Bolt-together frame kit guide for Compact Camping Concepts Explorer Box Camping Trailer Revision 2.30 08/01/17 Bolt-together frame kits are a budget friendly option for building an Explorer Box trailer on. There are many sources; Harbor Freight is a readily available and recognized name. This guide is based on Harbor Freight s, Haul-Master #62647 1720 lb. capacity super duty 4 x 8 trailer. #94564 is the previous discontinued part #. The model #62647 has a folding feature which isn t needed for home-built camping trailer projects. The folding hardware doesn t get installed and a couple extra bolts are used for securing the two halves together.
A standard Explorer Box is based on a 4 x 6 frame, so a few modifications are necessary. First, the length of the frame deck gets shortened from 96 to 72 long. Second, the position of the spring hangers gets relocated so the axle center line is 27 from the rear of the frame. To make these modifications, you will need a drill, 7/16 drill bit, a couple of clamps and a way to cut steel. For the steel cutting, a hacksaw works, although a 4 1/2" angle grinder with a cutoff wheel goes much faster. Start by reading the frame kit manual and understanding the standard frame building process. This guide follows and references the manual steps. Build the frame: Per the Steps 1-3 instructions, build up the front 4 x4 section. Leave the four #25 stake pockets and two #10 hinge plates off. Steps 4-6 require modifications, the side rails will be shortened and rear 2B cross member will not be used. Side rails 1RL &1RR get shortened to 24. The cut goes through the bolt hole where the center 2B cross member would normally be bolted. The shortened side rails need new 7/16 dia. holes drill for attaching the center 2B cross member which now becomes the rear one. Then assemble the shortened side rails with a front and rear cross member per the instructions, leaving the four #25 stake pockets and #10 L&R hinge plates off.
Per Steps 7-11 instructions, attach the tongue section. For Step 12, bolt the front and rear sections together with a couple extra M10 bolts and nuts. Then disregard Step 13.
Steps 14-18 get modified. The front of the spring hanger gets positioned 31 1/4" from the front of the frame. This places the axle centerline 27 from the rear of the frame. This requires drill new holes and bolting the hangers to the front and rear frame sections. Here is the spring hanger holes location information. Three new 7/16 diameter holes need to be drilled in each spring hanger. The new holes are C, D and E. Hole C is positioned over the rear section, front corner cross member hole. Holes D and E are position in approximately the same location as A and B on the front end of the bracket. F is the square hole on top of the spring hanger.
With the spring hanger clamped in place, drill the six (per side) new 7/16 diameter hole through the frame. F is drill through the square hole on top of the spring hanger. Now referencing Figure E in Phase 5, bolt the spring hangers in place. For A, B, D, E and F use part #B M10 x 25 bolts. For C use part #C M10 x 30 bolts. Per the Steps 19-24 instructions, attach the springs and axle, but do not attach the fender seats or fenders. Per the Steps 25-30 instructions, install the hubs and tires. DO NOT overlook Bearing Packing Instructions. Per the Steps 31-49 instructions, attach the couple and safety chain. Depending on where your taillights will be installed, you may defer wiring and attaching the lights at this time. Your Basic Frame is now complete! Be sure to read and follow the operating instructions and safety portion of your frame manual.
An additional item I put on all trailers is a swivel tongue jack. These make moving your trailer around much easier and allow you to level it.
Another additional item if your Explorer Box will be Tent Topped, is a pair of rear leveling / stabilizer jacks. Bolting them to the rear cross member is an easy way to install them. Too better protect them, make brackets and angle them in.