See: HB Racing

HB Racing have introduced a new rear gear box and three sets of arm mounts for the D418. The new rear gear box is designed for high grip astroturf and carpet race tracks. It raises the position of the diff and upper arm mount to match the roll center when using a low ride height. The HB Team Drivers report it makes the D418 easier to drive on high grip surfaces, improves corner speed, and smoothes out rear end grip. This new rear gear box should be used with D418 Arm Mounts 4, 5 or 6. The set includes one gear box, aluminum tube, R2 skid plate (standard, use with this application), and R4 skid plate (for future options).

The arm mount sets allow racers to lower the roll center of the D418 for the new breed of high grip astroturf and carpet race tracks. In general, if the rear has too much grip, try changing to a lower rear roll center using the new Arm Mounts 4, 5 or 6. If you need more rear grip, try a higher rear roll center. The same may apply to the front end, if the front has too much grip, try changing to a lower front roll center. If you need more front grip, try a higher front roll center. The new arm mounts are numbered for easy identification, machined from aluminum, and hard anodized black. They are available in pairs.