Reconditioning a Tandem Trailer

by John

My tandem trailer, was desperate for repairs and repainting. I bought the trailer about 23 years ago. It is 10′ x 5″, very solid construction, and a hydraulic tipper. I used it originally to transport animal manure to my olive trees. In recent years it gets more use on SWMBO’s building sites to remove builders rubbish.

The trailer as I bought it. I added the green “hungry sides” to increase the carrying capacity to about 5 cubic meters. The hydraulic pump runs off the Landcruiser battery. Here discharging rabbit manure to sit in piles for a few months before placing it around the olive trees.

Later, I increased the size of the ram to a multistage 5 ton unit, and changed the geometry to provide more lifting power. Also contracted a professional trailer maker to install Landcruiser hubs and wheels and heavier duty springs.

Landcruiser wheels. Looks more purposeful, and I can use the vehicle spare wheel as a trailer spare. On the farm I sometimes carried and tipped loads of 4-5 tons.

But the floor finally rusted through. So I installed a new 2mm thick steel floor over the top of the old rusted one. I should have removed the old rusted floor, but time was short, so I took the “lazy man’s” option.

Now, 23 years after the original trailer purchase, and about 18 years after the temporary floor fix, the floor needed to be replaced again. This time I did the job properly. I bought 2 sheets of checker-plate steel. Paid the supplier to fold the long edges. And started to remove both layers of the old floor.

The top layer of steel floor which I had welded in place came free after about 30 minutes of weld grinding. The original floor was attached by at least 100-200 welds, many in relatively inaccessible positions. After about 6 hours of exhausting work I removed about half of the badly rusted, excessively welded original floor. Another days work to remove the remainder. Then a lot of smoothing grinding, replaced one cross beam, treated rust, primed and painted the frame. Then attached the new checker plate. Then painted the entire trailer. The yellow seen is bright yellow before I added the red to give the hue an orange tint.
Some of the bends could only be made as the job progressed. This setup worked fairly well.
The folded up side lip should prevent water collecting along the corners, and slow down rusting in that rust prone location.
2 sheets of 2mm checker-plate, 2440mm x 1220mm. I had a 50mm lip folded along the long side of each sheet, cut one sheet into 3 pieces, tacked the pieces together. I asked my expert welder friend Tony to complete the welded joins. Here applying primer to the underside.

Then attached the new floor to the trailer frame with galvanised hex head screws. You might wonder why I did not weld it in place? Well, removing the previous floor which had been welded in position was job which I never want to repeat. Plus, whether the new floor is galvanised or painted, welding destroys the zinc or paint, including in areas which cannot be touched up. The technique which I used allowed all surfaces to be thoroughly painted. So I removed the newly joined floor, and primed and top coated all surfaces, including the frame underneath.

Then re-attached the new painted floor permanently to the frame with the gal screws, and cut off the protruding points. I decided to not weld the floor to the frame, because that would destroy the rust inhibiting paint. I used silicone roof and spout sealant in the screw holes, and between the trailer sides and the new floor side lips. Then applied more silicone sealant into any cracks between the side lips and trailer sides.

Oh, I forgot. The cross members were U sections with the opening at the top. No wonder they rusted. Any accumulated water could not escape. A really dumb design decision by the maker. So I drilled drain holes in every cross member, removed the rust with a needle gun, and painted the insides of the U sections. I will finish the painting when the steel repairs have been completed.

More painting required. The frame the hydraulic reservoir and pump, and trailer wheels yet to be prepared and top coated.
Quite a few hours of prep work, and 2 coats of paint to come. That is the 4 stage ram which I installed about 10 years ago. The new ram required a larger hydraulic oil reservoir, hence the extensions to the tank (bottom right). The end of this project is in sight!

Judging by the coats of existing paint, and alterations to the trailer construction, I reckon that this is the 4th major change to this trailer’s construction. It has done a lot of work. And lots more to come.

10 November 2021.

A bit more paint painting required in hidden areas, wheels, but this will be the final appearance. I am sure that the colour will not be to everyone’s taste, but I really like it. The spare wheel attaches to the post.
A new switch for the hydraulic tipper, and the lights still work. Ready for another decade or two.

It will probably outlast me.