Ford 8.8-Inch Ring Gear

Checking Differential Ring Gear Backlash

1. Remove the differential housing cover.
2. Using a suitable dial indicator and the special tool, measure and record the differential ring gear backlash in 4 opposing points on the ring gear.

Checking Tooth Contact Pattern and Condition of the Ring and Pinion

There are 2 basic types of conditions that will produce ring and pinion noise. The first type is a howl or chuckle produced by broken, cracked, chipped, scored or forcibly damaged gear teeth and is usually quite audible over the entire speed range. The second type of ring and pinion noise pertains to the mesh pattern of the gear pattern. This gear noise can be recognized as it produces a constant pitch or whine. Ring and pinion noise tends to peak in a narrow speed range or ranges and will tend to remain constant in pitch.

NOTE: In the following steps, the movement of the contact pattern along the length is indicated as toward the "heel" or "toe" of the differential ring gear.

Apply a marking compound to 1/3 of the gear teeth on the differential ring gear. Rotate the differential ring gear several complete turns in both directions until a good, clear tooth pattern is obtained.

Compare the contact patterns on the ring gear teeth with the following illustrations.

Good Contact Pattern

Pattern inspection allows the technician to detect gross errors in set up prior to complete assembly of the differential assembly. Pattern contact should be within the primary area of the ring gear tooth section. Avoid narrow or hard contact with the outer perimeter of the ring gear tooth. Pattern inspection should be on the drive side of the tooth.

Correct assembly of the drive pattern will result in satisfactory coast performance.

NOTE: If a gross pattern error is detected with the correct backlash, check the pinion shim selection.

Good Contact Pattern:

Low Contact Pattern That Is Contacting More Toward the Heel

Gross Pattern Error:

High, Thin Contact Pattern In the Center Of the Tooth

Gross Pattern Error:

Thick Contact Pattern That Is Contacting Tooth Toward the Heel

Gross Pattern Error:

Thick Contact Pattern That Is Contacting Tooth Toward the Toe