Differential Assembly: Adjustments

Contact Pattern

The ideal tooth bearing impression on the drive and coast sides of the gear teeth is evenly distributed over the working depth of the tooth profile and is located nearer to the toe (small end) than the heel (large end). This type of contact permits the tooth bearing to spread towards the heel under operating conditions when allowance must be made for deflection.

FAULT

In High Tooth Contact it will be observed that the tooth contact is heavy on the gear face or addendum. To rectify this condition, move the pinion deeper into mesh, that is, reduce the pinion cone setting distance, by adding shims between the pinion inner bearing cup and the housing and fitting a new collapsible spacer.

RECTIFICATION
Move the drive pinion deeper into mesh, i.e. drive reduce the pinion cone setting.

In Low Tooth Contact it will be observed that the tooth contact is heavy on the drive gear flank or dedendum. This is the opposite conditon from that shown in High Tooth Contact and is therefore corrected by moving the pinion out of mesh, that is, increase the pinion cone setting distance by removing shims from between the pinion inner bearing cup and housing and fitting a new collapsible spacer.

RECTIFICATION
Move the drive pinion out of mesh, i.e. increase the pinion cone setting.

Toe Contact occurs when the bearing is concentrated at the small end of the tooth.

RECTIFICATION
Move the drive out of mesh, that is, increase backlash by transferring shims from the drive gear side of the differential to the opposite side.

Heel Contact is indicated by the concentration of the bearing at the large end of the tooth.

RECTIFICATION
Move the drive gear closer into mesh, that is, reduce backlash, by adding shims to the drive gear side of the differential and remove an equal thickness of shims from the opposite side.

Note: It is most important to remember when making this adjustment to correct a heel contact that sufficient backlash for satisfactory operation must be maintained. If there is insufficient backlash the gears will at least be noisy and have a greatly reduced life, whilst scoring of the tooth profile and breakage may result. Therefore, always maintain a minimum backlash requirement of 0.15 mm (0.006 in.).