Round U-Bolts for full‑load Australian roads.
Standard round-bend profile for pipe mounts, leaf springs and trailer axle clamping. Formed from certified high-tensile steel at our Truganina, VIC hub and supplied nationwide.
How to measure your round U-bolt
Four measurements are all we need to match or replace a round U-bolt. Take them from the bolt itself, or from the pipe or axle it needs to clamp.
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01
Inside Diameter
The straight-line distance between the two inner legs of the bolt. This should match the outside diameter of the pipe, axle or spring pack being clamped.
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02
Inside Height
Measured from the underside of the crown down to the inside diameter line. Sets how much clearance the bolt has over the mounting surface.
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03
Thread Length
The length of threaded section on each leg, taken from the tip of the leg up to where the thread ends. Needs to clear your mounting plate plus nuts and washers.
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04
Thread Size
The diameter of the threaded leg itself — e.g. M6 through M24 — which determines nut, washer and mounting-hole size.
Round U-bolt sizes: M6–M24 sizing chart
Starting point for standard fleet and trailer applications. Custom drop lengths and thread sizes formed to your workshop's spec on request.
| Thread | Inside Diameter | Inside Height | Thread Length | Typical Use |
|---|---|---|---|---|
| M6 | 50–80mm | 60–100mm | 35–50mm | Light trailer, box trailer |
| M10 | 80–120mm | 100–160mm | 45–65mm | Caravan, tandem axle |
| M12 | 100–150mm | 120–180mm | 50–70mm | Single-axle box trailer, small plant |
| M16 | 120–180mm | 150–220mm | 60–90mm | Light truck, ute leaf spring |
| M20 | 150–220mm | 180–260mm | 70–100mm | Medium commercial fleet |
| M24 | 180–260mm | 220–320mm | 80–120mm | Heavy haulage, prime mover |
Need a size outside this range, or an odd-length leg to suit an existing spring pack? Send us your four measurements and we'll quote against current stock or a custom run.
Round U-bolt finishes: zinc-plated, galvanised or stainless
All round U-bolts are formed from certified high-tensile steel, then finished to suit the environment they'll be working in.
Zinc-Plated Steel
Cost-effective corrosion resistance for general trailer, ute and light-fleet work kept mostly under cover.
Hot-Dip Galvanised
Heavier zinc coating for coastal, rural and full-time outdoor exposure — the standard choice for commercial fleets.
Stainless Steel
Maximum corrosion resistance for saltwater exposure, boat trailers and washdown-heavy environments.
Why Australian workshops choose Kap round U-bolts
High-Tensile Steel
Certified stock, tested for full-load transport conditions.
M6–M24 Range
Light trailers through to heavy commercial axle assemblies.
AU Standards Compliant
Manufactured to strict Australian transport and fabrication standards.
Custom Drop Lengths
Non-standard leaf spring and axle configurations formed to spec.
Round U-bolt FAQs
What size round U-bolt do I need?
Four measurements are all we need: thread size (M6 to M24), inside diameter, inside height and thread length. Take them from the bolt itself, or from the pipe, axle or spring pack it needs to clamp. The inside diameter should match the outside diameter of what is being clamped.
What is the difference between zinc-plated, hot-dip galvanised and stainless round U-bolts?
Zinc-plated is a cost-effective finish for general trailer, ute and light-fleet work kept mostly under cover. Hot-dip galvanised has a heavier zinc coating for coastal, rural and full-time outdoor exposure and is the standard choice for commercial fleets. Stainless steel gives maximum corrosion resistance for saltwater exposure, boat trailers and washdown-heavy environments.
What thread sizes do your round U-bolts come in?
Our round U-bolts range from M6 to M24, covering light box trailers and caravans through to heavy commercial axle assemblies and prime movers.
Do you supply round U-bolts across Australia?
Yes. Our round U-bolts are manufactured at our Truganina, Victoria hub and supplied Australia-wide, including Melbourne, Sydney, Brisbane and Perth.
Can you make round U-bolts to a custom size?
Yes. Custom drop lengths and thread sizes can be formed to your workshop's spec on request, including odd-length legs to suit an existing spring pack. Send us your four measurements and we will quote against current stock or a custom run.
How do I get a quote for round U-bolts?
Email your thread size, inside diameter, inside height and thread length to jask@kapcomponents.com.au, call +61 402 999 801, or message us on WhatsApp.
Need round U-bolts in Australia? Have your four measurements ready.
Send your thread size, inside diameter, inside height and thread length — we'll quote against current stock at our Truganina hub.