This procedure covers removal and replacement of the transfer case chain in the BorgWarner electronic shift transfer case on a 2011-2014 Ford F-150 with 3.5L EcoBoost engine.

Warnings

Tools required

Parts

• Transfer case chain × 1 — Use OEM specification for BorgWarner unit
• Transfer case rear cover gasket or RTV × 1 — Use OEM or quality aftermarket
• Drain plug washer × 1 — Use OEM specification
• Transfer case output shaft seal (rear) × 1 — Replace if damaged during disassembly

Fluids

• Motorcraft Transfer Case Fluid — 2.5 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable to prevent accidental engagement of 4WD system
3. Raise and secure vehicle on jack stands at all four corners to provide adequate working clearance
4. Remove skid plates or underbody shields if equipped to access transfer case
5. Allow transfer case to cool completely if vehicle was recently driven
6. Clean exterior of transfer case thoroughly to prevent contamination during disassembly

Procedure

1. 1

   Drain transfer case fluid
   Position drain pan under transfer case. Locate and remove the drain plug on the bottom of the transfer case using appropriate socket. Allow fluid to drain completely (approximately 2.5 quarts). Inspect drained fluid for metal particles or debris that may indicate additional internal damage. Remove and discard drain plug washer.
2. 2

   Remove rear driveshaft
   Mark relationship between rear driveshaft and transfer case output flange for proper reinstallation alignment. Remove the four U-joint strap bolts at the transfer case end. Support driveshaft and carefully slide it rearward off the output shaft. Secure driveshaft out of work area or remove completely.
   Torque spec

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

   Disconnect electrical connections
   Locate the 4WD motor/actuator connector and shift motor connector on the transfer case. Depress locking tabs and disconnect both electrical connectors. Secure wiring harness out of work area to prevent damage during rear cover removal.
4. 4

   Remove transfer case rear cover
   Remove all rear cover mounting bolts in a crisscross pattern to prevent warping the housing. The rear cover contains the output shaft and bearing assembly. Carefully pry cover loose if stuck using a soft pry bar at designated pry points only. Do not pry on sealing surfaces. Once loose, carefully pull rear cover straight back to disengage output shaft from chain. The output shaft, bearing, and seal remain in the rear cover.
   Torque spec

   Mounting Bolts31 Nm (23 lb-ft)
5. 5

   Remove chain and inspect sprockets
   With rear cover removed, the chain is now accessible. Lift chain off the drive sprocket (input from transmission) and driven sprocket (planetary assembly). Inspect both sprockets for wear, damage, or missing teeth. Check sprocket engagement surfaces for excessive wear patterns. Mark sprocket orientation if replacement is needed. Inspect chain guides and wear pads inside the case for damage.
6. 6

   Remove and inspect chain tensioner
   Locate the chain tensioner assembly on the side of the transfer case. The tensioner is spring-loaded, so control it carefully during removal. Remove tensioner mounting bolts and extract tensioner with spring. Inspect tensioner shoe for wear grooves or damage. Inspect tensioner spring for proper tension and no signs of weakening. Replace tensioner if shoe wear exceeds 1mm depth or spring shows heat discoloration.
7. 7

   Inspect chain drive components
   Inspect the drive sprocket shaft seal and bearing for leakage or roughness. Check planetary gear assembly (driven sprocket) for proper rotation and no excessive play. Inspect range fork and shift collar for wear. Check all shift components for proper operation. If sprockets require replacement, this involves additional disassembly of internal components.
8. 8

   Clean all mating surfaces
   Thoroughly clean all gasket mating surfaces on both the transfer case housing and rear cover using gasket scraper and wire brush. Remove all old gasket material or RTV residue. Clean surfaces with brake cleaner and ensure they are completely dry. Inspect mating surfaces for damage, warping, or deep scratches that could cause leaks.
9. 9

   Install new chain and tensioner
   Install chain tensioner assembly with new or inspected spring. Install tensioner mounting bolts finger-tight initially. Route new chain around drive sprocket first, then around driven sprocket, ensuring proper engagement on both sprockets. Verify chain runs smoothly in chain guides and does not bind. Rotate input shaft by hand to verify smooth chain operation through full rotation. Tighten tensioner mounting bolts to specification once chain routing is confirmed.
10. 10

    Prepare rear cover for installation
    Inspect output shaft seal in rear cover for damage or leakage. Replace seal if necessary using seal driver. Apply thin bead of RTV silicone gasket maker to rear cover mating surface if not using pre-cut gasket. Apply RTV in continuous bead approximately 3mm wide, circling all bolt holes on the inside. If using pre-cut gasket, position gasket on rear cover and apply light coat of RTV to both sides.
11. 11

    Install rear cover assembly
    Carefully align rear cover output shaft with chain while guiding cover into position. Ensure output shaft engages properly with chain and cover seats fully against housing. Start all mounting bolts by hand to ensure proper alignment. Tighten bolts in crisscross pattern to proper torque specification to ensure even gasket compression and prevent warping.
    ⚠Do not force rear cover into position. Misalignment can damage output shaft or chain.
    Torque spec

    Mounting Bolts31 Nm (23 lb-ft)
12. 12

    Reinstall driveshaft
    Align marks made during removal and slide rear driveshaft onto transfer case output shaft. Install U-joint strap bolts and tighten evenly in crisscross pattern to proper torque specification to prevent joint binding.
    Torque spec

    Driveshaft U-Joint Straps20 Nm (15 lb-ft)
13. 13

    Reconnect electrical and refill transfer case
    Reconnect both electrical connectors to 4WD actuator and shift motor, ensuring locking tabs engage fully. Install new drain plug washer and reinstall drain plug, tightening securely. Locate fill plug on side of transfer case and remove. Using fluid pump or funnel with hose, fill transfer case with 2.5 quarts of Motorcraft Transfer Case Fluid through fill hole until fluid reaches bottom of fill hole threads. Reinstall fill plug and tighten securely.

Reassembly

1. Reinstall any skid plates or underbody shields removed during preparation
2. Reconnect negative battery cable
3. Allow RTV sealant to cure for minimum 1 hour before test driving (consult RTV manufacturer specifications)
4. Lower vehicle from jack stands carefully and torque wheel lug nuts if wheels were removed

Verification

• Start engine and cycle through all 4WD modes (2H, 4A if equipped, 4H, 4L) using dash switch to verify proper engagement
• Listen for abnormal noises during mode changes or unusual chain noise during operation
• Test drive vehicle in 2WD at low speed and verify smooth operation with no vibration or noise from transfer case
• Engage 4H and drive in a straight line on low-traction surface to verify proper power transfer to front axle
• After test drive, re-inspect transfer case for any fluid leaks around rear cover gasket area
• Recheck transfer case fluid level after test drive and top off if necessary
• Verify all 4WD indicator lights function properly and correspond to selected mode

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