Lister 5/1 Diesel

Drawbar Trailer Design & Build

Designing & Building Our 6-Wheel Drawbar Trailer Page 8


The next job was to fit the top cant rails at each side and front/back, so that the roof bearers could be fitted. Once that was done, we could fit the roof sheet. In practice, this was a big job, as the cant rails needed to be stuck in place with the corner castings as well, so it was a once-only job, we wouldn't get a second chance at it. In practice it went OK, the extrusion slots had to be primed with adhesive and then lifted up into place over the side panels, after which the corner casting caps could be fitted. It sounds fairly easy, but we had a couple of trial assemblies to make sure we had it right.

Picture of the roof bars going up into position. The roof vent was one of a pair that were
designed to go on the roof, but in the end we didn't use them.

Next were the roof support extrusion. We used a standard 'Top-Hat' extrusion which we cut to length to suit our own body. Each one is then fixed at each end with two bolts. A truck body builder would use large rivets, applied with a compressed air tool, but we didn't have the facility and pop rivets were too small for the strains involved. Although fairly 'bendy' when in place, they would support my weight if I spread it over a few beams with a plank or board.

Shot of the roof, almost finished.

We did fit four beams with one flange missing on one side, this was to give us the aperture for the roof vents. In practice we didn't go that route and found that the top opening window vents were more than adequate. Next job was to finish off the rear aperture as the body was not very strong in torsion with the end being completely open. The rear corner posts interfaced with other parts as well, so we had to get the whole area ready before we glued them into place. We did have to cut down the side panels by 8mm in length after we found that we had miscalculated the depth of the channels in the corner posts. That was done with the trusty angle grinder and cutting disc.


Rear door opening after we got the corner posts up.

The panels each side of the rear door and above it would have to be put into place now, and we got them cut and trimmed ready to put into place. We also made up stiffener panels to go across the joints in the panels to spread the load when the body twisted. The corners were dealt with by an aluminium casting that was used for all the four corners. Simple to fit and secure, they weren't cheap but a good solution.


Interior view of the bottom corner post fitting.

Getting the rear panel in place, it consisted of 3 pieces with horizontal joints that we covered with a stiffener panel. We used offcuts wherever possible.

Interior view of the top corner casting and corner post fitting.

We had been having warm and dry weather up until now, but then we got hit by a couple of heavy showers. The next picture shows the PVC/Nylon sheet over the roof beams to keep me dry! The rear panel is finished apart from the opening trim and the stiffener panels.

Interior view of the rear door aperture.

Looking along the floor and out of the back. Floor is waiting for the wheelboxes to be made.

Interior view of the stiffener panels over the joint in the rear panel. Panels are 14swg NS4 Dural.

The roofing sheet had arrived, a big coil of opaque glassfibre which was supplied in a standard width, but cut to your required length. This was stuck down the the cant rail tops and the top faces of the roof beams with heavy-duty doubled sided foam tape. Then it was held on all four sides by an aluminium moulding on top, riveted down with sealed pop rivets at 200mm centres. We used Sikaflex 221 between the moulding and the roof.

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