Drive Axle - Eaton Locking Differential Type GMC Sonoma Syclone

AXLE RATIO & IDENTIFICATION

To determine the drive axle ratio, refer to the correct DRIVE AXLE RATIO IDENTIFICATION article.

Removal and installation procedures are covered in conventional differential article. See appropriate article in DRIVE AXLES.

DESCRIPTION

Locking differential consist of either a 1-piece case or 2-piece case. The 1-piece case is used on all axles except models with 10 1/2" ring gear axle. The 10 1/2" ring gear axle uses the 2-piece case. The 1-piece case has 2 pinion gears. The 2-piece case has 3-pinion gears. Both types have a clutch disc pack behind each of the side gears.

Scheme 5

1. Using Governor Remover (J-26252), remove governor bushing. Remove "C" clips holding latching bracket in position on governor shaft. Move latching bracket down shaft.
2. Using governor remover, remove latching bracket bushing. (Scheme 5) Remove latching bracket, shaft, spring and governor from case. Remove stop pin on 9 1/2" ring gear units. (Scheme 5) Remove lock screw and pinion shaft on all models. Remove pinion gears and thrust washers from case by rotating a side gear.
3. Remove thrust block, right side gear, clutch pack and thrust washer. Remove left side gear, cam plate and cam unit (clutch pack) as an assembly. Remove thrust washer.

Disassembly (Cam Unit With 7 1/2", 7 5/8" Or 8 1/2" Ring Gear)

Remove retaining ring, clutch plates, guide clips and wave spring. Remove cam plate and left side gear.

Disassembly (Cam Unit With 9 1/2" Ring Gear)

Measure and record overall length of gear assembly from front of gear to back of thrust sleeve, including thrust washer. Remove guide clips. Using press and Bearing Remover (J-22912-01), press thrust sleeve from left side gear. Remove lock plates, wave spring and cam plate from left side gear.

Inspection

Clean all parts in solvent. Inspect all gears for cracks or scoring. Inspect all clutch components and thrust washers for damage. Check fit of side gears on axle shafts. Inspect thrust sleeve for wear. Replace components as necessary.

Note. If side gears or thrust block were replaced, adjust differential. Check side gear backlash and thrust block clearance. See 1-PIECE CASE .

Reassembly (Cam Unit With 7 1/2", 7 5/8" Or 8 1/2" Ring Gear)

Install cam plate on left side gear. Install wave spring. On units with 7 1/2" or 7 5/8" ring gear, install 8 clutch plates. Install 10 clutch plates on 8 1/2" ring gear units. Clutch plates must be installed in alternating sequence. (Scheme 5) Install retaining ring. Use grease to hold guide clips in place; install guide clips on clutch plates.

Reassembly (Cam Unit With 9 1/2" Ring Gear)

1. Install cam plate on left side gear. Install wave spring. Install clutch plates. Clutch plates must be installed in alternating sequence. (Scheme 5) Press thrust sleeve on left side gear until sleeve is even with left side gear disc splines' surface.
2. Use grease to hold guide clips in place; install guide clips on clutch plates. If side gear or thrust sleeve were replaced, measure and record overall length of gear assembly from front of gear to back of thrust sleeve and thrust washer.
3. Compare new measurement with original measurement taken during disassembly. If difference between the 2 measurements is.003" (.07 mm) or more, install new thrust washer to obtain measurement nearest to original measurement.

Scheme 6

1. Install thrust washer and left side gear (cam unit) in case. Install thrust washer for right side gear in case. Install clutch pack for right side gear. Clutch plates must be installed in alternating sequence. (Scheme 5)
2. Use grease to hold guide clips in place, and install guide clips on clutch plates. Install right side gear, thrust block, thrust washers and pinion gears. Install pinion gears in case, 180 degrees apart.
3. Rotate pinion gears and thrust block into the case. Ensure open side of thrust block faces small window opening.
4. Install pinion shaft and NEW lock screw. DO NOT tighten lock screw to specification at this time. NOTE: Once unit is installed in differential housing, tighten lock screw to specification.
5. Place governor assembly and latching bracket into case. Place straight end of latching bracket spring over governor assembly shaft. (Scheme 6)
6. On 9 1/2" ring gear units, install stop pin until pin is even with surface of case.
7. Latching bracket bushing has a tapered hole, and governor bushing has a straight hole. Press governor bushing into case until shaft end play of.004-.020" (.10-.51 mm) exists. Press latching bracket bushing into case so no shaft end play exists. Once unit is installed, tighten lock screw to 37 ft. lbs. (51 N.m) on 9 1/2" ring gear, or 27 ft. lbs. (37 N.m) on all others.

Scheme 7

1. With differential removed from housing, remove ring gear and side bearings. Remove screws from front face of ring gear flange. Place differential on differential case's right half.
2. Using a screwdriver, gently pry differential case halves apart at yoke hole locations. Remove differential case's left half. Hold thumb against inside of gear hub when separating differential case halves to prevent left side gear from falling out.
3. Remove governor and latching bracket assembly. (Scheme 7) Remove left side gear, clutch plates, guide clips and side gear thrust washer. Remove reaction blocks, pinion yoke, pinion gears and pinion thrust washers.

Scheme 8

1. Remove right side gear and side gear thrust washer. Measure and record length of gear assembly from front of gear to back of thrust sleeve, including side gear thrust washer. (Scheme 7)
2. Using press and Bearing Remover (J 22912-01), press thrust sleeve from right side gear. Separate clutch plates, guide clips, wave spring and cam plate from right side gear. (Scheme 8)

Clean all parts in solvent. Inspect all gears for cracks or scoring. Inspect all clutch components and thrust washers for damage. Check fit of side gears on axle shafts. Inspect thrust sleeve for wear. Replace components as necessary.

Note. If side gears or reaction blocks were replaced, adjust differential. Check side gear backlash and reaction block clearance. See 2-PIECE CASE under ADJUSTMENTS.

Reassembly (Cam Unit)

1. Install cam plate on right side gear. Install wave spring and clutch plates. Install clutch plates. Clutch plates must be installed in alternating sequence. (Scheme 8)
2. Press thrust sleeve on right side gear until sleeve is even with surface of right side gear disc splines.
3. Use grease to hold guide clips in place, and install guide clips on clutch plates. If side gear or thrust sleeve were replaced, measure and record overall length of gear assembly from front of gear to back of thrust sleeve and thrust washer.
4. Compare new measurement with original measurement taken during disassembly. If difference between the 2 measurements is.003" (.07 mm) or more, install new thrust washer to obtain measurement nearest to original measurement.

Reassembly (Differential)

1. Install side gear thrust washer and right side gear in differential case half. Install reaction blocks, pinion yoke, pinion gears and pinion thrust washers.
2. Install left side gear thrust washer and clutch plates in differential case half. Ensure clutch plates are installed in alternating sequence. (Scheme 7) Install left side gear and latching bracket assembly.
3. Install governor assembly. Ensure straight end of latching bracket spring is over governor assembly shaft. (Scheme 6) Hold left side gear in differential case half and install cases together. Install retaining bolts and tighten.

1-PIECE CASE

Note. If side gears or thrust block have been replaced, adjust differential. Adjust clearance using correct thickness of selective thrust block and selective side gear thrust washers. Left and right side gear backlash and thrust block clearance must also be adjusted.

Left Side Gear Backlash

1. Install cam unit and thrust washer in flange end of case. Install pinion gears and thrust washer into differential. Ensure thrust washers are aligned with pinion shaft hole.
2. Press side gear downward and install pinion shaft and lock screw. If side gear cannot be pressed down enough to install pinion shaft, install thinner thrust washer.
3. Rotate pinion gear closest to lock screw so one tooth is pointing downward (perpendicular to ring gear flange). Insert a screwdriver firmly between side gear and pinion shaft.
4. Install dial indicator on ring gear flange, with indicator stem positioned on tooth of pinion gear closest to lock screw.
5. Pull pinion gear against case and rotate pinion gear back and forth and note backlash reading. Repeat procedure on the opposite pinion gear. Backlash should be .010-.018" (.25-.46 mm).
6. Change thrust washer thickness to obtain correct backlash. If backlash is greater than specification, use thicker thrust washer. If it is less than specification, use thinner thrust washer.

Right Side Gear Backlash

1. Alternately assemble clutch plates. (Scheme 5) Use grease to hold guide clips in place, and install guide clips on clutch plates.
2. Install thrust washer, clutch plates and right side gear into case. Install pinion gears and thrust washers. Ensure they align with pinion shaft hole.
3. Press side gear downward and install pinion shaft and lock screw. If side gear cannot be pressed down enough to install pinion shaft, install thinner thrust washer.
4. Rotate pinion gear closest to lock screw or stop pin so one tooth is pointing downward (perpendicular to ring gear flange). Insert a screwdriver firmly between side gear and pinion shaft.
5. Install dial indicator on ring gear flange, with indicator stem positioned on tooth of pinion gear closest to lock screw.
6. Pull pinion gear against case and rotate pinion gear back and forth and note backlash reading. Repeat procedure on the opposite pinion gear. Backlash should be.002-.010" (.05-.25 mm).
7. Change thrust washer thickness to obtain correct backlash. If backlash is greater than specification, use thicker thrust washer. If it is less than specification, use thinner thrust washer.

Thrust Block Clearance

1. Install thrust washer, left side gear (cam unit), thrust washer, clutch plates and right side gear in case. Install pinion shaft and lock screw.
2. Insert a screwdriver firmly between each side gear and pinion shaft. Using a 1-2" telescoping gauge, measure distance between the faces (not gear teeth) of both side gears.
3. Remove telescoping gauge and measure with a micrometer. This is the side gear spread. With micrometer, measure original thrust block at outer corner. Thrust block thickness should be 0-.006" (0-.15 mm) less than side gear spread.
4. To adjust clearance, select thrust block with different thickness, or reshim right clutch pack. Ensure right side gear backlash remains at .002-.010" (.05-.25 mm).

2-PIECE CASE

Note. If side gears or thrust block have been replaced, adjust differential. Adjust clearance using correct thickness of selective thrust block and selective side gear thrust washers. Left and right side gear backlash and thrust block clearance must also be adjusted.

Right Side Gear Clearance

1. Install right side gear (cam unit) and side gear thrust washer in differential case's right half. Using washers, long bolt and nut, clamp right side gear unit in differential case.
2. Install pinion gears and thrust washers on pinion yoke. Install pinion yoke in differential case half. Loosen nut on the bolt. Position one pinion gear tooth facing downward (perpendicular to ring gear flange) and tighten nut.
3. Install dial indicator on ring gear flange, with indicator stem positioned on one tooth of pinion gear. Pull pinion gear against differential case half. Rotate pinion gear back and forth and note backlash reading.
4. Ensure pinion yoke remains seated while checking backlash. Repeat procedure on the remaining pinion gears. Backlash should be .010-.018" (.25-.46 mm).
5. Change thrust washer thickness to obtain correct backlash. If backlash is greater than specification, use thicker thrust washer. If it is less than specification, use thinner thrust washer.

Left Side Gear Clearance

1. Assemble clutch plates in alternating sequence. (Scheme 7) Use grease to hold guide clips in place, and install guide clips on clutch plates.
2. Install thrust washer, clutch plates and left side gear in differential case half. Using washers, long bolt and nut, clamp left side gear in differential case.
3. Install pinion gears and thrust washers on pinion yoke. Install pinion yoke in differential case half. Loosen nut on bolt. Position one pinion gear tooth facing downward (perpendicular to ring gear flange) and tighten nut.
4. Install dial indicator on ring gear flange, with indicator stem positioned on one tooth of pinion gear. Pull pinion gear against differential case. Rotate pinion gear back and forth and note backlash reading.
5. Ensure pinion yoke remains seated while checking backlash. Repeat procedure on the remaining pinion gears. Backlash should be.002-.010" (.05-.25 mm).
6. Change thrust washer thickness to obtain correct backlash. If backlash is greater than specification, use thicker thrust washer. If it is less than specification, use thinner thrust washer.

Reaction Block Clearance

1. Install left thrust washer, right thrust washer, side gears and clutch plates in differential case halves. Using washers, long bolt and nut, clamp both side gears in differential case.
2. Place straightedge across top of both side gears. Using depth micrometer, measure distance from face of straightedge to surface of differential case half. Subtract straightedge thickness from this measurement.
3. Add measurement of both sides together. This is the side gear spread. Assemble both original reaction blocks together and measure thickness of both reaction blocks.
4. Reaction block thickness should be 0-.006" (0-.15 mm) less than side gear spread. To adjust clearance, select reaction block with different thickness, or reshim left clutch pack. Ensure left side gear backlash remains within specification.

AXLE ASSEMBLY SPECIFICATIONS

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• 1-PIECE CASE