The dash of a friends 1996 2.8l A4 was warped severely by the Florida sun. It had pealed back at the leading edge all the way back to about the middle of the dash. The leading edge window area, upper air vent, and around the dash airbag were all severely warped. However, the underlying polyurethane dashboard cover foam was in good condition. The dash was out of the car for a heater core replacement and new or used dashboard replacement wasn't an option as this was a low budget repair project.
Note: The dash has low density polyurethane foam, so I had to stay away from adhesive polymers containing styrene or the styrene would eat the urethane foam.
I found an adhesive at the auto parts store which works specifically for automotive polyurethane applications (3M Super Trim Adhesive), which I bought from Discount Auto.
With this stuff, the trick seemed to be applying heat to the dash prior to applying the adhesive so the plastic top layer of the dash would become malleable (what's that made out of anyway; vinyl?)
Note: For heat, I used three 150W work lights about 1 foot away from the dash components.
Then I sprayed 4 layers of adhesive to both the plastic dash shelf, and to the dash cover foam.
Leaving the heat on the dash, I pulled the dash cover taught and clamped the worst areas with an old piece of wood molding I had laying around so I could distribute the clamp load to as much area as possible. I had to leave the clamps on for about 5 minutes, and then I kept moving on to other areas which needed clamping.
The heat helped the adhesive to set faster and allowed me to move quickly to keep clamping different areas before the adhesive set up, while still providing enough tack to hold the area I just glued.
My final step was to spray another coat of adhesive just along the leading edge where the dash snugs up against the window and clamp. I wanted to make sure that leading edge is really on there good assuming it will begin to peal again there first.
Unfortunately, the dash cover with foam had shrunk and couldn't be pulled tight enough to fully cover the plastic dash mount.When we installed the repaired dash, the exposed part of the plastic dash showed glue residue which could be seen through the windshield. We simply pulled it back out and painted the exposed portion flat black to conceal the flaw.
The end result didn't look too bad for a $12 repair job, especially considering how bad it was to start with.
We'll see how it holds up.
Dash Airbag - Before
Dash Airbag - After
Upper Vent - Before
Upper Vent - After (I was even able to get the accent contour back; rather than a bubble shape)
Front of Dash - Before (looks kind of like an alien robot warrior)
Front of Dash - Before
Front of Dash - After
Front of Dash - After