Here's why it's difficult and what's involved:
* No Direct Bolt-On Kit: There isn't a readily available, off-the-shelf kit to swap drum brakes to disc brakes on a 1989 Crown Victoria. You'll need to source parts from various sources and potentially fabricate custom components.
* Parts Sourcing: You'll need to find suitable rear disc brake calipers, rotors, backing plates, wheel hubs, parking brake components (often requiring modifications), and potentially new brake lines and a proportioning valve (to adjust the front-to-rear braking balance). Parts from other Ford models or even different makes might be adaptable, but this requires research and careful matching.
* Fabrication: You'll likely need to modify existing components or fabricate brackets to mount the new calipers and other parts. This requires welding, drilling, and other metalworking skills.
* Brake Line Routing: You'll need to run new brake lines from the master cylinder to the rear calipers. This requires careful bending and flaring of the brake lines, and proper bleeding afterward.
* Proportioning Valve Adjustment: Changing from drum to disc brakes alters the braking balance. An improperly adjusted proportioning valve can lead to poor braking performance or even lockups. This requires expertise and potentially specialized tools.
* Parking Brake Integration: Integrating the parking brake mechanism can be challenging, often requiring modifications or using different components.
* Wheel Compatibility: Your existing wheels might not fit over the larger disc brake setup.
Instead of a DIY conversion, consider these alternatives:
* Professional Installation: Find a reputable mechanic or shop with experience in this type of conversion. They have the tools, expertise, and access to parts to do the job safely and effectively. This is the best option for safety and reliability.
* Focus on Drum Brake Upgrading: Instead of a full conversion, consider upgrading the rear drum brakes themselves. This involves replacing worn-out components like shoes, drums, wheel cylinders, and hardware. This is a much simpler and more affordable project.
In short, while technically *possible*, a drum-to-disc conversion on a 1989 Crown Victoria is a complex and demanding project best left to professionals. The cost and effort involved may not be worth the outcome compared to simpler rear brake maintenance or upgrades.
