooth, predictable handling and extends the life of your entire drivetrain. For GROM owners seeking to upgrade from the standard plastic differential, this represents the ultimate solution for those serious about durability and performance.

Compact in size but uncompromising in durability, the FONZON all-metal differential is purpose-built for the GROM's mini-scale chassis, delivering the robust engineering you'd expect from full-size RC vehicles in a lightweight package that doesn't compromise handling or performance. Every component has been carefully selected and assembled to work in perfect harmony, ensuring that your GROM runs smoother, lasts longer, and performs more reliably than ever before.

Key Features

• Powder Metallurgy Planetary Gears — The differential employs precision-engineered powder metallurgy planetary gears that offer exceptional strength and accuracy in a compact form factor. This advanced manufacturing process creates gears with superior density and material properties, ensuring they withstand high-stress situations and maintain precise engagement tolerances that plastic gears simply cannot match.
• 7075-T6 Aluminium Alloy Diff Case — The central differential housing is machined from aerospace-grade 7075-T6 aluminium alloy, a material renowned for its exceptional strength-to-weight ratio. This lightweight yet rigid construction ensures the differential case maintains perfect alignment under load whilst keeping overall vehicle weight minimal, directly benefiting acceleration, handling and battery runtime on your RC car.
• Nickel-Chromium Alloy Steel Drive Cups — The drive cups that connect the differential to your half-shafts are manufactured from hardened nickel-chromium alloy steel, engineered to withstand the extreme RPM conditions and torque spikes that occur during aggressive driving. This superior material choice ensures these critical components resist wear and deformation far longer than standard plastic or cheaper alternatives.
• Powder Metallurgy Drive Bevel and Ring Gears — Both the drive bevel gear and ring gear utilise powder metallurgy construction, delivering consistent, reliable torque transfer through the drivetrain. This manufacturing method produces gears with uniform microstructure and superior fatigue resistance, meaning your GROM's acceleration remains smooth and predictable lap after lap, race after race.
• Grade 12.9 Black Corrosion-Resistant Screws — Every fastener used in this differential assembly is a Grade 12.9 black corrosion-resistant screw, the highest strength specification available for fasteners. Not only do these provide superior clamping force and resistance to vibration loosening, but the black oxide finish resists rust and corrosion, keeping your differential looking and functioning like new even after wet weather driving or storage.
• Pre-Filled with 3K cSt Differential Oil — The differential arrives factory pre-filled with premium 3K cSt differential oil, the ideal viscosity for smooth operation in the GROM's drivetrain. This eliminates guesswork during installation and ensures immediate optimal performance, whilst the oil provides lubrication that reduces friction and wear on all moving components.
• Fully Assembled and Ready to Install — Unlike some aftermarket differentials that require assembly, the FONZON unit arrives completely assembled and tested from the factory. This means you can install it directly into your GROM without additional work, saving time and eliminating the possibility of assembly errors that could compromise performance or durability.

Technical Performance

The FONZON FULL METAL REAR DIFF represents a quantum leap in durability and performance compared to the plastic differentials found in standard GROM setups. Every material selection has been made with longevity and performance in mind: the 7075-T6 aluminium alloy provides rigidity that prevents deflection under load, the nickel-chromium steel drive cups maintain their shape and surface finish through thousands of high-RPM cycles, and the powder metallurgy gears deliver precision that plastic alternatives simply cannot achieve. The 3K cSt differential oil provides the optimal balance of lubrication and resistance to sliding friction, ensuring smooth power delivery and reduced wear on all drivetrain components. This is not merely an upgrade; it is professional-grade engineering applied to a 1/18 scale RC vehicle. The combination of advanced materials, precision manufacturing, and intelligent engineering means that owners who install this differential will notice immediately smoother acceleration, more predictable handling during cornering, and significantly extended component lifespan. Whether you're running on tarmac, grass, dirt or mixed terrain in the UK, this differential will provide the foundation for a more reliable and enjoyable RC experience.

What's in the Box

• FONZON FULL METAL REAR DIFF with Input Pinion — completely assembled and factory pre-filled with differential oil

Frequently Asked Questions

• Is the FONZON full metal rear differential compatible with my ARRMA GROM? — Yes, this differential is specifically designed for the ARRMA GROM series and will bolt directly into your vehicle's rear axle assembly. The input pinion is matched to the GROM's drivetrain specifications, ensuring perfect engagement with your spur gear and seamless power delivery.
• What makes this metal differential better than the plastic one that came with my GROM? — The stock GROM differential uses plastic gears and housing, which are lighter but wear quickly under aggressive use. The FONZON metal differential features hardened steel and aluminium components that resist wear, deformation and material fatigue. Users report noticeably smoother operation, improved durability in crash situations, and significantly extended component lifespan — often doubling or tripling the life of the original differential before requiring service or replacement.
• Will this differential improve my GROM's speed or acceleration? — Whilst this is a durability upgrade rather than a power upgrade, improved mechanical efficiency and reduced internal friction means slightly smoother power delivery and potentially marginally improved acceleration. The main benefit, however, is reliability and longevity — your GROM will perform consistently lap after lap without the power loss that occurs as plastic gears wear.
• Do I need to service this differential after installation? — The differential arrives pre-filled with 3K cSt oil and ready to install. For casual use, it requires minimal maintenance; simply check the oil level periodically and top up if necessary. For intense racing or frequent high-RPM use, consider changing the differential oil every 10-15 hours of running time to maintain optimal performance and component protection.
• Is the FONZON metal differential suitable for beginners? — Absolutely. Whilst this is an upgrade component, installation is straightforward for anyone familiar with basic RC car maintenance. The differential bolts directly into your GROM's rear axle assembly, and no special tools or expertise are required. Beginners benefit from the enhanced durability, as it means fewer breakages and longer intervals between maintenance and repairs.
• What is the difference between the rear differential and front differential? — The rear differential handles power distribution to the rear wheels, whilst the front differential serves the same function for the front wheels. GROM owners can upgrade both independently; this product is specifically the rear unit. Some builders upgrade both for complete drivetrain reliability, whilst others start with the rear (which typically experiences higher loads) and upgrade the front later.
• Will installing a metal differential affect my GROM's handling or suspension geometry? — No. The FONZON differential is a direct replacement with identical mounting points, diameter and engagement specifications. Installation does not alter any suspension geometry, ride height, or handling characteristics. The only changes you'll notice are smoother operation, reduced wear, and improved drivetrain reliability.

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 FONZON FULL METAL REAR DIFF w/INPUT PINION - ARRMA GROM FZCSGRR01 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.