Limited Slip Clutch Pack

This procedure covers removal and replacement of the limited slip differential clutch pack in the rear axle, requiring differential disassembly and proper setup of pinion depth and backlash.

Warnings

Tools required

Parts

• Limited slip clutch pack kit (includes clutches and plates) × 1 — Use OEM specification for rear axle code
• Differential case shims (assorted kit) × 1 — Use OEM specification
• Differential cover gasket × 1 — Use OEM specification
• Pinion seal × 1 — Use OEM specification
• Pinion nut × 1 — Use OEM specification
• Differential bearing shims (if required) × 1 — Use OEM specification
• Friction modifier additive for limited slip × 1 — GM Part Number 88900330 or equivalent

Fluids

• ACDelco 75W-90 Synthetic Gear Oil — 2.5 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Place wheel chocks in front of front tires
3. Raise rear of vehicle and support securely on jack stands at frame rails
4. Remove both rear wheels and set aside
5. Verify axle identification tag to confirm limited slip differential type and gear ratio
6. Allow differential to cool if recently operated

Procedure

1. 1

   Drain differential fluid and remove cover
   Place drain pan under differential. Remove all differential cover bolts in a cross pattern to allow fluid to drain. Once fluid is drained, remove cover completely and scrape old gasket material from cover and housing mating surfaces. Inspect drained fluid for metal particles indicating gear damage.
   Torque spec

   Differential Cover Bolts35 Nm (26 lb-ft)
2. 2

   Mark driveshaft and remove
   Mark driveshaft yoke and pinion flange with paint or scribe for reinstallation alignment. Remove driveshaft U-joint strap bolts at pinion flange. Support driveshaft and slide forward to remove from pinion. Cap pinion opening with plastic bag to prevent contamination.
   Torque spec

   Driveshaft U-Joint Straps20 Nm (15 lb-ft)
3. 3

   Mark pinion bearing preload
   Before disassembly, use inch-pound torque wrench on pinion nut to measure and record pinion bearing rotating torque (PBRT). Rotate pinion several times and measure torque required to maintain rotation. This baseline measurement is critical for reassembly. Typical PBRT is 15-35 inch-pounds for used bearings.
4. 4

   Remove pinion flange and seal
   Using pinion holding tool to prevent rotation, remove pinion nut. Mark pinion shaft position relative to flange. Use appropriate puller to remove pinion flange. Pry out pinion seal using pick or seal puller. Do not damage seal bore surface.
5. 5

   Install differential spreader and measure spread
   Install differential spreader tool on axle housing according to manufacturer instructions. Mount dial indicator to measure case spread. Carefully spread housing no more than 0.015 inches (0.38mm) maximum. Excessive spreading will permanently damage housing.
   ⚠️Do not spread housing more than 0.015 inches. Excessive spreading will crack or permanently deform the housing.
6. 6

   Remove differential carrier assembly
   With housing properly spread, use pry bar to carefully work differential carrier out of housing. Remove bearing caps only if previously marked; otherwise mark them for correct reinstallation position. Keep all shims with their respective bearing caps - these control backlash.
7. 7

   Disassemble differential case
   Secure differential carrier in soft-jawed vise. Remove ring gear bolts (if clutch pack replacement requires case disassembly). Drive out differential pinion shaft lock pin using brass drift. Remove differential pinion shaft. Rotate side gears and remove differential pinion gears, side gears, and all clutch pack components. Keep left and right side components separated and note orientation of all clutches and plates.
   ℹ️Clutch packs are side-specific. Keep left and right components separated and photograph assembly order before removal.
8. 8

   Clean and inspect components
   Thoroughly clean differential case, side gears, pinion gears, and shaft. Inspect case for cracks or damage. Inspect side gear and pinion gear teeth for wear or chipping. Measure clutch plate thickness and compare to service specifications. Replace any worn components. Inspect bearing races in housing for pitting or wear.
9. 9

   Install new clutch packs
   Soak new clutch friction plates in gear oil for 15 minutes before installation. Install clutch packs into differential case following exact order from factory service manual or clutch pack kit instructions. Alternate friction plates and steel plates as specified. Install side gears into clutch packs. Ensure all components are oriented correctly for limited slip operation.
10. 10

    Reassemble differential case
    Install differential pinion gears and thrust washers into case, meshing with side gears. Rotate gears to align pinion shaft holes. Install pinion shaft and verify free rotation of all gears. Install new lock pin and stake in place. Measure and verify gear backlash within specification if ring gear was removed.
11. 11

    Install carrier and set backlash
    Apply thin coat of gear oil to carrier bearings. With housing spread using differential spreader, carefully install carrier assembly with original shims. Release spreader slowly. Install bearing caps in original positions with marks aligned. Torque cap bolts to specification. Mount dial indicator to housing and measure ring gear backlash at 4 points around gear. Backlash should be 0.003-0.009 inches. Adjust by moving shims from one side to the other maintaining total shim thickness.
    ⚠Moving shims between sides changes backlash but not bearing preload. Moving shims from one side to the other: decreasing left side shim increases backlash, decreasing right side shim decreases backlash.
    Torque spec

    Mounting Bolts34 Nm (25 lb-ft)
12. 12

    Install new pinion seal
    Clean pinion seal bore thoroughly. Apply thin coat of gear oil to new pinion seal lip. Carefully drive seal squarely into bore using appropriate seal driver until fully seated. Do not damage seal lip.
13. 13

    Install pinion flange and set preload
    Align pinion flange with previous marks and install onto pinion shaft. Apply thread locker to new pinion nut threads. Install new pinion nut and tighten while measuring rotating torque with inch-pound torque wrench. Tighten nut incrementally until PBRT matches original measurement plus 5 inch-pounds (to account for new seal drag). Do not over-tighten as pinion nut cannot be loosened and re-torqued.
    ⚠Pinion nut can only be tightened during this procedure. If over-tightened, pinion must be removed and new collapsible spacer installed. Tighten incrementally and check PBRT frequently.
14. 14

    Verify gear pattern
    Apply gear marking compound to several ring gear teeth. Reinstall driveshaft temporarily. Rotate pinion in both directions under light resistance. Remove driveshaft and inspect contact pattern on ring gear teeth. Pattern should be centered on tooth face. Adjust pinion depth shims if pattern is incorrect, though this requires pinion removal.
15. 15

    Install driveshaft and fill differential
    Align driveshaft marks made during removal and install to pinion flange. Install U-joint strap bolts and torque evenly. Clean differential cover and housing mating surfaces. Apply thin bead of RTV silicone gasket maker to cover or install new gasket. Install cover and torque bolts in cross pattern. Fill differential with specified gear oil plus friction modifier additive through fill hole until level reaches bottom of fill hole. Install fill plug.
    Torque spec

    Driveshaft U-Joint Straps20 Nm (15 lb-ft)

    Differential Cover Bolts35 Nm (26 lb-ft)

Reassembly

1. Install rear wheels and torque lug nuts in star pattern to specification
2. Lower vehicle to ground
3. Test drive vehicle and listen for abnormal gear noise or chatter during turns
4. Recheck differential fluid level after test drive and top off if necessary

Verification

• Start engine and verify no leaks from differential cover or pinion seal
• Test drive vehicle making both left and right turns under light acceleration - limited slip should engage smoothly without chatter
• Perform figure-8 maneuvers to verify proper limited slip operation
• Verify no whine or howl from differential during acceleration and deceleration
• Recheck differential fluid level after 50-100 miles and inspect cover for leaks
• Monitor for proper limited slip function - both rear wheels should drive together in low-traction conditions

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