Body - Highway Speed Wind Buffeting Noises: Overview

SI B54 04 08
Special Roofs

September 2009
Technical Service

This Service Information bulletin supersedes SI B54 04 08 dated August 2009.

[NEW] designates changes to this revision

SUBJECT
Wind Buffeting/Pressure Noise at Highway Speeds

MODEL
E93 (3 Series Convertible) produced up to 8/2008

SITUATION

When driving at highway speeds, typically between 55-65mph with the Retractable Hardtop (RHT) fully closed, a pulsating pressure sensation can be felt and heard.

The intensity of the noise increases when driving over coarse surfaces.

Driving outside this speed range will fully eliminate the noise.

This noise is most commonly compared to the noise heard when one of the rear windows is opened slightly on a 4-door vehicle.

CAUSE

A resonant frequency is reached at this speed which causes the convertible top cover (forward of the trunk lid) to vibrate, altering the acoustics inside the vehicle.





PARTS INFORMATION

The recommended applicator for the structural foam is the MIXPAC(R) pneumatic applicator, model number DP 400-85-01. This applicator may be obtained from Conveniently Packaged Adhesives (CPA) by:

^ Calling (401) 946-5508;





^ Faxing the order form shown above to (401) 946-5526; or

^ Emailing info@forcpa.com.

For additional information on this product or how to order it, please visit the CPA website at www.forcpa.com








WARRANTY INFORMATION

Covered under the terms of the BMW New Vehicle Limited Warranty.