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  1. #1

    Default Truck rack " whistle " Advice needed

    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
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  2. #2
    Join Date
    Feb 2008
    Location
    Seattle, WA
    Posts
    22

    Default

    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.

  3. #3
    Join Date
    Nov 2005
    Location
    Buhl, Idaho
    Posts
    53

    Default

    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.

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  4. #4
    Join Date
    Oct 2007
    Location
    Indiana
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    541

    Default

    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.
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  5. #5
    Join Date
    Aug 2007
    Location
    Vancouver BC Canada
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    605

    Default experiment a bit

    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
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  6. #6

    Default no holes

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

  7. #7
    Join Date
    Dec 2007
    Location
    Austin, TX
    Posts
    621

    Default

    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.
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  8. #8
    Join Date
    Aug 2007
    Location
    Vancouver BC Canada
    Posts
    605

    Default try to experiment first

    Im willing to bet that if you add a spoiler.... it'll go away...
    Will it weld? I loooove electricity!

    Miller 251/30A spool
    Syncro200
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    O/A
    Precix 5x10 CNC Router12"Z
    Standard modern lathe
    Cheap Chinese mill that does the trick... sort of...
    horizontal 7x12 bandsaw
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    54" laminator
    hammer and screwdriver (most used)
    little dog
    pooper scooper (2nd most used...)

  9. #9
    Join Date
    Aug 2006
    Location
    N.C.
    Posts
    362

    Default

    Rotate the front tube to make it look like this <> not like this []. If it still whistles you will need a "deflector"
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  10. #10
    Join Date
    Dec 2007
    Location
    Austin, TX
    Posts
    621

    Default

    Quote Originally Posted by 84ZMike View Post
    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: []>
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