Polyurethane Bushings and Cornering Power: A 30% Improvement on a Track‑Ready Honda Civic Type R

Few front‑wheel‑drive cars can match the factory‑honed chassis of the Honda Civic Type R (FK8 / FL5). Yet even the best production suspension leaves some performance on the table. One of the most effective and relatively inexpensive upgrades for serious track work is replacing the compliant rubber suspension bushings with polyurethane units. Independent testing on a well‑prepped Civic Type R has confirmed that this single change can unlock a 30% improvement in cornering power – a jump that transforms the car’s behavior through high‑speed sweepers and tight chicanes alike.

This article dives deep into the engineering behind polyurethane bushings, how they alter suspension kinematics, the specific bushings that matter most on the Type R, installation best practices, and the real‑world trade‑offs every enthusiast should consider before making the switch.

The Science of Bushings: Rubber vs. Polyurethane

Suspension bushings serve a dual purpose: they allow controlled rotation and movement of suspension links while isolating the chassis from road noise, vibration, and harshness (NVH). A bushing’s stiffness – or lack thereof – directly affects how much the suspension arm deflects under load.

Rubber Bushings – The OEM Compromise

Original‑equipment rubber bushings are engineered for comfort and durability over 100,000 miles of mixed driving. They offer excellent NVH damping but have relatively high compliance. Under lateral loads during cornering, rubber bushings allow the control arm to deflect several millimeters, causing the wheel to toe out slightly or lose camber. This deflection reduces the tire’s contact patch and delays steering response. On a Civic Type R, factory bushings are softer than many enthusiasts realize, and they are often the first component to introduce slop during aggressive cornering.

Polyurethane Bushings – Stiffer, More Predictable

Polyurethane bushings are manufactured from a thermoset polymer with a typical hardness (durometer) of 70A to 95A. For comparison, most OEM rubber bushings range from 55A to 65A. A harder bushing resists deflection far more effectively, preserving suspension geometry under load. The result is crisper turn‑in, more stable camber gain, and reduced toe change through the corner.

  • Stiffness: 50–80% less deflection under identical loads compared to rubber.
  • Durability: Resists oil, ozone, and UV damage better than rubber; does not crack or soften with age.
  • Lubrication requirement: Polyurethane bushings need proper grease to prevent squeaking and binding; rubber bushings are typically designed to be dry.

The trade‑off is increased NVH – some extra road roar and a firmer ride. For a track‑focused build, this is a worthwhile price for the grip gained.

How Bushings Affect Cornering Power on the Civic Type R

Cornering power – often measured as lateral acceleration (g‑force) and transient response – is heavily influenced by how the suspension maintains tire contact. Polyurethane bushings improve cornering through three primary mechanisms.

1. Reduced Compliance Steer

When a rubber bushing compresses under side load, the wheel can toe out slightly. This ‘compliance steer’ reduces the tire’s ability to generate lateral force and can make the car feel loose at the limit. Stiffer polyurethane bushings virtually eliminate this deflection, keeping the wheel aligned as the suspension travels. On the Civic Type R, the rear trailing arm bushings are a notorious weak point – replacing them with polyurethane units tightens the rear end, reducing the tendency to understeer on corner exit.

2. Improved Camber Retention

The front lower control arm (LCA) bushing on the Type R allows a certain amount of deflection that reduces negative camber under load. By locking that bushing down, polyurethane helps the wheel maintain its static camber angle through the corner. More negative camber means a larger tire contact patch during cornering, generating higher lateral grip. This is one reason many track drivers see a 0.5–1.0 g improvement in peak lateral acceleration after a full bushing upgrade.

3. Faster Steering Response

Softer bushings absorb steering input energy before it reaches the tire. Polyurethane bushings transmit more of the steering torque directly to the wheel. The driver feels a more immediate and linear connection to the road, allowing finer corrections at corner entry and exit. In slalom or quick transitions, the improvement in response time can be measured in tenths of a second per gate.

Specific Bushings for a Track‑Ready Honda Civic Type R

Not all bushings are equal in their impact on cornering performance. For the Civic Type R, the following locations provide the most meaningful gains.

Front Lower Control Arm (LCA) Bushings

The LCA bushing on the FK8/FL5 is a large, fluid‑filled rubber unit that offers excellent isolation but terrible compliance. Replacing it with a 95A polyurethane bushing stiffens the front suspension and reduces camber loss under braking and cornering. This is often the single most effective bushing upgrade for the Type R.

Rear Trailing Arm Bushings

These bushings control toe and camber changes in the rear. Softer rubber allows the trailing arm to rotate under load, causing rear‑end squat that reduces traction. Polyurethane trailing arm bushings stabilize the rear geometry, improving power‑down and exit speed. Many drivers report a noticeable reduction in understeer after this swap.

Rear Subframe Bushing Inserts

The rear subframe on the Civic Type R is mounted to the chassis with large rubber doughnuts. These bushings allow the entire rear suspension cradle to shift under high lateral forces. While full subframe bushings can be invasive to install, insert‑type polyurethane bushings (such as those from Whiteline or Hardrace) fill the voids in the factory rubber, reducing subframe movement by 50‑70%. This translates to sharper rear grip and more consistent alignment on track.

Sway Bar Bushings

Although small, the sway bar bushings on the Type R are often ignored. Upgrading to polyurethane sway bar bushings eliminates slop in the bar’s rotation, delivering more instantaneous roll resistance. Combined with a stiffer sway bar, polyurethane bushings can help fine‑tune the car’s cornering balance without additional spring rate.

Installation Guide: Replacing Bushings on a Civic Type R

Installing polyurethane bushings requires mechanical experience and proper tools. Below is a step‑by‑step overview. Always consult a service manual for torque specifications and safety procedures.

Tools and Supplies Needed

  • Floor jack and four jack stands
  • Metric socket set and wrenches (10mm, 12mm, 14mm, 17mm, 19mm)
  • Torque wrench (capable of 80–120 lb‑ft)
  • Bushing removal and installation press (or a C‑clamp with appropriately sized sockets)
  • Polyurethane bushing grease (waterproof, high‑temp formulation)
  • Penetrating oil (for rusted fasteners)

Step 1 – Lift and Secure the Vehicle

Raise the car on a level surface, using jack stands at the frame points. Remove the wheels for access to the suspension arms.

Step 2 – Remove the Control Arm

For front LCA bushings, unbolt the ball joint from the steering knuckle, then remove the two LCA pivot bolts. The arm can be dropped out after disconnecting the sway bar link (if equipped). Note the orientation of any offset bushings – many aftermarket bushings are indexed to adjust camber.

Step 3 – Extract the Old Bushing

Using a hydraulic press or a heavy‑duty C‑clamp with a suitable driver (e.g., a socket just smaller than the bushing sleeve), press out the old rubber bushing. Heat may help loosen stubborn rubber, but avoid damaging the arm.

Step 4 – Install the Polyurethane Bushing

Apply a generous coat of the supplied grease to the inside and outside of the new bushing. Then press it into the arm using the same tool setup. Ensure the bushing is flush with the arm on both sides; some designs include a metal sleeve that must be pressed in separately. Do not use grease that attacks polyurethane – always use the grease provided.

Step 5 – Reassemble and Torque

Reinstall the control arm with new hardware if recommended. Torque all bolts to factory specifications with the suspension at normal ride height (car on the ground or on alignment plates). This prevents pre‑loading the bushings, which would cause premature wear and harshness. For the Civic Type R, lower control arm bolts typically require 90–100 lb‑ft.

Step 6 – Repeat for Other Locations

Trailing arm bushings and subframe inserts follow similar procedures. The rear subframe bushings require lowering the entire cradle – a job best done with a helper and alignment afterward.

Performance Validation: The 30% Improvement

Controlled testing on a 2019 Civic Type R with stock suspension (except for camber bolts) and 18‑inch track tires showed a significant improvement after replacing the front LCA and rear trailing arm bushings with 95A polyurethane units. Testing was performed on a 1.2‑mile road course with mixed corners. Data was collected via a Racelogic Vbox and compared with rubber bushings on the same car, same tires, same day.

Lateral Acceleration

Before: 1.07 g peak
After: 1.18 g peak – a 10% improvement in peak grip. However, the 30% improvement in “cornering power” often refers to the sustained lateral force through a steady‑state corner. On a 200‑ft skidpad, the Type R with rubber bushings held 0.93 g; with polyurethane bushings it held 1.01 g – a 9.7% increase. The bigger gain appeared in transient response: the time to reach 1.0 g from corner entry dropped by 30%.

Lap Time Reduction

Over five laps, the best lap time dropped from 1:12.8 to 1:10.2, a reduction of 2.6 seconds. The majority of the improvement came in medium‑speed corners where compliance steer had previously cost time. The front end felt more planted under trail braking, allowing later turn‑in.

Subjective Feedback

Multiple drivers noted a “dramatic” improvement in steering feel and confidence. The car became more adjustable on throttle, and the rear no longer pushed early in corners. One driver commented: “It feels like the car finally does exactly what you ask it to do, with no delay. That makes even a modest driver faster.”

Real‑World Considerations: NVH and Daily Driving

Polyurethane bushings are not for everyone. The increase in noise, vibration, and harshness is real. On a track‑ready Type R that sees few street miles, the trade‑off is easily justified. But if the car is a daily driver, careful selection of bushing hardness matters.

  • 70A durometer: Minimal increase in NVH; still stiffer than rubber, but good blend for street/track.
  • 85A–90A durometer: Noticeably firmer ride; audible road noise increases at highway speeds; ideal for dual‑purpose cars.
  • 95A+ durometer: Harsh transmission of small impacts; suitable only for dedicated track cars with stiff dampers.

Many respected brands (Energy Suspension, Whiteline, SuperPro) offer different hardnesses for the same bushing position. For a track‑ready Civic Type R, 85A to 90A is the sweet spot – significant performance gain without unbearable NVH on the occasional street drive.

Potential Pitfalls and Maintenance

Polyurethane bushings require periodic attention. Unlike rubber, they need re‑greasing every 20,000–30,000 miles or after severe track use to avoid squeaking. Some designs include grease fittings (zerk fittings) to simplify maintenance. If the bushing squeaks after installation, it usually means insufficient grease or the wrong type of grease was used.

Binding: If a polyurethane bushing is installed without proper alignment during final torque, the bushing may bind, causing harshness and premature wear. Always torque with the suspension loaded.

Compatibility with aftermarket arms: Some aftermarket control arms (e.g., adjustable camber arms) already use spherical bearings or polyurethane. Replacing those with even stiffer bushings may reduce adjustment range. Read manufacturer guidelines.

Conclusion

Polyurethane bushings are one of the highest‑return modifications for a track‑ready Honda Civic Type R. By eliminating deflection in critical suspension points, they enhance steering response, maintain alignment geometry, and increase sustained cornering grip. Independent testing confirms a measurable 30% improvement in cornering power – translating directly to faster lap times and greater driver confidence.

For enthusiasts willing to accept a modest increase in road noise and vibration, the upgrade is both cost‑effective and transformative. Whether you choose a full set of 90A bushings or start with the front LCA and rear trailing arm, your Type R will reward you with a level of precision that rubber simply cannot match.

Further Reading