Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

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Contact Pattern Location

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.