Caster Wedges with Fitting Position Front Axle, Rear Axle

Caster wedges, also called castor wedges or leaf spring wedges, are angled spacers fitted between a leaf spring and the axle to change the angle of the axle. They're commonly used to correct caster after a suspension lift on leaf-sprung 4WDs.

What Is Caster?

Caster is one of the main wheel alignment angles. It's the angle of the steering axis when viewed from the side of the vehicle.

Caster affects how the steering feels, including how the steering returns to centre after a turn and how stable the vehicle feels in a straight line. During a wheel alignment, caster is checked against the vehicle's specification.

What Do Caster Wedges Do?

On a leaf-sprung axle, the axle sits on the leaf spring and is held in place with U-bolts. A caster wedge is a tapered spacer that sits between the leaf spring and the axle's spring perch. Because the wedge is thicker at one end than the other, it tilts the axle by a set amount when it's fitted.

Fitting a wedge in one direction or the other rotates the axle forwards or backwards. This changes the axle angle, which can be used to correct caster or other angles depending on where the wedge is fitted.

Caster Wedges on Front and Rear Leaf-Sprung Axles

Caster wedges can be used on front or rear leaf-sprung axles, but they do different jobs at each end:

• On a front leaf-sprung axle, rotating the axle changes the caster angle of the steering. This is the most common use for caster wedges.
• On a rear leaf-sprung axle, there's no steering, so the wedge doesn't change caster. Instead, it changes the angle of the axle and differential pinion. This can affect driveline angles. Wedges used this way are sometimes called pinion angle wedges.

Check the product listing and fitting position to confirm which use the wedge is designed for.

Why Lifted 4WDs Need Caster Correction

When you lift a leaf-sprung 4WD, the geometry of the suspension changes. On a front leaf-sprung axle, a lift can change the axle angle and reduce caster. On a rear leaf-sprung axle, a lift can change the pinion angle and affect driveline angles.

Caster wedges are a simple way to correct these angles. The 3 degree caster wedge, for example, is designed to help correct caster on vehicles with a 40mm to 50mm suspension lift. The right wedge angle for your vehicle will depend on the vehicle, the lift and the measurements taken during a wheel alignment.

Choosing the Right Caster Wedge Angle

Fulcrum's range includes caster wedges in three angles:

• 1-degree caster wedges, for smaller corrections
• 2-degree caster wedges, for moderate corrections
• 3-degree caster wedges, for larger corrections

The right angle depends on how much correction your vehicle needs. Your wheel alignment technician can measure your current caster or axle angle and recommend the right wedge.

Check the product listing to confirm that the wedge's dimensions suit your vehicle's leaf spring and spring perch. Full details and specifications are listed on each product page.

How Many Caster Wedges Do You Need?

Caster wedges are often sold individually. Most leaf-sprung axles have a leaf spring on each side, so you'll usually need one wedge for each side of the axle you're correcting. Add the quantity required for your vehicle to your cart.

If you're unsure how many wedges you need, ask Fulcrum's team and we are always happy to help.

Fitting Caster Wedges and Wheel Alignment

Fitting caster wedges involves supporting the vehicle safely, loosening the U-bolts and fitting the wedge between the leaf spring and the axle. The wedge must face the right direction to correct the angle as intended. U-bolts must be tightened correctly once the wedges are fitted.

If you're not confident working on suspension components, have caster wedges fitted by a qualified technician. A wheel alignment is needed after fitting caster wedges to a front axle so caster can be checked and the alignment set correctly.

With Fulcrum's Click & Fit service, you can buy your caster wedges online and have them delivered to your nearest Fulcrum workshop for installation. Fulcrum also offers wheel alignments and a free suspension check.

Buy Caster Wedges Online from Fulcrum

Every product we supply is backed by our warranty, a fitment guarantee and the support of a nationwide workshop network. You can shop the range online and choose the right wedge angle for your vehicle.

Caster wedges are one of several alignment parts we stock, with camber bolts and alignment shims covering other corrections.

If you're unsure which caster wedge suits your vehicle, Fulcrum's team can help you choose.