Contact Patterns

1. To check the gear tooth contact, paint the gear teeth with the special marking compound. A mixture that is too wet will run and smear; a mixture that is too dry cannot be pressed out from between the teeth.
2. Use a box wrench on the ring gear bolts as a lever to rotate the ring gear several complete revolutions in both directions or until a clear tooth contact pattern is obtained.
3. Certain types of gear tooth contact patterns on the ring gear indicate incorrect adjustment. Incorrect adjustment can be corrected by readjusting the ring gear or the pinion.

CONTACT PATTERN LOCATION
In general, desirable ring gear tooth patterns must have the following characteristics:
- Drive pattern on the drive side ring gear well centered on the tooth.
- Coast pattern on the coast side ring gear well centered on the tooth.
- Clearance between the pattern and the top of the tooth.
- No hard lines where the pressure is high.





Acceptable ring gear tooth patterns for all axles.





Correct backlash with a thinner pinion position shim required.





Correct backlash with a thicker pinion position shim required.





Correct pinion position shim that requires a decrease in backlash.





Correct pinion position shim that requires an increase in backlash.