Kyosho UMW720 Lightweight Aluminum Main Chassis Ultima RB6

The UMW720 is Kyosho's optional lightweight main chassis for the Ultima RB6, machined from A7075-T6 aluminum in a 3mm plate. It is roughly 25 grams lighter than the chassis supplied in the kit, and on a 2WD buggy that weight comes out of the lowest point in the car, which sharpens acceleration and lets the suspension work against less mass over bumps.

The weight saving is not the whole story. The plate is milled in specific areas to tune how the chassis flexes. Relief through the rear section adds longitudinal flex that helps the rear tires find forward bite on dry, dusty, low-grip tracks, while the milling along the sides increases torsional flex for high-traction blue-groove surfaces where a stiff car tends to traction-roll.

A7075-T6 is the same aerospace-grade alloy used in high-end racing chassis, chosen for its strength-to-weight ratio and its resistance to permanent bending after a hard landing. This is an upgrade over the stock chassis rather than a straight replacement, and it accepts all standard RB6 bulkheads, mounts and hardware.