DIY Network

Cargo-Trailer Kit -- Chassis Assembly From "Weekend Mechanic" episode WKM-111

advertisement

This cargo-trailer is 6 feet long by 4 feet wide, with a fiberglass body that protects cargo from exposure to the elements. This one was built in a single weekend. Figure A Figure B Figure C Figure D Figure E Figure F Figure G Figure H Figure I Figure J Figure K Figure L

In this episode, Weekend Mechanic Bruce Bonebrake builds a cargo trailer that allows you to tow large tools, equipment or other cargo behind your vehicle. The trailer is built from a kit, and features a fiberglass body and full wiring -- with brake lights and turn signals -- for highway safety.

The trailer shown in this demonstration was built from a kit. The finished trailer is 6 feet long by 4 feet wide. Its fiberglass body protects cargo from exposure to moisture and the elements.


DIY Difficulty Rating for Repair: Building a cargo trailer is not a very complicated project. However, there are a number of parts involved, and accurate measurements need to be taken. The entire process can be fairly time-consuming. The project should take about a day and a half to two days. We give it a difficulty rating of 2 on a 5-point intermediate-level scale.

Important: Included below are the steps in the assembly of the trailer from the kit shown in the episode. These steps are general guidelines that are applicable to most trailers of this type. With any particular trailer-kit, and depending on the vehicle you'll be towing with, there may be variations in assembly procedures, components, etc. Read and follow the instructions and any precautions that come with your kit, and consult your vehicle's service manual for towing recommendations.


In addition to standard auto-mechanic's tools, some of the specialty tools that will be needed for this project include metal file, power-drill with wood and metal bits, and a circular saw. An air-ratchet is optional, but will help speed the assembly process.

Note: The carrying capacity of the trailer shown in our demonstration is about 1200 pounds.


Assembling the Chassis

• Begin the project by unpacking all of the parts, and taking an inventory check to make sure you have all the necessary components.
  
  
  
  
• Make sure that you have ample workspace, and lay out the elements of the frame in the configuration that they fit together (figure A).
  
  
  
  
• Bolts are used to fasten the frame elements together. For safety, all bolts should be oriented so that the threads face inside the frame (figure B). Lock-nuts are used on the assembly bolts to ensure that the frame stays tight once assembled.
  
  
  
  
• Assembly of the basic frame is simple. The pieces interlock, and are then bolted together. Bolt the frame-rails together using the nuts and bolts provided (figure C). Install all of the bolts, but don't snug them down all the way just yet. You'll come back and tighten them all down securely later in the assembly.
  
  
  
  
• Two of the frame pieces have plates that hold the rear tail-lights. Make sure those face to the rear.
  
  
  
• A center-piece has a U-channel that will hold the trailer tongue. Install it to the front.
  
  
  
• Once the main elements of the frame have been put together, you may want to place the frame on jack-stands (figure D) to make the rest of the assembly easier.
  
  
  
  
• The trailer uses a leaf-spring suspension. Each leaf spring (figure E) is curved in an S-shape and has an eyelet with a nylon bushing on one end. The end with the eyelet is the front portion.
  
  
  
  
• Place the front end of the spring in the frame's spring-bracket (figure F) and bolt it in place with the threads of the bolt facing inside.
  
  
  
  
• The kit offers two different ways to set up the axle and suspension. The axle may be mounted on top of the leaf springs (figure G) to provide a lower ride-height. This is best suited for towing motorcycles, lawn-mowing equipment or other equipment that is best unloaded low to the ground. In this case, the axle is bolted to the spring using pre-drilled holes.
  
  
  
  
• The second option is for the axle to be mounted beneath the spring (figure H). This configuration provides greater ground clearance and a softer ride. For our demonstration, we used the second option.
  
  
  
  
• To mount the axle in this way, a mounting plate is placed on top of the leaf-spring (figure I) with the spring's center-bolt extending up through the plate's center-hole.
  
  
  
  
• The axle us fastened to the mounting plate using U-bolts and lock-nuts (figure J).
  
  
  
  
• With the frame elements assembled, the tongue is attached to the center-rail of the frame using two clevis pins with clips (figure K).
  
  
  
  
• The tongue attachment is designed in this way so that the tongue can easily be removed (by removing the clips and pulling out both pins) for easy storage of the trailer. Also, if only the front-pin is removed, the trailer can be tilted back for easier unloading of the cargo.

  Safety Alert: Be sure that both pins are in place whenever you take the trailer on the road.

With the frame and tongue all assembled (figure L), the next phase of the project includes installing electrical wiring, tail-lights and flooring. Those steps are covered in the segment that follows.

RESOURCES :

The Complete Idiot's Guide to Trouble-Free Car Care
Author: Dan Ramsey
ISBN: 0028635833
Alpha Books

Auto Repair for Dummies
Author: Deanna Sclar
ISBN: 0764550896