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C4 Corvette Convertible Top Replacement - Just Top This!
Installing A New Convertible Top On Your C4 Is Possible
Apr 11, 2007
Sawyer, MI 49125
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C4 Corvette Convertible Top Replacement - Just Top This!
If this is your first convertible top or your fiftieth, organization always saves time and aggravation. We use a compartmentalized container to place the various screws into and lay each weatherstrip retainer out on the cardboard in their respective right and left positions during disassembly. It may seem impossible, but I've found the weatherstrip retainers switched from side to side.
Removing the antisqueak pads from the front bow takes some tugging, but they usually can be removed intact. If necessary, the soft side of some Velcro works for a replacement pad. These things stick to everything, so be careful where you set them if you plan on reusing them.
While we're at the front bow, we remove the convertible-top material front-bow retainer. These screws are longer thread-cutting screws. This is where you can get in trouble with screw length. Keeping the screws in the correct compartment saves heartache later. Through the ten years of production we've found different combinations of screws used, so just watch the length and their replacement during the install.
The screws that retain the headliner at the front are a machine thread and a specific length. Installing the front-bow material retainer screws during assembly can ruin your day. The screws can go through the top material if the top fits tightly. We run our fingers across the outside of the top in this area before we remove any screws to make sure the correct length screws were in place. In many cases, the screws are incorrect if the top has been previously replaced.
The headliner is now captured over the bow with the plastic strip. Our plastic weatherstrip stuffing tool is used for removal to avoid bow damage from scratches that can cause corrosion. Once the headliner strip is removed, you may find three Phillips head screws that retain the top to the center bows that require removal. While original tops before 1994 used the screws, most of the newer replacement tops don't use them. If you plan on using the original top center-bow retainers, be sure to remove them from the sleeves that they slide into on the top.
The front horizontal and rear vertical weatherstrip and their retainers must be removed to access the top material. The center weatherstrips can be left in place. We're using our plastic weatherstrip stuffing tool to release the weatherstrip just in case we plan on saving them for replacement. We found that peeling back the weatherstrip and applying a 3M weatherstrip release agent (spray can form) behind the weatherstrip helps remove them with less damage.
We've safely removed the weatherstrip, thus revealing the plastic pushpin at the rear of the front weatherstrip that positions it properly. Be careful prying out the pushpin as they're hard to find, even from GM. The weatherstrip had way too much glue and was put together too late, and it never bonded properly. The front weatherstrip retainers have tabs at the front to maintain weatherstrip position. When the top is in the raised position, note the position and be sure to put them in the same place.
The convertible-top material and weatherstrip at the front bow covers the cables used to keep the top material tight against the top frame. These cables must be removed from the top frame. By moving the top to the raised position and then flipping the front section of the top to a vertical position works best during cable removal.
Rear weatherstrip retainer removal can be aggravating since there's a screw buried under the adhesive in the top corner. Screw length is critical here. If you replace any vertical weatherstrip retainer screws, make sure it's the same length. Longer screws will prevent the top from lowering completely.
Once the rear vertical weatherstrip retainer is removed, we can remove the top material retainers. The screws can be tight. Always blow out (via compressed air) the accumulated dirt and debris from the screw head before trying to loosen them. These hard-to-find top material retainers are plastic and sometime stick to the material, so be careful pulling them up.
At the rear bow, we removed this weatherstrip previously and just threw it away. This is the one weatherstrip we have never been able to save. Once it's glued in position, it always tears on removal, so plan on replacing the rear-bow weatherstrip. These retainers are the only means of mechanical convertible-top material retention. We rely on them during top installations to keep the top material in place.
Before you finish ripping off the old top, disconnect the rear-window defogger wiring from both sides of the rear glass. If you raise and lower your top a lot, check the wiring for wear at the connectors. If you convert to a glass top from a plastic top, the wiring is provided in the kit for it to operate properly. On the plus side, GM has provided the wiring under the carpet near the frame pivot points for a quick hookup on a retrofit.
My wife Hope came up with this really slick idea to remove the old weatherstrip adhesive. She applies the Xylene-soaked cloth strips in the retainers to soften the glue. After a little while, the adhesive comes out with ease. We originally would soak the retainers in Xylene, but every time we did, the entire finish coat would come off the retainers, requiring a lot of extra work.
Before you lay the top on, take a minute to knock the staples back into position. They're not visible when the top is on, but eventually they wear at the inside of the top material. Check the center-bow staples as they will also back out over time. The top of the rear bow has the soft-sided Velcro applied to it to prevent glass scratches during top lowering. If it's in bad shape, replace it now.
This is the crucial part of the top installation. If the top positioning is off here, the entire top placement will suffer. We originally would glue the top material around the rear bow by measuring carefully and hoping that the top was in the correct position when we got to the sides. We then realized that gluing the vertical section first made more sense. This procedure allows the top material to find its own relaxed position and avoid wrinkles or too tight areas.
This is what a correctly positioned top looks like. The corner is covered, and the material welting is right on top of the vertical raised edge. When the plastic retainer strip is installed, it has a tendency to pull the welting inward which won't allow the weatherstrip to lay flat. We push the material into the recess for the retainer to avoid welting misplacement. Now is a good time to take a break and let the adhesive dry for 30 minutes. The lower vertical portion of the convertible-top material can slide around if the adhesive isn't totally dry.
We pulled the top material over the rear bow in preparation of applying adhesive. This is another crucial step in proper fit. The idea is to let the material seek its "happy place" and roll the edge over the lip of the bow. Once the material is in place, the adhesive is applied while rolling the material over the edge and holding it in place for a few minutes. The convertible top has two pieces of material to be glued on the rear section of the bow, while the sides only use one piece of material for retention.
If the vertical positioning of the top was correct, when you finish gluing the rear bow, the corners should look like this: rolled over the edge with no buckling of material. Nothing looks worse than a top that is rolling away from the bow and has a big gap between the rear deck and the top when latched in position. When properly placed, the top material should be close to the deck at all points.
We use a homemade hooked wire to pull the cables through the sewn-in chases for the side retention cables. The cables are then hooked into the frame at the front-bow area. These cables are also available from Corvette Central if necessary. Since they help keep wind noise down and prevent water intrusion, you don't want to leave them out.
Now that the cables are in place, we can finish the top install at the front. We roll the material over the front bow and then put the top in the raised position to again let it seek its proper position naturally. We also can take a look to see if things are fitting correctly. If yes, we then apply adhesive and finish up the gluing. Remember to keep the edge of the welting slightly upward and tight against the edge when gluing for the best finished look.
All of the later tops use an adhesive applied to the center-bow retainer strips to keep the retainer strips in place until the headliner retainer strips are clipped over the center bows. We stuck the top center strips in place, and now we're pushing the headliner retainer in place, which can be very difficult. We found that silicone spray can help ease the retainer in place. these center top retainer strips can rip loose, giving some tops that "ballooning" effect.
GM used closed-cell foam to seal the weatherstrip retainers to the convertible-top frame which we found difficult to source. Home Depot has a roll of a very similar product called Armacell insulating wrap. This product allows you to cut it to fit, and it provides the same type seal with an adhesive backing as the original product.
Now is the time for any needed adjustments to reposition the top, and these can be made at the rear bow. Remember the rear bow weatherstrip is a one-shot install, so make sure you're satisfied with the top placement before you glue the weatherstrip in place. When everything looks correct, and the excess top material is cut from the rear bow, the rear bow weatherstrip is installed by stuffing it into the retainer after applying a bead of adhesive.
If you're replacing all the weatherstrip like we did, you can install the center weatherstrips now. The two plastic pushpins can be aggravating to install because they're placed at an angle into the retainer. It's important to use them for proper weatherstrip placement. Just feel around until they start to go into place. They will go in somewhat easily once positioned properly. The job is now complete.
A brand-new top on a sweet Corvette is hard to beat.
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