NV125 Transfer Case Drive Chain HV-059 for BMW X5

This is a replacement drive chain for the New Venture NV125 transfer case, the all-wheel-drive case BMW used in the X5. It is sold under the HV-059 and HV-088 numbers and cross-references to 27293, 88935661 and LWX 500. The supplier also lists NP126, NP226 and NV140 applications, so match the number on your old chain before you order.

Why it gets replaced: the chain is the only link between the rear output and the front output, and on a high-mileage NV125 it stretches until it rattles against the case on acceleration and deceleration. A worn chain shows up as a clunk when you get on and off the throttle, a grinding or rattle from the case at low speed, and fine metal in the transfer case fluid. Left alone, a stretched chain can skip on the sprockets or chew into the aluminum case.

On the bench: drain the fluid, remove the front and rear driveshafts and the transfer case. Separate the case halves, then lift out the chain together with the front output shaft and sprocket. Inspect both sprockets and bearings; replace anything with worn teeth or rough bearings so the new chain is not riding on damaged parts. Install the new chain, reseal the case, and refill with the fluid specified for your vehicle.