Understanding the GR86 Suspension Upgrade Process

Upgrading the suspension on your GR86 is one of the most impactful modifications you can make for improved handling, reduced body roll, and a more connected driving feel. Whether you are a first-time installer or a seasoned mechanic, this expanded guide will walk you through every step of the process — from choosing the right kit to final alignment. Proper installation not only enhances performance but also ensures safety and long-term durability. We will cover both front and rear systems, common pitfalls, and pro-level tips to help you achieve professional results at home.

Choosing the Right Suspension Kit for Your GR86

Before touching a wrench, you need to select the appropriate suspension components for your driving goals. The GR86 shares its platform with the Subaru BRZ, so most parts are interchangeable, but subtle differences exist.

Coilover Kits vs. Strut-and-Spring Combos

Coilover systems integrate the spring and damper into a single unit, offering adjustable ride height, damping, and often camber plates. They are ideal for track use or aggressive street driving. For daily driving or budget builds, a traditional strut and lowering spring combination can be sufficient, but you sacrifice fine-tuning ability.

Key Factors to Consider

  • Spring rate – Softer rates (4-6 kg/mm) suit street comfort; stiffer rates (7-10 kg/mm) are for autocross or track days.
  • Damper adjustability – Look for kits with at least 20-30 clicks of rebound/compression adjustment.
  • Ride height range – A drop of 1.0–1.5 inches is common for street use; more than 2 inches may require roll center correction.
  • Top mounts – Pillow-ball mounts with camber adjustment allow for precise geometry setting.

For a deep dive into spring rates and damping curves, the FT86 Club suspension forum is an excellent resource for real-world user reviews.

Tools and Materials: The Complete Checklist

Gathering everything upfront prevents frustrating trips to the tool box mid-job. Here is a comprehensive list:

  • Metric socket set (10 mm to 22 mm, deep and shallow)
  • Combination wrenches (10, 12, 14, 17, 19, 22 mm)
  • Torque wrench (1/2″ drive, 20–150 ft-lb range)
  • Jack with at least 2-ton capacity
  • Pair of heavy-duty jack stands (3-ton recommended)
  • Spring compressors (screw-type or hydraulic)
  • Breaker bar and impact gun (optional but helpful)
  • Pry bar or trim removal tool for brake line clips
  • Anti-seize compound and thread locker (medium strength)
  • Safety glasses, mechanic gloves, and a creeper
  • Penetrating oil (e.g., WD-40, PB Blaster)
  • Digital or beam-style angle finder for setting camber
  • Masking tape and marker for marking hardware orientation

Preparation Steps for a Safe Installation

Proper preparation prevents mistakes and reduces risk. Follow these steps in order.

Workspace and Vehicle Positioning

  • Park on a level concrete surface; avoid asphalt that could soften under jack stands.
  • Engage the parking brake and chock the rear wheels if lifting the front first.
  • Loosen the lug nuts on all four wheels (turn ¼ to ½ turn) before jacking.
  • Use a floor jack under the front crossmember (behind the oil pan) to lift the front. Place jack stands on the frame rail pinch welds, using rubber adapters to prevent damage.
  • For the rear, lift at the differential housing and place stands under the rear subframe.

Pre-Set Ride Height and Preload

If using coilovers, set the initial ride height on the bench before installation. Most manufacturers recommend starting with 50–75% of the total adjustment range. For damping, set all four corners to the middle of the click range (e.g., 12 of 24 clicks) for a baseline. Preload should be adjusted according to the kit instructions — typically zero preload (spring just snug) to avoid harshness.

Removing the Factory Suspension: Front

With the vehicle safely lifted, remove the front wheels. Work one side at a time to keep the other side as a reference.

Disconnect Brake Lines and Sensors

  1. Use a flathead screwdriver to release the brake line from the strut’s bracket clip.
  2. If the car has ABS wheel speed sensors, unclip the wire from the strut; do not pull on the wire itself.
  3. Optionally, you can remove the front anti-roll bar end link from the strut using a 5 mm hex key to hold the shaft while loosening the 14 mm nut.

Unbolt the Strut Assembly

  1. From inside the engine bay, locate the three top mount nuts (usually 12 mm or 14 mm). Hold the strut shaft with a hex bit to prevent spinning, then remove the center nut.
  2. Below, remove the two lower strut-to-knuckle bolts (17 mm and 19 mm common). Use a breaker bar; these are often torqued high.
  3. Carefully maneuver the strut out by tilting it inward and pulling downward. Watch for the spring compressor tool clearance if the springs are still compressed.

Tips for Removing Stubborn Bolts

  • Apply penetrating oil 30 minutes before removal.
  • Use a six-point socket to avoid rounding bolt heads.
  • If the lower knuckle bolt is seized, gently tap the knuckle with a rubber mallet to break corrosion.

Removing the Factory Suspension: Rear

The rear setup on the GR86 uses a multi-link independent suspension. The coilover (or strut) is mounted separately from the spring on many models, but aftermarket coilovers often replace both.

Accessing the Top Mount

  1. Remove the rear seat cushion and side bolsters to access the upper strut tower. On the GR86, this may require removing a plastic trim panel.
  2. Remove the top nut while holding the shaft with a hex key, as done upfront.

Detach Lower Mounts

  1. Unbolt the lower strut mount from the knuckle (usually a 17 mm bolt). You may need to slightly compress the suspension by jacking up the lower control arm.
  2. Remove the rear anti-roll bar end link if necessary.
  3. Carefully remove the strut assembly. The rear springs are separate on stock cars; if you are swapping to coilovers, the spring and perch must also be removed by unbolting the lower spring perch from the control arm.

Installing the New Suspension: Front

Now the fun begins. Follow these steps for a clean install.

Pre-Assemble the New Coilover (if needed)

  • Loosely assemble the spring, perches, and top mount on the damper body.
  • Use spring compressors to safely mount the spring onto the coilover. Tighten the top nut to manufacturer specification (typically 30–50 ft-lb) while holding the shaft with a hex key.
  • Set the initial ride height by rotating the lower spring perch. Mark the threads with a marker for consistent left/right settings.

Install the Front Coilover

  1. Insert the top mount into the chassis tower. Three studs should align with the chassis holes.
  2. Hand-tighten the top nuts to 20–30 ft-lb, then torque to spec (refer to the kit instructions, often 35–45 ft-lb).
  3. Lower the knuckle and attach the lower strut bolts. Use anti-seize on the bolt threads. Torque the lower bolts to the factory specification: typically 90–110 ft-lb for the large lower bolt.
  4. Reconnect the brake line bracket and end link. Ensure the brake hose is not twisted or under tension at full droop.

Front Installation Pro Tips

  • Torque suspension bolts only when the vehicle is at ride height (suspension loaded) to prevent bushing binding. A quick method: lift the control arm with a jack until the car’s weight is on the wheel hub.
  • Check for clearance between the coilover spring and the tire (especially with wider wheels). Use a 5 mm spacer if needed.

Installing the New Suspension: Rear

The rear is slightly more fiddly due to the compact space.

Lowering the Rear Coilover In

  1. Slide the top mount into the chassis hole, then pivot the bottom into the lower mount.
  2. For coilovers with an adjustable lower mount, set the height before installation by measuring from the center of the lower eye to a reference point.
  3. Torque the top nut (same spec as front) and the lower bolt (80–100 ft-lb typical).
  4. If you retained the factory rear spring, install it with a new isolator pad. For coilover systems, the spring is part of the assembly, so skip the separate spring.

Rear Bushing Considerations

Aftermarket coilovers often use spherical bearings that can introduce noise. If you are daily driving, consider staying with rubber or polyurethane bushings to keep NVH low. Tighten all bolts with the suspension loaded to avoid preloading the bushings — a common cause of premature wear.

Final Adjustments and Retorque

Do not rush this stage. Proper adjustments transform a mediocre install into a great one.

Ride Height and Corner Balancing

  • Set the ride height on all four corners to your desired drop. Use a tape measure from center of wheel to fender lip. Repeat on all corners.
  • For best corner balance, the car should have the driver’s weight simulated (e.g., a 150-pound bag of sand in the driver seat). Adjust each corner spring perch to equalize diagonal weight if possible.

Torque All Fasteners

Go through every bolt and nut you touched. Use a torque wrench and the values from your suspension kit’s manual. Common values:

  • Top mount nuts: 35 ft-lb
  • Lower strut bolts: 85–100 ft-lb
  • Anti-roll bar end links: 40–50 ft-lb
  • Wheel lug nuts: 85 ft-lb (GR86 spec)

Alignment Setup (Before Leaving for the Shop)

Set a rough alignment at home to drive safely to a professional alignment shop. Use a camber gauge and a toe plate (or string method) to get within 0.2 degrees. Targets for aggressive street/track:

  • Front camber: -2.0° to -2.5°
  • Rear camber: -1.5° to -2.0°
  • Front toe: 0 to 1/16″ toe out
  • Rear toe: 1/16″ toe in total

A proper alignment is critical for tire wear and handling. This Engineering Explained video covers suspension geometry fundamentals that apply directly to the GR86.

Test Drive and Break-In

  1. After lowering the car, check all bolts again for tightness.
  2. Drive slowly (under 30 mph) for the first mile, listening for clunks or rubbing. Stop and inspect nothing is loose.
  3. Perform a few gentle corners to let the suspension settle. Note any odd vibrations.
  4. After 100 miles, recheck torque on all suspension fasteners. The bushings will settle into their new position.
  5. Schedule a professional alignment within 200 miles. Bring your target specs.

Conclusion

Installing a new suspension on your GR86 is a rewarding project that dramatically changes the car's character. Whether you choose a high-end coilover or a budget-friendly spring-and-strut setup, the process remains the same: careful preparation, methodical removal, precise installation, and a thorough final setup. By following this expanded guide, you can complete the job safely and with confidence, whether you are in your home garage or a professional shop. For ongoing maintenance, plan to inspect suspension hardware every oil change and clean any exposed threads to prevent corrosion.

For more GR86-specific install guides and community advice, visit the GT86 Owners Club forum and Tire Rack's suspension installation resource for general best practices.