Trunnion Bushes with Fitting Position Front Axle

Trunnion bushes are suspension components used at specific pivot or mounting points in trunnion suspension arrangements. They allow controlled movement between connected components while helping maintain the intended location of the suspension assembly.

Because trunnion designs can vary considerably, replacement bushes need to match the particular suspension position and assembly. Upper, lower, outer and threaded trunnion arrangements can have different requirements, making correct identification especially important before choosing a trunnion bush kit.

What Is a Trunnion in Suspension?

A trunnion is a mounting or pivot arrangement that allows a component to rotate or move around a defined point. The term is used across many areas of engineering, but in suspension it refers to a particular pivot or connection within the suspension assembly.

In a trunnion suspension system, bushes can form part of this pivot connection. They help support controlled articulation as the suspension moves while maintaining the relationship between the components at the mounting point.

The exact construction and function of a trunnion varies between suspension designs. For this reason, "trunnion" should not be treated as the name for one universal suspension component.

A trunnion bush is specifically the bush used within or around the relevant trunnion mounting or pivot arrangement. Its dimensions, construction and installation requirements depend on the suspension design and its position within the assembly.

Types of Trunnion Bush Kits

Trunnion bush kits can be intended for different positions within a suspension assembly. Identifying the exact mounting point is therefore essential when choosing replacement components.

Front Upper Trunnion Bushes

Front upper trunnion bushes are used at an upper trunnion or pivot position within applicable front suspension systems. Their role is to provide the required movement at the connection while helping keep the associated suspension components correctly located.

Because upper and lower mounting points can use different dimensions and designs, an upper trunnion bush should not be assumed to be interchangeable with bushes elsewhere in the assembly.

Front Lower and Outer Trunnion Bushes

Lower or outer trunnion bushes relate to different mounting positions within the suspension arrangement. Depending on the design, these positions may experience different movement and loading from an upper pivot.

When servicing these bushes, the precise position should be identified before replacement. Similar-looking bushes can have different dimensions or installation requirements.

Greaseable and Threaded Trunnion Bushes

Some trunnion arrangements use threaded components or bushes designed to operate with lubrication. Where a greaseable trunnion bush is specified, maintaining appropriate lubrication can be important to the operation and service life of the assembly.

Greaseable components should be maintained according to the requirements of their particular design. The correct lubricant and servicing procedure can vary, so the fitting and maintenance information for the specific component should be followed rather than applying a universal lubrication schedule.

Threaded trunnion assemblies also require particular attention during installation because the threaded connection itself can form part of the pivoting arrangement.

Signs Your Trunnion Bushes May Need Inspection

Trunnion bushes and associated pivot components are subject to repeated movement as the suspension operates. Over time, wear or deterioration can introduce unwanted movement into the mounting point.

Reasons to have the trunnion and surrounding suspension inspected can include:

• Knocking, clunking or other unusual suspension noises
• Excessive movement detected at a suspension pivot
• Changes in steering or suspension behaviour
• Visible deterioration or damage around a bush
• Uneven or unexplained tyre wear
• Movement identified during routine suspension inspection

These symptoms do not confirm that a trunnion bush has failed. Similar concerns can result from other suspension, steering, wheel or alignment problems.

Inspection should therefore include the complete pivot arrangement and nearby suspension components. This helps determine whether unwanted movement is coming from the bush, another part of the trunnion assembly or a separate suspension component.

Trunnion Bush Materials and Construction

Trunnion bushes can use different materials and construction methods depending on the suspension design and the requirements of the mounting point.

Where polyurethane is suitable for the application, its resistance to deformation can help control unwanted movement at a suspension pivot while still allowing the movement intended by the bush design. Polyurethane is also valued in suspension applications for its durability and resistance to deterioration.

Other trunnion arrangements may use different bush materials or constructions, particularly where the pivot incorporates threaded or lubricated components.

The appropriate choice therefore depends on more than material alone. The design of the trunnion, mounting position, dimensions and required movement all need to match the particular suspension application.

What to Check Before Buying a Trunnion Bush Kit

Correct identification is particularly important with trunnion bushes because the term can describe several different positions and arrangements.

Before selecting a trunnion bush kit, check:

• The exact suspension mounting or pivot position
• Whether the bush is upper, lower, inner or outer
• Whether the trunnion uses a threaded or other specialised arrangement
• Whether lubrication or ongoing maintenance is required
• Whether individual bushes or multiple components are required for the repair
• Accurate fitment information for the application

If the source of suspension movement or noise hasn't been confirmed, inspection before ordering can help establish which part of the trunnion assembly actually requires attention.

Fitting and Maintaining Trunnion Bushes

The procedure for replacing trunnion bushes depends heavily on the design of the suspension assembly. Access may require suspension components to be removed, and specialist equipment can be required for some bush installations.

The condition of the complete trunnion assembly should be checked during replacement. Mounting hardware, pivot surfaces and surrounding suspension components may also require inspection, particularly where excessive movement has developed.

For greaseable trunnion bushes or threaded assemblies, correct lubrication and maintenance are also important. These components should be serviced according to their specific requirements rather than assuming every trunnion bush is maintenance-free.

Following suspension work, wheel alignment should be considered where components affecting suspension geometry have been removed, loosened or repositioned. Whether an alignment is necessary depends on the particular suspension design and work performed.

Find Trunnion Bushes for Your Vehicle

Finding the correct trunnion bushes starts with identifying the suspension arrangement and exact pivot position that requires servicing. This is particularly important because trunnion bush kits can differ according to their location and construction.

Fulcrum Suspensions can help identify suspension components and inspect the surrounding suspension when the source of unwanted movement or noise has not been confirmed. Professional installation is also available where specialist equipment or suspension disassembly is required.

Trunnion bushes are part of our full suspension bushes range, which also includes control arm bushes for the rest of the front end.

If you're unsure which trunnion bush kit you need, starting with accurate fitment information and a confirmed mounting position can help avoid confusing upper, lower, outer or specialised trunnion components and ensure the replacement is appropriate for the suspension assembly.