1. Sourcing Parts: This is the most critical step and requires careful research. You won't find a readily available kit. You'll need to source parts from various sources, potentially including junkyards, online retailers, and possibly even custom fabrication. Key components include:
* Rear Disc Brake Calipers: These will likely need to be sourced from a later-model S10 Blazer or a similar GM vehicle that came with rear disc brakes. The year and model will significantly influence fitment. You may need to adapt calipers from another GM vehicle.
* Rear Disc Brake Rotors: Again, sourcing these will depend on the calipers you choose. The rotor diameter and bolt pattern must match the calipers.
* Parking Brake Mechanism: You'll need a suitable parking brake mechanism compatible with the new disc brakes. This might involve using a cable-operated system from a donor vehicle or potentially a completely different setup.
* Brake Lines: You'll need new brake lines routed to the new calipers. These will likely require custom bending or purchasing pre-bent lines specific to the caliper and rotor setup. Flared fittings and proper line connection are crucial for safety.
* Brake Hoses: Flexible hoses will connect the rigid brake lines to the calipers.
* Axle Flanges (Possibly): Depending on the donor parts, your existing axle flanges might be incompatible.
* Mounting Brackets (Likely): You will likely need to fabricate or adapt mounting brackets to secure the calipers to the axles. This is where most of the custom fabrication will be needed.
* Wheel Studs (Possibly): The wheel studs' length may need adjustment depending on the caliper and rotor thickness.
2. Preparation:
* Gather Tools: You'll need a comprehensive set of tools, including wrenches, sockets, jack stands, a torque wrench, brake line flaring tool, and potentially a welder (depending on the fabrication required).
* Disconnect Battery: Always disconnect the battery's negative terminal before working on the brake system.
* Remove Old Drum Brakes: Completely remove the old rear drum brakes, including the backing plates, drums, wheel cylinders, and brake shoes.
3. Installation:
* Install Rotors: Mount the new rotors onto the axle flanges. Ensure they are properly seated and torqued to specifications.
* Mount Calipers: This is where things get tricky. You'll likely need to fabricate or adapt mounting brackets to secure the calipers to the axle. This is likely to require welding and precise measurements.
* Install Brake Lines and Hoses: Carefully route and connect the new brake lines and hoses. Proper flaring is essential to prevent leaks.
* Bleed Brakes: Once everything is installed, thoroughly bleed the brakes to remove any air from the system. This is crucial for proper braking performance and safety. Use a pressure bleeder for best results.
* Connect Parking Brake: Install and adjust the parking brake mechanism.
* Test: After bleeding, thoroughly test the brakes in a safe, controlled environment before driving the vehicle.
4. Considerations:
* Proportioning Valve: Your existing proportioning valve might need adjustment or replacement to account for the change in braking bias caused by the addition of rear disc brakes.
* Master Cylinder: Depending on the size of the rotors and calipers, your master cylinder might need to be upgraded to provide adequate braking force.
* Safety: Working on the brake system requires meticulous attention to detail. Improper installation can be extremely dangerous. If you're not comfortable performing this work yourself, it's strongly recommended to have a qualified mechanic do it.
In short: Converting from drum to disc brakes on a 1990 S10 Blazer is a complex project that is best left to experienced mechanics unless you have significant fabrication and automotive repair experience. The cost of parts and the labor involved will likely make this a substantial investment. Consider the cost and difficulty before starting this project. It's often simpler and safer to buy a later-model S10 with factory rear disc brakes.
