January 25, 2016 The Fabricator 4 Rotor Build, Strictly Fabrication, BB RX-7 Sub-Frame Steering Rack Drop - #FourRotorFun January 25, 2016 The Fabricator 4 Rotor Build, Strictly Fabrication, BB A necessary sub-frame and steering rack modification for 20b and 26B Rotary Engine Swaps in the FD3S Chassis.