Anytime you install any aftermarket product on the exterior of your vehicle you are changing the aerodynamic flow of air around the design of your vehicle. This is not limited to just the installation of racks but any product like window visors, roll bars, brush guards, etc. The following paragraphs give you some helpful tips on what to do if you experience any excessive wind noise or whistle after installing A truck rack or van rack.
Note: FORD SUPER DUTY TRUCKS:
We recommend a 32" leg (Model 81432 & 81452) for use on these model trucks
Here are some quick tips to try if you are experiencing noise such as whistling from your rack.
Reread through the installation instructions enclosed in your parts bag. Be sure to check to make sure all hardware is fastened securely. Periodically check to make sure all hardware is securely fastened and rack is in good repair.
After you have properly installed the rack and all the mounting hardware is tight, be sure to seal all areas where tubes telescope. This will not only prolong the life of your rack by disallowing moisture to enter inside the cross bars (especially on steel models), it will also block wind, reducing whistling and keeping everything tight and secure.
Nine times out of ten, simply moving the front cross bar forward or backward a few inches will dramatically effect any noise. If the front cross bar is in direct flow of air coming off the windshield, move the front bar out of "the line of fire".