In this How To, I will show you how to align new rub strips perfectly in a repeatable way. I recently installed a new rub strip on my passenger door, so that process will serve as the example.
1. Obtain a long, wide straight-edge. Attach to the door with clamps (not too tight) as shown. You will want to generally place the straight edge just below the door handle, in the case of a door, since the handle is relatively fixed in position. Side marker lenses could also be used in the case of working on a fender.
2. Obtain a contour gauge. One like this can be purchased from Lowes for $5.95.
3. With the contour gauge placed perpendicularly to the straight-edge, press gently to capture the shape of the straight-edge and door profile. We will use this shape to align the straight-edge at the opposite edge of the door. You'll note that the straight-edge creates a nice rectangular "slot" in the contour gauge.
4. Move to the opposite edge of the door, and using your contour gauge, adjust the straight-edge vertically so that the contour gauge pins align with both the "slot" for the straight-edge, and the profile of the door. Do not disturb the pins of the contour gauge when doing this, since doing so will lose our reference.
5. Once the straight-edge has been adjusted, double check the previous edge, near the door handle, to make sure that we did not shift the opposite side of the straight-edge while we were adjusting. Simply checking the fitment of the contour gauge against the door handle once more will accomplish this. Now, with the wax paper still attached, allow the rub strip to lie on the straight edge and visually inspect it.
6. In general, you will be comparing space between the central "ridge" of the door/fender with the location of the rub strip. The distance should appear uniform, and it is easiest to verify this by looking at the door from a low angle like this:
7. If satisfied, remove the wax paper slowly, and work your way down the door, pressing the rub strip into position, using the straight edge as a guide. I have found that rub strips need to be stretched very slightly to avoid gaps between the door handle and/or door edge.