39mm Round Axle

Part No: 39R Categories: , Tag:

$125.58 - $156.00

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39mm Round Axle suit Standard Bearings and made in Australia

39mm Round Axle suits small box and boat trailers. 750kg is the maximum rating for LM or standard bearings. Measure axles from the tip of the thread to the end of the thread. Quality axles are not easy to manufacture. Let’s run through the process from the video below.

How to measure bare or straight axles

How to measure bare or straight axles.

Measure bare or straight axles from tip to tip.

made in australia


  1. A solid beam of steel is cut to the correct length.
  2. Couplemate developed a program to use a roughing tool, a finished tool, and a threading tool.
  3. The first tool used in the video is a roughing tool. This tool removes most of the steel before we arrive at the finishing profile.
  4. The finishing tool skims over the profile and produces a journal within 0.02mm.
  5. Once the finishing tool has done its job, a threading tool is engaged, which also cuts a thread within 0.02mm of its specification.
  6. The CNC technician manually fits the front and back bearings to ensure a tight fit. The axle nut is then tested for tightness.
  7. Finally, the axle is removed from the lathe if all the above steps pass.

Standard or LM Bearing Sizes are

  • Inner ID 31.75mm, OD 59.10mm
  • Outer ID 19.05mm, OD 45.20mm
  • Seal ID 37.5mm, OD 59.10mm
  • Dust Cap 45.20mm

Couplemate manufactures 39mm round 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. The 39mm Round Axle is perfect for your trailer, caravan, or camper if you are towing your rig straight and true. If not, then below are a few tips.

Common problem:

  • Too much weight will bend this 39mm Round Axle to experience excess 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 the load is over 750kg, axle flex will occur.
  • If the axle is 39mm round and bending, buy a 45mm round axle and update it to 1.5t.
  • It is not expensive in comparison to replacing springs that have suffered fatigue.

Other Common Problems:

  • Rough seal journals can cause a loss of grease through the rear seal.
  • Some suppliers supply non-virgin or scrap steel and forge this steel into a solid square or round shape for axle production.
  • Chinese bearings are the second most significant cause of axle failure. If you plan to drive on the highway, use Japanese bearings. The combination of Japanese Bearings and 39mm round Axle will help you significantly with lower maintenance for your rig.

Calculating The Correct Axle Measurements

As a result of viewing the video above, calculate the face-to-face measurement.
  1. Measure the offset wheel. The wheel offset is the distance between the hub’s inside and the rubber’s outside.
  2. Add 50 mm to the offset. Alternatively, choose your distance between the rubber and the chassis.
  3. Multiply by 2 for both sides. Add your chassis width to the above number.
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.

News Articles

Caravan axles and their maximum rating.

39mm Round Axle

Additional information

Dimensions240 × 50 × 50 cm
Tip to Tip Length

1475mm – 58-inch, 1500mm – 59-inch, 1525mm – 60-inch, 1550mm – 61-inch, 1575mm – 62-inch, 1600mm – 63-inch, 1625mm – 64-inch, 1650mm – 65-inch, 1675mm – 66-inch, 1700mm – 67-inch, 1725mm – 68-inch, 1750mm – 69-inch, 1775mm – 70-inch, 1800mm – 71-inch, 1825mm – 72-inch, 1850mm – 73-inch, 1875mm – 74-inch, 1900mm – 75-inch, 1925mm – 76-inch, 1950mm – 77-inch, 1975mm – 78-inch, 2000mm – 79-inch, 2025mm – 80-inch, 2050mm – 81-inch, 2075mm – 82-inch, 2100mm – 83-inch, 2125mm – 84-inch, 2150mm – 85-inch

Axle Profile

Our Service Lifetime Warranty

Our goods come with guarantees that cannot be excluded under the Australian Consumer Law. You are entitled to a replacement or refund for a major failure and compensation for any other reasonably foreseeable loss or damage. You are also entitled to have the goods repaired or replaced if the goods fail to be of acceptable quality and the failure does not amount to a major failure.

Couplemate™ is a manufacturer and vendor of high-quality towing, trailer, and caravan components. Couplemate™ Core Goods and Custom Work are guaranteed to be free of defects for the service lifetime of the product when used as intended.

Warranties are non-transferrable and Couplemate™ requires satisfactory proof of purchase prior to issuing a remedy. The full Couplemate™ Warranty Policy can be found in the Terms & Conditions: Section 8 – Consumer Guarantees & Warranty.

Warranties are in addition to your rights under the Australian Consumer Law. If something is wrong with your order, please contact our team.

60-Day Returns

After 60 years of experience, we know that life has its unpredictable moments.

All Couplemate™ orders (online, over the phone, or in-store) have a 60 day period for change-of-mind returns and exchanges. There are some items that can’t be returned and some returns may incur a 15% restocking fee.

You can view our full policy for change-of-mind returns here.


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