Throttle and Brake Linkage Adjustment

Throttle and Brake Linkage Adjustment

The following steps outline how to reset the throttle/brake servo to the factory setting and how to adjust the linkage. 

1) Fresh batteries: Install fresh batteries in the 4-cell battery holder and transmitter. 

2) Throttle neutral adjustment: the throttle neutral adjustment is located on the transmitter's faceplate and controls the forward and reverse travel of the throttle trigger. There are two settings: 50/50 provides equal travel in both forward and brake directions of the throttle trigger; 70/30 provides more throttle travel and less brake travel. 

Traxxas recommends the 50/50 position for nitro powered vehicles and electric models equipped with a mechanical speed control (MSC) or a forward and reverse ESC. The 70/30 is exclusively for electric vehicles equipped with a forward and brake only electronic speed control (ESC).

3) Throttle trim adjustment: The throttle trim adjustment knob is located on the transmitter's faceplate and adjusts the neutral point of the throttle/brake servo. Set the throttle trim to the '0' position. 

4) Centering the servo: remove the servo horn from the servo by loosening the 2x6mm self-tapping screw. Next, turn on the radio and slide the car's on/off switch to the on position. The servo will jump momentarily and return to the neutral position. 

5) Throttle and brake linkage adjustment: The car's transmitter and on/off switch must be turned on and all the steps outlined above must be performed before adjusting the throttle and brake linkage. Loosen the two screw collars with a 1.5mm "L" shaped Allen wrench and adjust the throttle linkage so that when the servo is in its neutral position, the carburetor is in the idle position. On the Revo make sure that there are small gaps between the servo horn and the collar and between the brake spring and the brake arm when the radio system is on and at neutral. Re-tighten the screw collars, but make sure that the screw collar that backs up against the throttle tension spring applies a slight amount of pressure on the rod guide. Next, loosen the screw collar on the brake rod and push it up against the small piece of fuel tubing so that it applies a slight amount of pressure on the brake cam lever. Operate the throttle trigger on the transmitter to insure that the throttle/brake servo is operating properly. When the throttle/brake servo is in the neutral position, the carburetor should be in its idle position. When the throttle trigger is pulled all of the way, the carburetor should be in the fully open position. When the throttle trigger is pushed forward, the brake should engage and the throttle should not close any further than when at idle. 

6) Many hobbyists make the mistake of adjusting the throttle trim on the transmitter to raise the idle speed instead of adjusting the idle speed screw on the carburetor. This accomplishes two negative effects: first, the engine may stall every time the brakes are applied. Second the brakes may not engage at all, which can lead to other problems.