Truck rack " whistle " Advice needed

[scott-n-montana]

I'll try and make this simple. The crossbar that goes over the top of the cab makes a whistling sound when you hit about 45 mph. I figured it would because it had happened to me years ago using a round bar. On my last truck I had the bar out in front of the cab. Now that I have a 4 door though I don't want to extend the rack out that far. There are 2 bars over the cab and the front one is a little higher off the cab than the 2nd one. I have the rack down at the powdercoaters now, but would go down there and cut off the 2nd bar if I knew it would stop the noise. Also the top part of the rack is only bolted on to the bottom part so most of the time I will not even have the extension on. Does anyone have any info on this and how far the bar would need to be above the cab to stop the noise. Thanks to any advise. Scott

[jonsam]

Are there any holes in the structure? If I'm imagining the "whistling" sound right a hole in one of the tubes with air flowing over it could act just like a flute.

[trevwelder]

Mine did the same thing, I ended up raising the racks from about one inch from the top of the cab to 5'' inches. The whistle stopped. I liked the looks of it lower but the whistle drove me nuts. Good luck.

[tnjind]

I couldn't tell from the pics, but if there are open ends on the tubing it may cause it. You probably already checked but thought I might suggest it anyway.

[SignWave]

Just for sh ts and giggles, Try taping up some of the areas that have holes. By that I mean the down tubes that are at mid box. Wherever the wind can swirl around will cause noise. The noise is caused by the air accelerating to a high speed and then creating a shock wave. I cant really explain the physics all that well but
I know some good spots to check. Have a look at your doctored photo ive attached. by using tape you should be able to eliminate possible locations that are causing you the grief. you could have someone ride in the back.....

to solve the troble without making you r rack look like hel... try adding spoilers to the problem areas once you fint the culprit. I suspect that a stirp of aluminum tacked in place will stop you whistle. you shouldnt need more than a 3/8x 3x 0.125 peice... again make a spoiler from some tape first and "tune it" until you find waht works. Good luck

[scott-n-montana]

There are no holes on the tubes. It has to do with the wind going over the top of the cab.

[tasslehawf]

It looks like all the tubing is capped.

I would second the idea of raising the rack. I could never figure out why racks are always so much higher than the roof of the cab; I guess that's why.

[SignWave]

Im willing to bet that if you add a spoiler.... it'll go away...

[84ZMike]

Rotate the front tube to make it look like this <> not like this []. If it still whistles you will need a "deflector"

[tasslehawf]

Rotate the front tube to make it look like this <> not like this []. If it still whistles you will need a "deflector"

Tack a piece of angle iron onto the front tube like this: []>