How to: Install Trailer Fairings

John Baxter | December 01, 2010

Streamline your trailer

If you own a dry van or reefer, adding trailer fairings should improve your fuel economy and highway performance. Installing a kit requires only basic tools, a helper at times and most of a day.

TOOLS

• An electric drill and bits able to penetrate trailer cross-members. Consult installation manual for bit diameter.

• Two sets of standard open-end and socket wrenches.

• Four vice grips.

• A chalk line or string and marker.


1.  Pre-assemble the hinges, which will allow the lower edges of the fairings to be held in place by diagonal braces. The hinges need to be bolted to the fairings, and the support rod attaching bolts and clamps that attach them to the cross-rails must be assembled.

2.  Slide tandems forward all the way. Mark a point three inches forward of the front edges of the tires on the trailer’s side rail. The rear corner of the fairing will be mounted on the nearest cross-member forward of this point. It will angle in two inches inside the landing gear. Use a chalk line or string to run a line from the rear mounting point to the front mounting point. Mark every cross-member where the fairing will run.

3.  Using the markings, place the fairing sections along the bottom of the trailer. Clamp in place with vise grips.


4.  Install the fasteners attaching the sections together at the top and along their sides. You’ll need a helper to hold the bolts. The fasteners at the sides use rubber-coated washers and are unthreaded on part of their shafts. Tighten just snug.





5. Drill a hole through the top bracket of each fairing and the horizontal section of every second cross-member. Drill away from the vertical part of the cross-member so you’ll be able to tighten the nut.




6. Some trailers have shallower, steel cross-members at the front. Use a fiberglass block as deep as the difference between the cross-member heights (about 11⁄4-inch) to mount to these. Drill through each block.




7. Install the bolts, nuts and washers that hold both fairings to the cross-members. Then assemble the diagonal braces and the clamps that hold them to the cross-members. Adjust the clamps so the fairings are vertical and straight prior to final tightening of the clamps. n

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