FEATURE Is It Bent? WMABA Learns About Structural Diagnosis at Annual Membership Dinner “Is it bent, and how do you know?” Shawn Hart (Audi) read the title of the structural diagnosis class he was about to teach as he quipped, “Is that a trick question? When we discuss vehicle structure and damage analysis, we first talk about body structure because when a technician seeks to remove one damaged part, they often have to take six other parts off the car in order to remove that one part. I assure you there isn’t a laboratory in Germany where evil engineers are thinking up ways to screw body shops - everything that’s done to the body during production is done for a purpose.” WMABA welcomed Hart for a presentation on “Structural Diagnosis: Is It Bent? How Do You Know?” during its Annual Membership Dinner at PJ Skidoos in Fairfax, VA. The body structure of a vehicle is supposed to do two things: absorb energy and transfer energy, according to Hart. Crumple zones were designed to absorb as much energy as possible, but once that energy reached a point where nothing more could be absorbed, vehicle manufacturers had to find a way to transfer it. “Engineers developed different load paths for that energy to follow, so that it goes around the passenger compartment and not through the passenger compartment,” Hart explained. “Because of these load paths, we get damages in places where people don’t think about, such as a car that was hit in the front and there’s a buckle in the roof. For example, on an Audi A8, the upper rail is part of that load path that helps direct energy up into the A pillar and into the roof, and you’ll see the lower, smaller frame rail transfers that energy into the engine crossmember and down underneath the car, so that energy has someplace to go.” Hart identified several visual cues that can help technicians identify potential structural damage while they’re diagnosing a car, including the appearance of cracked paint or body sealer, stressed and split seams, broken welds, panel tension, bent or broken interior components, NVH (squeaks, rattles and vibrations) and out of spec panel gaps. “You have to have the right tools for the job when we get to the point of measuring things,” Hart stressed. “Those tools are used to more accurately determine where things are broken and bent, but you also need to reference the specifications to double check your work and make sure things are bent or not bent.” While measurements are necessary, they’re pointless
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without the manufacturer’s specifications which are also useful for demonstrating to the customer that the repair was performed properly. “In Audi’s repair procedure manuals, we provide information on measurements which show the different dimensions that can Shawn Hart be checked, but it also gives the technician some additional information they’ll need, like the tolerances on our vehicles when they’re measuring,” Hart said. Vehicles manufactured by Audi have a strict structural tolerance of only two millimeters, and “if it’s outside that dimension in either direction, one of two things is happening on most of Jordan Hendler our cars,” Hart cautioned. “If it’s on the front, either something’s getting cut off and replaced, or straightened, depending on the model.” Hart shared that Audi only permits cold straightening these days, before he dove into some of the precautions that technicians need to take into consideration with modern cars and electrical control modules, especially on hybrid and electric vehicles. “Technicians need to understand how to disconnect the battery because it’s not as simple as ‘disconnect this lead or this lead;’ when you look at our batteries now, they have a lot of leads so you don’t always know which one you need to disconnect,” Hart elaborated. “You may need to follow a procedure to de-energize the battery or the whole system, and it’s important to note that most of our cars now have a secondary 48-volt system. If you disconnect that without de-energizing things, that’ll put you down.” Hart reiterated the importance of reviewing OEM repair procedures before performing any repair, structural or otherwise, and suggested that a valuable resource for this important information is oem1stop.com.
