Upgrading a Subaru Outback to deliver around 300 horsepower transforms the wagon from a practical daily driver into a seriously capable performance machine. But with that extra power comes increased stress on the suspension components, especially the rubber bushings that connect the control arms, sway bars, and trailing arms. Stock rubber bushings, designed for comfort and cost savings, will flex and deflect under high torque and aggressive cornering, leading to vague steering, excessive body roll, and premature wear. Replacing them with polyurethane bushings is one of the most effective modifications you can make to tighten up the chassis, improve steering response, and put that 300 HP to the ground with confidence. This guide walks you through a successful DIY installation, covering the tools, techniques, and pro tips that separate a clean install from a weekend gone wrong.

Why Polyurethane Bushings Matter for a 300 HP Outback

Before diving into the installation, it’s worth understanding exactly why polyurethane is a necessary upgrade for a higher-powered Outback. A stock 2.5-liter or even 3.6-liter Outback makes around 170–256 horsepower. At 300 HP, you’ve likely added a turbocharger, performance tune, or a engine swap. The physics are simple: more torque means more twisting force on the suspension arms. Rubber bushings, which are essentially soft rubber bonded to a metal sleeve, can compress and deform significantly under load. That deformation causes a lazy, delayed reaction when you turn the wheel, and it allows the wheels to move out of alignment under acceleration or braking. Polyurethane bushings are firmer, with a durometer rating typically around 80A–95A, which provides minimal deflection and immediate response.

The key benefits for a 300 HP Outback include:

  • Sharper steering response: The front control arm bushings hold the wheel in place under load, so turn-in is crisp and predictable.
  • Reduced brake dive and acceleration squat: Firmer rear trailing arm and front lower control arm bushings keep the chassis level.
  • Improved traction: By preventing bushing deflection, the tires maintain better contact patch through corners.
  • Longevity: Polyurethane resists oil, grease, and ozone far better than rubber, lasting years longer in harsh underbody conditions.

Many enthusiasts also report that polyurethane bushings reduce the unsettling “wiggle” that high-power Subarus exhibit during hard shifts. For an Outback – already a heavy vehicle – this stability is critical for driver confidence.

Comparing Polyurethane vs. Rubber Bushings

If you’re on the fence, consider the key differences. Rubber bushings are comfortable and quiet, but they have limited service life, especially with high horsepower. A 300 HP Outback will chew through rubber bushings in 20,000–30,000 miles, leading to clunks and alignment issues. Polyurethane lasts 100,000 miles or more with proper lubrication. The trade-off is increased noise, vibration, and harshness (NVH). You will feel more road imperfections and hear a slight increase in suspension noise, but for a performance-oriented build, the feedback is welcome. If you daily drive the car and value absolute silence, stick with rubber. But if you want the car to handle like it means business, polyurethane is the right choice.

Tools and Materials

A clean, well-organized workspace is half the battle. Here’s what you need:

  • Floor jack and four jack stands (minimum 3-ton capacity for the Outback’s weight)
  • Metric socket set (10mm, 12mm, 14mm, 17mm, 19mm, 21mm) with extensions and a breaker bar
  • Torque wrench (ft-lb scale, 0–150 ft-lb range)
  • Ball joint separator or pickle fork (for control arms)
  • Large C-clamp or bench press (for installing bushings)
  • Pry bars (18" and 24")
  • Propane torch or heat gun (to remove stubborn rubber)
  • Wire brush and brake cleaner (to clean bores)
  • Polyurethane bushing grease (silicone-based, never petroleum-based as it degrades polyurethane)
  • Threadlocker (blue Loctite for bolts subject to vibration)
  • Safety glasses and gloves

For the bushings themselves, reputable brands like Energy Suspension and SuperPro offer complete kits for the Subaru Outback. Make sure the kit includes the correct, greasable bushings for the front lower control arms, rear trailing arms, and sway bars. Avoid no-name kits from generic sellers as the durometer may be inconsistent.

Preparation: Safety and Access

Start on a level surface and chock the rear wheels (if raising the front) or front wheels (if raising the rear). Engage the parking brake. Do not rely on the jack alone – always set the car on jack stands placed under the factory frame rails or subframe mounting points. For an Outback, the front jacking point is the crossmember behind the oil pan, and the rear is the diff housing. Jack stands go under the pinch welds (with adapters) or under the subframe.

Remove the wheels. This gives you access to the control arm bolts, sway bar links, and trailing arms. Spray all bolts with penetrating oil like PB Blaster or WD-40 an hour before starting; Subaru hardware often corrodes, especially in salt-belt regions. Take photos of the suspension before disassembly – this makes reassembly far easier. Label each side, because some bolts are handed or have specific washers.

Step-by-Step Installation: Front Lower Control Arms

Remove the Old Bushings

The front lower control arm on a Subaru Outback usually has two bushings: a front bushing pressed into the arm (often offset) and a rear bushing that is sometimes a separate piece. To remove the arm:

  1. Loosen the bolts securing the control arm to the subframe and the knuckle. Use a breaker bar – these are often torqued to 100–130 ft-lb.
  2. Separate the ball joint from the knuckle using a pickle fork or ball joint separator. Be careful not to damage the boot.
  3. Remove the control arm from the car.
  4. To remove the old rubber bushings, you have three options: press them out with a hydraulic press (best), burn them out (messy but effective), or cut them out with a sawzall and chisel. If you lack a press, a large C-clamp with a socket slightly smaller than the bushing outer diameter can push it out. Apply heat if needed.
  5. Clean the bore thoroughly with a wire brush and brake cleaner. Any rubber residue will prevent the polyurethane from seating correctly.

Install the New Polyurethane Bushings

Polyurethane bushings often come as two-piece shells with a center sleeve. Follow these steps:

  1. Liberally apply the included grease (or a compatible silicone grease) to the inner sleeve and the outer shell of the bushing. Also grease the control arm bore. Do not skip this – polyurethane will squeak without lubricant.
  2. Place the two halves of the bushing over the sleeve, then align them into the bore. For a tight fit, use a bench vise or C-clamp to press the bushing into place. Keep it straight to avoid cocking the sleeve.
  3. Insert the bushing’s center pin (if separate) and install the washers and nut. Do not fully tighten yet. Polyurethane bushings must be tightened with the suspension at ride height, otherwise they will bind and fail prematurely.
  4. Reinstall the control arm onto the subframe and knuckle. Hand-tighten all bolts.

Torque Specifications

Use the factory torque values from your Subaru service manual. On most 2005–2014 Outbacks, front control arm bolts are 100–130 ft-lb, sway bar link bolts are 35–40 ft-lb, and trailing arm bolts are 80–90 ft-lb. If you don’t have a manual, refer to a trusted source like SubaruOutback.org for verified numbers. Over-tightening can crack the polyurethane or strip threads.

Step-by-Step Installation: Rear Trailing Arms

The rear trailing arms on a 300 HP Outback take significant punishment under hard acceleration, causing wheel hop if the bushings are loose. The process is similar:

  1. Remove the wheel and support the rear hub with a jack stand.
  2. Remove the bolt connecting the trailing arm to the subframe and the bolt at the hub end.
  3. Press out the old rubber bushings as described above. Subaru rear trailing arm bushings are notoriously stubborn; a torch helps.
  4. Clean the bores, grease, and press in the polyurethane bushings. Ensure the metal sleeve is centered.
  5. Install the arm and hand-tighten the bolts.

Step-by-Step Installation: Sway Bar Bushings

Upgrading sway bar bushings is the quickest win. The stock rubber bushings allow excessive bar roll, but polyurethane replacements clamp tighter.

  1. Remove the two bolts holding the sway bar bracket to the subframe.
  2. Slip out the old bushing.
  3. Grease the new polyurethane bushing and the bar where it contacts. Use plenty of grease to prevent squeaks.
  4. Reinstall the bracket and torque to spec (around 30–40 ft-lb on most Outbacks).
  5. Repeat for the front sway bar (if equipped) and the rear sway bar.

Critical Step: Ride Height Torquing

After all bushings are installed and all suspension bolts are hand-tight, lower the car onto its wheels (or place ramps under the tires to simulate ground contact). With the vehicle’s full weight on the suspension, torque all bolts to the specified values. This ensures the bushings are not twisted when the car is at rest, which would cause premature wear and harsh ride quality. This is the most common DIY mistake – torquing while the car is in the air. Don’t skip it.

Post-Installation: Alignment and Test Drive

Polyurethane bushings often change the suspension geometry slightly because they prevent the old rubber deflection that masked misalignment. You will need a professional four-wheel alignment after installation. The toe settings will almost certainly be off, and camber may shift. A proper alignment ensures even tire wear and straight-line stability.

After the alignment, go for a test drive. Start on smooth roads to listen for squeaks. Minor rubbing noises are normal for the first few miles as the polyurethane settles. If you hear loud grinding or popping, stop and recheck all bolts – something might be loose. Once settled, try some spirited driving: hard brakes, sharp turns, and a few quick accelerations. You should feel a dramatic reduction in body roll and steering vagueness. The car will feel more planted and responsive. Some additional road noise is expected, but it’s a small price for the handling gain.

Common Mistakes and How to Avoid Them

  • Using the wrong grease: Petroleum-based grease destroys polyurethane. Always use the grease that comes with the kit or buy a silicone-based polyurethane grease.
  • Overtightening bolts: This can crush the bushing or distort the sleeve. Follow torque specs precisely.
  • Not torquing at ride height: As discussed, this will cause the bushing to bind and tear.
  • Forgetting to clean the bore: Rust and debris prevent the bushing from seating flush, leading to premature wear.
  • Installing bushings in the wrong orientation: Some front control arm bushings have an offset to alter caster. Mark the position before removal.

Maintenance and Long-Term Care

Polyurethane bushings are low-maintenance but not zero-maintenance. Every 12 months, inspect them for cracking, excessive dry-out, or loss of grease. If a squeak develops, you can inject additional grease using a grease needle (if the bushing has a zerk fitting) or by removing and regreasing. Silicone spray can temporarily quiet a dry bushing. Avoid high-pressure car washes on the bushings, as water can wash away grease over time. With care, your polyurethane bushings will outlast the car.

Conclusion

Installing polyurethane bushings on a 300 HP Subaru Outback is a weekend project that delivers immediate, noticeable improvements in handling, steering feedback, and confidence. By taking your time, using the right tools, and following the critical steps – especially torquing at ride height – you can avoid headaches and enjoy a transformation that makes your Outback truly perform. Whether you’re carving mountain roads or merging aggressively on the highway, the difference is night and day. Pair these bushings with a good set of coilovers or performance shocks, and you’ll have a wagon that handles like a sports car.