New steels impact Mercedes repairs

Mercedes-Benz has introduced boron into the body construction of its three latest models, which means technicians will need to take a new approach when making repairs.

In his technical presentation during the I-CAR International Annual Meeting Friday, Gregg Butts, education supervisor for the Mercedes-Benz Collision Program, outlined where these components are in the new S-Class, CL-Class and W204, and discussed the new repair procedures.

The S-Class includes boron in the inner rocker panel and B-pillar; the CL includes boron in the inner rocker panel, B-post and part of the rear seat/floor cross member; and the W204 includes it in the B-pillar and inner roof rail.

“There are more specific work instructions that have to be followed,” Butts says. “MIG welding is out, because it can turn the boron very brittle. The new mantra for joining technology is: resistance welding first (with or without bonding adhesive), riveting second (with or without bonding adhesive), and MIG or MAG welding as a last resort, but never on boron steel.”

For repairers, this means the cost to repair these models will increase. The spot-weld bits for boron steel are almost $100 a piece, as are the drill bits for making rivet holes.

Any boron that is kinked has to be replaced as a complete unit. “The exception would be the rocker panel on the S-Class and CL,” Butts says. “We have a sectioning procedure for that that uses a heavy-gauge sleeve behind it with adhesive and a lot of rivets.”

Mercedes also recommends MIG brazing for all splice joints on exterior panels. “The reason for this is we have fully galvanized bodies now, and MIG brazing doesn’t destroy that galvanized coating the same way that regular MIG welding can,” Butts says.

Mercedes has updated its repair manuals for these new procedures. All procedures are available online through STAR TekInfo, www.startekinfo.com, for a fee. All Mercedes-certified shops are required to have a full-year subscription to the service, but other shops can purchase daily, weekly, or monthly access.

Butts also provided an overview of new Mercedes safety features and other technology including the Pre-Safe System. If the Pre-Safe system detects that the vehicle is about to crash, it automatically moves the electric seats into safer positions, rolls up the windows and adjusts the seat belts. If the airbags deploy, the windows are automatically rolled down to help expel the gas and powder.

Using the Distronic radar-controlled cruise control, drivers can program a traveling distance to maintain between their vehicle and the vehicles in front of them. Using radar technology, the car automatically adjusts its speed to maintain that distance. Mercedes also offers a “night vision” infrared camera that sends images to a display on the instrument panel. The system provides better visibility than is possible by just relying on the headlights.

In addition, Mercedes has altered its training program so that it awards hour credits instead of day credits to more closely align with I-CAR classes.