The installation of a convertible top on an MGB requires careful attention to detail to ensure a weather-tight and durable result. The process involves removing the existing top, fitting a new one, and correctly folding the top for storage to prevent damage. MGB roadsters produced between 1971 and 1980 utilize the same top frame and are compatible with the same tops. Variations exist in rear window design, with models from 1977 onward featuring a zip-down center rear window for improved ventilation. Proper installation includes securing the top with both glue and snaps, and attention should be paid to the condition of the frame seals.
Removing the Existing Soft Top
Prior to installing a new soft top, the existing one must be removed. The initial step involves unclipping and folding the current top rearward. Following this, the rubber seal from the header rail is removed by pulling it out, and the retaining rivets are drilled out to facilitate its removal. This prepares the frame for the installation of the new top.
Installing the New Soft Top: Initial Steps
The installation process begins with transferring the rear retaining bar from the old top to the new one. Once the frame is erected, the new soft top is clipped into position at the rear. Before fully securing the top, the draught excluder should be rolled inward, toward the cockpit side, and then the snaps pushed over the pegs. Positioning the front of the top is performed with the frame unclamped from the windscreen and slightly folded back. This allows for positioning without tension. The two self-tapping screws, along with cup washers, are then refitted through the soft-top tabs at the front corners, ensuring correct alignment around the blocks.
Securing the Front of the Top
Securing the front of the top involves wrapping the fabric around the header rail and installing an alloy retaining channel. Initially, only the first rivet is installed on each side to allow for adjustment. It is crucial to avoid pulling the gutter too far forward during this wrapping process. After the corners are fixed, the frame is closed, and any excess fabric is draped over the windscreen. Contact adhesive is then applied to both the front fabric and the header rail. The fabric is pulled taut and bonded to the frame. Finally, the remaining rivets are fitted along the alloy channel, and the rubber seal is refitted. Any excess fabric is carefully trimmed with a sharp craft knife.
Rear Frame Bow Attachment
The procedure for attaching the rear frame bow depends on the type of frame. If the MGB has a folding frame, the rear strap is wrapped around the rear bow. However, packaway frames do not require this step.
Snap and Glue Considerations
Manufacturers vary in their approach to snap installation. Some pre-install snaps, while others, like the supplier referenced in the provided documentation, supply the snaps separately. This allows the owner to transfer the location of existing body studs to the new convertible top, ensuring a more reliable fit. The process involves gluing the front of the top to the header rail in coordination with the positioning of the snaps. The documentation emphasizes the importance of this coordination for a secure and weather-tight installation.
Convertible Top Variations and Fabrics
MGB roadsters experienced variations in convertible top design over the years. From 1963 to 1970, two types of convertible top frames were used: one designed to fold up and be stored, and the other a traditional fold-down type. All subsequent MGB roadster convertible tops utilized the traditional fold-down frame. Rear window options include fully welded-in windows or a zip-down center rear window, introduced in 1977, which allows for improved airflow when the top is raised.
Most aftermarket MGB convertible tops are now manufactured using a leather-grained convertible top vinyl made in the United States, mimicking the original British Everflex material. This vinyl is typically available in black, white, and tan.
Folding the Soft Top: The Correct Procedure
For MGB models from 1971 to 1980, equipped with the black folding top (often referred to as the “Micheletti” top), a specific folding procedure is recommended to prevent damage to the clear plastic windows. This procedure is outlined in the owner’s manual and was also the subject of a Technical Service Bulletin (TSB 71-C-2). The correct method involves unzipping the rear window (if applicable) and carefully folding the top in a manner that avoids stressing the plastic windows. A video demonstration by John Twist further illustrates this process.
The rationale behind this specific folding method is to protect the plastic windows from becoming brittle in cold weather and to prevent tearing of the fabric or scratching/cracking of the windows due to incorrect folding. Always unclip the rear before folding the fabric clear of the frame, then fold the fabric over the top of the frame and protect with a cover.
Important Precautions
Several precautions are recommended during both installation and maintenance. Dry-fitting the top before making any permanent marks is crucial, as marked tops may not be eligible for exchange. Installation is best performed in a warm environment to ensure the material is supple and easier to work with. Care should be taken to avoid trapping the rear quarters of the soft top in the frame, as this can cause tearing. Frost can make the plastic windows brittle, so they should not be folded or touched when frozen.
Conclusion
Installing a new soft top on an MGB requires a methodical approach, attention to detail, and adherence to the correct procedures. Understanding the variations in top design, window options, and folding techniques is essential for a successful installation and long-lasting performance. Following the guidelines provided in the owner’s manual and utilizing appropriate tools and materials will ensure a weather-tight and aesthetically pleasing result. Proper folding techniques are vital to prevent damage to the top and extend its lifespan.