40mm Square Axle


Couplemate - Engineered For Quality

Couplemate accepts PayPal, Visa and Mastercard.

40mm Square Axles to suit Standard Bearings

40mm square axle suits wider small box trailers and boat trailers up to 1000kg.

Axles are measured from the tip of the axle to the tip of the axle. When measuring from the face of the axle, add 100mm to this measurement to get the tip of the thread to the tip of the thread length.

Standard Bearing Sizes

Couplemate manufactures 40mm square trailer axles in Wynnum, Queensland. BlueScope or One Steel provides the best axle money can buy. If you can find a better product, please tell me.

For more information about why we use quality steel, check out my article, Axle Steel for Caravan and Trailer Axles.

Your 40mm square axle may be perfect for your trailer, caravan or camper if you are towing your rig straight and true, perfect. If not, then below are a few tips.

Common problems:

  • Too much weight will bend this 39mm Round Axle causing axle flex.
  • An overloaded axle causes axle flex. You can read about axle flex and vibration here.
  • Axle flex occurs when heavily loaded trailer springs rebound on the highway, causing the axle to flex up and down in the middle of the axle.
  • Springs to fatigue – fail prematurely under axle flex loading conditions.
  • If your load is over 1000kg, you will start to experience axle flex.
  • If your axle is 40mm Square and bending, buy a 45mm square axle and update to 1.5t.
  • It is not expensive in comparison to replacing springs that have suffered fatigue.
  • Rough seal journals can cause a loss of grease through the rear seal.
  • Are your tandem tyres wearing unevenly? How to Align Caravan Wheels
  • Some suppliers supply non-virgin steel or scrap steel and forge this steel into a solid square or round shape for axle production.
  • Chinese bearings are the second biggest cause of axle failure. If you plan to drive on the highway, use Japanese bearings. Combining Japanese Bearings and a 39mm round Axle will help you significantly with lower maintenance for your rig.

Finally, after reading the above information on axles, I invite you to comment in the review box below. We never get too old to learn.

Calculating The Correct Axle Measurements

  1. Measure the offset wheel. The wheel offset is the distance between the inside of the hub and the outside of the rubber.
  2. Add 50 mm to the offset. Alternatively, choose your own distance between the rubber and the chassis.
  3. Multiply by 2 for both sides. Add your chassis width to the above number.

Metric to Imperial Converter

Convert Imperial (inches) to metric (mm)

  • =

Still unsure of what measurements to take? Check out this handy guide below:

[P] – Check material specifications. What size and profile is the axle (for example, 45mm Square)
[T] – Overall axle length (tip to tip)
[F] – Hub face-to-hub face measurement
[A] – Chassis width
[C] – Tyre clearance
[B] – Back offset
[H] – Tyre to chassis
[G] – Axle pad centres

How To Measure An Axle

Identifying Bearing Combinations

You will also need to identify your bearing combination, which can be done by pulling off a hub and bearings and locating the number laser engraved onto the bearing. You will require both the inner and the outer bearing number.

Where to identify bearing number. Look for the laser engraved number on the bearing.

Caravan axles and their maximum rating.

Additional information

Weight40 kg
Dimensions230 × 40 × 40 cm
Tip to Tip Length

1500mm Long, 1525mm Long, 1550mm Long, 1575mm Long, 1600mm Long, 1625mm Long, 1650mm Long, 1675mm Long, 1700mm Long, 1725mm Long, 1750mm Long, 1775mm Long, 1800mm Long, 1825mm Long, 1850mm Long, 1875mm Long, 1900mm Long, 1925mm Long, 1950mm Long, 1975mm Long, 2000mm Long, 2025mm Long, 2050mm Long, 2075mm Long, 2100mm Long, 2125mm Long, 2150mm Long, 2175mm Long, 2200mm Long, 2225mm Long, 2250mm Long, 2275mm Long, 2300mm Long, 2325mm Long, 2350mm Long, 2375mm Long, 2400mm Long


    Be the first to review “40mm Square Axle”

    Your email address will not be published. Required fields are marked *