Replace the inner CV boot on the front axle shaft to prevent grease loss and contamination of the CV joint.

Warnings

Tools required

Parts

• Inner CV boot kit with clamps × 1 — Use OEM or quality aftermarket boot kit for 3.5L EcoBoost 4WD
• CV joint grease × 1 — Included in boot kit or purchase separately
• Axle nut × 1 — Use new one-time-use nut if staked type
• Front differential drain plug gasket × 1 — Motorcraft or equivalent
• Shop towels or rags × 1 — Standard

Fluids

• 75W-90 GL-5 Gear Oil — 1.5 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Loosen wheel lug nuts while vehicle is on the ground
3. Loosen but do not remove the front axle nut while vehicle is on the ground (36mm socket)
4. Raise vehicle and support securely on jack stands at frame contact points
5. Remove wheel completely
6. Place drain pan under front differential on the side being serviced

Procedure

1. 1

   Remove axle nut and disconnect outer components
   Remove the 36mm axle nut completely and set aside (it should be replaced with a new one upon reassembly). Remove the cotter pin if equipped. Mark the orientation of the axle shaft to the wheel hub for reassembly reference.
   Torque spec

   Axle Nut250 Nm (184 lb-ft)
2. 2

   Disconnect lower ball joint or tie rod
   Remove the lower ball joint pinch bolt or tie rod end nut to allow the knuckle to pivot downward. Use a ball joint separator tool to separate the components if needed. This provides clearance to remove the axle shaft from the hub.
3. 3

   Remove axle shaft from wheel hub
   Pull the wheel hub/knuckle assembly outward to disengage the axle shaft splines from the hub. If the shaft is stuck, tap gently on the end with a rubber mallet. Do not let the axle shaft hang unsupported as it can damage the outer CV joint.
   ⚠Support the axle shaft with mechanics wire or a bungee cord to prevent damage to the outer CV joint and boot.
4. 4

   Mark and disconnect inner CV joint from differential
   Locate the six CV bolts connecting the inner CV joint to the front differential stub shaft. Mark the orientation with paint or a marker for proper alignment during reinstallation. Remove all six bolts using a 13mm socket. Some differential fluid will drain when separated.
   ℹ️Expect approximately 0.5-1 quart of differential fluid to drain when the axle is disconnected.
   Torque spec

   CV Bolts70 Nm (52 lb-ft)
5. 5

   Remove axle shaft assembly
   Carefully pull the inner CV joint away from the differential stub shaft. Support the entire axle shaft and remove it from under the vehicle. Place it on a clean workbench for boot replacement. Plug the differential opening with a clean rag to prevent additional fluid loss and contamination.
6. 6

   Remove old inner CV boot clamps
   Using boot clamp pliers or cutting the clamps carefully, remove both the large and small clamps securing the inner CV boot. Slide the old boot away from the CV joint toward the shaft center. Clean any old grease from the joint housing.
7. 7

   Inspect and clean inner CV joint
   Wipe all old grease from the inner CV joint, housing, and shaft. Inspect the joint for wear, pitting, or damage. Check the balls, races, and cage for any signs of wear. If damage is found, the entire joint should be replaced. Clean the shaft surface where the new boot will sit using a wire brush and shop towels.
   ℹ️If the CV joint shows any wear or damage, replace the entire axle shaft rather than just the boot.
8. 8

   Install new inner CV boot
   Slide the new small boot clamp onto the axle shaft, followed by the new inner CV boot (small end first). Position the small end of the boot in the groove on the axle shaft. Install the small clamp and tighten using boot clamp pliers, ensuring it is seated properly in the boot groove.
9. 9

   Pack CV joint with grease and seat boot
   Pack the inner CV joint housing with the grease provided in the boot kit (typically the entire packet). Work the grease into all areas of the joint. Slide the large end of the boot over the CV joint housing and seat it in the housing groove. Ensure the boot is not twisted and sits properly.
10. 10

    Install large boot clamp
    Position the large boot clamp in the groove on the CV joint housing. Before fully tightening, burp the boot by inserting a small screwdriver between the boot and housing to equalize air pressure, then remove the screwdriver. Tighten the large clamp securely using boot clamp pliers. Verify both clamps are tight and the boot has no twists.
11. 11

    Reinstall axle shaft to differential
    Remove the rag from the differential opening. Guide the axle shaft back into position, aligning the inner CV joint with the differential stub shaft using the marks made during removal. Install all six CV bolts hand-tight first, then torque in a star pattern to specification.
    ℹ️Ensure the inner CV joint is properly seated against the differential stub shaft before tightening bolts.
    Torque spec

    CV Bolts70 Nm (52 lb-ft)
12. 12

    Reinstall axle shaft to wheel hub
    Guide the outer end of the axle shaft through the wheel hub, ensuring the splines engage fully. Push the knuckle assembly back into position and reconnect the lower ball joint or tie rod end. Install and tighten the pinch bolt or nut to specification.
13. 13

    Install new axle nut
    Install a new axle nut onto the axle shaft threads. With the vehicle still on jack stands and the wheel removed, use a breaker bar to hold the hub while initially tightening the nut. Final torque will be applied with wheels on the ground.
    Torque spec

    Axle Nut250 Nm (184 lb-ft)
14. 14

    Refill front differential
    Remove the front differential fill plug. Add 75W-90 GL-5 gear oil until it begins to seep from the fill hole (approximately 1.5 quarts). Reinstall the fill plug. Check the drain plug for leaks and tighten if necessary.
15. 15

    Reinstall wheel and final torque
    Reinstall the wheel and hand-tighten all lug nuts. Lower the vehicle to the ground. Torque the lug nuts to specification in a star pattern. With the vehicle on the ground and brakes applied, torque the axle nut to final specification. Stake the nut or install a new cotter pin as applicable.
    Torque spec

    Wheel Lug Nuts140 Nm (103 lb-ft)

    Axle Nut250 Nm (184 lb-ft)

Reassembly

1. Ensure all boot clamps are properly tightened and the boot has no twists or kinks
2. Verify the inner CV joint bolts are torqued in a star pattern to prevent uneven loading
3. Always replace the axle nut with a new one if it is a staked or one-time-use design
4. Check front differential fluid level after test drive and top off if necessary

Verification

• Test drive the vehicle and listen for clicking, popping, or grinding noises from the front axle during turns
• Verify no vibration is present during acceleration or at highway speeds
• Inspect the new CV boot for any grease leaks after test drive
• Check front differential for leaks around the stub shaft area
• Verify axle nut is properly torqued and secured with cotter pin or staking

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