Technical Bulletin Bulletin No: TCH-002-010 Subject: Effective Date: 6/2/08 Cancels: N/A Retrofitting Wide-Based Tires: Increased Vibration Requires Improved Air Chamber Bracket Supports This Bulletin addresses vehicles originally equipped with dual tires on the drive axles which are retrofitted with “wide-based” tires (also referred to as “Super Singles”). Test data has shown that retrofitting “wide-based” tires can result in higher vibrational loading of vehicle drive axles and wheel ends. As a result, the air chamber bracket supports are potentially exposed to vibrations and stresses beyond their original design capabilities. As with all retrofits, Bendix recommends that the installer confirm with the vehicle Original Equipment Manufacturer (OEM) that the changes to be made to the vehicle are approved and obtain from the OEM any vehicle modifications that are required (e.g. suspension clearances, etc.) before proceeding. When vehicles equipped with Bendix foundation brake components are retrofitted with wide-based tires, Bendix requires the vehicles to be further equipped with: • • Page: 1 of 2 Air chamber brackets with gussets (see Figure 1). If the air chamber brackets do not have gussets, they must be replaced with Bendix approved air chamber brackets with gussets. Identify the part number stamped into the support arm (see Figure 2 for location) and refer to BW7253 for the proper gusseted replacement. Bendix “Marion” air chamber bracket supports or other Bendix approved air chamber bracket supports, welded to the axle, are required (see Figure 2). Failure to make all necessary changes when retrofitting wide-based tires will void the warranty on all Bendix® foundation brake products equipped on the vehicle. GUSSET Example of Air Chamber Bracket without Gusset Example of Air Chamber Bracket with Gusset FIGURE 1 - EXAMPLES OF AIR CHAMBER BRACKETS WITH AND WITHOUT GUSSETS AIR CHAMBER BRACKET PART NUMBER STAMPED HERE “MARION” AIR CHAMBER BRACKET SUPPORT (TYPICALLY 820188) FIGURE 2 - EXAMPLE OF “MARION” AIR CHAMBER BRACKET SUPPORT WARNING: Follow all standard industry safety guidelines when welding, including disconnection of batteries. (Continued over) Bulletin No: TCH-002-010 Effective Date: 6/2/08 Cancels: N/A Page: 2 of 2 FIGURE 3 - EXAMPLE OF SUPPORT WELD ARRANGEMENT Whenever available, use the axle manufacturer’s recommendations for welding the additional “Marion” brackets - the welding notes below are shown for reference only (See Figure 3): • • • • E70T-5 FCAW or ER70S-6 GMAW Single Pass Process 600F (15.50C) Minimum Pre-Heat Temperature Maximum Fit up gap of 0.16 inch (4mm) The order of welding may be reversed or started on the opposite side The direction of welding may be completely reversed Reference: Application Guideline Catalog - BW7260 Illustrated Parts List - BW7253 Available from the Literature Center at www.bendix.com and also from www.Roadranger.com. Questions or changeover information: Call 1-800-Air-Brake (1-800-247-2725) © 2008 Bendix Spicer Foundation Brake LLC 6/08. All Rights Reserved. Printed in U.S.A.