Noisy Homemade Pickup Rack

[andyfletcher]

I made my rack out of 1-1/4in square tubing for my truck this time and now I'm getting wind resonance. I made them out of round tubing on my other trucks I've owned with no problems.

I was thinking of wrapping the overhead cross members with thin ribbed vinyl tubing such as they use in swimming pool drain pipe, or filling the cavity with aerofoam spray can insulation, but not sure if it is dense enough to prevent resonance. Using mortar cement sand would be messy and impractical but that would work.

Next rack I'm making, I'm going back to round tubing.

Any help would be appreciated.

Thanks

Andy /forums/images/graemlins/frown.gif

 

[jimmysisson]

On our pickup racks most of the noise comes from the front crossbar. We experimented with welding a piece of 1½" angle iron on the front so that the V faces forward. That helped, but the best result was doing the same but welding it on the back of the front bar with the V facing rear. You can experiment on your own with a piece of wood taped on in various positions to try it out before welding. Or, as one of my guys did, leave his trial piece on for two years with duct tape.
I think it just breaks up the swirl of wind behind the bar. My round rack crossbars hummed too; mine's even curved forward in the middle of the bar; still hums > 70 mph.
The wedge only has to be 12-16" long to do the trick. Try it and let us know.
Jim

 

[andyfletcher]

Jim, Thanks for the tips. If the vinyl doesn't do it I'll rip up some 2 X4 and give it a try.

Andy

 

[Slamfire]

The Wright Brothers proved in their wind tunnel that round stock has more resistance than square stock with radiused corners. /forums/images/graemlins/wink.gif