CORVETTE HARDTOP REPAIR (SERVICE PROCEDURE)

Model and Year: 1989-90 Y CAR

The following gives information necessary for the repair of damage to hardtop roof sections on 1989 and 1990 Chevrolet Corvettes.

IMPORTANT INFORMATION:

A small number of early 1989 hardtops (before VIN K5121847) may exhibit a depression, or sag. If this condition exists, call American Sunroof Corporation using their hardtop help line to receive a replacement top at:

HARDTOP HELP LINE: 1-800-ASC-BGKY (1-800-272-2459)

The help line is also to be used for any technical questions regarding the repair of Corvefte hardtops.

Before cutting, drilling or performing any similar operation, be sure to check the opposite side of the area to insure that the repair will not cause damage to any electrical, structural, or cosmetic portions of the top. Be sure that the operation will not interfere with and/or cause binding of any mechanical or electrical functions.

Straightening of steel and aluminum parts in the hardtop must be done with caution. Fiberglass parts can not be straightened because they do not "take a set" like most metal parts do.

Check the top thoroughly for cracks and broken bonds before, during and after repair. These conditions will usually grow larger if left uncorrected.

IMPORTANT: Because the hardtop is made of R.T.M., which is different material than the S.M.C. which makes up the Corvette body panels, polyester (and not epoxy) is recommended when performing repairs to the hardtop.

COSMETIC REPAIRS OF SCRATCHES, PITS, AND MINOR IMPERFECTIONS:

Cosmetic damage is a type of flaw in the body panel. It merely detracts from the appearance of the panel, but does not cause any actual physical damage, such as a loss of strength. Typically, these flaws are surface imperfections, such as scratches or chips that penetrate through the paint and perhaps only slightly into the fiberglass laminate.

In many instances, a scratched panel will involve only a paint refinishing job. In cases where the panel has been scratched or pitted into the plastic laminate, the following procedure should be used:

PROCEDURE:

---------- 1. By sanding, remove all the paint down to the plastic laminate in the area of the damage.

2. Feather the edge of the repair area using #80 - #1 20 dry sandpaper on an orbital DA sander.

IMPORTANT: DO NOT SAND TOO DEEPLY INTO THE FIBERGLASS MAT. Should it be necessary to cut fairly deep into the fiberglass mat, use the repair suggested in "Plastic Build-Up Technique."

3. Use Sikkens Polystop LP or equivalent to build-up area to establish the original contour.

4. Finish block sand areas with #280 - #320 dry sandpaper.

5. It is recommended that the entire hardtop be repainted. See Chevrolet Dealer Service Bulletin No. 87-292-10 for paint specifications and application.

PLASTIC BUILD-UP TECHNIQUE

In some instances, the damaged area requires a plastic build-up to restore the original contour. When the fiberglass laminate is not pierced through or the damage is not extensive, the repair is as follows:

1. By sanding, remove paint down to the fiberglass laminate from the area surrounding the damage.

2. Grind or file to form a "V" at the damaged area. The side of the "V" should have a pitch for maximum bonding surface.

3. Scuff sand area surrounding damaged area to provide a good bonding surface.

4.Clean work area with Sikkens M-600 cleaning solvent or equivalent. Use a tack rag for finish clean up.

IMPORTANT: Cleanliness is very important. Be sure repair area is clean and free from dust and debris.

5. Cut to proper size, buildup patches out of 1-1/2 ounce fiberglass mat.

6. Mix polyester resin and hardener as indicated by the manufacturer.

IMPORTANT: Remember, cleanliness is important. Mix the polyester in a clean container. Do NOT use waxed cups for mixing. Be sure to close resin and hardener containers after use.

7. Apply a layer of resin and then work in a fiberglass patch until the resin completely penetrates through the fibers.

8. Continue to build up layers of fiberglass and resin until the surface is approximately 0.8mm (1/32 inch) below the normal contour of the surface.

9. Finish the last build-up with Sikkens Polystop LP or equivalent.

10. Apply heat to repair area. Heat lamps are recommended to be used at least 300mm (12 inches) away from the repair. Allow at least one hour curing time. If heat lamps are unavailable, allow to cure at room temperature of 21 to 24 Celsius (70 to 75 Fahrenheit) for eight to ten hours.

11. Finish the repair by grinding, sanding and cleaning in the usual manner.

12. It is recommended that the entire hardtop be repainted. See Dealer Service Bulletin No. 87-292-10 for paint specification and application.

STRUCTURAL REPAIRS

Damage to the hardtop such as cracks or holes that pass completely through the thickness of the fiberglass laminate and into the foam core are known as structural damage. This type of damage can affect the strength and structural soundness of the laminate. All structural repairs require the use of fiberglass patches to provide the mechanical strength needed to keep the repair structurally and visually intact during normal usage. The patch also provides the required foundation to build and form the exterior surface to match the original contours. The following is recommended for these types of repairs:

IMPORTANT: Any damage that fractures the hardtop through both layers of laminate and foam core substructure is to be considered non-repairable structural damage and the hardtop should be replaced. Any damage that deforms the roll bar or steel reinforcements in the hardtop, even though there appears to be no major fractures in the laminate, should be considered non-repairable damage and the hardtop should be replaced.

1. Sand off finish from around the damaged area and inspect for cracks in the laminate.

2. Remove all broken and fractured laminate and grind a "V" around the hole to provide maximum adhesion.

3. Cut fiberglass patches to fit the opening.

4. Clean area to be repaired with Sikkens M-600 or equivalent.

IMPORTANT: Cleanliness is very important. Be sure that the repair area is clean and free from dust and debris.

5. Mix polyester resin and hardener at ratio recommend by manufacturer.

IMPORTANT: Remember, cleanliness is important. Mix the polyester in a clean container. Do NOT use waxed cups for mixing. Be sure to close resin and hardener after use.

6. Coat opening with resin/hardener mixture and apply fiberglass patch. Using a 25mm (1 inch) brush saturated with resin/hardener mixture, pack fiberglass firmly into opening. Make sure you have thoroughly wetted the fiberglass patch.

7. Repeat step 6 until the damaged area is built up to approximately 0.8mm (1/32 inch) below the original contour of the surface.

8. Finish the build up with Sikkens Polystop LP or equivalent.

9. Apply heat to repair area. Heat lamps are recommended to be used at least 300mm (12 inches) away from the repair. Allow at least one hour of curing time. If heat lamp is unavailable, allow to cure at room temperature of 21 to 24 Celsius (70 to 75 Fahrenheit) for eight to ten hours.

10. Finish the repair by grinding, sanding and cleaning in the usual manner.

11. It is recommended that the entire hardtop be repainted. See Dealer Service Bulletin No. 89-292-10 for paint specification and application.

Labor Operation: Labor Time: --------------- ----------- A0915 Panel, Removeable Hardtop Color Coat Inner Material GH 1.6 Hours

A0916 Panel, Removeable Hardtop Color Coat Outer Material GM 2.0 Hours

B2625 Panel, Removeable Hardtop R and R 0.5 Hours

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.