Ring Gear and Pinion Tooth Pattern Interpretation
Ring Gear and Pinion Tooth Pattern Interpretation
1. The final pinion position will be verified by using the gear contact pattern method described as follows:
2. NOTE: When making pinion position changes, shims should be changed in the range of .05mm (.002 inch) to .10mm (.004 inch) until correct pattern has been obtained.
The toe of the gear tooth is the portion of the tooth surface at the end towards the center. The heel of the gear tooth is the portion of the tooth surface at the outer end. The top land of a gear tooth is the surface of the top of the tooth. Every gear has a characteristic pattern. The illustrations show typical patterns only, and explain how patterns shift as gear location is changed.
3. NOTE: When making changes, note that two variables are involved. For example, if you have the backlash set correctly to specifications and you change the pinion position shim, you may have to readjust the backlash to the correct specification before checking the pattern. Refer to pattern interpretation.
WARNING: GEAR TEETH MAY HAVE SHARP EDGES. WHEN HANDLING GEARS, USE CARE TO AVOID PERSONAL INJURY.
When a change in backlash is required, backlash shims should be changed in the range of 1-1/2 times the amount of backlash required to bring the gears into specification. For example, if the backlash needed to be changed by .10mm (.004 inch), the shim pack should be changed by .15mm (.006 inch) as a starting point. The actual amount of backlash change obtained will vary depending upon the ratio and gear size. High backlash is corrected by moving the ring gear closer to the pinion. Low backlash is corrected by moving the ring gear away from the pinion. These corrections are made by increasing or decreasing the thickness of the shims located between the differential bearing cone and differential case.
4. Paint ring gear teeth with a marking compound on both the drive and coast side.
5. Rotate ring gear one complete revolution in both directions while load is being applied with a large screwdriver or similar tool between the carrier casting and differential case flange.
Ring Gear Patterns:
Pattern Movements Summarized
1. The following summarizes how pinion and ring gear movements will obtain satisfactory roll patterns:
a. Decreasing backlash moves the ring gear closer to the pinion.
Drive pattern (convex side of gear) moves slightly lower and toward the toe.
Coast pattern (concave side of gear) moves lower and toward the toe.
b. Increasing backlash moves the ring gear away from the pinion.
Drive pattern moves slightly higher and toward the heel.
Coast pattern moves higher and towards the heel.
c. Thicker pinion position shim with the backlash constant moves the pinion closer to the ring gear.
Drive pattern moves deeper on the tooth (flank contact) and slightly toward the toe.
Coast pattern moves deeper on the tooth and toward the heel.
d. Thinner pinion position shim with the backlash constant moves the pinion further from the ring gear.
Drive pattern moves toward the top of the tooth (face contact) and toward the heel.
Coast pattern moves toward the top of the tooth and slightly toward the toe.
2. Apply a bead 3.175-6.35mm (1/8-1/4 inch) high and 3.175-6.35mm (1/4-1/2 inch) wide of Silicone Rubber RTV sealant D6AZ-19562-AA (clear) or -BA (black) or equivalent meeting Ford specification ESB-M4G92-A or ESE-M4G195-A cover.
3. NOTE: Allow one hour curing time before adding lubricant and operating vehicle.
Assemble cover to housing. Tighten cover screws to 27-34 Nm (20-25 lb-ft).