What is the correct pinion bearing preload?

Depending on the style of the assembly, either a crush collar or shims can be used to adjust pinion depth. Once the pinion depth has been set, pinion preload must be applied while rotating the pinion. For used bearings, set preload at 15 in. -lbs.; with new bearings, set preload with 25 in.

What is pinion bearing preload and why is it important?

This preload prevents the sideways thrust that moves the pinion gear to the outside edge of the ring gear.

How much preload do carrier bearings have?

If there was no friction then the force requried to turn a 1000 pound carrier is the same as a 30 lb carrier. Think about it this way: The bearing preload causes at least 100 times the frictional force in the bearings than the weight of a heavy carrier.

What can happen if the pinion bearing preload was set incorrectly?

The pinion gear rotates at driveshaft speed and can mimic a driveshaft speed-related vibration. Improper pinion bearing preload can cause what appears to be a pinion seal leak, but the seal is fine, the pinion gear is moving vertically, horizontally, or diagonally as is rotates.

How do you fix a loose pinion bearing preload?

Use an inch-pound torque wrench to check the preload. If the preload is too loose then remove shims so that the bearings will be tighter against the races and increase the preload. If the preload is too tight then remove the pinion gear and add shims so that the bearings will not be as tight against the races.

Why are differential bearings given preload?

An axial preload ensures constant contact between the ball complement and bearing races reducing or eliminating both modes of play. Properly preloading a bearing can increase its life and eliminate the vibration and noise that results from specified clearance, manufacturing precision, and wear.

Why do tapered bearings need preload?

Some applications are set with cold preload to increase rigidity and axial positioning of highly stressed parts that would otherwise be dramatically affected by excessive deflection and misalignment. Excessive operating preload must be avoided as bearing fatigue life can be drastically reduced.

What is preload differential?

Preload is the amount of force pressing the tapered roller bearings, mounted on the ends of the differential, together. Preload is used to pre-compensate for wear in the bearings (prevents the bearings from getting loose as they wear), and is defined as the amount of rotational drag induced by the load on the bearings.

How do you measure bearing preload?

Similarly, where there is a very light or no external load on the bearing in operation then preload may be required to ensure a minimum load. Applying the preload is typically done by measuring a force, sometimes a displacement over a distance or path, or by measuring the frictional torque during mounting.