2-Speed Shift Point Adjustment

Article #50771

2-Speed Shift Point Adjustment

The Nitro 4-Tec comes equipped with a 2-speed transmission. When the shift point on this transmission is adjusted correctly, it will maximize acceleration, improve driveability, and minimize lap times. Use a 2.0mm allen wrench to adjust the shift point.

NOTE: It is important that your engine is properly tuned and has reached full operating temperature before making shift point adjustments. Stop the engine before making adjustments.

1) Stop the engine.

2) Rotate the drum until the access hole is visible from the top.

3) Hold the spur gear set, and roll the car forward while looking through the access hole. Note that you will see two set screws through the access hole as you roll the car forward. The first one holds the 2-speed mechanism to the shaft. Do not loosen this screw unless you want to remove the two speed mechanism. The second is the shift point adjustment screw. Refer to the drawing to identify the screws.


4) Insert a 2.0 allen wrench through the clutch drum and into the adjustment set screw (see diagram).

5) Turn the adjustment screw clockwise to raise the shift point (later shifts). Be careful not to over tighten the adjustment screw or you may damage the tension spring.

6) Turn the adjustment screw counterclockwise to lower the shift point (earlier shifts). Be careful not to loosen the set screw too much or you may cause the screw and spring to fall out.

7) Use 1/8 turn increments to find the approximate, desired shift point.

8) Check performance by running a test lap after each adjustment.

9) Use 1/8-1/16 turn increments to fine tune the shift point.

NOTE: The transmission may not shift if the adjustment screw is turned too far in (locked in first gear), or too far out (locked in second gear). If the car has quick acceleration and does not appear to shift, the transmission is never reaching the shift point.The shift point needs to be lowered by turning the adjustment screw counterclockwise.

If the car has poor acceleration but very high top speed, the transmission is shifting into second gear almost instantly. The shift point needs to be raised by turning the adjustment screw clockwise.

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