Why Upgrade to Prothane Polyurethane Bushings on Your 2006 Honda Civic Si

The 2006 Honda Civic Si (FA5) is already a sharp-handling front-wheel-drive machine from the factory, but its rubber suspension bushings are a soft spot. Over time, factory rubber bushings compress, crack, and lose their ability to control suspension geometry. Replacing them with Prothane polyurethane bushings transforms the car's feel. Polyurethane is significantly stiffer than rubber, reducing deflection under cornering and braking forces. This translates to more precise steering response, reduced body roll, and better tire contact patch management. The result is a car that reacts predictably and instantly to driver inputs. This upgrade is one of the most cost-effective ways to tighten up a 2006 Civic Si’s chassis without moving to full spherical bearings.

This guide provides a detailed, step-by-step installation process for the front lower control arm bushings using a Prothane kit. While the rear suspension also benefits from polyurethane bushings, the front control arms are the most impactful and common starting point. Expect the job to take a full afternoon for a first-time installer. With the right tools and preparation, you can complete it without a press.

Tools and Materials You Will Need

Having everything ready before you lift the car saves frustration. Do not skip the safety gear or the grease. The Prothane bushings come with a small packet of grease, but many installers prefer to use an additional high-quality polyurethane-compatible lubricant to prevent squeaks long term.

  • Prothane polyurethane bushing kit (part number specific to 2006-2011 Civic Si front lower control arms)
  • Jack and jack stands (at least two stands rated for the vehicle weight)
  • Socket set (metric sockets: 10mm, 12mm, 14mm, 17mm, 19mm)
  • Torque wrench (range 20-150 ft-lbs)
  • Polyurethane-compatible grease (e.g., Prothane Super Grease or Energy Suspension silicone grease)
  • Wrenches (combination wrenches matching socket sizes)
  • Pry bar (18-inch or longer, with a flat end)
  • Hammer (ball-peen or dead-blow)
  • Socket or drift punch (slightly smaller than bushing outer diameter for pressing)
  • Safety glasses
  • Mechanics gloves
  • Breaker bar (for stubborn bolts)
  • Penetrating oil (e.g., PB Blaster or WD-40 Specialist)
  • Rubber mallet (for coaxing control arms without damaging them)

Preparation – Setting Up for Success

Begin on a level, solid surface. Concrete is ideal; avoid gravel or dirt. Engage the parking brake and place wheel chocks behind the rear wheels. Loosen the front wheel lug nuts about half a turn before lifting the car. It is critical to do this with the car still on the ground to prevent the wheel from spinning.

Jack up the front of the Civic Si at the front crossmember or designated jacking point in the owner's manual. Place jack stands under the front subframe or reinforced pinch weld points. Lower the vehicle onto the stands so it sits securely. Verify the car is stable by giving it a gentle push at a corner. Do not work under any vehicle that wobbles.

Before removing any bolts, spray penetrating oil on the control arm pivot bolts and the sway bar end link nuts if they are in the way. Allow it to soak for at least five minutes. This will make disassembly far easier on a car that may have seen years of corrosion.

Removing the Factory Bushings

Step 1: Remove the Front Wheels

Using the now-loosened lug nuts, remove the front wheels completely. Set them aside out of the work area. This exposes the front lower control arms and the knuckle area.

Step 2: Disconnect the Control Arm Ball Joint

Each lower control arm connects to the steering knuckle via a ball joint. Before unbolting the control arm from the chassis, separate the ball joint from the knuckle. Use a 17mm socket and breaker bar to remove the two bolts holding the ball joint to the lower part of the knuckle. A pry bar can help gently separate the taper. Do not hit the ball joint stud directly with a hammer to avoid damaging the threads. Once separated, let the knuckle and hub assembly hang free—the axle should have enough slack. Support the control arm with a jack stand or block to avoid stressing the inner bushings during the removal.

Step 3: Remove the Control Arm Bolts from the Chassis

The front lower control arm is attached to the subframe at two points: the front bushing and the rear bushing. Use a 19mm socket and breaker bar to remove the front bolt. Then move to the rear bushing bolt, which often requires a 14mm or 17mm socket depending on the aftermarket control arm hardware. Note that the rear bushing bolt may be longer and have a captured nut within the subframe. Keep all bolts and nuts organized; they are not interchangeable.

Step 4: Extract the Old Rubber Bushings

With the control arm free, take it to a workbench or a clean area on the ground. The factory bushing removal is often the most physically demanding part. The old rubber bushings have an outer metal shell that is press-fit into the control arm. You have several options:

  • Hammer and socket method: Place the control arm on two blocks of wood with the bushing centered over a gap. Position a socket (with an outer diameter slightly smaller than the bushing's metal sleeve) on top of the rubber bushing. Strike the socket sharply with a hammer until the bushing drives out. This can be exhausting but is effective.
  • Use a bushing removal tool or press: A universal ball joint press kit can carefully force the bushing out without hammering. This is recommended if you have access to one.
  • Burn or drill out the rubber (then cut the shell): As a last resort, you can burn out the rubber (outdoors, safely) and then use a chisel to collapse the metal outer sleeve. This creates a lot of smoke and is messy but works when the bushing is seized.

Whichever method you choose, avoid damaging the control arm’s mounting eyelets. If the inner surface becomes gouged, the new polyurethane bushing may not seat properly. Clean the inside of the control arm bores with a wire brush and solvent to remove any rubber residue, rust, or burrs.

Installing the Prothane Polyurethane Bushings

Step 1: Lubricate the Bushings

Prothane bushings are two-piece designs: an outer polyurethane sleeve and an inner metal sleeve. Apply a generous coating of the supplied grease or your polyurethane-compatible grease to the inner sleeve and to the inside of the polyurethane part. Also grease the area where the metal sleeve contacts the bolt and the control arm housing. Insufficient grease will lead to squeaking that can be heard inside the cabin.

Step 2: Insert the Bushing into the Control Arm

Line up the Prothane bushing with the control arm mounting hole. Polyurethane bushings are often slightly oversized to ensure a tight fit. Use a bench vise or a C-clamp to press the bushing in evenly. If you must use a hammer, place a block of wood over the bushing and strike the block—this prevents damaging the polyurethane. Drive the bushing until it is centered in the control arm eyelet. Do not force it at an angle; it should go in straight.

Once the bushing is flush, insert the inner metal sleeve. It should slide through with light hand pressure. If it is tight, tap it gently with a rubber mallet. The sleeve ends should be even with the outer polyurethane on both sides.

Step 3: Reinstall the Control Arms

Lift the control arm back into position under the car. Align the front bushing hole with the subframe mount. Install the bolt and a new nut if supplied. Hand-tighten. Then align the rear bushing hole and insert its bolt. Do not fully tighten any bolts now; the control arms must be loaded (vehicle on the ground) when torqued to specification.

Reattach the ball joint to the knuckle. Torque those bolts to 47 ft-lbs (64 Nm) as per factory spec. Double-check all fasteners are started by hand to avoid cross-threading.

Step 4: Torque the Bushing Bolts Under Load

Lower the vehicle so its full weight rests on the suspension again. Use the jack to lift slightly to remove the stands, then lower the car to the ground. With the wheels still off, the car is now sitting on the control arms at normal ride height. Now tighten the front control arm bushing bolt to 95 ft-lbs (129 Nm). Tighten the rear bushing bolt to 54 ft-lbs (73 Nm). This step is crucial; if you torque the bushings with the suspension hanging, the polyurethane will be twisted excessively and wear prematurely or bind.

Final Assembly and Critical Checks

Reinstall the Wheels and Test Drive

Place the wheels back on, hand-tighten the lug nuts, lower the car fully, then torque the lug nuts in a star pattern to 80 ft-lbs (108 Nm). Turn the steering wheel lock-to-lock to ensure nothing is binding. Take the car for a slow test drive in a safe area. Listen for any clunks or loud squeaks. A faint squeak from polyurethane is normal initially but should diminish after a few miles; excessive noise suggests insufficient grease or misalignment.

Alignment Is Mandatory

Replacing front control arm bushings changes the suspension geometry slightly, especially caster angle. Drive the car to an alignment shop and have a full four-wheel alignment performed. Expect the technician to adjust toe and possibly camber. The 2006 Civic Si has some adjustability in the front; aftermarket camber bolts may be needed if you are lowered. A proper alignment will maximize the handling benefits of the new bushings and prevent uneven tire wear.

Benefits of Prothane Bushings – What to Expect

After installation and alignment, you will notice immediate differences. The steering will feel more direct—there is less rubber compliance between the wheel and the road surface. Turn-in response becomes sharper, and the car feels more planted during hard cornering. However, expect a slight increase in road noise and vibration transfer; that is the trade-off for performance polyurethane. In daily driving, the difference is subtle until you push the car through a series of curves. For autocross or track use, this upgrade is nearly essential.

To further understand the science behind bushing compliance, read this guide on suspension bushing material properties from HP Academy. For community tips and torque specs specific to the 8th-gen Civic Si, check this 8th Generation Civic Forum. If you plan to upgrade the rear suspension too, this Prothane product page for 2006-2011 Civic provides all available kits.

Common Mistakes to Avoid

  • Skipping lubrication: Always grease the entire contact surface. Polyurethane without lubricant will squeak loudly and may seize on the bolt.
  • Tightening bolts with suspension unloaded: This is the most common error. Always torque control arm bolts at ride height to prevent bushing preload.
  • Using impact wrenches on polyurethane: Use hand tools to avoid over-compressing the bushing or stripping threads.
  • Reusing old bolts: Suspension bolts are often torque-to-yield and should be replaced with new OEM or high-strength aftermarket bolts for safety.
  • Forgetting the alignment: Driving without an alignment will wear tires rapidly and negate the handling improvement.

Maintenance After Installation

Prothane polyurethane bushings require minimal maintenance. Inspect them during oil changes for cracking or excessive wear. Re-grease only if they begin to squeak—this usually requires partial disassembly. In northern climates where roads are salted, consider cleaning the bushing contact areas annually to prevent corrosion between the metal sleeve and bolt. With proper care, these bushings will outlast the original rubber bushings and continue delivering precise handling for years.

Conclusion: A Worthwhile Upgrade for Your 2006 Civic Si

Installing Prothane polyurethane bushings on your 2006 Honda Civic Si is a hands-on project that rewards you with sharper, more connected driving. By following this comprehensive guide and taking your time with each step, you can achieve professional-grade results at home. The critical points are proper lubrication, torque under load, and a follow-up alignment. Once completed, you will feel the difference every time you turn the steering wheel. Your Civic Si will corner flatter, respond quicker, and feel more like the driver’s car Honda intended. Upgrade your bushings and re-discover the potential of your FA5.