ARC’s latest 1/8th nitro on-road racing car, the R8.4, has been released for the 2023 racing season. Based on the R8.3, the R8.4 features numerous improvements to deliver a massive step in overall performance.

NEW FEATURES:

1. All-new chassis with a stiffer mid-section

While we lowered the engine position on the R8.2 LCG by removing the material below the engine area, the new R8.4 chassis has no milling below the engine to help increase chassis hardness and improve rear side bite.

2. All-new lower suspension arms

The new front and rear lower suspension arm design is a result of extensive R&D during the 2022 racing season in various traction levels around the world. The new arms are thinner all around but features reinforced areas in the rear lower arm for better impact resistance.

The new arms bring significantly more corner speed and makes the car much easier to drive. These improved characteristics have been proven across various traction levels and at varying tire diameters.

3. New middle belt tensioner

With the middle belt being the longest belt, this can result in the belt flipping over the rear pulley under super high traction conditions. The new middle belt tensioner features an additional ball bearing just above the rear pulley for significantly reduced belt deflection and prevents the belt from disengaging even under the harshest racing conditions.

4. Adjustable front shock base

An option part released late last year, the adjustable shock base is now standard on the R8.4, the adjustable shock base can be used to fine-tune the shock angle by adding or removing 0.5mm or 1.0mm shims below the shock absorber.

5. New front and rear bulkhead

The new front and rear bulkheads now feature recessed mountings for the anti-roll bar ball bearings. This increases the contact surface area for the anti-roll bars, bringing more precision to the chassis’ handling response.

6. New anti-roll bar stopper

There are 5 different anti-roll bar stoppers for R8.4 – 2.2mm, 2.4mm, 2.6mm, 2.8mm, and 3.0mm – with each stopper being tailored specifically for each anti-roll bar thickness. Doing this ensures precise suspension operation, reduce tweak and greatly improved handling consistency, especially during long finals.

7. New 2-speed adaptor

The new 2-speed adaptor moves the 2-speed 1.5mm further from the bulkhead. This greatly reduces the chance of ball bearing oil coming into the 2-speed shoes, especially when replacing the ball bearing onto the main shaft.

8. New main shaft bulkheads

The new main 2-speed shaft bulkheads are designed to move each side ball bearing as far outside as possible to reduce stress on the ball bearings. Combined with a carbon fiber stiffener above the bulkhead, flex in this area is significantly reduced to increase shaft rotation stability and increase the efficiency of the transmission.

9. New bushing for main shaft ball bearing

The new bushing design for the main shaft comes with two dimples that slot inside the bulkhead. This prevents both the bushing and the bearing from spinning at the same time, further improving drivetrain efficiency and the overall durability of this assembly.

10. Optional adjustable rear shock base

The adjustable rear shock base is an option on the R8.4. The adjustable rear shock base allows fine-tuning of the rear shock angle by adding or removing shims.