* A completely different roof structure: Convertibles have a folding top mechanism, reinforcements for the open top, and often different strengthening components throughout the chassis. A hardtop needs a solid roof structure, often with integrated headliners and potentially different window frames and seals. This isn't a simple bolt-on affair.
* Reinforcements: Hardtops are significantly stiffer and stronger than convertibles due to the lack of folding mechanism. Adding a hardtop necessitates significant structural reinforcements to the chassis and body to maintain rigidity and safety standards. This might involve welding new support structures or extensive fiberglass work.
* Window and Seal Modifications: The windows and seals are different between a hardtop and convertible. The convertible windows likely have a more complex mechanism, while a hardtop would require different seals and possibly even different window shapes and sizes.
* Aesthetics: Getting the hardtop to seamlessly integrate with the existing bodywork requires significant skill in panel beating, bodywork repair, and possibly custom fabrication.
* Safety Certification: After all this work, the modified vehicle would likely need significant testing and potentially recertification to ensure it meets safety standards.
In short, converting a convertible to a hardtop is a major undertaking, usually only feasible for highly specialized automotive shops with extensive experience in custom fabrication and restoration. It's far more cost-effective and practical to simply buy a hardtop version of the car.
