The best G-body rear disc brake upgrade kits offer improved stopping power, easier maintenance, and a cleaner installation for classic GM cars. This guide targets two common buyers: restoration enthusiasts who want a factory-style upgrade and performance-minded builders seeking better braking for street or occasional track use. Below, five top options are analyzed for fit, features, and practical trade-offs. A quick comparison table helps you decide at a glance.
| Product | Key Benefit | Best For | Includes |
|---|---|---|---|
| Inline Tube 1978-87 GM G-Body Rear Disc Conversion (Cross Drilled & Slotted) | Cross drilled/slotted rotors for heat management | Performance street use | Rotors, calipers, cables, lines, hoses, nuts/bolts, brackets, shims, hose tabs |
| JEGS 631474 Disc Brake Conversion Kit Standard (Non E-brake) | Standard conversion kit for non-E-brake setup | Easy upgrade for drum-to-disc on non-E-brake cars | Standard kit components |
| Baer Brakes 11.65″ CLSC Rear System (78-88 G-Body) | Premium performance components | High-performance builds or professional installs | CLS-C rear brake system parts |
| Speedway Rear Drill/Slotted Disc Brake Kit (77-88 GM G-Body) | Economical option with big stopping power | Budget-conscious builds | Disc brakes and bracketry for GM 10/12 bolt housings |
| JEGS 631475 Disc Brake Conversion Kit Standard with E-brake (1978-1988) | Standard kit with E-brake for factory feel | Factory-look E-brake-equipped builds | Full standard kit with E-brake |
Inline Tube Cross Drilled And Slotted Rear Disc Kit with Parking Brake
Best for performance-minded street cars that benefit from improved heat dissipation and fade resistance. This kit includes cross drilled and slotted rotors, calipers, cables, lines, hoses, nuts and bolts, caliper brackets, shims, and hose tabs. It provides a complete upgrade path to rear disc braking on 1978-87 G-bodies with parking brake integration. Choose this if you want a robust upgrade with a factory-compatible parking brake solution. A potential limitation: cross drilled rotors can be more prone to rotor cracking if abused in extreme conditions.
JEGS 631474 Disc Brake Conversion Kit Standard (Non E-brake)
Best for non-E-brake 1978-1988 GM G-Body builds seeking a straightforward upgrade. The standard kit provides essential components for a drum-to-disc conversion without an electronic parking brake. This option is suitable for buyers who want a simple, reliable upgrade with widely available parts. Limitation: lacks an integrated parking brake solution, so users must plan alternative mounting for emergency braking if needed.
Baer Brakes 11.65″ Rear Disc System for 78-88 G-Body
Best for enthusiasts seeking premium, high-quality performance components. Baer Brakes emphasizes precise manufacturing for a perfect fit and professional-grade performance parts. This kit is well-suited for serious builds where braking performance and consistency are prioritized. Limitation: higher cost and potentially longer lead times compared to budget options; ensure compatibility with your vehicle’s rear axle and mounting hardware.
JEGS 631475 Disc Brake Conversion Kit Standard With E-brake
Best for buyers needing an E-brake integrated solution while upgrading to rear discs. This standard kit with E-brake is designed to preserve the factory parking brake feel and function. It is a solid choice for restorations or daily drivers where a functional parking brake matters. Limitation: may involve more complex installation due to E-brake components and routing.
Speedway Rear Drill/Slotted Disc Brake Kit for GM G-Body
Best for budget-conscious projects that still want a modern braking upgrade. The Speedway kit provides drag-reducing, larger rotor options and bracketry compatible with GM 10- and 12-bolt housings. It offers straightforward installation and significant stopping power relative to drums. Limitation: pricing is economical, but some buyers report needing careful alignment and fitment to avoid clearance issues with non-standard configurations.
Right Stuff Detailing AFXRD78 Rear Disc Conversion
Best for a fully packaged unit that emphasizes ease of installation in a restoration project. The kit is branded for a rear disc conversion with a focus on complete components. Note: the packaging is large and may contribute to longer lead times; verify that the kit contents align with your vehicle’s needs.
Buying Guide: G-Body Rear Disc Brake Upgrade Considerations
- Vehicle compatibility: Confirm axle type (10-bolt or 12-bolt) and the presence of or need for a parking brake.
- Brake balance: Consider rotor size and caliper options to achieve desired stopping power without overpowering the front system.
- Parking brake integration: Decide whether you need a factory-like parking brake or an alternative method.
- Installation complexity: Some kits are plug-and-play, others require brackets, lines routing, or custom fittings.
- Quality and durability: Cross drilled vs. slotted rotors offer heat management with trade-offs in rotor longevity under extreme use.
- Cost vs. benefit: Premium components typically offer better performance and longevity, at a higher upfront cost.
Frequently Asked Questions
- What is the main benefit of upgrading to rear disc brakes on a G-Body? – Increased braking power, improved fade resistance, and easier maintenance compared to drums.
- Do these kits require professional installation? – Some kits are straightforward for DIY installers, while others benefit from a professional alignment and bleeding procedure.
- Is an E-brake kit necessary with these upgrades? – Not always; choose a standard kit if you do not need E-brake, or select a kit with E-brake for factory compatibility.
- Will this upgrade affect front brake balance? – It can; ensure the overall brake system is balanced for safe stopping, possibly adjusting front calipers or line routing as needed.
- Can I reuse existing lines and hoses? – Some kits include new lines and hoses; others require adapters or new hardware to fit properly.
- What rotor material is best for street use? – Slotted rotors provide consistent performance and are common for street use; cross drilled rotors add heat dissipation but may wear differently under aggressive driving.