A DIY Rebuild
Like engine timing chains, transfer-case drive chains eventually stretch. The tipoff is often intermittent popping noises or thunks coming from the center of the vehicle. Differences in front and rear driveshaft play when 4WD is engaged and the vehicle is parked are another indicator that the chain is jumping teeth on the sprocket.
Replacing a transfer case chain is entirely doable for anyone who has seal drifts/large sockets and snap-ring pliers. Craig Calkins, owner of CRC Performance Transmission, demonstrated the job. He has 30 years’ experience and does it from memory, but the average enthusiast might want to have a shop manual on hand for torque specs and any model-specific procedures.
- Lifetime fluid isn’t. Heat and condensation degrade it. CRC recommends changing it about every 30,000 miles, depending on use and conditions. Chain-drive transfer cases often use ATF. Consult an owner’s or shop manual for recommended fluid.
- Even electric-shift 4WD systems should be run in low-range (at low speed) monthly. This keeps the actuation motor from seizing.
- The same model BorgWarner transfer case could be used in multiple vehicles. However, internal parts might not be interchangeable among different automakers.
- A cracked case is often a death sentence. Less popular BorgWarner applications such as Hyundai and Kia can be expensive in junkyards. New, they might exceed the vehicle’s value. Rockland Standard Gear (www.rsgear.com) is one comprehensive source for different models and applications.
- Carefully separate the case. Snapping off an ear can undermine the overall effort.
- Spray all fasteners and especially plastic parts liberally with penetrating lubricant prior to removal.
- Inspect clutches for burn marks or wear on the fiber.
- Mark locations of all brackets and ID tags prior to removal for accurate reassembly.
- Aluminum case castings can be rough. To prevent leaks, coat the lip liberally with silicone before screwing the case back together.