Heavy Duty Transmission Installation Tips

Vibrations & Broken Synchronizer Pins

Probably the most common failure in heavy-duty transmissions is broken rear section synchronizer pins. This sort of damage is the result of a torsional vibration.

If the source of the vibration is not found and fixed, similar failure will occur.


Some possible vibration sources are worn driveline components, improper driveline angles, worn suspension, improperly adjusted air suspension and worn or damaged differentials.

By far, the most common source of torisional vibration is improperly adjusted air suspension.

Power Take-offs (PTOs)

Power Take-offs (PTOs) can cause transmission noise, excessive and premature wear and damage to transmission if they are not installed properly. PTOs must be installed with shims for proper gear mesh. If you are unfamiliar with the shimming procedure or have questions, please call us and ask for technical assistance.

Furthermore, a LEAK in a PTO can cause all of the fluid to drain from the transmission, causing severe damage.

Worn Shift Lever/Linkage

Shifting problems can often be caused by a worn shift finger, shift lever housing or shifting linkage. Inspecting for wear on the shift finger and shift lever housing should be part of any transmission repair.

Yoke Installation

When installing the rear yoke, make sure to tighten the yoke nut to the manufacturer’s torque specifications. Additionally, make sure to switch the speedometer drive gear or exciter ring from the transmission core. Failure to do so will damage the output seal.