Background

The “truck bed” is the rear flat surface surrounded by bed front and side walls, and closed up at the end by the tailgate.

Conceived for work, pickup trucks began their evolution in the early 20th century as simple, inexpensive, easy to repair, and utilitarian vehicles designed to haul stuff. To save weight, expense, and enable easy repair, the bed steel frame was finished with planks of broad leaf Southern (Ford used Northern) yellow pine.

A GM truck pine plank bed treated with with a dull black coating

The wood was usually soaked in creosote to prevent fungus and treated with linseed oil/coal pitch giving the bed floor a dull black color. The planks were held in place by metal skid strips also painted black. By the mid-50s, wood planks were often painted in the truck’s body color but the finish remained rough. Needless to say, manufacturers did not pay attention to the wood bed appearance as a key selling feature.

The fan base of the classic 1959-87 El Camino together with restorers of vintage pickups began to re-think the humble wood bed with stunning results.

Example of a beautifully restored El Camino wood bed

Instead of pine, restorations experimented with oak, ash, and other hardwoods. Planks were sanded smooth, stained, and then finished properly to handle a harsh environment.

Modern Ford F-150 stock sheet metal bed

Meanwhile, modern truck beds, like those in the popular Ford F-150’s, have evolved into complex sheet metal structures that depart from the simple lines of the Beetle Ute’s form factor.

There is nothing to emulate in the modern styling, so it’s back to the classic look for inspiration.

Aluminum bed floor

The Smyth Ute kit includes an extruded aluminum bed floor (about 39 x 60″) that can be left “raw”, but this look is neither modern nor classic. Narrow wood pieces might be added to level the floor and echo somewhat the wood bottoms of the past.

Hard anodized aluminum (dark grey) with varnished wood strips

Isosceles trapezoid shape of truck bed strip

The extruded aluminum bed flooring has grooves similar to an isosceles trapezoid shape that adds significant structural rigidity. These indented grooves could be filled in with wood to make a completely flat bed surface.

Fabrication would use 16 5-foot inserts, each running the entire length of the bed floor and fastened to the support cross pieces. Unlike traditional 3/4″ wood bed floors that are held in place by special metal bed skids (also called bed strips), the narrow pieces in this design would be entirely decorative.

Aluminum and wood floor structure (not to scale)

The fastening system could be modified with longer 1/4-20 bolts — 2″ length instead of 1/2″ — to accommodate the thickness of the wood fillers.

Truck bed fastening system (not to scale)

The fastening system must use rivnuts because, unlike a traditional truck bed that is fully exposed underneath (and bolts can easily be tightened to hold down wood planks), the Ute bed rests on top of the chassis infrastructure and cannot be accessed directly. Thus, a “blind” thread must be used. While it is possible to tap holes in the supporting beams, their thickness is insufficient to guarantee a strong enough hold.

Disadvantages

One vulnerability of wood inserts is the fastening system. As wood faces the elements (shrinking in the cold, swelling with moisture, and so on) the critical bolts that “sandwich” the inserts against the aluminum floor to connect the frame may loosen causing rattles and possibly safety issues. Wood-to-metal tightening is not nearly as secure as metal-to-metal fastening.

Both the raw aluminum and enhanced wood insert floor enhancement is difficult to remove when access the the fuel level sensor or spare tire hold is required. At least one of the three aluminum sheets would need to be unscrewed completely involving many bolts and a non-trival re-fitment procedure.

Wood bed floor

It is possible to install a traditional wood bed in the ute, but specially fabricated parts would be necessary since none of the existing classic truck models match our specifications.

Truck bed construction has basically not changed in over fifty years.

Bed strip hidden fastener

A bed strip (or skid) fits into a 3/4″ plank (typically pine) that has milled indents that hold the strip in place.

Recently the trend is to use hidden fasteners for a flush look, but the basic assembly method remains similar: the classic style is to have bolts showing at the top held in position with square punch holes in the strip.

Bed strips hold planks with a 1/2″ space between them.

End strips have a 90-degree bend to finish the edge and hold down the planks on either side of the bed.

Given standard lumber sizes and the 39.4″ bed width, there are 6 practical plank patterns.

Bed wood plank patterns

The highlighted blue rows above indicate plank widths that are the most similar to classic truck bed wood dimensions.

Patterns A and B use planks widths that are larger than classic styling. Patterns C, D, and G use more bed strips and are therefore more complicated and expensive to install. Pattern F is probably the closest to the vintage truck bed look.

Mock up of F pattern bed wood with strips

When compared to the El Camino treatment above, this Ute bed certainly has vintage roots.

Bed wood profile

To hold bed strips, a router cuts this plank profile:
A – 3/4″ plank thickness
B – 1/4″
C – 1/4″
D – 1/2″
E – 1/8″

The supports under the wood bed could employ rivnuts to hold bolts coming down from the top of the strip.

8M bolt and rivnut

This cross section shows an 8M bolt and rivnut fastening the wood strip to the supporting aluminum beam (either cross bars or end plates) to hold the bed securely. The 90-degree end strips could be bolted to the bed side and front walls.

Sixteen bolt/rivnut combinations spaced along the support infrastructure along with the side and front end strips should be sufficient to insure a tight no-vibration wood bed.

Access simplification

To access either the fuel level sensor or spare tire hold, a wood design could eliminate the rather laborious task of removing entire aluminum floor sections. For example, loosening the bed strips might permit sliding down a plank or two to access the fuel level sensor.

Marine deck plate for fuel sensor access

Alternately, a small marine-style deck plate could be embedded into one of the planks for access to the fuel level sensor, eliminating entirely any need to de-construct the bed (although access to the spare tire hold would still require disassembly).

By the way, the tire hold can only accommodate a 16-inch wheel so New Beetle models fitted with 17-inch wheels, like the Turbo S, cannot carry a full-size spare.