What is the first gap to check when fitting a replacement door?

When fitting a replacement door, the most critical initial gap to check is the door-to-rocker panel gap. This gap is essential because it ensures that the door aligns properly with the vehicle's body structure, allowing for smooth operation and a good seal when closed. An accurate door-to-rocker panel gap is crucial for maintaining the structural integrity of the vehicle and ensures that the door does not bind or create leaks.

By starting with this gap, technicians can also check if the door is sitting correctly in relation to the body of the vehicle. Adjustments made to this gap can influence the alignment of all other areas, including the gaps at the windshield pillar, rear fender, and trunk lid. Focusing on the door-to-rocker panel gap first provides a solid foundation for further adjustments throughout the fitting process.