The installation of a convertible top is a complex and time-intensive process that requires attention to detail, mechanical skill, and patience. Whether replacing a damaged top or upgrading to a new design, users must carefully follow procedures to ensure proper alignment, functionality, and durability. This guide synthesizes key insights from multiple installation experiences, manufacturer instructions, and technical manuals to provide a detailed overview of the steps, tools, and considerations involved in the process.
Overview of Convertible Top Installation
Convertible top installation involves replacing the soft or hard top of a vehicle, often including adjustments to the frame, cables, and hardware. The process is typically more involved for older models, such as the 1972 Oldsmobile Cutlass Supreme Convertible and the 1978 MGB roadster. These vehicles use a two-piece top system, commonly found in GM A-body cars and classic British sports cars. The top is often paired with a rear curtain and window assembly, which must also be properly aligned and secured.
According to several sources, the installation process can take over 30 hours, especially for first-time installers. It is described as a "frustrating and fragile process," where instructions are often unclear, and hidden issues are frequently uncovered during disassembly. Users are advised to proceed methodically, document each step, and ensure that all components are compatible and in good condition before beginning.
Pre-Installation Preparation
1. Assessing the Existing Condition
Before installing a new top, it is essential to inspect the existing one and the supporting components. As noted in one of the sources, a 1972 Cutlass had signs of water damage in the trunk, tears along the sides, and rust on the top frame. These issues can affect the fit and performance of the new top, and may require repairs or replacements before proceeding.
The frame, hydraulic mechanisms, and tack strips should be evaluated for wear or damage. Any rust or corrosion should be cleaned and treated. If the frame is not functioning properly, it may need adjustment or replacement. In some cases, users opt to restore the trunk area to improve the overall condition of the vehicle.
2. Selecting the Right Replacement Top
Replacement tops are typically available in two styles: vinyl or canvas. Vinyl is the original option for many classic vehicles, but canvas is often preferred for its durability and aesthetic appeal. Users must consider factors such as color, material, and the type of rear window—plastic or glass. Glass windows are generally more durable and offer better visibility, while plastic windows are lighter and easier to handle.
Additional options include a zip-in rear window, which allows for better ventilation, and a complete top package that includes the rear curtain and all necessary hardware. Users are encouraged to research different manufacturers and compare their return policies, warranties, and fitment guarantees.
3. Gathering Tools and Materials
The installation process requires a variety of tools and materials. These include:
- Basic automotive tools (wrenches, screwdrivers, hammers)
- A rubber mallet
- A drill and 1/8" bits
- A pop rivet gun
- A screw gun with fine Phillips or Torx tips
- A staple gun (preferably pneumatic)
- A center punch
- A utility knife
- A flat plastic tool
- A 6–8 foot length of 1/8"–3/16" nylon rope
- A helper for positioning and adjustment
Materials include the replacement top, pop rivets, staples, hold-down cables, adhesive, and sealant. Users should also have a sunny weekend to work, as some installation steps are easier in warm weather.
Step-by-Step Installation Process
1. Preparing the New Top
Before attaching the new top to the vehicle, it should be laid out on a clean surface. Some users prefer to place the old top over it for alignment. Marking the bolt hole locations and the rear tack strip alignment on the new top helps ensure accurate placement. This step is critical for achieving a snug and secure fit.
The frame should be assembled and tested for movement. Adjustments may be necessary to accommodate the window operation and fit. Any worn or damaged tack strips should be replaced, and the frame should be cleaned and painted for a fresh appearance.
2. Attaching the New Top to the Frame
Once the frame is ready, the new top can be mounted. The side cables should be threaded through the pockets and connected to their appropriate places. The top frame should be raised halfway and latched at the front. The cables should be tight, and the top should be aligned from side to side.
Users may need to slide the top forward or backward to position the quarter flaps correctly. The seam that holds the quarter flaps should align with the edge of the top frame. This step ensures that the top fits properly and operates smoothly.
3. Installing the Rear Curtain and Window Assembly
The rear curtain must be installed into the well area of the car. The ends of the rain gutter retainer wire should be inserted into the retainer holes before lowering the unit. The correct hardware must be installed on the rear curtain retainer bracket and lower control link–attaching stud. Incorrect hardware can lead to malfunctions, such as a jammed or broken window.
The rear window control links should be reattached to the window brackets using the correct hardware. The nylon bushing must be able to pivot in the bracket, and the lower pin bushing must slide easily along the long slot in the control arm. Once the pin and bushings are in place, a retaining washer and locking pin should be used to secure them.
The rear assembly should be secured to the car using the correct mounting bolts. Before installing the bolts, users should ensure that the pivot bushings are in place. Once the assembly is mounted, the top should be raised and checked for wrinkles or misalignment. If necessary, the assembly may need to be removed for further adjustments.
4. Final Adjustments and Testing
After the top is installed, users should test its operation to ensure that it opens and closes smoothly. The cables should be tight, and the top should align evenly on both sides. Any wrinkles or misalignments should be adjusted before finalizing the installation.
The rear window should also be tested for smooth movement and proper sealing. If the window jams or breaks, the hardware may need to be replaced or adjusted. Users should also check the fit of the quarter flaps and ensure that they are aligned with the top frame.
Once all adjustments are complete, the installation can be considered successful. Users are encouraged to take their time and ensure that every step is done correctly to avoid future issues.
Common Challenges and Tips
1. Patience and Planning
The installation process can be frustrating, especially for first-time users. It is important to be patient and methodical. Users should plan ahead and decide how deep they want to go with the project. Some may choose to replace only the top, while others may opt to restore the entire frame and hydraulic system.
2. Accuracy in Alignment
Proper alignment is critical for the performance and longevity of the new top. Users should take the time to mark and adjust the top carefully. Even small misalignments can lead to issues with the fit and function of the top.
3. Use of Adhesives and Sealants
Adhesives and sealants are used to secure the top to the frame and to prevent leaks. Users should follow the manufacturer's instructions for application and allow sufficient drying time before testing the top.
4. Weather Considerations
Some installation steps are easier in warm weather. Users should try to schedule their installation on a sunny day, as this can make the material more pliable and easier to work with.
Conclusion
Convertible top installation is a complex but rewarding process that requires attention to detail, mechanical skill, and patience. The process involves preparing the vehicle, selecting the right replacement top, and carefully following installation steps to ensure a proper fit and function. Users should assess the condition of the existing components, gather the necessary tools and materials, and proceed methodically to avoid errors and ensure a successful outcome.
While the process can be time-consuming and challenging, the result is a restored or upgraded convertible that functions smoothly and looks great. By following the steps outlined in this guide and consulting the manufacturer's instructions, users can achieve a professional-quality installation that meets their needs and expectations.