Introduction: Why Upgrade to Polyurethane Bushings on a 450 HP Evo X

When your Mitsubishi Evolution X pushes 450 horsepower to all four wheels, every component in the suspension and driveline is stressed far beyond stock levels. The factory rubber bushings, designed for comfort and noise isolation, begin to flex excessively under high torque and aggressive cornering loads. This flex introduces slop, delays steering response, and allows unwanted wheel alignment changes. Replacing those soft rubber cushions with polyurethane bushings—specifically the polyurethane bushings from BBR Motorsports—is one of the most effective suspension upgrades you can make. Polyurethane is much stiffer than rubber, yet it retains enough compliance to avoid the harshness of solid spherical bearings. The result is sharper turn‑in, more consistent geometry under braking, and improved rear‑end stability during power‑down on corner exit. This guide provides a comprehensive walkthrough for installing a BBR Motorsports polyurethane bushing kit on your 450‑HP Evo X, covering everything from tool selection to post‑installation alignment checks. Follow these steps carefully to extract maximum performance from your chassis without unnecessary hassle.

BBR Motorsports is known for precision‑machined polyurethane components that fit snugly into OEM control arms, trailing arms, and subframe mounts. The installation demands patience, but the gains in steering feel and durability make it worthwhile for any serious Evo X owner. For more background on why polyurethane outperforms rubber in high‑performance applications, check out this Super Street article on polyurethane bushing basics.

Tools and Materials Needed

Before you lift the car, gather every tool and consumable listed below. Working with bushings is far easier when you have everything within arm’s reach. Missing one item can stop the job cold.

  • BBR Motorsports polyurethane bushing kit – verify it’s the correct set for your model year (2008‑2015). Most kits include bushings for the front lower control arms, rear trailing arms, rear knuckle, and rear subframe.
  • Floor jack and four jack stands – minimum capacity of 3 tons. You’ll need all four corners in the air for many bushing locations.
  • ¼‑inch and ½‑inch drive socket set – metric sizes from 10 mm to 22 mm. Common Evo X fasteners: 14 mm for lower control arm bolts, 17 mm for strut‑to‑knuckle, 19 mm for subframe mounts.
  • Combination wrench set (metric) – for holding nuts while loosening bolts.
  • Torque wrench – capable of readings up to 150 ft‑lb, ideally a ½‑inch drive model. EvolutionM.net torque specs thread is a useful reference for critical fastener values.
  • Rubber mallet or dead‑blow hammer – for persuading stubborn bushings without damaging them.
  • Bushing press kit (optional but highly recommended) – a C‑frame press makes removal and installation much cleaner. Budget alternatives include large sockets, a long bolt, washers, and a nut to create a makeshift press.
  • Polyurethane grease or lithium‑based assembly lube – BBR often supplies a tube of specific grease; if not, use a quality synthetic grease that won’t degrade the polyurethane.
  • Penetrating oil (e.g., WD‑40, PB Blaster) – for seizing bolts on older, rust‑prone hardware.
  • Cutoff wheel or reciprocating saw with metal blade – only if the old rubber bushings are bonded or corroded and refuse to come out intact.
  • Safety glasses and mechanic’s gloves – metal shards and solvent splashes are real hazards.
  • Shop rags and brake cleaner – to clean bushing bores before installing new polyurethane.
  • Permanent marker – for marking bolt positions during removal.

Preparation and Safety

Park the Evo X on a perfectly level concrete surface. Chock the rear wheels if you lift only the front, but the full job is easier with the entire car elevated equally. Let the exhaust and engine cool completely—working near hot manifolds increases burn risk. Disconnect the battery negative terminal if you need to access any electrical connectors (not strictly required for bushing work, but a wise habit). Review the BBR kit instructions to identify which bushings go where. Some kits differentiate left‑ and right‑hand parts; lay them out on a clean workbench in order of installation. Confirm that all hardware supplied (bolts, washers, sleeves) matches the original fasteners. If any bolt feels undersized or the shoulder length is wrong, contact BBR before proceeding.

Step 1: Lifting and Securing the Vehicle

Position the floor jack under the front crossmember or reinforced subframe pickup point. Raise the front end until both tires are just off the ground, then place jack stands under the factory‑designated lift points—forward of the front pinch welds near the wheel wells. Repeat at the rear using the differential housing (only if it’s a solid mount) or the rear subframe jacking point. Lower the car onto the stands and give it a firm shake to ensure stability. Do not rely on a single jack or scissor stands. With the car safely suspended, remove all four wheels using a breaker bar and socket. Set them aside out of the work area.

Step 2: Removing the Old Rubber Bushings

2.1 Front Lower Control Arm Bushings

The front lower control arm (LCA) has two bushings: a forward (compliance) bushing and a rear (lateral) bushing. Use a 17 mm socket and wrench to remove the two bolts that attach the LCA to the knuckle and the chassis. Carefully lower the arm. On the bench, press out the old rubber bushings. A press works best: position the LCA on the press cradle with the appropriate‑sized receiver cups (often 1.5‑inch inner diameter). Apply penetrating oil to the rubber/metal interface if the bushing is seized. If you don’t have a press, use a bench vise and a large socket to drive the bushing out. Cut the rubber center with a drill or saw if the metal sleeve is bonded—removing the rubber core first relieves tension, making shell extraction easier. Wear safety glasses; metal fragments and rubber particles can fly.

2.2 Rear Trailing Arm and Knuckle Bushings

At the rear, the trailing arm connects the subframe to the knuckle. Remove the bolt at the chassis side (usually 19 mm) and the bolt at the knuckle side (14 mm). The trailing arm will swing free. On some Evo X years, the knuckle bushing requires subframe drop for access—check your BBR kit instructions. Remove the subframe bolts (four large 19 mm bolts) and lower the subframe a few inches using a jack. This gives clearance to press out the old bushings with a long‑reach press tool. For the knuckle itself, a hydraulic press is almost mandatory unless you use a blind‑hole puller set. Take your time—the steel sleeves are often rusted into the aluminum knuckle. Heating the knuckle with a torch (to about 200°F) can expand the aluminum and ease removal. Do not heat the bushing itself; polyurethane will degrade above 300°F. When all old bushings are out, clean each bore with brake cleaner and a wire brush to remove any rubber residue, rust, or grease. A clean bore ensures the new polyurethane bushing seats squarely.

Step 3: Preparing the New BBR Motorsports Bushings

Lay out the new polyurethane bushings. Each one will likely have a metal inner sleeve and sometimes a separate outer shell. Compare them to the old bushings to confirm orientation. Some are beveled or have alignment arrows. Apply a thin, even coat of the supplied polyurethane grease to the outer diameter of each bushing and to the inner bore of the control arm or knuckle. Do not use petroleum‑based greases; they can attack the polyurethane. The grease serves two purposes: it prevents squeaking and acts as a lubricant during insertion. If BBR did not include grease, use a high‑quality silicone‑based or PTFE‑infused assembly lube designed for polyurethane. Apply just enough to make the surface slick—excess will squeeze out and attract dirt.

Step 4: Installing the New Bushings

4.1 Pressing with the Bushing Press

Position the new bushing at the mouth of the bore, angled slightly if needed to start. Use a press or the DIY washer‑and‑bolt method: place a large flat washer larger than the bushing’s outer diameter against the bushing, then thread a long bolt through a stack of washers and a large socket on the opposite side to act as a receiver. Tighten the nut to draw the bushing into place. Push straight and steadily. If it binds, stop, clean the bore again, and apply more grease. Never hammer directly on the polyurethane—it can deform or crack. Use a rubber mallet only as a last mild tap.

4.2 Subframe Bushings

Rear subframe bushings are the most difficult. You may need to fully remove the subframe to use a press. Alternatively, a portable hydraulic press tool with a cup attachment can work in situ. Follow BBR’s specific instructions for the subframe bushings, as misalignment can cause chassis binding. After each bushing is seated, verify the inner sleeve rotates freely (it should not be bound). Insert the new hardware (bolts, washers) that came with the kit, but do not fully torque yet—all suspension bolts must be tightened at ride height to avoid preloading the bushings.

Step 5: Reassembling Components – Torque at Ride Height

This is the most critical step for bushing longevity. Reattach the control arms, trailing arms, and subframe. Hand‑tighten all bolts. Lower the vehicle onto a set of ramps or use the jack to bring the suspension to its normal ride height (the car should be on its wheels with full weight on the ground). Then, using the torque wrench, tighten each bolt to the EVO X factory specification. For example:

  • Front LCA rear bushing bolt: 81 ft‑lb (110 N·m)
  • Front LCA forward bushing bolt: 40 ft‑lb (54 N·m)
  • Rear trailing arm chassis bolt: 76 ft‑lb (103 N·m)
  • Rear knuckle bushing bolt: 72 ft‑lb (98 N·m)
  • Rear subframe bolts: 85 ft‑lb (115 N·m)

Always verify with a reliable source; variations exist between model years. Tightening at ride height prevents the polyurethane from being twisted in the neutral position, which would cause premature fatigue and noise. Mark each bolt head with a paint pen after torquing so you can visually inspect later.

Step 6: Final Checks and Test Drive

Reinstall the wheels and lower the car completely. Pump the brakes a few times to seat the pads (if you disturbed them). Start the engine and let it idle to bring fluids up to temperature. Listen for any clunks or squeaks that indicate a bushing is not seated or a bolt is loose. Take the car on a short, low‑speed drive on a smooth road, then return and recheck torques on all the bushings you installed. Polyurethane may settle slightly after the first few miles; a retorque after 100 miles is recommended. For a 450‑HP Evo X, a proper alignment is essential. The new bushings will alter the static alignment angles—especially camber and toe. Drive to a reputable alignment shop and request an aggressive street/track alignment (e.g., -1.5° front camber, -1.0° rear camber, 0–1/16” total toe). This setup will maximize the handling benefit of the stiffer bushings.

During the first 500 miles, avoid hard launches and full‑load cornering to let the bushings settle. After that break‑in period, you can push the car hard. You’ll notice immediate improvements: reduced steering slop, more precise turn‑in, and a more connected feel through the chassis. The polyurethane bushings will maintain their performance for many tens of thousands of miles, far outlasting rubber. For ongoing maintenance, occasionally inspect the bushing faces for cracking and re‑grease if squeaking develops.

Frequently Asked Questions

Will polyurethane bushings make my Evo X too harsh for daily driving?

There is a modest increase in road vibration, especially at low speeds over rough pavement. However, BBR Motorsports formulated their polyurethane to be a medium‑durometer (around 80A to 90A Shore), which is firm but not harsh. Most owners describe the NVH increase as acceptable—far less than solid bearings. If you drive the car only on weekends or at the track, the trade‑off for sharper response is easily worth it.

Do I need to replace all bushings at once?

For a 450‑HP car, replacing all suspension bushings simultaneously is strongly recommended. Mixing old worn rubber with new polyurethane creates uneven deflection and may hide handling problems. The BBR kit provides a comprehensive set for front and rear, so it’s efficient to do them all in one session.

Can I install these bushings without removing the subframe?

Some rear subframe bushings can be pressed in with the subframe still attached using a long‑reach press tool. However, clearance is tight. Removing the subframe (four bolts) gives you better access and reduces the chance of damaging the bushing. With an extra pair of hands, dropping the subframe only takes 15 minutes.

Conclusion

Upgrading to BBR Motorsports polyurethane bushings transforms your 450‑HP EVO X from a powerful but slightly vague machine into a precise tool that rewards every steering input. The installation demands mechanical competence and patience, especially when dealing with pressed‑in bushings and the need to torque at ride height. But the payoff on track and canyon roads is dramatic—consistent geometry under power, minimal deflection, and greatly improved feedback. By following this step‑by‑step guide and respecting the torque and alignment requirements, you ensure a long‑lasting, rattle‑free installation. For further reading on suspension tuning for the Evo X, visit EvolutionM.net chassis forum and check BBR Motorsports’ official site for product updates and support.