Some Thinks suffer from headliners that droop down and irritate tall drivers. We’ve consulted a local auto upholstery shop about this and were told that it is common for the thin plastic foam type to deform after sitting in the heat of a closed car in the sun. We have attempted to repair the headliners by gluing plastic foam stiffeners to the top side of the headliners, but some of these have come back only to have a much more firmly sagging headliner. I am not certain whether it was my choice of material (dumb, I know to use basically the same material that had already failed) or adhesive (dumb, I know, to use hot glue in a high temperature application) or both that failed.
The upholstery shop advised us of a good temperature stable adhesive to use on the headliner: Silglaze II, GE SCS2800. They also suggested for a quick fix we could simply squirt some adhesive above the headliner, use a 2×4 to wedge it right up to the plastic roof panel and let it set like that. I would still like to pursue a solution that keeps the headliner removable from the car and leaves a bit of an air buffer between the interior and exterior for noise and temperature insulation.
Update:
I haven’t yet found a good rigid temperature-stable foam, but I did try a different approach: I cut out fairly thin ABS plastic arches which have the bending stiffness that I need (except for buckling). I then sandwiched the ABS between two similar shapes of (poly?)urethane foam (camera case foam) which prevent buckling and provide area to bond to the top side of the headliner. The Silglaze is kind of expensive, but it seems to work. I have 1 or 2 of these headliners all glued up and ready to swap out, but the whole composite beam idea is kind of a lot of work, so I’d rather just wait to advertise a new and improved fix until I try out a better material. I’d also like to try doing the retrofit with the headliner not really removed from the car– sneak the beams in from the side and wedge the headliner up until the glue sets.
Below is a photo of the first repair attempt using polyethylene foam: A disappointing failure!
JM