45mm Square x 150mm M16 U-Bolt Kit
Price
$65.00 Inc.GST
- Perfect Fit: Designed precisely for 45mm square axles or frames.
- Heavy-Duty Strength: Features robust M16 threading for maximum secure clamping.
- Generous Length: 150mm setup accommodates thick springs and mounting plates.
- Complete Kit: Includes premium nuts and washers for a ready-to-install setup.
Shipping
45mm Square Heavy-Duty U-Bolt Kit – Medium & Heavy-Duty Trailers
The Couplemate™ CM601 is a Spring U-bolt kit for 45mm square axles. Designed to attach leaf springs to the axle securely, Couplemate™️ calls these the “heavy-duty” kits because they feature thicker U-bolts and fish plates.
Product Specifications
- Internal U-Bolt Width: 45mm
- Internal U-Bolt Leg Length: 150mm
- Thread Type: M16x2 (or 5/8″ UNF)
- Length of Thread: 75mm
- Coating: Electro-Plated
Couplemate™️ often supplies Heavy-Duty u-bolt kits with trailer axle rebuilds over 1600kg (up to 4500kg ATM).
This kit is supplied with:
- 4 x U-Bolts
- 8 x Washers
- 8 x Nyloc nuts
- 2 x Fish Plates
- 2 x Axle Pads/Spacers
Installation (User Guide)
Couplemate™️ 45mm Square U-Bolt Kits make trailer spring maintenance easy.
- Place a U-shaped curve over the axle beam.
- Align the centre spring bolt and U-bolt legs with the fish plate holes.
- Secure the fish plate to the leaf spring using the supplied washers and nylock nuts. Tighten nuts to 100Nm with a socket.
Important: Check U-bolts and re-tighten nuts after the first trip and every 250 km thereafter.
Safety Precautions
Do not reuse nylon nuts. Nyloc nuts are often less effective after the first use because the nylon material (the key component of a nylon nut) has already conformed to the thread profile.
Do not use a rattle gun to tighten. Rattle guns often tighten U-bolts too fast, too tight, and unevenly. This can cause the nylon to overheat and risk undue wear.
Ensure the axle has welded axle pads. If not, use the axle pads supplied with the spring U-bolt kit.
Related Towing Products
- 45mm Square Heavy Duty U-Bolt Kit
- 50mm Square x M16 U-Bolt Kit – 180mm Long
- 60mm Round Heavy Duty U-Bolt Kit
- 65mm Round x 16mm U-Bolt Kit – 200mm Long
Are 16mm Heavy-Duty U-Bolts worth it?
Within the industry, Trailer U-Bolts lack a standardised testing procedure.
However, Couplemate™ Engineers has developed its rigorous testing method. In this process, we subject u-bolts, nuts, and fish plates to a static load test until destruction occurs.
All of our 16mm Heavy-Duty U-bolt Galvanised Kits undergo a 200-tonne test. During this testing, the u-bolts in the right-hand image ultimately broke at the 23t threshold.
The u-bolts in the right-hand image broke at 23t.
Understanding Caravan and Trailer U-Bolts
- Read why U-bolts could be the primary cause of accidents.
- Loose Axle U-Bolts cause Highway Havoc.
- This article is the catastrophic result of the incorrect tightening of the U-bolt on a truck chassis.
- How to Reduce Dangerous Caravan Vibration Fatigue
- Heavy Duty Trailer Guide and Lock 3.5t Rated
Related Towing Products
- 45mm Square x 16mm Heavy Duty U-Bolt Kit
- 50mm Square x M16 U-Bolt Kit – 180mm Long
- 60mm Round Heavy Duty U-Bolt Kit
- 65mm Round x 16mm U-Bolt Kit – 200mm Long
16mm Individual U-Bolts
Installation Do’s & Don’ts
Do’s
- Measure Twice: Confirm your axle or frame measures exactly 45mm square before starting your installation.
- Cross-Torque Progressively: Tighten the M16 nuts evenly in a diagonal pattern to ensure parallel clamping force across the mounting plate.
- Check Thread Clearance: Verify that the 150mm length leaves enough exposed thread after passing through your spring pack and fish plates to fully engage the locking nuts.
- Re-Torque After Use: Inspect and re-tighten the hardware after the first 100 kilometers of towing to account for initial settling.
Don’ts
- Do Not Reuse Old Nuts: Avoid pairing the new M16 bolts with worn hardware, as thread fatigue can compromise the torque hold.
- Do Not Use Power Tools for Final Torque: Avoid using high-impact wrenches to finish the job, as they can cause thread galling or over-stretching.
- Do Not Force the Fit: Avoid forcing the 45mm square bend over a wider or rounded axle, which stresses the corners and creates weak spots.
- Do Not Ignore Coating Wear: Avoid leaving bare metal exposed if the protective zinc or Dacromet layer gets scratched during installation; treat it immediately to prevent rust.
Additional information
| Weight | 5.2 kg |
|---|---|
| Dimensions | 20 × 10 × 5 cm |
| U-Bolt Length | 150mm |
| U-Bolt Width | 45mm |
| Coating | Electro-Plated |
| Stud Thread | M16x2, 5/8" UNF |
| Bolt Diameter | 16mm |
| Fastener Type | U-Bolt |
| U-Bolt Application | Spring U-Bolts |
| Spacer Plate Type | Fish Plate, Spring Spacer |
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.
“Used these to mount a new set of springs on a 45mm square axle. The heavy galvanised finish gives great peace of mind against rust, and the inclusion of nyloc nuts ensures nothing backs off over rough roads.”
Origin: Anaconda Stores
“Perfect dimensions for a heavy-duty setup. The true bolt diameter and precise M16 threading make clamping down boat trailer chassis rails incredibly secure. The coating holds up well to marine environments.”
Origin: Trailer Spares Direct
“Outstanding kit that fits 45mm square axles perfectly. Very reliable seller with accurate descriptions, and the heavy-duty hardware included made my caravan suspension overhaul simple and secure.”
Origin: eBay Australia Marketplace
“Comes exactly as described with heavy plates and solid square bends. The 150mm length provides plenty of thread space to accommodate both the multi-leaf spring pack and the fish plates safely.”
Origin: Huntsman Products
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