Upgrading Front Polyurethane Bushings to Achieve Mazda Spirit Racing Tight Steering Specs
You turn the steering wheel, and there’s that annoying delay—a half-second of nothing before the front end finally responds. That’s not you. That’s your worn-out rubber bushings flexing like wet noodles. Mazda’s Spirit Racing division figured this out years ago: tight steering starts with tight bushings. Here’s how to upgrade your front control arm bushings to polyurethane and get that razor-sharp, immediate turn-in you’ve been chasing.
TL;DR:
Factory rubber bushings soften and crack over time, allowing suspension arms to move unpredictably under load . This movement creates vague steering, delayed turn-in, and inconsistent alignment. Upgrading to polyurethane bushings—specifically around 80 Shore A hardness for fast road use—eliminates this compliance . The result is steering that responds instantly, stays planted in corners, and communicates exactly what the front tires are doing. Mazda’s Spirit Racing division equips their track-ready MX-5 models with Bilstein dampers and chassis reinforcements to achieve the same “tight steering spec” philosophy . This guide walks you through pressing out the old rubber, installing polyurethane replacements, and dialing in the alignment to match Spirit Racing standards.
Key Takeaways:
- Rubber flexes; polyurethane doesn’t—factory bushings allow up to several degrees of alignment change under hard cornering
- 80 Shore A is the sweet spot for street performance—stiff enough for control, compliant enough for daily driving
- Front lower control arm rear bushings make the biggest difference—these are the most stressed bushings during cornering
- Press out, don’t burn out—removing old rubber bushings requires a hydraulic press or specialized tool; torching them ruins the control arm
- Alignment is mandatory after bushing replacement—camber and toe WILL change; expect to pay $100-150 for a performance alignment
- Spirit Racing philosophy prioritizes mechanical feedback—their 12R model achieves 197 naturally aspirated horsepower with chassis tuning that emphasizes driver connection
Why Rubber Bushings Are Killing Your Steering Feel
Let me explain the hidden enemy hiding inside your suspension arms.
Bushings are the flexible joints that connect your control arms to the chassis. Their job is to allow suspension movement while damping noise and vibration . But here’s the problem: rubber is a compromise.
According to Powerflex’s technical explanation, “OEM suspension bushings are manufactured from a rubber compound which deteriorates with age. They become softer and more pliable, resisting the forces applied less and less. These tired rubber pieces allow more and more movement of suspension components and offer less and less control over suspension geometry as they age.”
What happens when you corner hard:
| Force | What Rubber Does | What You Feel |
|---|---|---|
| Lateral load | Bushing compresses and twists | Steering wheel feels loose, car drifts wide |
| Braking force | Bushing allows arm to move rearward | Nose dives, steering wanders |
| Acceleration load | Bushing stretches | Torque steer, vague front-end feel |
The motorsport bushing guide adds: “Unlike rubber bushings, which can compress and flex under load, polyurethane bushings offer greater rigidity and stiffness. This results in reduced body roll, improved steering precision, and better feedback from the road.”
Italic highlight: Worn bushings are often the single biggest reason older cars feel loose. Powerflex notes that “bushings are the single biggest reason you can instantly tell the difference between an older car and a new one” . But even new cars benefit from the upgrade.
What Polyurethane Brings to the Table
Polyurethane isn’t just “harder rubber.” It’s a fundamentally different material with distinct advantages.
Material Properties Compared
| Property | Factory Rubber | Polyurethane |
|---|---|---|
| Stiffness | Soft, progressive | Firm, linear |
| Durability | Cracks at 5-8 years | Lasts 15+ years |
| Oil resistance | Swells and degrades | Unaffected |
| Temperature stability | Softens when hot | Maintains stiffness |
| NVH transmission | Low (absorbs vibrations) | Moderate (transmits more) |
According to LLRacing’s bushing guide, “Polyurethane bushings are offered in different hardness levels, typically around 80 ShA (red) for fast-road and 90 ShA (yellow) for race applications. The harder compound limits how far the bushing can deflect, keeping control arms and subframes located more accurately relative to the body.”
What this means for your Mazda: A polyurethane front control arm bushing is roughly 25-30% stiffer than a new rubber bushing . Compared to a worn one? The difference is night and day.
The SuperPro bushing kit description notes: “Improves steering feedback and response; a complete, premium upgrade” .
Safety Note: Increased stiffness does transmit more noise and vibration into the cabin. As LLRacing notes, “Some increase in NVH is expected, particularly if you stiffen engine and subframe mounts as well as control arms” . For a dedicated track car, this is a feature. For a daily driver, stick with 80 ShA “fast road” compound.
The Spirit Racing “Tight Steering” Philosophy
Mazda’s resurrected performance division—Mazda Spirit Racing—has a specific approach to chassis tuning. And it starts with eliminating compliance.
The Spirit Racing Roadster 12R produces 197 horsepower from a naturally aspirated 2.0L engine—not by adding a turbo, but by improving breathing and reducing internal friction . The same philosophy applies to the chassis: tighten what’s there instead of adding complexity.
Spirit Racing chassis upgrades include:
| Component | Spirit Racing Spec | Benefit |
|---|---|---|
| Dampers | Bilstein adjustable C-ring | Precise body control |
| Chassis bracing | Front strut tower brace | 23% increase in rigidity |
| Brakes | Brembo 4-piston calipers | Consistent stopping power |
| Wheels | Rays TE37 forged | Reduced unsprung weight |
| Tires | Yokohama ADVAN A052 | Maximum mechanical grip |
Notice what’s missing from that list? Power-adders. Turbochargers. Complicated electronics. Spirit Racing’s formula is simple: reduce compliance, increase feedback, let the driver feel everything.
Italic highlight: The 12R’s 23% increase in chassis rigidity comes from welded reinforcements and a front strut tower brace . Upgrading your bushings attacks compliance at the same source—the flexible joints between suspension components.
A Spirit Racing review notes that the mechanical upgrades “focus on delivering superior handling… the six-speed manual gearbox exclusively (no automatic option)” . This is a car built for drivers who want to feel connected to the road.
Which Bushings to Upgrade (And in What Order)
Not all bushings are created equal. Some make a massive difference; others are barely noticeable.
Priority 1: Front Lower Control Arm Rear Bushings (The Big One)
This bushing experiences the highest loads during cornering and braking. It’s the single most effective upgrade for steering feel.
According to SuperPro’s product page, this kit includes “6 Control Arm Bushings, 2 Sleeves & Tubes” and takes approximately 3 hours to install .
OEM part numbers for reference: GS1D-34-200C , C513-34-350 , EH44-34-300C .
Priority 2: Front Lower Control Arm Front Bushings
This bushing sees less load than the rear, but still benefits from upgrade. Replace it while you’re in there.
Priority 3: Front Sway Bar Bushings
Sway bar bushings affect body roll control. They’re cheap and easy to replace—often a 30-minute job.
Priority 4: Rear Subframe Bushings
These affect rear-end stability under power. They’re more involved to replace but worth it for a complete chassis refresh.
A LLRacing guide suggests focusing on “key areas” rather than replacing every bushing: “Partial upgrades, like replacing front control arm and rear subframe bushings, can deliver much of the performance benefit with a smaller comfort penalty” .
Durometer Selection: Matching Your Driving Style
Durometer (Shore A hardness) determines how stiff the bushing is. Choose wrong, and your car will either feel no different or ride like a lumber wagon.
| Durometer | Color (Typical) | Best For | NVH Level |
|---|---|---|---|
| 70-75 ShA | Black or blue | Daily driver, comfort-focused | Minimal increase |
| 80-85 ShA | Red or purple | Fast road, autocross, spirited driving | Moderate increase |
| 90-95 ShA | Yellow or orange | Track-only, race car | Significant increase |
According to LLRacing’s guide, “Red 80 ShA parts are aimed at sporty road use, while yellow 90 ShA versions target circuit and competition where geometry control is more important than comfort” .
The motorsport bushing guide confirms: “Polyurethane bushings offer enhanced durability, improved handling and responsiveness, optimized suspension performance, and reduced maintenance requirements” .
Italic highlight: For a Mazda that sees both daily driving and weekend canyon runs, 80 ShA is the sweet spot. It’s stiff enough to transform steering feel but not harsh enough to rattle your fillings loose.
Safety Note: SuperPro offers a lifetime warranty on their polyurethane bushings . This is a testament to their durability—rubber bushings would be long gone before the warranty expired.
Installation Guide: Pressing Out Old, Pressing In New
Replacing control arm bushings isn’t a beginner job, but it’s doable with the right tools and patience.
Tools You’ll Need
| Tool | Purpose |
|---|---|
| Hydraulic press (12-ton minimum) | Removing old bushings, installing new ones |
| Bushing removal tool set | Alternative to press (if you have one) |
| Torque wrench (50-150 ft-lb range) | Proper bolt tightening |
| Ball joint separator | Separating control arm from knuckle |
| Jack and jack stands | Lifting the vehicle |
| Penetrating oil (PB Blaster, Kroil) | Loosening rusted bolts |
| Anti-seize compound | Preventing galvanic corrosion |
Step 1: Remove the Control Arms
- Jack up the front of the car and support on jack stands
- Remove the front wheels
- Disconnect the sway bar end link from the control arm
- Remove the ball joint pinch bolt (replace with new one)
- Separate the ball joint from the knuckle using a ball joint separator
- Remove the two bolts securing the control arm to the subframe (front and rear)
- Remove the control arm from the vehicle
Step 2: Press Out the Old Bushings
Safety Note: NEVER torch out rubber bushings. The fumes are toxic, and the heat can weaken the aluminum control arm. Use a hydraulic press only.
According to LLRacing’s guide, “Polyurethane is ideal for exposed locations such as subframe mounts, diff mounts and engine or gearbox supports” . But getting the old rubber out requires mechanical force.
Proper procedure:
- Use appropriately sized sockets or press tools to support the control arm around the bushing
- Press the old bushing out from the control arm
- Clean the inside of the bushing bore thoroughly (wire brush, then brake cleaner)
- Inspect the control arm for cracks or damage
Step 3: Install the New Polyurethane Bushings
Unlike rubber bushings that require specific orientation, polyurethane bushings are typically symmetrical.
Installation steps:
- Apply the supplied grease to the inner and outer surfaces of the new bushing
- Press the bushing into the control arm using the hydraulic press (support the arm properly)
- Press the metal inner sleeve into the bushing (if separate)
- Ensure the bushing is fully seated and centered
A Powerflex guide notes that their bushings are “made using a proprietary urethane material which… overcome the common noise and harshness problems associated with harder bushings” .
Step 4: Reinstall Control Arms
- Reinstall the control arm using the new bolts (or cleaned old bolts with anti-seize)
- Do not fully tighten the subframe bolts yet—the suspension needs to be at ride height
Step 5: Torque at Ride Height (Critical!)
This is the most commonly skipped step—and the one that kills bushings.
- Lower the car onto ramps or jack stands under the control arms
- With the suspension at normal ride height, torque the subframe bolts to factory spec
- Reconnect the ball joint and torque the pinch bolt (use a NEW bolt)
Italic highlight: Tightening suspension bolts with the wheels hanging in the air preloads the bushings. They’ll twist every time the car sits on the ground, leading to premature failure. Always torque at ride height.
Alignment: The Non-Negotiable Final Step
After replacing bushings, your alignment WILL be off. According to SuperPro’s notes, the kit “improves steering feedback and response” —but only if the alignment is correct.
Recommended Performance Alignment Specs (Spirit Racing Inspired)
| Parameter | Stock Spec | Performance Spec | Why |
|---|---|---|---|
| Front Camber | -0.5° to -1.0° | -1.5° to -2.0° | More cornering grip |
| Front Toe | 0° to +0.10° (in) | -0.05° to -0.10° (out) | Sharper turn-in |
| Rear Camber | -1.0° to -1.5° | -1.5° to -2.0° | Balanced rotation |
| Rear Toe | +0.10° to +0.20° (in) | +0.10° to +0.15° (in) | Stability under power |
The Spirit Racing 12R’s chassis tuning philosophy prioritizes “interaction directe entre le conducteur et la voiture”—direct driver-to-car interaction . Your alignment should do the same.
Safety Note: Too much negative toe-out on the street will cause twitchy highway behavior and increased tire wear. Start with conservative settings and adjust incrementally.
What to Expect After the Upgrade
The transformation isn’t subtle. Here’s what you’ll notice immediately.
| Before (Worn Rubber) | After (Polyurethane) |
|---|---|
| Steering wheel has dead play | Steering responds instantly |
| Car drifts wide in corners | Holds line precisely |
| Nose dives under braking | Brake dive reduced |
| Vague feedback from front tires | Clear communication of grip limit |
| Alignment changes under load | Geometry stays consistent |
A motorsport-focused review notes: “By providing more consistent and predictable suspension behavior, polyurethane bushings allow drivers to push their vehicles to the limit with greater confidence. Whether navigating tight corners on a racetrack or executing precise drift maneuvers, polyurethane bushings contribute to a more stable and controlled driving experience” .
Italic highlight: The first time you turn into a corner after this upgrade, you’ll feel it immediately. That “squishy” delay is gone. The car just goes where you point it—no negotiation, no hesitation.
Visualizing the Performance Gain
This chart shows how polyurethane bushings reduce suspension deflection under cornering load compared to worn rubber, directly translating to tighter steering feel .
📊 Suspension deflection under cornering load: rubber vs. polyurethane bushings.
Frequently Asked Questions
1. Will polyurethane bushings make my Mazda ride harshly?
Not if you choose the right durometer. The 80 ShA “fast road” compound offers a noticeable improvement in response without making the car uncomfortably harsh . The track-focused 90 ShA compounds are best reserved for dedicated track cars.
2. How long do polyurethane bushings last?
Significantly longer than rubber. SuperPro offers a lifetime warranty on their bushings . Rubber typically lasts 5-8 years before cracking; polyurethane can last 15+ years.
3. Do I need to lubricate polyurethane bushings?
Yes. Quality kits come with special grease that prevents squeaking. Without lubrication, polyurethane can develop noise over time. Re-grease every few years or if you hear squeaking.
4. Can I install polyurethane bushings myself?
Yes, but you’ll need a hydraulic press (12-ton minimum) to remove the old bushings and press in the new ones. If you don’t have access to a press, have a machine shop do the pressing—then install the arms yourself .
5. Do Spirit Racing cars use polyurethane bushings?
Mazda hasn’t published exact bushing specifications, but their chassis philosophy emphasizes eliminating compliance. The 12R features Bilstein dampers, a front strut tower brace (23% rigidity increase), and chassis reinforcements that work alongside stiffer bushings .
6. How much does a full bushing upgrade cost?
A front lower control arm bushing kit runs approximately $150-200 . A full car kit (all control arms, sway bars, subframe) costs $500-800. Installation adds 3-6 hours of labor if you don’t DIY.
7. Do I need an alignment after replacing control arm bushings?
Absolutely. “A complete, premium upgrade” like bushing replacement WILL change your alignment . Schedule an alignment immediately after installation—expect to pay $100-150 for a performance alignment.
The Bottom Line
Here’s what you need to remember about upgrading your front polyurethane bushings to achieve Spirit Racing tight steering specs.
Rubber flexes. Polyurethane doesn’t. That simple material difference transforms how your Mazda drives. Every steering input goes directly to the tires instead of being absorbed by squishy bushings.
The Spirit Racing philosophy is about connection. Their 12R doesn’t rely on turbos or complicated electronics. It’s about mechanical feedback, reduced compliance, and driver engagement . Upgrading your bushings follows the exact same principle.
Start with the front lower control arm rear bushings. This single upgrade makes the biggest difference in steering feel . You can always add more later.
80 Shore A is the sweet spot for daily-driven performance cars. Stiff enough to transform the driving experience, compliant enough to keep your spine intact .
Don’t skip the alignment. All that precision is useless if your wheels aren’t pointing where they should.
The SuperPro product page sums it up: “Enhances your vehicles handling and performance… Unaffected by extreme temperatures, oils, water or coolant. A superior alternative to rubber” .
Your Mazda deserves to feel alive. Tight bushings are the first step.
Have you upgraded your Mazda’s suspension bushings to polyurethane? Which durometer did you choose, and how did it transform your steering feel? Drop your experience in the comments below!