39mm Round Galvanised U-Bolt with Nylocs

SKU: N/A Category: U-Bolts and Kits Tag: U-bolts Brand: BoltBiz

39mm Round Galvanised U-Bolt for Trailer or Caravan | Couplemate Trailer Parts

Price

Price range: $6.00 through $8.00 Inc.GST

U-Bolt Length

Clear

U-bolt Kit: Add roughly 13mm to your length for the spacer plate and nut/washer.

✓ Galvanised U-bracket with 60mm thread length.
✓ Includes 2 x Galvanised Nyloc nuts (1/2″ BSW).
✓ Also available in a U-bolt clamp kit.

All dimensions (length, width) are the internal U-Bolt measurements.

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39mm Round Galvanised U-Bolt (Includes Gal Nylocs)

Heavy-duty trailer chassis protection. Couplemate 39mm round galvanised U-bolts (also known as 40mm round) feature rolled threads for maximum strength. Each high-tensile U-bolt comes complete with a galvanised flat washer and a captive nylon insert nyloc nut for a secure, vibration-proof lock.

Product Description

Secure your trailer axle with confidence using Couplemate’s premium 39mm Round Galvanised U-Bolts. These U-bolts are engineered for harsh Australian marine and road conditions, offering superior corrosion resistance. Featuring robust rolled threads rather than cut threads, they maintain structural integrity under heavy loads.

Safety is paramount when towing. Loose or failing U-bolts are a leading cause of severe accidents involving caravans and trailers. During manufacturing, Couplemate batch-tests these 1/2-inch U-bolts to destruction, ensuring they withstand loads exceeding 17,000kg. For ultimate safety on the road, they are safely de-rated to 375kg each, providing a massive safety margin for your 750kg single-axle setup.

Safety Tip: Steel naturally stretches slightly under initial load. Always retighten your U-bolts approximately 200 hours after installation to ensure roadworthiness.

Key Features & Specifications

Brand: Couplemate
Shape: Round
Diameter: 39mm (Compatible with 40mm round variants)
Thread Length: 60mm rolled thread
Material: High-grade galvanised steel
Inclusions: 1x Galvanised Flat Washer, 1x Galvanised Nyloc Nut
Destruction Test Load: Exceeds 17,000kg
Safe Static Rating: 375kg per U-bolt (1500kg per set of 4)

Axle Compatibility

This U-bolt perfectly fits the following trailer axles:

39mm Round Axle
39mm Round Axle – Galvanised
39mm Round Unbraked Lazy Axle
39mm Round Galvanised Lazy Axle

Looking for Complete Clamp Kits?

Read Article: How Humble U-Bolts Cause Serious Caravan Accidents

Frequently Asked Questions

How do I calculate the correct U-bolt size for my trailer?

To find the total length needed, measure and add together the following components: Spring Width + Axle Pad (8mm) + Axle Width + Nyloc Nut Thickness. Ensure the total length allows the U-bolt thread to pass fully through the nylon insert of the nut.

How do I correctly measure a physical U-bolt?

Always measure a U-bolt from the inside curve of the “U” down to the very tip of the threaded end.

Can I reuse my old nyloc nuts?

No. The captive nylon insert is the key mechanism that locks the nut onto the thread. Removing a nyloc nut permanently weakens this nylon insert. Always use fresh nyloc nuts during installation to prevent road failure.

Why do U-bolts need to be retightened after 200 hours?

New steel U-bolts naturally experience microscopic stretching when subjected to road vibrations and heavy loads. Retightening them after roughly 200 hours of use ensures they maintain their critical clamping force.

Australian Towing Regulations & Safety Compliance

Ensure your trailer build or repair meets strict Australian standards. Check the official government guidelines regarding light vehicle towing, trailer suspension, and safety compliance:

There are no FAQs for this product.

Additional information

Weight	0.5 kg
Dimensions	10 × 6 × 1 cm
Bolt Diameter	12.7mm
Coating	Galvanised
Fastener Type	U-Bolt
U-Bolt Width	39mm
Stud Thread	1/2" BSW
U-Bolt Length	100mm, 115mm, 125mm, 140mm, 150mm
Torque	1/2-inch – 60Nm

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.