Traxxas Rear Shock Spring GTR Progressive 1.042 Rate Natural Finish TRX8445

Overview

The Traxxas Spring, shock, Rear (natural finish) (GTR) (progressive, 1.042 rate) (2 pcs) TRX8445 is a premium suspension upgrade designed specifically for the Traxxas UDR Unlimited Desert Racer Pro-Scale 4WD Short Course Truck. These progressive-rate springs represent Traxxas's commitment to delivering responsive, tunable suspension performance for serious RC enthusiasts across the UK. Whether you're bashing at the weekend or competing in organised events, quality shock springs are fundamental to how your RC car handles, responds to terrain and maintains control through challenging courses.

Built to the exacting standards you'd expect from Traxxas, one of the world's leading RC manufacturers, these GTR shock springs are custom-wound to deliver the perfect balance between compliance and control. The progressive-rate design means the springs respond softly to small bumps and obstacles, keeping your RC car planted and stable during normal driving, whilst progressively stiffening to absorb harder impacts when you hit rough terrain or jump landings. This dual-nature performance characteristic makes these springs ideal for diverse driving conditions, from smooth tracks to rocky desert courses. The natural finish coating protects the steel springs from corrosion whilst maintaining the classic, proven aesthetic Traxxas is known for.

If you're searching for genuine Traxxas RC car suspension spares in the UK, or looking to upgrade your UDR's handling characteristics, these rear shock springs deliver authentic performance enhancement. The 1.042 spring rate gives you a moderate stiffness profile that works well as a baseline for most driving weights and styles, and the fact that they come as a pair means you have matched springs for balanced suspension geometry.

Key Features

• Progressive-rate design — The springs use a progressive spring rate mechanism, which means they compress softly initially to absorb small bumps and maintain traction over terrain variations, then become progressively stiffer as they compress further, effectively handling larger impacts and jumps without bottoming out or feeling harsh. This engineering approach delivers superior ride quality and control compared to fixed-rate springs.
• Custom-wound construction — Each spring is precision custom-wound by Traxxas, ensuring consistent performance, exact rate specifications and long-term durability. This manufacturing rigour guarantees that both springs in the pair perform identically, which is critical for balanced handling and predictable vehicle dynamics.
• Natural finish steel — The springs feature a natural metallic finish that protects against corrosion whilst maintaining visibility of the spring condition. The high-quality steel construction ensures the springs retain their rate characteristics through thousands of compression cycles without weakening or degrading.
• 1.042 spring rate — This moderate spring stiffness rating provides an excellent baseline setup for the UDR platform, suitable for general bashing and recreational driving. The 1.042 rate can be considered a starting point for suspension tuning; if you find your car sits too low or bottoms out easily, you can upgrade to a stiffer rate, or if it feels too firm, you can try a softer rate.
• 139 mm length specification — These springs are precisely dimensioned at 139 mm to match the GTR shock absorbers used on the UDR platform, ensuring perfect fitment and correct suspension geometry. Using the wrong length springs would compromise handling and potentially cause chassis contact issues.
• Sold as a matched pair — Both rear springs are included, providing the suspension symmetry essential for balanced handling. Installing unmatched springs would cause uneven weight distribution and unpredictable handling characteristics.
• Suspension tuning capability — GTR springs are offered in multiple rates by Traxxas specifically to allow you to fine-tune your vehicle's suspension performance. Different rates compensate for lighter or heavier vehicle configurations and different driving styles, giving you precise control over how stiff or soft your suspension feels. The higher the spring rate number, the firmer the spring, providing more support for heavier setups or aggressive driving.

Technical Performance

The Traxxas GTR spring system represents the culmination of professional RC racing development and consumer feedback. The progressive spring rate technology is engineered to deliver exceptional performance across varying terrain conditions and driving intensities. At 1.042 rate, these springs strike an optimal balance for the UDR platform—stiff enough to minimise excessive body roll and maintain consistent ride height during cornering, yet compliant enough to maintain wheel contact and traction over rocky, uneven surfaces. The 139 mm dimension is specifically engineered for the GTR shock mount system used on the UDR Unlimited Desert Racer, ensuring perfect fitment within the suspension geometry. The natural finish steel construction utilises high-tensile material that withstands the repeated compression and extension cycles of off-road RC driving without developing fatigue cracks or permanent deformation. These springs are manufactured to the same quality standards as springs supplied on new RTR and competition vehicles, meaning they represent genuine OEM-equivalent parts rather than aftermarket compromises. For UK RC drivers, having access to genuine Traxxas suspension components means maintaining the vehicle's original handling character and reliability. Whether you're running an out-of-the-box UDR or a highly tuned competition version, these springs provide the foundation for predictable, responsive suspension performance that translates directly to faster lap times and more enjoyable bashing sessions.

What's in the Box

• Traxxas GTR shock spring, rear, natural finish, 139 mm, 1.042 rate (x2)

Frequently Asked Questions

• What vehicles is the Traxxas TRX8445 spring compatible with? — These rear shock springs are specifically designed for the Traxxas UDR Unlimited Desert Racer Pro-Scale 4WD RTR Short Course Truck. Compatible model numbers include TRX85086-4-RGD1 (UDR with Rigid Industries lighting) and TRX85086-4-FOX1 (UDR with Fox Racing suspension graphics). The 139 mm length and GTR mounting specification make them exclusive to the UDR platform; they will not fit other Traxxas models like the Rustler, Slash or Stampede.
• What is the difference between spring rates in the GTR range? — Traxxas offers GTR springs in multiple rates; the higher the number, the stiffer the spring. A 1.042-rate spring like this model provides moderate stiffness, making it suitable as a baseline setup. If your UDR sinks too low in the suspension or bottoms out easily during jumps, you would upgrade to a higher rate spring like 1.146 or higher. If the suspension feels too stiff and harsh, you would downgrade to a lower rate. Spring rate selection depends on your vehicle weight (including battery and fuel tank if applicable), your weight as a driver, and your driving style—aggressive drivers often prefer stiffer springs.
• Why is progressive spring rate better than a fixed rate? — Progressive springs use a variable winding pitch that starts soft and gradually becomes stiffer as the spring compresses. This delivers multiple benefits: small bumps compress easily without harsh feedback, but large impacts and jumps are progressively absorbed without bottoming out the shock. This contrasts with fixed-rate springs that compress with constant resistance throughout their travel, which tends to feel either too soft (allowing bottoming) or too stiff (causing harsh, bouncy handling). Progressive rates are considered more advanced and perform better across varied terrain.
• Can I mix different spring rates on one vehicle? — Technically you can, but it's not recommended. Mixing different spring rates front-to-rear or left-to-right creates asymmetrical suspension geometry, causing unbalanced handling, unpredictable cornering behaviour and potential chassis flex. Always use matched pairs of springs with identical rates on each axle for predictable, consistent performance. If you want to adjust suspension tuning, change the rates on both rear springs or both front springs together.
• How often should shock springs be replaced? — With normal recreational driving, quality springs like these Traxxas GTR components typically last many seasons. However, springs should be replaced if you notice permanent deformation (the spring no longer returns to its original length), visible cracks or stress marks, or if your vehicle's ride height has settled noticeably lower than when new. Heavy competition use may require more frequent replacement. Storing springs away from extreme heat and UV light extends their lifespan.
• Do I need to replace springs if I change my vehicle weight? — Yes, significant weight changes may require spring rate adjustments. If you add heavy electronics, a larger battery, or a heavy fuel tank, you may need stiffer springs to maintain correct ride height and prevent excessive bottoming. Conversely, removing weight may allow you to run softer springs for improved compliance. Many UK RC drivers experiment with multiple spring rates to find the optimal setup for their specific configuration.
• Are these springs suitable for beginners? — Yes, absolutely. The 1.042 rate is Traxxas's recommended baseline rate for the UDR, making it an excellent starting point whether you're new to the platform or experienced. Beginners will find these springs provide responsive, predictable handling that helps them develop smooth driving technique, whilst experienced drivers can use them as a foundation for further tuning. You don't need to be an expert to fit these springs—the process involves removing the shock assembly and swapping the springs, taking approximately 15 minutes per shock.

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 Traxxas Spring, shock, Rear (natural finish) (GTR) (progressive, 1.042 rate) (2 pcs) TRX8445 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.