Manufacturer communication — 2006 GMC YUKON DENALI XL

• Applies to 1999-2013 GM light duty trucks and utilities.

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  Models: 1999-2013 GM Light Duty Trucks and Utilities

Steps to confirm (in the document’s order)

1. If the measured pinion shim comes out near either end of the range, compare it with the shim that was removed or recheck the setup of the measuring tools.

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   If the technician has determined that the pinion shim needed is close to one of the ends of the range, the technician should either compare the measurement to the shim removed or recheck the setup of the measuring tools! (Important rule of thumb to always follow).

2. To verify side bearing preload, the total torque to turn at the pinion should rise 5 - 10 in. lbs (= 0.565–1.13 N·m) after the differential case is installed.

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   11. To verify actual side bearing pre-load, the total torque to turn after the differential case is installed should increase 5 - 10 in. lbs at the pinion.

3. Axle shaft end play specification is 0.012 inch (= 0.305 mm) per side; radial (up and down) is 0.002 - 0.003 inch (= 0.0508–0.0762 mm).

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   13. Axle shaft end play spec is 0.012″ per side. Radial (up and down) is 0.002″ - 0.003″.

Repair

1. On an 8.6 axle the pinion shim used or stacked behind the pinion is 0.050 inch (= 1.27 mm) at most and 0.020 inch (= 0.508 mm) at least.

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   Maximum pinion shim to be used or stacked behind the pinion is 0.050″. Minimum pinion shim is 0.020″ for an 8.6 axle.

2. Set backlash to 0.003 to 0.005 inch (= 0.0762–0.127 mm) on a new ring and pinion for any AAM application, and check the gear pattern.

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   3. Backlash should be set to 0.003″ to 0.005″ on a new ring and pinion for any AAM application. As always, the gear pattern should be checked.

3. Rule of thumb for an 8.6 inch (= 218.4 mm) axle with a 5 cut gear set: use a 0.035 inch (= 0.889 mm) pinion shim and set backlash to 0.004 inch (= 0.102 mm).

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   However, a good ″rule of thumb″ for setting up an 8.6″ axle with a 5 cut gear set is to use a 0.035″ pinion shim and set backlash to 0.004″.

4. Use backlash to move the pattern heel to toe, and the pinion shim to move the pattern height (crest to root).

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   8. When setting up the gear pattern, try to use backlash to adjust the pattern heel to toe. Use the pinion shim to adjust the height of the pattern (from crest to root or top to bottom).

5. Drive pinion bearing preload is 15 - 30 in. lbs (= 1.69–3.39 N·m) with new bearings; with old bearings, check the rolling torque before disassembly and reset to only 3 - 5 in. lbs (= 0.339–0.565 N·m) above the original.

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   10. The proper drive pinion bearing pre-load is from 15 - 30 in. lbs with new bearings. With old bearings the rolling torque should be checked prior to 1 disassembly and reset to only 3 - 5 in. lbs higher than the original rolling torque.

6. Use a new pinion nut whenever the old one is removed; never reuse a used nut.

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   12. A new pinion nut must be used whenever the old one is removed which is noted in the service procedures. The new nut makes it easier to locate the pinion crush sleeve during torqueing. A used nut should never be reused.

Caution

• A ring and pinion can be reused or adjusted only below 500 miles (= 804.7 km) and only if not used for towing; if the vehicle has towed anything, the gear set must be replaced.

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  4. The ring and pinion can be reused or adjusted if the mileage is less than 500 miles, if not used for towing. If vehicle was used to tow anything, the gear set must be replaced in order to achieve proper setup.

• A "roller coaster" or "hourglass" pattern on the bearings may be normal up to 10,000 miles (= 16,093 km) and possibly longer, because the bearings have not fully broken in.

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  5. A ″roller coaster″ or ″hourglass″ pattern on the bearings may be normal up to 10,000 miles and possibly longer. This is because the bearings have not fully broken in or fully seated themselves completely.