G-Body Rear Upgrade: Quick Performance Rear End & Wilwood Brake Installation for Ultimate Speed and Stopping Power
Upgrading your classic GM G-body’s rear suspension and braking system is one of the best ways to transform your ride, especially when you're pushing for higher horsepower and improved handling. In this detailed guide, we’ll walk through the entire process of swapping out the factory rear end for a Quick Performance G-Body 9-inch rear and installing Wilwood's rear G-Body disc brake upgrade.
Whether you’re a street cruiser or a weekend racer, this G-body rear suspension and brake overhaul will elevate your driving experience. Let’s dive into the step-by-step process and the key components involved in this rear suspension transformation.
Removing the Factory Rear End and Assessing the Setup
We started by removing the factory 7.5-inch G-body rear end from the car. This removal was pretty straightforward — unbolting the lower trailing arms, upper arms, and disassembling the shocks on the bottom. We left the shocks hanging to make the rear end easier to drop out from underneath the car. Fortunately, having a lift made this process much easier, eliminating the need for jacks.
The car had been running a factory replacement setup for a while — specifically, our stage two power tour package. This package features fixed-length upper and lower control arms with poly bushings on both sides, which is a solid setup for street driving. However, since the plan was to put somewhere between 400 and 500 horsepower through this rear, we needed something more robust to handle the extra power and provide better traction.
One important note: the car came with factory drum brakes, which are notorious for their limited stopping power. Upgrading the brakes was a no-brainer to match the increased performance we were expecting.
Upgrading to the Quick Performance 9-Inch Rear End
The Quick Performance nine-inch rear end we installed is a game-changer. This rear end is built with all the provisions to add high-performance Wilwood brakes, making it an ideal choice for a comprehensive rear suspension and brake upgrade.
Along with the new rear end, we replaced the factory trailing arms with adjustable roto joint style arms. Our roto joints strike a perfect balance — they’re not as harsh as rod ends for street use, but still offer the adjustability and durability needed for racing or spirited driving.
Our adjustable rear roto-joint upper control arms (UMI part #3037) feature a hex adjuster, allowing on-car pinion angle and lateral location adjustments. This level of tuning capability is invaluable for optimizing your rear suspension geometry based on your specific setup and driving style.
We paired these upper arms with our double adjustable roto joint lower trailing arms (UMI part #3043), which are equally versatile and capable for both street and race applications. This combination provides excellent control and durability, ensuring the power gets to the ground efficiently without compromising ride quality.
3037 – Rear Upper Control Arms, Adjustable, Roto-Joints
In stock
$299.99
3043 – 1978-1988 G-Body Rear Lower Control Arms, Double-Adjustable, Roto-Joints
In stock
$399.99Sealing the Rear End: Tips and Tricks
Sealing up the rear end properly is crucial to prevent leaks and ensure longevity. After sealing, we carefully knocked the axle seals into place using a specialized seal installation set. This tool is essential to avoid damaging the seals, which can happen if you try to hammer them in without protection. Then, the axles were slid into the housing, and axle locks were installed to secure everything.
Customizing Brake Line Mounting for a Clean Look
One of the challenges with a new rear end housing is figuring out a clean way to attach the brake lines without welding additional holders, especially since the housing was freshly powder-coated. To solve this, we drilled two small 3/16” holes in the housing and fabricated a custom bracket to mount the brake lines. This approach keeps the look clean and professional while protecting the powder coat finish.
Installing the bushings required a bit of muscle, and although Dave is not known for hammer-swinging skills, the task was completed successfully with a little help.
Installing the Rear End and Upgrading Suspension Brackets
The Quick Performance 9-inch rear end is a bit heavier than the factory unit, so we placed it on a cart and lowered the car onto it to avoid strain on our backs. This method simplifies the installation process and ensures safety.
We then installed our 3054 coilover brackets, specifically designed for the G-body Quick Performance rear ends. These brackets provide excellent coilover mounting points and improve shock travel angles, which is vital for maintaining good suspension performance and drivability. They also offer more clearance for exhaust systems, which in this build will be three-inch true duals.
Product Spotlight: UMI 3054 Quick Performance Rear Coilover Conversion Brackets
- Designed for 1978-1988 GM G-Body with Quick Performance axle
- Multi-position bracket for ±¾” ride height and shock location adjustment
- Five trailing arm positions to match Quick Performance adjustable lower control arm brackets
- Compatible with Quick Performance single hole non-adjustable bracket (without lower control arm adjustability)
- Minor drilling required for installation
- Allows precise suspension tuning and improved ride quality
3054 – 1978-1988 GM G-Body Rear Coilover Conversion Brackets, Quick Performance
In stock
$199.99
3054-X – 1978-1988 GM G-Body Rear Coilover Conversion Kit, Quick Performance
In stock
$1,009.99
Operational Speed Supply: Quality Fluids for Your Build
We want to give a big shoutout to Josh at Operational Speed Supply, who hooked us up with Redline synthetic fluids for this build. We’re running their synthetic oil, synthetic power steering fluid, rear end fluid, and brake fluid. These high-quality fluids ensure that every component in the drivetrain and braking system performs at its best.
If you’re looking for top-tier fluids for your car or build, check out Operational Speed Supply — they’re well-regarded in the autocross and performance communities for their excellent products and support.
Installing the UMI Pro-Tour Rear Sway Bar
The rear sway bar installation required an extra set of hands to hold all the bracketry up and get everything lined up correctly. We used painter’s tape as a simple but effective method to hold the brackets in place while mounting the sway bar and U-bolts.
Proper centering of the sway bar on the rear end housing is critical. We measured from the backing plates to ensure the sway bar was perfectly centered, which is essential for balanced handling and proper sway bar function.
Since this is a chassis-mounted sway bar, we flipped the brackets up and installed them on the cross member. Using a paint marker, we marked the holes for drilling, ensuring everything was aligned and would fit nicely under the vehicle.
After drilling, we mounted the brackets to the chassis and finished by attaching the sway bar end links. This completes a sturdy and effective sway bar installation that complements the upgraded rear suspension.
Product Spotlight: UMI 3054 Quick Performance Rear Coilover Conversion Brackets
- Lightweight 1” tubular sway bar with CNC precision bends for excellent geometry and strength.
- Chassis and differential housing mounts reduce binding, enhancing handling and performance over factory sway bars.
- Adjustable with a billet steel hex adjuster for preload tuning, ideal for drag racing and various driving conditions.
- Heavy-duty race-style chromoly spherical rod ends with Teflon race for durability and smooth operation.
3044 – 1978-1988 GM G-Body Sway Bar, Rear, Tubular, 1″, Chassis Mounted, Pro-Tour
In stock
$519.99
Wilwood Rear Brakes: Enhancing Stopping Power
Wilwood brakes are a staple on nearly every vehicle we work on, whether it’s a race car, shop car, or street cruiser. For this application, we installed Wilwood four-inch piston rear calipers, which offer a significant improvement over the factory drum brakes.
The brake lines were replaced with nickel-copper lines, chosen for their ease of flaring and installation, as well as their clean appearance. This upgrade not only improves braking performance but also enhances the overall look of the brake setup.
Using all new brake lines ensures reliability and safety, especially important when upgrading to a higher-performance braking system.
Conclusion: Transforming Your G-Body with Performance Upgrades
This G-body 9-inch rear end and disc brake upgrade alongside the rear suspension overhaul is a comprehensive solution for anyone looking to boost their classic GM G-body’s performance. From removing the factory rear end to installing the Quick Performance G-Body 9-inch rear upgrade, UMI rear adjustable roto joint trailing arms, G-Body coilover conversion brackets, chassis-mounted sway bar, and Wilwood G-Body rear disc brakes, every step is designed to enhance handling and stopping power.
Upgrading the rear end and brakes is essential when increasing horsepower, ensuring your car stops safely and handles better with the new boost in power. The components we used — including UMI Performance parts, Quick Performance, Wilwood brakes, and quality fluids from Operational Speed Supply — are proven, reliable, and built for performance.
For anyone interested in upgrading their G-body, this setup offers a perfect blend of street comfort and race-ready capability, making it a standout choice for enthusiasts who demand the best from their classic muscle cars.
