Weather stripping protects your car from wind and moisture, keeping the elements away from your door and windows. Door seals are needed to keep your window mechanisms in good working condition and to protect the door panels from rust and corrosion. They also cushion the door frame during numerous door-slammings that could otherwise jolt hardware and mechanisms. Many minor repairs can be performed on loose moulding, but when weather stripping becomes hard and cracked, it is best to replace it entirely.
Purchase an after-market weather stripping for the make and model of your car. After-market stripping is often of better quality than factory-installed door seals and is available in appropriate lengths with pre-seated T-clips on some models. You will also need a tube of weather stripping adhesive available in most retail store automobile sections. If you have a choice of colours, pick one that most closely matches the colour of the weather stripping.
Check for any screws you may need to remove in the old stripping and remove, if needed. Lightly peel the old stripping from the frame, pulling the rubber studs from the holes carefully.
If the stripping is old and hard to remove, apply a weather stripping remover over the seal, allowing it to soften for easier removal. Be sure to remove any leftover adhesives that remain in the door frame as well. Be sure the area is clean and free from debris.
Check to be sure the new weather stripping matches what you just removed, lining it up to see that it has the same channels and studs on the underside as the original stripping. Use a small amount of adhesive on both the strip and surface of the frame on the end of the stripping you will be applying to the door frame first. It is recommended to start on the top corner with most hardtops and convertibles.
Misaligning your weather stripping can cause problems down the line such as window warping---a problem that occurs after time from repeatedly forcing a window closed over a misplaced piece of rubber. Start in one corner of the window, making sure to match up the studs, and lightly apply the adhesive to frame and strip. Push the rest of the stripping into place as you continue around the door frame, continuing to apply adhesive as you go along. Do not stretch the rubber as you go, and be sure the corners are lined up properly. When satisfied, press firmly and replace any screws, if needed.
For door seals that have small air leaks, use a clear silicone sealer to seal in the cracks.