Pre and Post Measuring Collision Damage
Why panel gap movement has changed?
Two words, pedestrian safety! Have you noticed that on most vehicles the fenders do not bolt directly to the upper fender apron rail? The fenders are bolted to perches that are weak and bend easily. This is not a design flaw, but an effort to reduce severity of injuries to a pedestrian if struck, allowing the collison energy to be absorbed by the vehicle and not the pedestrian .
These pedestrian safety advancements coupled with new structural substrates such as, advanced steels and aluminum, allow for structural movement without any changes in the panel gaps. So, what does this mean for our ability to use traditional visual indicators to determine the need for a structural/frame repair? The reality is, panel gaps are no longer reliable to use as the determining factor regarding whether a vehicle needs to be measured for structural misalignment.
ADAS adds complexity
In the past, structural alignment had almost everything to do with panels fitting properly and the vehicle tracking straight down the road. However with today’s vehicles, ADAS adds a very important layer to the need for ensuring the structure is correct. The frame and unibody must be returned to the designed structural dimensions in order for the ADAS to function properly. In order for the ADAS sensors to track the position of the vehicle in space and real-time, the thrust angle must be true to the structural centerline. This creates the need to pre-measure the vehicle to determine if the structure has moved in length, width or heighth.
There are many reasons to “post” measure a vehicle and here are our top two:
- Confirmation that the vehicle’s structure is repaired to the safety and functionality intended in the design. We can no longer “eye ball” things and assume everything is right when we can measure and know for certain. Following OEM procedures is necessary to restore the vehicle, however, simply having the repair procedure in the file is not enough.
In addition to the OEM procedure documentation, you must take photos of the vehicle during the different stages of repair to provide proof that you actually followed those repair procedures. In addition, when the installation method calls for welding, you must create test weld coupons to ensure the welder is functioning properly. Including photos of the test weld coupons before and after their destructive testing is another excellent way to provide proof of adherence to the manufacturer’s requirements. One area where almost everyone is missing the mark is providing post repair measurements to show absolute proof that the vehicle has been restored to OEM specifications.
- Ensuring that all ADAS sensors, cameras, radar or lidar units and their mounting brackets are returned to their proper locations during the repair is extremely important. Did you know that if the radar or lidar unit of the forward assist braking or adaptive cruise control systems is off by just 3mm, at 300 feet in front of the vehicle, the beam is off by almost 18 feet! At 600 feet it is double that amount. That same 3mm difference on one of the cameras of the blind spot warning system could allow the driver to change lanes into another vehicle because the system didn’t see it correctly. A 3mm difference, which is about the thickness of 3 dimes is imperceptible to the naked eye, but will cause the systems to function improperly. If the vehicle owner is relying on the systems to perform as they did prior to the repair, this could result in another collision event.