Modifications > Adding a second axle

The skilled engineers at FELK are experienced in all modifications and adjustments for trailers of most makes and models. Modifications are performed on site at our Warner Bay factory, and adhere to current RMS and Australian standards, in preparation for blue or brown slip inspections.

We mostly do this modification for

  • Box trailers
  • Boat trailers
  • Camping trailers
  • Plant trailers


The vast majority of trailer types support a second axle, whether part of a new build or required to upgrade a second-hand trailer.

We manufacture new axles in-house at the FELK factory, however, on occasion, we may order them in to suit a specific model.

After the second axle modification

Why are second axle additions required

The most common request for a second axle addition is when clients upgrade their Gross Vehicle Mass (GVM). The shared load with the suspension gives a smoother ride over rough roads, so clients on industrial/rural sites often benefit from second axles.

Before the second axle modification

Axle modifications for existing trailers

When adding a second axle to an existing single-axle trailer, our engineers will first assess if a trailer can, or should be upgraded. Where there is a lot of rust damage for example, it’s not recommended.

There are also other parts/modifications required, depending on what is trying to be achieved such as:

  • Upgraded brakes
  • Upgraded wheels/bearings
  • Upgraded coupling
  • Suspension/springs
  • Two new mudguard brackets per side
  • New bolts
  • All equipment to attach mods together

After the second axle modification

When we add a second axle, we typically move the existing axle forward and put the ‘lazy’ axle on the rear.  Having two axles placed in appropriate proximity helps to disperse the weight load of the cargo evenly.

The previous axle is moved forwards because, in some cases, it has existing brake setups that can be reused at the front.

Brakes are installed at the front because when the brake is applied, the force will push the weight to the front axle.

Both square and circular axles are available and are usually matched to the existing setup. Square is typically a bit stiffer.

It should be noticed that excessive weight on an axle results in the vehicle’s wheels “flaring” out, or having “too much camber”. Felk typically engineers axle setups to prevent any issues like this and much more. We are very experienced.

suspension, axels & tyres underneath a trailer

Thicknesses of axles that trailers commonly use

39/40mm = 1 Tonne GVM

45mm = 1.4 Tonne GVM

50mm = 2 Tonne GVM

61mm = 3 Tonne GVM

50mm x 2 = 3.5 tonne GVM – will give up to 4 Tonne GVM

61mm x 2 = 4.5 tonne GVM – will give up to 6 Tonne GVM

Timeframes to add a second axle

FELK machine most axles inhouse, which has been servicing the trailer and caravan community for more than 50 years. Once you are booked in, we typically only need one week in the FELK workshop to add a second axle.

If you have any queries about adding a second axle or trailer modification or wish to book your trailer into our workshop, please contact us.