TSBs

Quieting BMW cracking noise

May 30, 2025

This bulletin applies to rear wheel drive BMW vehicles equipped with the 8HP51 automatic transmission only (no xDrive models).

Mike Mavrigian

Related To:

Mitchell 1

While holding the flange stationary, torque the new collar nut to 60 Nm (44.25 ft-lb).

This bulletin applies to rear wheel drive BMW vehicles equipped with the 8HP51 automatic transmission only (no xDrive models).

A cracking, metallic noise may be heard from under the center of the vehicle, when there is a load reversal from off-throttle to on-throttle or vice versa, or while stationary when changing gear from drive to reverse or reverse to drive.

The cause: unfavorable tolerances of the output flange to the automatic transmission.

Replace and re-torque the collar nut on the transmission output flange. Do not remove the flange. Replace the collar nut and tighten to 60 Nm. Peen the nut with an 8mm punch. The M27-15 nut is available as P/N 24-20-7588761.

About the Author

Mike Mavrigian | Motor Age Editor

Mike Mavrigian has written thousands of automotive technical magazine articles involving a variety of specialties, from engine building to wheel alignment, and has authored more than a dozen books that crisscross the automotive spectrum. Mike operates Birchwood Automotive, an Ohio shop that builds custom engines and performs vintage vehicle restorations. The shop also features a professional photo studio to document projects and to create images for articles and books.