Lateral Arm Bushings for 2017 Audi A3 Prestige

On a multi link rear end, the arms running across the car are the ones setting where the wheels point.

The bushings in them decide whether your Audi A3's setting holds when the car is loaded up in a corner, or whether the rear quietly steers itself.

What a Lateral Arm Does

A lateral arm, also called a lateral link, runs transversely across the vehicle from the subframe to the hub carrier.

Its job is lateral location of the hub. It controls how far the bottom or top of the hub sits from the center of the car, which is what sets camber and, depending on the arm's position, toe as well.

Most multi link rear suspensions use two or more lateral arms per side at different heights and different fore and aft positions. Between them they define the hub's angle in two planes while the trailing arm handles fore and aft location.

That division of labor is the whole point of a multi link design. Each arm controls one thing, which gives the engineer far more freedom than a single wishbone does.

Why Audi A3 Lateral Arm Bushings Set Your Rear Alignment

This is the part worth understanding before deciding these are a wear item rather than a handling part.

Camber and toe at a rear wheel are defined by the length of each lateral arm and where its inner pivot sits. Change either one of those and the angle changes with it.

A bushing with play in it effectively changes the pivot position under load. The arm moves inboard or outboard slightly, and the hub angle moves with it.

That means the alignment reading taken on a rack with no load on the suspension is not the alignment the car has mid corner. The rack sees the static position and the road sees the deflected one.

The further the bushings have gone, the bigger the gap between those two numbers.

Passive Rear Steer Built Into Audi A3 Lateral Arm Bushings

Factory bushings are soft for a reason beyond comfort.

Manufacturers use controlled bushing deflection to introduce a small amount of rear toe-in as cornering load builds. The rear wheels turn very slightly into the corner, which makes the car feel stable and encourages gentle understeer.

That is deliberate engineering on a road car and it works well while the bushings are new.

As they age the rubber hardens, cracks and separates from its sleeve. The deflection becomes uncontrolled, so the rear axle still steers and no longer does it predictably or symmetrically.

A car that used to feel planted starts moving around mid corner, and it behaves differently turning left to turning right because the two sides have not worn identically.

Bad Lateral Arm Bushing Symptoms on Your Audi A3

• The rear feeling like it steps sideways over mid corner bumps
• A car that behaves differently turning each way
• Rear tire wear on the inner or outer edges with no fault found
• Rear alignment that will not hold its settings between services
• Vague or delayed response on turn in
• A clunk from the rear over bumps and driveways
• Visible cracking, splitting or separation in the bushing rubber
• Movement visible at the inner pivot when the arm is levered

Alignment that drifts is the most reliable of those. The rear geometry is set by these arms and nothing else, so a toe reading that moves between visits means the bushings are moving rather than the alignment being wrong.

What Audi A3 Polyurethane Lateral Arm Bushings Change

Replacing soft rubber here does something more fundamental than on most joints.

On a trailing arm, a firmer bushing holds the axle against braking and acceleration loads. On a lateral arm it holds the wheel's angle, which is a different and arguably more important job.

Polyurethane keeps its shape under cornering load, so the arm's effective length stays constant and the hub angle stays where the alignment set it. Turn in sharpens, the rear follows the front instead of steering on its own, and the car does the same thing every time.

The trade is the usual one with polyurethane. More road noise and more suspension sensation reaching the cabin, and the loss of the designed-in compliance that made the car forgiving.

For a car driven for handling that exchange is worth making. For a quiet commuter it is worth thinking about.

Audi A3 Offset Lateral Arm Bushings

Some applications offer offset versions, which do more than restore the original position.

The inner sleeve sits off center, so fitting the bushing moves the arm's pivot point by a known amount. That changes the arm's effective length, which changes camber or toe at that wheel depending on which arm it goes in.

On a lowered car with excessive rear negative camber, that correction is often the only practical option, since many multi link rear ends offer no factory adjustment at all.

Orientation is what decides the direction of correction. The same bushing corrects one way or the other depending on how it is pressed home, so the listing for your application specifies it and getting it wrong sends the correction backward.

Check your current rear alignment readings before ordering, since the correction needs to match the gap rather than a figure chosen in advance.

Front and Rear Lateral Arms

Both ends can use them and the rear is where they matter most.

Rear lateral arms are the common application, since most modern multi link rear suspensions use two or three per side to control camber and toe independently.

That independence is why rear lateral arm bushings have such a direct effect on how the car behaves. There is no steering input at the rear, so any angle change comes from the suspension itself, and the driver has no way to correct for it.

Front lateral arms appear on some multi link front ends, where they do a similar job alongside the steering arm. Wear there affects camber and the steering feel together.

Front suspension faults announce themselves through the wheel, which is why rear bushings tend to go unnoticed for far longer despite having a bigger effect on stability.

Checking Audi A3 Lateral Arm Bushings

A few checks narrow it down before anything comes apart.

With the car on a hoist, lever against each arm at the inner pivot and watch the bushing. Any visible movement at the sleeve means the arm is not being held.

Look for rubber bulging past the washer or separating from the metal sleeve, which is the usual failure rather than outright splitting.

Compare both sides of the car against each other. These rarely wear evenly, and a difference between them is what produces a car that behaves differently turning each way.

Pull the last two alignment printouts and compare the rear toe figures. A reading that has drifted with no impact or component change points straight at the bushings.

Check the rear tires at the same time, since inner or outer edge wear with no recorded alignment fault is the physical evidence of geometry that has been moving.

Lateral Arms, Trailing Arms and Control Arms

The terms overlap in catalogs and the distinction is worth making.

A lateral arm or lateral control arm runs across the car and controls side to side position, camber and toe.

A trailing arm runs fore and aft and controls the hub's position against braking and acceleration.

A control arm is the general term for either, and on a double wishbone front end it usually describes the upper or lower wishbone doing both jobs at once.

A rear lateral link is the same component as a lateral arm, with link being more common where the arm is a simple rod rather than a forged A shape.

Check the shape and orientation of what is on your Audi A3 rather than relying on the name in a listing.

Replacing Audi A3 Lateral Arm Bushings

These are a press fit, so proper tooling rather than improvised methods.

The bushing has to come out and the new one go in square, with the housing supported. Hammering distorts the eye and cracks aluminum arms.

Orientation matters on offset bushings and it is the step most often rushed. Mark the correct position before pressing, because getting it out again to rotate it is another full operation.

Replace them in pairs across the axle every time. One firm bushing against one perished one gives the car different rear behavior on each side, which is worse than leaving both.

Torque the arm bolts with the car on its wheels at ride height rather than hanging, since a bushing takes its set from the position it is clamped in.

Have the rear alignment set afterward without exception, because the geometry has moved.

Find Lateral Arm Bushings for Your Audi A3

Dial in the whole multi-link rear with trailing arm bushings and toe link bushings from the same Whiteline bushings lineup.

Select your Audi A3 to see the lateral arm and lateral link bushings available for it, including offset versions where rear camber or toe correction is needed. If the rear moves around over bumps or the alignment will not hold, these are the joints to look at first.