DIY drop-sides

Most tray bodies come with aluminium drop-sides, but that’s not the look we wanted for our 30-year-old ‘Cruiser 75 Series.

When we put a customised aluminium ute tray on ‘Harry’ we thought we’d re-use the steel drop-sides we’d had fitted to the old steel tray about 15 years ago. They were still in good nick, but somehow just didn’t look right. 

They also were slightly oversize, as well, so we’d have had to do a cut-and-shut, plus a repaint and they still wouldn’t look quite right.

On top of that, we’ve had issues with conventional drop-sides for years, because the aluminium ones are quite flimsy and they deform if you run tie-downs over them from the tray’s tie-down rails. Sure, you can countersink tie-down rings into the tray deck, but they’re not always exactly where you want them.

The ideal drop-sides would have a space between their lower edges and the tray, so that tie-down ropes or straps could be run under the drop sides. Ah yes, you say, but then bulk materials would run out under the drop-sides and you’d be right, if you didn’t first lay an over-sized tarp in the tray before loading bulk material. The excess tarp folds back over the load and acts as a cover.

We’ve always liked the look off traditional US tray-back trucks that were fitted with ‘stake-side’ bodies. These were made from horizontal timber (‘lumber’ in the USA) planks attached to vertical posts – stakes – that dropped into sockets on the tray edges. Later versions of these had hinged drop-sides instead of stakes and some modern ones are made from aluminium extrusions.

I mocked up how such a drop-side body would look, by clamping a couple of spare deck planks in place on the side of the tray and she-who-must-be-obeyed reckoned it looked fine, but needed three-high, not two-high planks. The die was cast.

I stripped the hinges, straps and over-centre clips from the old steel drop-sides and gave them a good clean up and polish. I retained the steel head-board panel, with its toggle pins, to ensure the leading edges of my drop-sides would be secure.

Off we went to Bunnings and picked up nine 2.7-metre-long x 90mm wide x 19mm thick Merbau pre-oiled deck planks. I selected the straightest from the stack and brought them home for work to begin. I also selected some duragal channel section to function as vertical end caps for the planks.

Step one was measuring the vertical distance from the hinge pins on the sides of the tray to the top edge of the top plank, so that it would line up with the leading-edge toggle pins. That worked out at an overall drop-side height of 340mm, with planned spacing of 19mm between successive planks, however, that spacing varied slightly along the drop-side length, because of slight variations in plank ‘trueness’.

Then I measured the length of the planks for the drop-sides and tailgate and the drop saw did the rest.

After repeated measuring and re-measuring I drilled additional holes in the steel hinge straps – thanks to cobalt drill bits – and then drilled the three planks per side accordingly. 

Because I wanted no intrusions on the inside surfaces of the planks, I drilled the planks for M6 bolts and then countersunk 14mm-diameter holes on the inside of the bolt holes, to a depth of around 8mm. That way, the M6 bolts ran through the hinge straps and planks, while the countersinking allowed a 10mm socket to fit into the countersunk holes, to tighten the nuts and washers.

I chiselled one-millimetre thickness out of the ends of the planks, to allow a snug fit for the channel-section end caps. Incidentally, cutting this thin steel extrusion into 300mm lengths was a pain, until I worked out that jamming a piece of old 18mm-thick soft wood snugly inside it acted as a brace and cutting it became much easier.

The leading edge of each drop-side needed a 25mm hole for the toggle pin and my hole saw did the trick.

With the end caps in place and secured by 6mm button-head screws, it was time to fit the drop-sides and tailgate, and it worked!

However, variations in plank straightness meant that at one corner, between tailgate and drop-side, there was a height variation of 3mm, so I had to lozenge one tailgate bolt hole, to raise that top plank slightly. The change in plank gap is imperceptible to casual observers, but I know it’s there!

Finishing touches were sticking adhesive-backed, gap-filling rubber strips to the drop-side end caps; attaching the over-centre clips to drop-sides and tailgate; then brushing the pre-oiled planks with three additional coats of left-over boat deck oil.

I’m happy with the end result and, more importantly, so is she-who-must-be-obeyed!