What procedure must be done when assembling a twin countershaft transmission main section?

Timing the countershafts to the main drive gear is critical for the proper functioning of a twin countershaft transmission. In this type of transmission, the countershafts must be synchronized with the main drive gear to ensure that power is transmitted efficiently and without excessive wear on the gears. When the countershafts are timed correctly, each gear engages at the right moment, which helps maintain proper gear contact and alignment during operation.

Proper timing reduces the likelihood of gear noise, improves shifting precision, and enhances the overall reliability of the transmission. If the countershafts are not timed correctly, it could lead to gear clash or other mechanical failures, potentially damaging the transmission or affecting the vehicle's performance.

Setting the main-shaft bearing clearance and timing the main drive gear to the main-shaft are important as well, but they do not directly address the specific coordination required between the countershafts and the main drive gear for optimal operation of the transmission. Timing the auxiliary drive gear is also relevant for other aspects, but in the context of assembling the main section, the focus should be on the relationship between the countershafts and the main drive gear.