Gear Tooth Contact Pattern Inspection. GMC Truck Sierra

GM Service Manual Online

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2007 🢒 Sierra - 4WD 🢒 Driveline/Axle 🢒 Rear Drive Axle 🢒 Gear Tooth Contact Pattern Inspection

Table 1:

Pattern Evaluation (Ring Gear)

Drive Side

Coast Side

Pattern Condition

Corrective Action

Heel Toe

Toe Heel

•	If the pinion depth needs to be adjusted, refer to Pinion Depth Adjustment.

•	If the backlash needs to be adjusted, refer to Backlash Adjustment.

•	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.

Drive Side Centered - Coast Side Centered

No correction required.

Drive Pinion Issue - 2-Cut Gearset

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.

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

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).

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).

Drive Side Centered - Coast Side Centered

No correction required.

Drive Pinion Issue - 5-Cut Gearset

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.

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

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).

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).

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