Why Upgrade to a BMR Suspension Kit?

Upgrading your GTO’s suspension system is one of the most effective ways to unlock the car’s true performance potential. The factory suspension was engineered for a balance of comfort and cost, but it leaves significant room for improvement in handling, stability, and cornering capability. BMR Fabrication has built a reputation for precision-engineered suspension components that address the GTO’s inherent weaknesses — especially in the rear IRS (independent rear suspension) where toe deflection and bushing compliance can cause unpredictable behavior under hard driving.

The benefits of a BMR Suspension Kit extend far beyond simple part replacement:

  • Eliminated Deflection: Factory rubber bushings flex under load, allowing suspension geometry to change mid-corner. BMR’s polyurethane or spherical bearing bushings maintain consistent alignment, giving you predictable grip.
  • Reduced Body Roll: Stiffer springs, adjustable sway bars, and upgraded control arms work together to minimize body roll. This allows higher cornering speeds without sacrificing tire contact patch.
  • Improved Weight Transfer: Properly tuned suspension kits improve launch characteristics by controlling squat and dive. That means better acceleration out of corners and more consistent drag strip performance.
  • Longevity and Durability: BMR components are built from high-strength steel or chromoly with corrosion-resistant finishes, outlasting factory parts that wear out or bend under track conditions.
  • Customizable Handling: Many BMR kits offer adjustability in ride height, spring preload, and sway bar stiffness, allowing you to tune the car for autocross, road racing, or daily driving.

For those who push their GTO on track days or weekend twisties, the difference is night and day. As noted by BMR Fabrication, their components are designed to work together, solving the unique geometry challenges of the GTO platform. Enthusiast forums like LS1GTO.com contain hundreds of user testimonials confirming that a well-executed BMR suspension upgrade transforms the car from a comfortable cruiser into a corner-carving machine.

Understanding BMR Suspension Components

Before diving into installation, it’s helpful to understand the specific components that make up a typical BMR Suspension Kit for the GTO. Kits vary by generation — 2004–2006 models share the same chassis — but common elements include:

  • Lower Control Arms (Rear): Replace the factory stamped-steel arms with adjustable tubular arms that eliminate bushing deflection and allow rear toe adjustment.
  • Upper Control Arms (Rear): Often paired with the lower arms to correct pinion angle and improve rear suspension geometry under acceleration.
  • Adjustable Sway Bars: Thicker hollow or solid bars with multiple end-link mounting positions to tune roll stiffness front and rear.
  • Coilover Kits: Replace the separate spring/shock units with adjustable-height coilovers that allow ride height, damping, and sometimes spring preload adjustment.
  • Subframe Connectors: While not always included, BMR also offers subframe braces that stiffen the chassis, improving how the suspension components work.
  • Bushing Kits: Polyurethane or Delrin bushings for the control arms and sway bar mounts to replace compliant OEM rubber.

Depending on your goals — street performance, autocross, drag racing, or road racing — BMR offers tailored packages. The Street Performance kit often includes poly bushings and mild spring rates, while the Track kit features monoball/spherical bearings and stiffer springs for minimal deflection. Understanding your intended use will help you choose the right level of upgrade.

Tools and Materials Needed

Installing a BMR Suspension Kit requires a solid selection of tools. The job is moderately difficult — expect a half-day of work for the rear and another half for the front if you are experienced. Below is a comprehensive list of what you’ll need:

  • Floor jack (2-ton capacity minimum) and two heavy-duty jack stands
  • Metric socket set (10mm to 21mm), including deep sockets
  • Torque wrench capable of reading 150 ft-lbs (most suspension bolts require 80–140 ft-lbs)
  • Breaker bar with 1/2-inch drive for stubborn bolts
  • Ball joint separator or pickle fork
  • Set of Allen wrenches (many BMR components use Allen-head fasteners)
  • Penetrating oil (e.g., PB Blaster) to loosen rusted bolts
  • Anti-seize compound for reassembly
  • Die grinder or file to deburr any weld slag (rare but possible on aftermarket parts)
  • Safety glasses, gloves, and a sturdy work surface
  • Optional: Spring compressor if you are not using coilovers and need to remove stock springs

Do not attempt this job on a car supported only by a scissor jack — the forces involved are dangerous. Always secure the vehicle on jack stands placed under the frame rail jacking points. Also, have the BMR installation manual handy; each kit may have specific torque values and installation sequences.

Preparing Your GTO for Installation

Proper preparation saves time and prevents problems. Start by parking the GTO on a flat, level concrete surface. Engage the parking brake and chock the front wheels if working on the rear (or vice versa). Loosen the lug nuts on all four wheels about a half-turn while the car is still on the ground — this makes wheel removal easier once the car is lifted.

Rinse the undercarriage with a hose or pressure washer to remove caked-on dirt and grease. This not only keeps your work area cleaner but also helps you see bolt heads and avoid damaging new components with grit. Allow the car to dry before you start.

Disconnect the battery negative terminal if your GTO has suspension components near exposed electrical wiring (unlikely, but a good safety habit). Take reference photos of the existing suspension from multiple angles. These photos help during reassembly, especially if you need to reference how factory parts were oriented.

Lastly, gather all BMR kit parts on a clean surface and verify them against the included inventory sheet. Note any missing fasteners or damaged parts before beginning installation, so you can contact BMR’s support if needed.

Step-by-Step Installation Guide: Rear Suspension

The rear suspension on a GTO is independent (IRS) and benefits the most from a BMR kit. Most installers start at the rear because it’s more complex and time-consuming. Use a licensed hydraulic lift if available, otherwise a jack and stands.

1. Remove the Rear Wheels and Brake Calipers

Jack up the rear of the car and place stands under the subframe or frame rails, not the control arms. Remove the wheels. To access suspension bolts, you may need to unbolt the parking brake cable retainers and drop the exhaust slightly (if it’s in the way). Remove the rear brake calipers and hang them from the spring or body using zip ties — do not let them hang by the brake hose.

Using a socket and wrench, remove the nuts from the rear sway bar end links. On the GTO, the end links connect the sway bar to the lower control arms. You may need to hold the ball joint stud with an Allen wrench while turning the nut. Set the end links aside; you will reuse them or replace with BMR units.

3. Remove the Factory Lower Control Arms

Two large bolts secure each lower control arm to the rear knuckle and the subframe. Using a breaker bar and appropriate socket, remove these bolts. The forward bolt (subframe side) is often tight; use penetrating oil if needed. Carefully slide the arm out. Repeat for both sides. With the arms removed, you can see the rear knuckle and the camber/toe adjustment eccentrics.

If your BMR kit includes upper control arms, you must remove the stock uppers. They attach to the subframe and knuckle with two bolts each. One bolt may require a swivel socket due to tight clearance. Mark the location of the eccentric bolt (if any) for reference if you plan to reuse the stock bolts. If you are only upgrading lower arms, you can skip this step.

5. Install BMR Control Arms

Start with the lower control arms. Apply anti-seize to the bolt threads and bushing sleeves. Position the arm in the subframe and knuckle, but do not fully tighten the bolts yet — leave them snug so the bushing can rotate freely during final torque. BMR usually includes spherical bearings or poly bushings; do not over-torque polyurethane bushings as they can bind. Follow the torque specifications in the BMR manual (typically 90–130 ft-lbs for lower arm bolts).

If installing upper arms, repeat the process. Pay attention to the orientation of any offset bushings — these are designed to correct rear camber. The BMR instructions will specify which side faces forward.

Now install the new sway bar end links if included. Tighten them to the manufacturer’s specifications. Do not preload the sway bar — the car must be at ride height before final tightening of any sway bar connections to avoid binding.

7. Reassemble Brakes and Wheels

Reinstall the brake calipers, wheels, and lug nuts. Tighten the lug nuts to 100 ft-lbs. Lower the car so it rests on its wheels (on stands if you still need to adjust). Lightly bounce the suspension to settle it, then proceed to torque all suspension bolts to final spec with the car at normal ride height. This is critical — torquing control arm bolts with the suspension hanging will cause premature bushing wear and incorrect alignment.

Repeat the same general process for the front suspension if your BMR kit includes front components. For front control arms, note that the GTO has a MacPherson strut front suspension; you will need to compress the spring if not using coilovers. Refer to the BMR instructions specific to front arms and sway bars.

Post-Installation Alignment and Tuning

After installing any aftermarket suspension components, a professional alignment is mandatory. BMR parts adjust not only camber and toe but also thrust angle. The factory alignment specs are conservative; with BMR arms you can dial in more negative camber for cornering (e.g., -1.5 to -2.5 degrees front, -1.0 to -1.5 rear) while keeping toe within spec to prevent tire wear.

If your kit includes adjustable coilovers, now is the time to set ride height. A common recommendation is to lower the GTO about 1.0–1.5 inches from stock, keeping the suspension geometry in the sweet spot. Measure from the fender lip to the center of the wheel hub — shoot for about 13.5–14 inches front and 13.7–14.2 inches rear depending on your preference. After setting height, adjust the preload on the coilover springs so that the car sits evenly side-to-side.

Take the car for a short test drive to let the suspension settle, then revisit the alignment rack for final adjustments. Many shops that specialize in performance alignments, such as those listed on the SCCA website, can help you dial in settings for maximum grip. Additionally, online communities like LS1Tech.com have alignment threads where owners share successful specs for different uses.

Common Mistakes to Avoid

Even experienced mechanics can make errors during a suspension upgrade. Here are the most frequent pitfalls and how to avoid them:

  • Skipping the final torque at ride height: As mentioned, torquing bolts with the suspension unloaded will lead to bushing bind and poor ride quality. Always lower the car on ramps or stands (with wheels on) before final tightening of control arm and sway bar bolts.
  • Over-torquing polyurethane bushings: Polyurethane does not compress like rubber. Over-tightening can cause the bushing to seize on the sleeve, leading to noise and reduced travel. Follow the BMR torque values exactly.
  • Ignoring the parking brake cable: After reinstalling, make sure the parking brake cable is not routed incorrectly or interfering with the new control arms. A caught cable can cause brake drag or even a fire.
  • Not checking subframe condition: GTO subframes can develop rust or crack at the control arm mounts, especially in northern climates. Inspect the subframe before installation; repair or reinforce weak spots before bolting on new parts.
  • Installing without a plan for alignment: Some buyers attempt to eyeball the toe setting. Even a slight deviation will cause rapid tire wear and vague handling. Budget for a professional alignment immediately after the install.

By remaining vigilant about these details, you’ll enjoy the benefits of your BMR Suspension Kit without unnecessary complications.

Conclusion

Installing a BMR Suspension Kit on your GTO is more than just a weekend project — it’s a fundamental transformation of how your car behaves on the road and track. From eliminating deflection in the rear IRS to sharpening turn-in response with stiffer sway bars, the upgrade pays dividends in driver confidence and lap times. With careful preparation, the right tools, and a methodical installation sequence, you can achieve results that rival or exceed factory sports packages from the factory.

The investment of time and money returns a vehicle that is not only faster through corners but also more predictable and enjoyable to drive. Pair your new suspension with quality tires and alignment, and you’ll have a car that can handle modern performance cars twice its price. Whether you’re heading to your local autocross, a track day, or simply seeking that rewarding backroad connection, a BMR-equipped GTO is a true driver’s machine.