While not an especially complicated procedure, replacing a convertible top is anything but easy. This little restoration project can run the gamut from labor-intensive to almost impossibly frustrating, depending on your level of skill, patience and experience. All it really requires is a the proper replacement materials, a good set of tools and a weekend's worth of daylight hours.
Before replacing any convertible top, you must first asses what materials you're going to need. Most cars came with a glass rear window (called a "rear curtain" in body-shop parlance), but many have received a vinyl replacement after the original glass (inevitably) broke. When choosing a replacement, you're going to need to decide whether or not to go with a glass window for clarity and originality, or a vinyl equivalent for cost, fitment and durability. Modern vinyl windows are a lot tougher and more UV-resistant than older kinds, but will still eventually suffer from tiny scratches and scuffs. You'll also need to determine whether or not the convertible top's frame components are damaged and in need of replacement. After all, a top is only as good as the components that raise and lower it.
Removing the top is pretty simple, but you're going to need to note the location of the rear bow (support). While many upholsterers shops have manuals with measurements for rear bow locations, you probably don't. Easier to just make the measurements and mark the locations yourself.
Almost all convertible tops are held on in the same way: the top it stapled to cardboard or vinyl rubber tack strips that are held to the frame with industrial adhesive. Shun originality of cardboard tack strips in favor of the vinyl's functionality; cardboard absorbs a lot of moisture and will hasten the development of rust in the frame. Just make sure to strip all of the old tack strip material from the frame, or you're certain to encounter leaks.
Don't expect to get a perfect fit the first time; many professional upholsterers go through several cycles of fitting, stapling, removing and adjusting the top before they achieve the perfect fit. One trick is to fit your top material with the frame elevated from the windshield mount by about a foot; that way, the material will tighten itself when you drop the top.
When finishing up your installation, most upholsterers recommend letting the top sit in the sun for a day to allow for stretching, and leaving the top up for a month so it will maintain the proper shape.
Many cars (particularly older GM models) have hinges with a nasty habit of shucking their protective covers and tearing holes through the top. Make a couple of hinge slip covers from some thin interior carpet, and install them with zip ties.
Rear seat backing trays take a lot of abuse, and an old one will make your new top install look cheap and ill-executed. When replacing a backing tray, always install it with the vinyl side facing down.
