I love the ability to toss my bike, skis or kayak on the roof of my car. Unfortunately, my Subaru came with factory bars but they were super flimsy. They worked ok for a ski rack but a bike or kayak caused them to flex and the load would wobble terrifyingly. I didn't really want to shell out hundreds of dollars for yakima or thule systems. So what is one to do? Build your own.
I wanted aero-bars that were quiet, looked good, secure and would still work with my ski and bike racks. Scrap cedar is light and easy to shape so getting the aero shape was easy. I was concerned that simple wood bars would not be strong enough so I wrapped them in fiberglass composite to make a super strong bar that are also waterproof.
Scrap wood (I used cedar fence planks)
U-bolts, nuts and lock washers
Vacuum bag and pump (optional)
**I apologize in advance, this is my first instructables and I'm not used to taking photos of the process so I'm missing a few that I would otherwise have included.
Step 1: Measure, Prep and Glue
Measure the distance between the rails on your car. Measure the distance at the front and the rear of the rails, they may not be parallel.
Choose some scrap pieces of wood that are long enough to span the rails. I used leftover cedar fence boards but any wood will work.
If the wood is too rough, as mine was, run it through a planer to smooth it out.
Gather enough planks to form a board that is a little thicker than your bars will be. I used 5-6 pieces about 1/2in thick to make a beam about 2.5in x 5 in. (we will rip this into two crossbars later)
Liberally glue the boards and clamp them together. This will essentially create a glue-lam beam that will form the bars.
Step 2: Rip, Mark and Plane
Rip the beam with a table saw into two smaller blanks. Make sure they are just a little bit bigger than your final bars will be. If they are too large you will have to plane off more material
Mark the ends in an aesthetically pleasing oval. This will be a guide when you shape the bars. Keep in mind that your racks will still need to be able to clamp to your bars. My bike rack could clamp onto thicker bars than my ski rack. Use the smallest as your guide; it would suck to find out you can't attach your rack after you are done.
Plane the bars into an oval shape.
Mark where the bars will cross the factory rails and with a chisel, notch the bars so they will fit snugly on the rails without rolling or sliding. My car had a little bump on the rail so I had to make a sort-of L-shaped notch in the bars.
Step 3: Laminate, Drill, Attach
Choose an epoxy with good UV resistance. Most epoxies will degrade in UV overtime so it is important to choose one that will last as long as possible. I like Resin Research epoxy. It has good UV resistance, a nice viscosity and has a good balance of strength vs. elasticity.
If you have a vacuum setup, laminate your bars and fiberglass in a vacuum bag. A vacuum bag will help push the composite into any nooks and crannies of the bars. If you don't have a vacuum bagging setup, you can lay up the bars by hand but you may have to do one side and then the other.
When the epoxy has cured cut away any extra fiberglass drill the holes for the u-bolts. Use the drill-fill-drill technique. That is- drill a large hole, fill it with epoxy, and then drill a smaller hole in the center of the epoxy fill. This will seal the wood and protect it from any water damage.
Give the bars a coat or two of varnish to add a final layer of UV protection and mount them to your car with the u-bolts. If the bolts stick up too far you can always cut them down with a hacksaw or sawsall.
Periodically check the tightness of the bolts (especially at first) to make sure none of them are coming loose.
After driving with them for a while, I can say that they are as quiet as the original bars and skis and bikes seem to be even more secure. I would have extended them farther beyond the end of the factory rails but I guess that will be part of V2.0