Kyosho IFW455 Aluminum Throttle Servo Horn MP9

An aluminum throttle servo horn for 23 tooth splines, fitting Sanwa, KO Propo and JR servos, sold by Kyosho as an option part.

On a nitro car the throttle servo controls both throttle and brake through a single linkage, and the horn is what converts servo rotation into that movement. Where the linkage attaches to the horn sets the ratio between servo travel and carburettor opening, which affects how progressive the throttle feels off the bottom, and it sets brake travel at the other end.

Aluminum matters because the horn sits at the start of the linkage, so any flex is multiplied downstream. A plastic horn deflects under the load of a stiff brake linkage, which costs you braking feel and consistency, and its spline eventually wears until the horn slips on the servo output. That failure leaves you with no throttle or brake control at all.

An aluminum horn removes the flex and will not strip its spline. Kyosho lists it as an option part for the Inferno MP9, with the compatibility list extending to the MP10 range, MP10T and Inferno GT2 Race Spec. Note Kyosho now supplies this as IFW455B.