The following article describes rebuilding and installation of a Ford 8.8" Traction-lok limited slip differential.
It can be applied to any vehicle with a solid-axle Ford 8.8" (Including the Crown Victoria / Grand Marquis / Town Car), or an IRS Ford 8.8" with a few changes to the procedure.

The following article was authored by Metroplex and has been converted into UBB format
Traction-Lok Rebuild and Installation by: Metroplex

Parts Required:
  • FMS-M-4700-B, Traction-Lok Rebuild Kit (Standard clutches)
    • optional - FMS-M-4700-C, Traction-Lok Rebuild Kit with Carbon Fiber clutches
      (OEM on 03-04 Cobra)
  • FMS-M-4216-A300, Ring Gear bolts
  • Timken SET36 x2 (or Timken LM603049 bearings x2, LM603012 races x2)
  • E0AZ-4214-A, 28-spline S-Spring (in case your S-Spring is shot)
  • F3TZ-4214-A, 31-spline S-Spring (most commonly used in the +1 clutch mod,
    (I do not recommend this S-Spring)
  • Spare clutches x2, 0.100" nominal thickness +0"/-0.003"
    (req'd for +1 mod, not req'd for std)

*OPTIONAL: The 4700-C carbon fiber clutches are retailing for $110, but are designed to better handle high torque applications.

Materials Required:
  • 3 qt dino gear oil for breaking in the differential/clutches
  • 3 qt synthetic gear oil (GL-5, 75W-90, or 75W-140)
  • Red High Strength Threadlocker
  • Liquid Penetrant Spray
  • Anti-sieze
  • Brake Cleaner (x2 bottles)
  • Silicone dielectric grease
  • White/Red/obvious colored nail polish - this is your marking compound
    (usually $0.25/bottle)

Tools Required:
  • 1/2" drive breaker bar
  • 1/2" drive ratchet
  • 1/2" drive torque wrench (capable of 50-150 ft-lb)
  • 3/8" drive torque wrench (capable of 5-30 ft-lb)
  • Crow-bar
  • various blocks of wood
  • various extension bars
  • Hammers / Mallets
  • Drift (wooden and at least 1 metal drift, I used the sharp pointy insert for the impact hammers)
  • 1/2" combination wrench
  • Long-reaching needle nosed pliers
  • Dial Caliper (0.001" precision, calibrate before using)
  • Dial Indicator (0.001" precision)

Sockets Required:
  • 6-point 13/16" socket, 1/2" drive, long socket
  • 6-point 3/4" socket, 1/2" drive, long socket
  • 6-point 10mm socket, 3/8" drive, short socket
  • 6-point 1/2" socket, 3/8" drive, short socket
  • 6-point 5/16" socket, 3/8" drive (1/4" drive if adapter is used)

If Removing Old bearings from carrier:
  • 1 1/4" socket, 1/2" drive<
  • bolt that fits in the hole of that socket
  • 2-jaw gear puller (heavy-duty vise also required)

Procedure: Steps 1-20 are required
IF you're replacing the carrier. If you're just rebuilding the already installed T-Lok carrier, go to 21 directly.

  1. Set wheel chocks, shift into Neutral, release the parking brakes. Loosen the lugnuts for the rear wheels just 1 turn each. Turn off rear air suspension if equipped.
  2. Verify that the vehicle won't move around, jack up the rear end of the vehicle and stick jackstands under the frame rails.
  3. Release the jack SLOWLY until the frame rails are supported by the jackstands and the vehicle should not move around. Set up auxiliary jackstands in case the primary stands fail.
  4. Remove the wheels (13/16" socket).
  5. Remove the differential case cover bolts (1/2" socket / wrench) and let the gear oil drain out into a suitable container.
  6. As the gear oil is draining, remove the rear caliper bolts (10mm) and set aside the bolts. Gently pry the calipers out (the top outboard pad has a spring clip) and do NOT let it hang on anything.
  7. Remove the brake rotors (usually it is either stuck to the brake shoes or stuck to the axle flange).
  8. Spray liquid pentrant at the ABS sensor and remove the ABS sensor bolt (10mm). The sensor will be stubborn but it has to come out so the axles can be pushed in w/o damaging the sensor.
  9. Depending on what differential you have, removing the cross-pin/pinion shaft may be different. I will assume you have an open differential, so use the 5/16" socket to loosen the pinion shaft bolt and remove the shaft (keep it in a safe place).
  10. Push in the axles and remove the C-Clips using the pliers.
  11. Gently pull out the axles enough so that the splines clear the carrier housing.

  12. Using the breaker bar (and possibly a cheater bar add-on) with the 3/4" socket, remove the bearing cap bolts. This requires a decent amount of leverage so be careful.
  13. Remember how the bearing caps are oriented. On my Vic, the text reads from bottom to top. W3 is on the bottom of the left cap, W10 is on the bottom of the right cap.
  14. Using a piece of wood to prevent marring the pumpking housing on the left side, use the crow bar and pry out the carrier housing using the ring gear bolts as the pulling point. These should be grade 9 bolts so they can take a decent amount of punishment. The carrier is HEAVY so watch out if it falls out.

    Left to Right: Axle Housing, Traction-Lok Carrier, Spider Gear comparison
  15. Make sure you keep the shims and bearing races and mark their original locations (left shim, right shim, etc...)
  16. Put the carrier on a bench vise and secure with wooden blocks to prevent marring the carrier housing.
  17. Using the breaker bar and 3/4" socket again, remove the 10 ring gear bolts.
  18. Using the metal drift and a hammer, gently tap through the bolt holes (making sure you do not mess up the threads) in a cross pattern until the ring gear falls down. Make sure you have some cushioning to prevent damage to the gear teeth.
  19. Soak your ring gear bolts and bearing cap bolts in a parts cleaner.
  20. Now it is time to prep your Traction-Lok carrier. If you purchased a brand new pre-assembled Traction-Lok carrier then you can skip the next step
  21. Rebuilding the Traction-Lok differential:
    1. Using a drift and hammer, remove the S-spring and inspect for excessive wear. If you can feel massive steps in the worn parts of the S-spring, it is time to get a new one.

    2. Using a hammer and wooden drift, rotate the spider gears out and using marking compound to mark the orientation/location.Remove the Side gears, clutches, steel discs, and shims. Make sure the shims come out, they can stick to the carrier housing.Clean the old clutches by wiping them with a clean cotton cloth or paper towel. Do not use solvents/brake cleaner of any kind. Make sure nothing is clogging the porous clutch material. Measure the thickness of each clutch.
      Find ones that measure 0.100" +0/-0.003" and keep them in a safe location. The ones that are thinner than 0.097" should be discarded or kept as 2nd tier replacements. You just need 2 good extra clutches since the rebuild kits only contain 6 clutches. You need 8 for the +1 mod. If no suitable clutches can be found, stick with the factory clutch pack layout.
    3. The factory clutch pack layout goes:

      Bland but gets the job done: 3 clutches per side
      Shim, Friction, Steel, Steel, Friction, Steel, Steel, Friction, Side Gear
      (4 steels, 3 friction discs)
    4. The alternate "+1 Clutch Mod" layout goes
      Beautiful: 4 clutches per side
      Shim, Friction, Steel, Friction, Steel, Friction, Steel, Friction, Side Gear
      (3 steels, 4 friction discs)

      Left to Right: Steel Discs, New Clutches, New Clutches with 2 old clutches that measure ~0.100"
    5. . My theory is that the more clutches you have, the longer it should last since you have additional friction from each clutch, rather than extra steel plates slipping around.
    6. The factory shim measuring tool uses a 0.640" measurement. Anything under that thickness requires a shim.
      So in other words, clamp your new clutch/steel pack together (minus the side gear and shims) with a C-Clamp and measure the thickness using a dial caliper. My alternate layout measured 0.645" so a shim was not required. If yours measured 0.613" (the factory layout should measure this amount) round it to the nearest 0.005" which is 0.615". The difference between 0.640" and 0.615" is 0.025", so use a 0.025" shim for that pack.
    7. I would not use the 31-spline "F-150" S-Spring since it is a PITA to hammer between the side gears and just isn't required. The S-Spring applies initial loading of the clutches but afterwards, the acting forces of the axles and side gears applies the necessary loading of the clutches.
    8. Soak the clutches in friction modifier for at least 1 hour. Assemble the clutch packs onto the corresponding side gears and install them in the carrier housing.
    9. Line up the spider gears visually and rotate them into place in the housing (hint, spin the side gears and apply force to the spider gears simultaneously).
    10. Use something to keep the spider gears still, and hammer in the S-Spring. Make sure it's oriented properly (allows the pinion shaft to be installed). Vise grip pliers are recommended but I just used a BFH to pound it in.
    11. install the pinion shaft to verify everything is lined up and then remove it. Don't use the pinion shaft bolt with the loctite (included with the rebuild kit) until the very end.
  22. If you are just rebuilding the Traction-Lok that is still installed in the axle housing, skip to 31.
  23. If you need to remove the carrier bearings and install new bearings, using the 1 1/4" impact socket + bolt + 2-jaw gear puller to pull the bearings. The bolt head prevents the puller's "stud" from destroying the socket when you drop it into the hole. Grade 8 is recommended.
  24. Using a press, install new bearings.
  25. Clean the contact surfaces of the carrer and the ring gear. Use 1500 grit or finer sandpaper if necessary. Swap over the ring gear and gently tap it in place with a wooden mallet making sure the bolt holes are aligned. Then use 2 ring gear bolts to completely seat the ring gear.
  26. Remove those bolts and clean the bolt threads and surfaces again. Apply the red high strength threadlocker on the threads of the ring gear bolts and snug them down.
  27. Torque the bolts to 77 ft-lb in a criss-cross pattern and allow the threadlocker to cure for at least 12 hours.
  28. Getting the bearing races and shims ready, install the carrier. It's easier to have someone help with this step. Insert the shim into the passenger side FIRST. Then when the carrier and races are seated properly, insert the driver side shim.
  29. Check the backlash for the gear using the dial caliper. If it is anything more than 0.015" you need to re-shim it. 0.008"-0.013" is good to go. Generally speaking, re-using the stock shims will work just fine.
  30. Install the bearing caps and torque the bolts to 77 ft-lb in a cross pattern.
  31. Push in the axles gently and install the C-Clips. Install the pinion shaft and torque the pinion shaft bolt to 20 ft-lb (no more than 20-25 ft-lb).
  32. Apply anti-sieze to the shiny part of the ABS sensors as well as the ABS sensor bolts. Torque to 8 ft-lb.
  33. Apply anti-sieze to the face of the axle flange as well as to the small "hub" of the axle flange.
  34. Apply anti-sieze to the threads of the brake caliper bolts, and silicone grease on the unthreaded part of the bolt. Install the brake rotors and the calipers. Torque the bolts to 20 ft-lb.
  35. Install the differential cover + gasket, and snug down the bolts. I usually snug it down enough w/ a 3/8" ratchet to the point where I have to really apply effort to tighten it further.
  36. Remove the rear fill plug and pour in 4 oz of FM additive along with 2-2.25 qt of gear oil. Then tighten the fill plug.
  37. Install the tires and lugnuts, snug the lugnuts for now.
  38. Drop the vehicle and torque the lugnuts to 90-95 ft-lb in a cross pattern.
  39. Check for leaks and go for a test drive. It should make weird cracking/groaning noises for the first few miles only when turning. Eventually you'll hear just weird "vibrations" and groaning when making turns. This is very prevalent when turning in reverse.
  40. After about 500 miles, drain out the gear oil and inspect for any damage/loose parts. Refill with 2-2.25 qt of synthetic gear oil and use 4-6 oz of FM.
  41. That's it, you're done.

--------Courtesy Metroplex
-Panther info & FAQs-

Former owner of a Grand Marquis with a few mods, Grand Marquis "LSE S/C"