Custom DIY Ute Tray Sides: A Professional Step-by-Step Fabrication Guide

Fabricating custom ute tray sides requires precise measurement of your existing coaming rail, robust material selection such as structural steel or marine-grade aluminium, and exact hinge alignment to prevent binding. This guide details the engineering steps to construct durable, rattle-free drop-sides using professional welding techniques, hinge gudgeon placement, and over-centre latch installation. Following these technical specifications ensures your custom sides withstand heavy payloads and meet standard transit load-bearing requirements.

Engineering Design and Material Selection for Custom Tray Sides

Before cutting any metal, you must determine the primary use case of your utility vehicle (ute) to select the correct raw materials and structural profiles. Steel offers unmatched impact resistance and ease of welding for heavy-duty commercial applications, but it adds substantial tare weight to the vehicle. Aluminium reduces weight, preserves payload capacity, and resists corrosion, though it requires specialised alternating current (AC) TIG welding or a MIG spool gun and costlier materials.

Most commercial ute trays use a drop-side height of 250mm to 300mm. This height provides a balance between cargo volume and physical ease of loading over the sides. The base frame must interface cleanly with your tray's existing coaming rail, utilising weld-on or bolt-on hinge gudgeons that allow the sides to swing down 180 degrees without binding against the tray chassis or mudguards.

Fabrication Kit and Material Checklist

• Structural Profiles: 250mm or 300mm aluminium drop-side extrusion (6060-T5 grade) or 30mm x 30mm x 2.0mm steel Square Hollow Section (SHS) for framed steel sides.
• Infill Sheet (for framed steel sides): 1.6mm or 2.0mm zinc-anneal steel sheet.
• Hinge Hardware: Heavy-duty weld-on or bolt-on steel gudgeon hinges (20mm or 25mm pin diameter).
• Latch Mechanisms: Over-centre latches (antiloc style) with matching catch plates.
• Welding Equipment: Multi-process MIG welder with ER70S-6 wire and Argon/CO2 shielding gas (for steel) or AC-capable TIG welder with 4043 filler rods (for aluminium).
• Cutting & Prep Tools: Metal-cutting band saw or cold saw, angle grinder with ultra-thin cutting discs, 80-grit flap discs, and wire brush.
• Precision Tools: Digital calipers, engineer's square, long straightedge, heavy-duty locking F-clamps, and a center punch.
• Project Budget & Timeline: Expect a material cost of $250 to $600 AUD and a duration of 8 to 12 hours of fabrication time.

Step-by-Step Drop-Side Ute Tray Fabrication

Step 1: Measuring the Coaming Rail and Laying Out Tolerances

Accurate measurements are critical because even a 2mm deviation across a two-metre tray length can cause the drop-sides to bind or fail to latch. Measure the total outer length of the tray's coaming rail from the back of the headboard to the rear edge of the tray.

To determine the final cut length of your side gates, subtract a tolerance of 10mm from the total length. This clearance budget allocates 5mm at the headboard interface and 5mm at the rear corner post, allowing the gate to swing freely without rubbing the paint or powder coat. Measure the rear tailgate width across the back of the coaming rail, subtracting 6mm on each side (12mm total) to accommodate the rear corner post latches.

Step 2: Cutting the Frame Profiles and Sheet Infills

Set up your cold saw or band saw to ensure perfectly square 90-degree cuts. If you are building framed steel sides, cut your 30mm x 30mm SHS perimeter pieces to length. For a standard 2.4-metre tray side with a 250mm height, you will need two long rails at 2390mm and three vertical uprights (one at each end, one in the middle for structural rigidity) at 190mm.

If you are using single-piece extruded aluminium drop-side planks, make a single straight 90-degree cut to your calculated gate length. Deburr all cut edges thoroughly using a file or an angle grinder fitted with a flap disc. This prevents sharp edges from slicing your skin during handling and ensures clean, contaminant-free weld joints.

Warning: Avoid using abrasive chop saws if cutting aluminium profiles. Abrasive wheels embed carbon particles into the aluminium matrix, which causes severe porosity and structural failure during the welding process. Always use a dedicated non-ferrous carbide-tipped circular saw blade with lubricant.

Step 3: Jigging, Tacking, and Welding the Main Assembly

Place your cut frame pieces onto a flat, heavy steel welding table. Use magnetic squares and heavy F-clamps to lock the components into square. Measure diagonally from corner to corner in an "X" pattern to verify the frame is perfectly square; the two diagonal measurements must match within 1mm.

Tack weld each joint at the diagonal corners first to counteract the pulling forces of the cooling weld metal. Once the frame is tacked, re-measure the diagonals. If the frame remains square, proceed to weld the joints completely.

For steel frames, use a push technique with your MIG torch, running short 50mm welds and skipping from corner to corner to distribute the heat evenly. If you are welding sheet infills to the frame, stitch-weld 20mm sections every 150mm to prevent the sheet metal from warping.

Pro-Tip: When welding thin sheet metal (such as 1.6mm zinc-anneal) to structural SHS frame rails, direct 70 percent of your arc's heat onto the thicker SHS member, dragging the puddle gently onto the thinner sheet to prevent blow-through.

Step 4: Aligning and Fitting the Hinge Gudgeons

The secret to smooth-dropping tray sides lies in the perfect collinearity of the hinge pins. Clamp a straight piece of steel angle or RHS along the bottom edge of the tray's coaming rail to act as a physical alignment jig. Position your weld-on gudgeons (the hinge eyes) along this jig. Space them evenly, typically placing one hinge 150mm from each end and a third hinge dead-centre for sides longer than 1.8 metres.

Insert the hinge pins through the gudgeons on the tray and align them with the corresponding hinge brackets on the bottom of your newly fabricated gate. Tack weld the brackets to the gate frame while the gate is clamped firmly in its closed, square position. Swing the gate down to its open position to test the action. If you feel any resistance or binding, cut the tacks on the offending hinge, realign it using a digital level on the pins, and re-tack. Fully weld the hinges only when the gate swings smoothly through its full 180-degree range of motion.

Step 5: Installing Over-Centre Latches and Corner Posts

To hold the sides upright, you must install vertical corner posts at the rear of the tray if your tray does not already have them. Fabricate these posts out of 40mm x 40mm heavy-wall RHS and weld or bolt them securely to the rear corners of the tray frame.

Position your over-centre antiloc latches on the top corners of the drop-sides. The latch body is typically welded or bolted to the drop-side gate, while the receiving catch eyelet is mounted to the headboard at the front and the corner post at the rear.

When positioning the latches, pull the latch handle tight to pre-tension the mechanism by 2mm to 3mm before marking your drill holes or weld lines. This pre-tension ensures that when the latch snaps shut, it compresses any rubber seals or metal interfaces tightly, completely eliminating road vibration and rattles.

Technical Specifications: Steel vs. Aluminium Construction

Selecting the correct material grade and processing method dictates the ultimate strength and longevity of your ute tray sides. The table below outlines the critical engineering and material properties you must consider when choosing between steel and aluminium for your build.

Field Corrections for Common Fabrication Faults

Problem 1: The drop-side gate is bowed or warped along its length after welding

• Root Cause: Excess heat input during the welding of the infill sheet or the frame joints caused the metal to contract as it cooled, pulling the middle of the gate inward.
• Actionable Fix: Clamp the warped gate to your heavy steel fabrication bench with a thick wooden block or steel spacer placed directly under the peak of the bow. Use heavy-duty clamps on either end of the gate to pull the ends down past the point of straightness, slightly over-bending it in the opposite direction. Heat the stressed weld zones gently with an oxy-acetylene torch to relieve the built-up tension, then allow it to cool slowly at room temperature before releasing the clamps.

Problem 2: The gate binds and will not drop down fully to a vertical 180 degrees

• Root Cause: The pivot axes of the hinge gudgeons are out of alignment (non-collinear), or the bottom edge of the gate frame is making physical contact with the outer flange of the tray's coaming rail.
• Actionable Fix: Use a long, straight steel rod that matches the inner diameter of your hinge gudgeons and slide it through all three hinges simultaneously. If the rod catches or cannot pass through, use an adjustable crescent wrench to gently bend the misaligned gudgeon bracket until the rod slides through effortlessly. If physical clearance is the issue, grind a 3mm chamfer along the back bottom corner of the gate profile to clear the coaming rail during rotation.

Problem 3: Severe rattling from the drop-sides when driving over corrugated surfaces

• Root Cause: Insufficient tension on the over-centre latches or excessive clearance play between the hinge pins and the gudgeon sleeves.
• Actionable Fix: Cut or unbolt the latch catch plates and relocate them 3mm further away from the latch body to increase the mechanical closing leverage. Alternatively, apply heavy-duty, self-adhesive neoprene rubber d-section strip seals along the inside mating surface of the coaming rail. When the gate is latched, this rubber compresses, absorbing road vibrations and sealing the tray bed against water intrusion.

Frequently Asked Questions

What is the standard height for DIY ute tray sides?

The industry standard height for commercial drop-sides is between 250mm and 300mm. This height provides sufficient cargo containment for toolboxes, soil, or equipment without restricting access or making it difficult to reach into the tray from the side of the vehicle.

Can I use timber for my ute tray sides instead of metal?

Yes, timber can be used, particularly hardwood planks like Tasmanian Oak or Spotted Gum, which offer a classic look. However, they require heavy steel metal straps, bolt-on hinges, and regular oiling to prevent rotting, warping, and splitting under UV exposure.

Is aluminium or steel better for a heavy-duty work ute?

Steel is superior for harsh construction environments where heavy, sharp items like concrete blocks or steel scrap are thrown into the tray, as it resists denting and tearing. Aluminium is better for general trade use, coastal environments, or touring setups where reducing vehicle weight is critical to staying under the Gross Vehicle Mass (GVM) limit.

How do I stop my drop-sides from rattling when driving?

Eliminating rattles requires installing high-tension over-centre latches and applying compressible rubber weatherstripping along the coaming rail. Ensuring your hinge pins fit snugly inside their gudgeons without excessive side-to-side play is also essential.

Upgrade Your Vehicle with Custom Tray Accessories

Now that you have mastered the fabrication of heavy-duty, rattle-free tray sides, complete your utility vehicle build by upgrading to professional-grade hardware. Choose high-tensile over-centre fasteners and zinc-plated gudgeons to ensure your custom tray stands up to the harshest Australian conditions.