Trailing Arm Bushing with Fitting Position Front, Rear for 2018 Subaru WRX STI Sport-tech

Nolathane trailing arm bushings hold your Subaru WRX STI's rear wheels or axle in position front to back. Each trailing arm bushing sits at a mount on the arm, cushioning it against the body, subframe, or axle while letting it swing as the suspension moves. When rear trailing arm bushings wear, the rear end starts to shift under power and braking, and you?ll usually hear it before you feel it.

The range covers cars with independent and beam rear suspension, AWD and RWD performance vehicles, and trucks and 4x4s with upper and lower trailing arms. Each listing shows the position, the kit contents, and whether it fits your Subaru WRX STI.

How Trailing Arms Locate the Subaru WRX STI Rear Wheels

A trailing arm runs forward from the rear wheel or axle to a mount on the body or chassis. Its main job is fore and aft control. When you accelerate, the driveline pushes the wheel forward. When you brake, the tire drags it back. The trailing arm and its bushings resist both.

On many independent rear suspension (IRS) cars, the angle of the trailing arm also affects toe. As the arm swings through its arc, the wheel can steer slightly, and any extra movement at a worn bushing adds unwanted rear steer.

On trucks and 4x4s with a 4-link rear axle, upper and lower trailing arms work together. The lower arms carry most of the fore and aft load, while the upper arms control axle rotation. Worn bushings at either let the axle shift and twist under load.

Subaru WRX STI Trailing Arm Bushing Positions

Trailing arms use bushings at different points depending on the suspension design.

Front Mount Bushings

The front mount is where the arm attaches to the body or chassis. It takes most of the acceleration and braking load, so it?s often the first bushing to wear.

Rear Mount Bushings

The rear mount connects the arm to the axle, knuckle, or hub carrier. It handles a mix of fore and aft and vertical movement as the wheel travels.

Center Pivot Bushings

Some designs use a single large center pivot bushing, often in beam-type rear suspension. These bushings are typically larger and carry the arm?s full movement at one point.

Upper and Lower Trailing Arm Bushings

On 4-link rear axles in trucks and 4x4s, both upper and lower trailing arms have bushings at each end. Kits may cover one arm or the full set.

Bad Trailing Arm Bushing Symptoms on Your Subaru WRX STI

Bad trailing arm bushing symptoms usually build over time. Watch for:

• A clunk or thump from the rear on take-off, braking, or over bumps
• Rear steer, or a loose, shifting feel from the rear end in corners
• Wheel hop under hard acceleration
• Uneven wear on the rear tires
• An alignment that won?t hold rear toe
• Cracked, torn, or off-center bushings at the arm mounts

A clunk that happens only when you accelerate or brake often points to the front mount bushings, since they carry those loads.

How Bushing Wear Affects Subaru WRX STI Handling

When trailing arm bushings wear, the rear geometry no longer stays fixed. It changes with load, so the rear end behaves differently when you accelerate, brake, or corner.

Under braking, a worn bushing lets the wheel move rearward, which can unsettle your Subaru WRX STI and make it feel less stable. On solid rear axles, worn bushings allow more axle wrap, where the axle twists under torque and can cause wheel hop.

An alignment alone won?t fix this. The alignment can be set correctly while the car is still on the rack, but worn bushings let the geometry move again as soon as the vehicle is driven. Replacing the bushings first gives the alignment something stable to hold.

Rubber and Polyurethane Trailing Arm Bushings for the Subaru WRX STI

Factory rubber trailing arm bushings are soft and quiet, but they deteriorate faster on heavier and more powerful vehicles, where the loads are higher.

Polyurethane trailing arm bushings hold the arm more firmly in position. They offer high load-bearing capability for towing and payload, and they resist oil, grease, ozone, and weathering. The hardness, or durometer, is chosen for each position to balance firm location with vibration control.

The trade-off is a little more road feel, since polyurethane passes slightly more vibration than soft rubber.

Choosing Trailing Arm Bushings for Your Subaru WRX STI

Getting the right kit means matching the position and the arm. Each listing shows the details.

Mount Position and Arm

Identify whether you need front, rear, or center pivot bushings, and on 4-link setups whether they?re for the upper or lower arms.

Single-Position Kits and Complete Sets

Some kits cover one position, while complete sets cover every bushing on the arm. If one position is worn, the others are often close behind.

Center Pivot Outside Diameter

Center pivot bushings come in different sizes. For sized kits, the bushing matches the dimensions shown in the listing, so measure the housing first.

Arm and Bracket Condition

Before rebushing, check the arm for bends and the bushing bores for wear. A damaged arm or an oval bore won?t hold a new bushing properly.

Replacing Trailing Arm Bushings on Your Subaru WRX STI

Trailing arm bushing replacement is best handled by a qualified installer. The general process looks like this:

• Support the axle and body safely on stands
• Remove the trailing arm
• Press out the old bushings using a press or a trailing arm bushing tool
• Fit the new bushings with the shells, tubes, and plates as supplied
• Grease the bushings as specified
• Refit the arm and tighten the bolts to specification at ride height
• Have a wheel alignment carried out

Check the torque again after the first few hundred miles.

Subaru WRX STI Trailing Arm Bushing Limitations and Trade-Offs

Trailing arm bushings solve a lot of rear end problems, but they have limits:

• Polyurethane transmits slightly more noise and vibration than rubber
• It can squeak if it isn?t greased
• New bushings can?t fix a bent arm, a worn bracket, a sagging spring, or worn shocks
• Replacing one position alone can leave play elsewhere in the arm
• An alignment is always needed after replacement on IRS cars

Compliance and Insurance

Make sure your Subaru WRX STI meets the inspection requirements of the state where it?s registered, and let your insurance company know about any suspension modifications.

Warranty and Support

Nolathane trailing arm bushings carry a lifetime warranty against manufacturing defects in material and workmanship, for the original vehicle. Plates, shells, tubes, and washers are backed by Nolathane?s warranty. Our local support team can help you find the right kit.

Shop Trailing Arm Bushings for Your Subaru WRX STI

Trailing arm bushings make up one of the bigger lines in our polyurethane bushings selection. When the arm is bent, trailing arm kits replace it outright.

Find trailing arm bushings for your Subaru WRX STI and order online with fast shipping. Every kit is covered by our fitment guarantee.