Re: Wood Bed Patterns

[lucifer]

The bed wood in the Chevrolet & GMC trucks was originally a southern yellow pine. The Advanced Designed Trucks bed wood came from the factory treated with a combination of linseed oil and lampblack, giving it a dull black color. The boards were held down by metal strips between the boards which were also painted black . The later model trucks came with the bed wood painted the same color as the exterior of the trucks. Many choose to use a variety of clear finishes to bring out the beauty of the wood grain. When purchasing a clear finish for this purpose, be sure to get a finish that is UV resistant to reduce the potential damage from the suns UV rays. Most marine type varnishes will meet this criteria, most highly recommended are those developed specifically for salt water application by the marine industry. Polyurethane is also a excellent choice in a clear finish due to its long lasting finish that withstands salt, & moisture extremely well.
If you are looking to make your own boards, you will need dimensions. From 1947 to early 1951, there were 9 boards making up the bed, from late 1951 -1972 Stepside's used 8 boards, the 1960-1972 Fleetside used 12 boards. The boards were nominally 1" thick (making them a measured 3/4" thick). The width of the boards varied depending on position. The tables below show the width of each board and its relative position.

1947 to Early 1951 - 9 Boards
4 1/4" 5" 5 1/2" 5 1/2" 6 3/8" 5 1/2" 5 1/2" 5" 4 1/4"

Late 1951 to 1953 - 8 Boards
4 1/4" 7 1/4" 5" 7 1/4" 7 1/4" 5" 7 1/4" 4 1/4"


Late 1954 to 1957 - 8 Boards
4 1/4" 7 1/4" 5" 7 1/4" 7 1/4" 5" 7 1/4" 4 1/4"




Late 1958 to 1959 - 8 Boards Stepside
4 1/4" 7 1/4" 5" 7 1/4" 7 1/4" 5" 7 1/4" 4 1/4"



Late 1958 to 1959 Fleetside - 12 Boards
4 1/2" 5 1/2" 5 1/2" 7 1/2" 5 1/2" 7 1/2" 7 1/2" 5 1/2" 5 1/2" 4 1/2"




Late 1960 to 1972 Stepside - 8 Boards
3 1/8" 7 7/16" 7 7/16" 5 7/16" 5 7/16" 7 7/16" 7 7/16" 3 1/8"



Late 1960 to 1972 Fleetside - 12 Boards
2- 6 3/8"* 7 7/16 7 7/16 7 7/16 5 7/16 5 7/16 7 7/16 7 7/16 7 7/16 2- 6 3/8"*


* = One board in front of wheelwell, one board behind

The lengths of the boards depended on several factors, ton rating and wheelbase. The table below summarizes board lengths for the AD pickups and later model pickups.

Board Lengths
1947-1953 1/2 T Short Bed 77"
1947-1953 3/4,1 T Long Bed 85 3/4"
1954-1959 1/2 T Short Bed 77 1/8"
1954-1957 1/2,3/4 T Long Bed 89"
1957-1959 2nd Series 1/2, 3/4 T Long Bed 97"
1954-1959 1 T 97"
1960-1966 1/2, 3/4 T Short Bed Step Side 77 1/8"
1960-1966 1/2, 3/4 T Long Bed Step Side 97"
1960-1966 1/2, 3/4 T Short Bed Fleet Side 77 1/8"
1960-1966 1/2, 3/4 T Long Bed Fleet Side 97"
1967-1972 1/2, 3/4 T Short Bed Step Side 77 1/8"
1967-1972 1/2, 3/4 T Long Bed Step Side 97"
1967-1972 1/2, 3/4 T Short Bed Fleet Side 77 1/8"
1967-1972 1/2, 3/4 T Long Bed Fleet Side 97"
1967-1972 1/2, 3/4 T Longhorn Bed Fleet Side 103"


The individual boards are held down by steel strips ("wear strips") which sit in grooves cut into each board. You will note from the drawing below that the outer edges of the wear strip came down lower than the middle of the wear strip. This explains the somewhat unusual groove pattern of the wood (see below for dimensions.)



Dimensions
A. 3/4" (board thickness)
B. 1/4"
C. 1/4"
D. 1/2"
E. 1/8"


The two outside boards had grooves only on their inside edges. All the other boards had grooves running down both sides. The drawing below shows how the boards were grooved. The shallower the inside groove is, the higher the wear strips will ride above the bed wood. Originally, the top protrusions of the wear strips were just slightly higher than the bed wood. Some prefer to alter this dimension to raise or lower. If making your own bed wood and using new bed strips you should measure your new wear strips for precision cutting measurements. Cuts should also take into account that different woods and there coatings will allow wood to swell and shrink at different rates. We also highly recommend that you add a groove running every 1' of board length from the C dimension to the outside edge of the D dimension allowing for the flow of water off the inset groove to allow trapped water in the groove easier drainage than only at ends of boards to greatly preserve the life of the boards.

Long Wheelbase Fleetside Bed Wood Short Wheelbase Fleetside


1967-72 SWB Fleetside Bed Wood Holes Locations

The reason for the unusual design is wood movement due to moisture content change. A six inch wide board can easily change width cross grain by 1/16" - 1/8" due to seasonal humidity changes. The groove design allows the boards to float without buckling while still being firmly held to the steel supports underneath during the expansion and contraction of the wood.
The beds may change width by over an inch between dry winter conditions in storage and humid spring & summer conditions. For people who are making bed wood please note: different species of wood move different amounts in response to humidity (moisture content) changes. It is important to allow clearance between the hold down bolts and the wood so that movement can occur. If you're working dry wood in a heated shop (shrunk condition) more expansion room should be allowed than if you're working air dried wood in the humid part of summer with no heat in the shop (expanded condition). Varnish or polyurethane does not prevent this natural wood movement but may slow it down some, so If you don't varnish or seal both the upper and lower surfaces of the boards, they will change moisture content faster on the unsealed surface causing cupping of the wood. Interestingly, the wood changes little along the grain (lengthwise) so it is not necessary to allow for much change in length. To decrease your chances of cupping you should select all wood from heartwood. This can be indentified by examining rings of groth on the ends of the boards. The ones that have the center set of rings from the heart of the tree, if heartwood is not available be sure to groove the boards with the curve of the grain going up. Doing this ensures that center of board will rise rather than dip thus standing water will not occur and will instead run off helping to prevent retention of excess moisture.