Gear Tooth Contact Pattern Inspection

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Pattern Evaluation (Ring Gear)

Drive Side Heel Toe	Pattern Condition	Coast Side Toe Heel	Pattern Condition	Corrective Action
Face Hobbing
Courtesy of GENERAL MOTORS CORP.	Toe Contact	Courtesy of GENERAL MOTORS CORP.	Heel Contact	Pinion shim correct. Increase backlash.
Courtesy of GENERAL MOTORS CORP.	Desirable Pattern - Drive pattern should be centered on tooth	Courtesy of GENERAL MOTORS CORP.	Desirable Pattern - Coast pattern should be center to slightly toe on tooth	No correction required.
Courtesy of GENERAL MOTORS CORP.	Top Toe Contact	Courtesy of GENERAL MOTORS CORP.	Top Heel Contact	Backlash correct. Increase in pinion shim.
Courtesy of GENERAL MOTORS CORP.	Root Heel Contact	Courtesy of GENERAL MOTORS CORP.	Root Toe Contact	Backlash correct. Decrease in pinion shim.
Courtesy of GENERAL MOTORS CORP.	Top Heel Contact	Courtesy of GENERAL MOTORS CORP.	Top Toe Contact	Pinion shim correct. Decrease backlash.
Courtesy of GENERAL MOTORS CORP.	Root Toe Contact	Courtesy of GENERAL MOTORS CORP.	Root Heel Contact	Pinion shim correct. Increase backlash.
Face Milling
Courtesy of GENERAL MOTORS CORP.	Desirable Pattern - Drive pattern should be centered on tooth	Courtesy of GENERAL MOTORS CORP.	Desirable Pattern - Coast pattern should be center to slightly toe on tooth	No correction required.
Courtesy of GENERAL MOTORS CORP.	Top and Slightly Heel Contact	Courtesy of GENERAL MOTORS CORP.	Top and Slightly Toe Contact	Backlash correct. Increase in pinion shim.
Courtesy of GENERAL MOTORS CORP.	Root and Slightly Toe Contact	Courtesy of GENERAL MOTORS CORP.	Root and Slightly Heel Contact	Backlash correct. Decrease in pinion shim.
Courtesy of GENERAL MOTORS CORP.	Heel Contact	Courtesy of GENERAL MOTORS CORP.	Toe Contact	Pinion shim correct. Decrease backlash.

Drive Side	Coast Side	Pattern Condition	Corrective Action
Heel Toe	Toe Heel	Pattern Condition	Corrective Action
If the pinion depth needs to be adjusted, refer to Pinion Depth Adjustment (10.5 Inch Axle) or Pinion Depth Adjustment (8.6 Inch Axle) . If the backlash needs to be adjusted, refer to Backlash Adjustment (8.6 Inch Axle) or Backlash Adjustment (10.5 Inch Axle) . For the ring gear to pinion gear wear pattern test and the proper identification of the 2-Cut and 5-Cut, refer to Differential Drive Pinion Gear and Ring Gear Description and Operation .
Courtesy of GENERAL MOTORS CORP.	Courtesy of GENERAL MOTORS CORP.	Drive Side Centered - Coast Side Centered	No correction required.
Drive Pinion Issue - 2-Cut Gearset
Courtesy of GENERAL MOTORS CORP.	Courtesy of GENERAL MOTORS CORP.	Drive Side Low Heel Contact - Coast Side High Heel Contact	Inspect the backlash to ensure that it is approximately 0.08-0.13 mm (0.003-0.005 in) If backlash is correct, move the drive pinion closer to the ring gear by increasing the thickness of the pinion shim on a one-piece axle housing or by decreasing the thickness of the pinion shim on the 10.5 inch two-piece axle housing.
Courtesy of GENERAL MOTORS CORP.	Courtesy of GENERAL MOTORS CORP.	Drive Side Low Heel Contact - Coast Side Low Toe Contact	Inspect the backlash to ensure that it is approximately 0.08-0.13 mm (0.003-0.005 in) If backlash is correct, move the drive pinion away from the ring gear by decreasing the thickness of the pinion shim on a one-piece axle housing or by increasing the thickness of the pinion shim on the 10.5 inch two-piece axle housing.
Backlash Issue
Courtesy of GENERAL MOTORS CORP.	Courtesy of GENERAL MOTORS CORP.	Drive Side High Heel Contact - Coast Side High Toe Contact	Backlash incorrect. The ring gear is too far away from the drive pinion. Inspect and adjust the backlash as necessary to ensure that it is approximately 0.08-0.13 mm (0.003-0.005 in).
Courtesy of GENERAL MOTORS CORP.	Courtesy of GENERAL MOTORS CORP.	Drive Side Low Toe Contact - Coast Side Low Heel Contact	Backlash incorrect. The ring gear is too close to the drive pinion. Inspect and adjust the backlash as necessary to ensure that it is approximately 0.08-0.13 mm (0.003-0.005 in).
Courtesy of GENERAL MOTORS CORP.	Courtesy of GENERAL MOTORS CORP.	Drive Side Centered - Coast Side Centered	No correction required.
Drive Pinion Issue - 5-Cut Gearset
Courtesy of GENERAL MOTORS CORP.	Courtesy of GENERAL MOTORS CORP.	Drive Side High and Slightly Heel Contact - Coast Side High and Slightly Toe Contact	Inspect the backlash to ensure that it is approximately 0.08-0.13 mm (0.003-0.005 in) If backlash is correct, move the drive pinion closer to the ring gear by increasing the thickness of the pinion shim on a one-piece axle housing or by decreasing the thickness of the pinion shim on the 10.5 inch two-piece axle housing.
Courtesy of GENERAL MOTORS CORP.	Courtesy of GENERAL MOTORS CORP.	Drive Side Low and Slightly Heel Contact - Coast Side High and Slightly Toe Contact	Inspect the backlash to ensure that it is approximately 0.08-0.13 mm (0.003-0.005 in) If backlash is correct, move the drive pinion away from the ring gear by decreasing the thickness of the pinion shim on a one-piece axle housing or by increasing the thickness of the pinion shim on the 10.5 inch two-piece axle housing.
Backlash Issue
Courtesy of GENERAL MOTORS CORP.	Courtesy of GENERAL MOTORS CORP.	Drive Side Heel Contact - Coast Side Toe Contact	Backlash incorrect. The ring gear is too far away from the drive pinion. Inspect and adjust the backlash as necessary to ensure that it is approximately 0.08-0.13 mm (0.003-0.005 in).
Courtesy of GENERAL MOTORS CORP.	Courtesy of GENERAL MOTORS CORP.	Drive Side Toe Contact - Coast Side Heel Contact	Backlash incorrect. The ring gear is too close to the drive pinion. Inspect and adjust the backlash as necessary to ensure that it is approximately 0.08-0.13 mm (0.003-0.005 in).