Remotely shifted two-speed transmission

Installation notes

• Choose one transmitter route, not both. If a listed transmitter is already owned, retain it; the factory two-channel transmitter cannot provide the shift channel.
• 9892 supplies the shift servo, horn and torsion spring. Remove the manual shift lever and reuse the 1.6x7 screws marked in the servo instructions. Hold the horn while securing the spring.
• Do not backdrive the servo horn while powered. Plug the shift servo into CH3 of the ECM Brushless, not an accessory/light port.
• 9891 supplies the transmission, mounting bracket, two 2x6 screws and optional 22T gear adapter. Transfer serviceable center shafts, battery tray and the original fasteners identified in its sheet.
• 9891 includes a brushed motor. Replace it with the 3350KV brushless motor and mounting plate from 6250; do not connect the brushed motor to the brushless ECM.
• Keep the stock 9891 18T adapter with its 9776 gearing for this recipe: 32.7:1 low and 9.9:1 high are transmission reductions, not final drive ratios. 9776X/22T is a separate gearing choice.
• Use the original supported 2S LiPo configuration and connectors. Bind the selected transmitter to the new ECM and check steering, throttle and both gear positions before driving.
• If converting an already modified truck, inspect installed parts first; this bill assumes the stated 97054-1, 97074-1, 97064-1 or 97044-1 edition, not every later TRX-4M edition.

Sources