Is that sagging headliner in your car or truck becoming ugly? No one wants to drive around with fabric hanging down from the roof of their vehicle. Its not only an eyesore it can be dangerous. Sometimes what starts as a small bubble in your car's headliner can turn into an bigger and bigger mess. This is easy enough to fix.
With your socket set, disconnect the negative battery terminal cable, cutting all power to the vehicle.
Remove all overhead interior light fixtures completely, including all wires that might prohibit their removal. Mark the wires with masking tape and label them in some way so that you can reattach them properly.
Remove the screws or TORX bits (depending on the make of your vehicle) from the mouldings that hold the headliner in place, and remove the mouldings. The headliner should now be free.
Carefully remove the headliner from the vehicle, trying not to bend it.
Place the headliner face up on a clean surface and inspect the fabric.
Peel back the fabric as necessary to expose the cardboard underneath. Peel it back slightly beyond the locations of the initial problem areas.
Using your putty knife or scraper, remove any loose debris left over from the old glue or foam.
Apply a light 3-4 inch swath of spray glue across the length of the exposed area closest to the edge where the fabric is still attached. Using your hand, slowly apply the fabric onto the newly sprayed area, pushing out any bubbles or kinks as you go. It is not advisable to spray the entire area in one shot. The smaller the area you work in, the easier it will be to get good results.
Keep repeating the glue process until you've reattached the fabric to all sections. Follow the dry-time guidelines for the spray glue. Once dry, inspect the headliner for any bubbles and reverse the removal steps to reinstall the headliner.
Use a good quality, fabric-safe spray glue. And don't overuse it. Excess glue will soak into the fabric and ruin it with dark crusty spots. If you want a perfect, seamless, factory-uniform look, it might be best to buy some new fabric and start from scratch. Most headliners have a thin layer of foam which deteriorates, so the newly glued area may have a slightly different look.