FORMULA, SUPERPRO, H&R, MSA Alignment Shims

Alignment shims are precision adjustment components used to help alter suspension geometry during a wheel alignment. Depending on the suspension design and shim location, they can provide additional adjustment to alignment angles such as camber and caster.

Rather than replacing major suspension components, an alignment shim changes the position or relationship of compatible mounting points by a controlled amount.

This makes wheel alignment shims useful where additional adjustment is required to bring suspension geometry closer to the desired specification or to achieve a particular alignment setup.

What Are Alignment Shims?

An alignment shim is a thin spacer fitted at a specified suspension or alignment mounting point.

Its purpose is to create a small, controlled change in component position. That change can alter the geometry of the suspension and therefore affect wheel alignment.

Alignment shims may be supplied individually, in packs or as part of an alignment shim kit. Different applications can require different shim designs and thicknesses.

Depending on the suspension system, alignment shims may be used for:

• Camber adjustment
• Caster adjustment
• Fine-tuning suspension geometry
• Increasing the available alignment adjustment
• Correcting alignment after suspension changes
• Setting up an application for specific alignment requirements

Alignment shims aren't universal in how or where they are installed. The correct shim and installation position depend on the suspension design and the adjustment required.

How Do Alignment Shims Work?

Wheel alignment depends on the position and angles of suspension and steering components relative to the wheels and chassis.

An alignment shim works by slightly repositioning a compatible suspension component or mounting point.

Although the physical change may be small, it can produce a measurable change in wheel alignment.

For example, adding or changing a shim at a suitable mounting location may alter the position of a control arm or another suspension component. That change can then affect the angle of the wheel.

The amount and direction of adjustment depend on:

• Shim thickness
• Installation position
• Suspension design
• Existing suspension geometry
• The alignment angle being adjusted

This is why alignment shims should ideally be selected using actual wheel alignment measurements rather than guesswork.

Camber & Caster Adjustment

Camber and caster are two important measurements within wheel alignment, and Fulcrum's alignment shim products specifically include solutions designed to provide additional camber or caster adjustment.

Camber

Camber describes the inward or outward inclination of a wheel when viewed from the front of the vehicle.

Incorrect camber can affect how the tyre contacts the road and may contribute to uneven tyre wear.

Where the suspension design allows it, camber shims can help reposition a mounting point to provide additional camber adjustment.

Caster

Caster describes the angle of the steering axis when viewed from the side.

Caster contributes to steering characteristics such as straight-line stability and steering return.

A compatible caster shim arrangement can provide additional adjustment where the suspension design allows it.

Some alignment shim systems can influence both camber and caster depending on where and how the shims are installed.

When Are Alignment Shims Used?

Alignment shims aren't necessarily components that wear out and require routine replacement. In many cases, they're adjustment components used to achieve the required suspension geometry.

They may be considered when:

• Available factory adjustment isn't sufficient to reach the required alignment setting.
• Suspension components have been changed and geometry needs to be checked and corrected.
• Ride height has changed, potentially altering suspension geometry.
• An alignment technician needs additional adjustment at a compatible mounting point.
• A particular alignment setup is required for the way the vehicle is being used.
• Existing shims are damaged, missing or unsuitable for the required setup.

Uneven tyre wear, steering pull or an off-centre steering wheel can indicate an alignment problem, but these symptoms don't automatically mean alignment shims are required.

Worn bushes, damaged suspension components, incorrect tyre pressures and other mechanical issues can also affect wheel alignment and handling.

The suspension should be inspected before alignment correction is attempted.

Alignment Shims vs Other Alignment Parts

Alignment shims are only one method of adjusting suspension geometry.

Fulcrum separates alignment shims from other alignment components including camber bolts and caster wedges because each works differently and suits different suspension designs.

Alignment Shims

Shims create a controlled spacing change at a compatible mounting point.

They can be particularly useful where the suspension is designed to accept shim-based adjustment.

Camber Bolts

Camber bolts typically use an eccentric or offset design to change the position of a suspension component when the bolt is rotated.

They provide an alternative form of adjustment where the suspension design supports them.

Caster Wedges

Caster wedges are used in suitable suspension configurations to alter the relationship between components and change caster geometry.

The correct alignment solution therefore depends on the suspension design rather than simply choosing whichever adjustment component provides the largest range.

Choosing the Right Alignment Shims

Choosing alignment shims starts with understanding what needs to be adjusted and by how much.

A professional wheel alignment provides measurements that show the existing geometry and how it compares with the appropriate specifications or desired setup.

Important considerations include:

• Suspension compatibility: The shim must suit the relevant mounting arrangement.
• Adjustment required: Determine whether camber, caster or another geometry setting requires correction.
• Shim thickness: Different thicknesses create different amounts of positional change.
• Installation position: Where the shim is fitted influences the resulting geometry change.
• Existing adjustment hardware: Some shims are designed to work with particular adjusters or factory mounting arrangements.
• Overall suspension condition: Worn components should be addressed before attempting precise alignment.

Why Professional Wheel Alignment Matters

Alignment shims are designed to make relatively precise changes to suspension geometry. That makes accurate measurement particularly important.

Simply adding a shim without knowing the existing alignment measurements can move the geometry in the wrong direction or create too much correction.

A professional wheel alignment allows a technician to:

• Measure existing camber, caster and toe
• Identify which angles require correction
• Check whether the available factory adjustment is sufficient
• Determine whether additional alignment components are required
• Make controlled adjustments
• Re-measure the geometry after changes is made

The condition of surrounding suspension components should also be considered.

If bushes, ball joints or other suspension components have excessive movement, achieving a consistent wheel alignment may be difficult regardless of the adjustment hardware fitted.

Fine-Tune Your Suspension Geometry

Alignment shims are useful when additional camber or caster adjustment is required and the suspension design supports shim-based correction.

Before selecting alignment shims, the existing wheel alignment should be measured to determine:

• Which alignment angle needs adjustment, such as camber or caster.
• How much correction is required based on the current measurements.
• Whether shim adjustment is suitable for the suspension design.
• What shim thickness is appropriate for the required correction.
• Whether worn suspension components need attention first before the alignment is adjusted.

The goal isn't simply to add more adjustment. It is to make a controlled change that brings the suspension geometry to the required setting.

Explore alignment shims at Fulcrum Suspensions to find the right adjustment solution for your suspension setup.

Shop Alignment Shims with Fulcrum Suspensions

Find quality alignment shims at Fulcrum Suspensions, backed by decades of suspension experience and support from a nationwide network of suspension specialists.

Order online for convenient delivery, or visit your nearest Fulcrum workshop for expert assistance. With professional fitting and wheel alignment services also available, Fulcrum makes it easy to purchase the parts you need and have the job completed in one place.