Batboard

Guys,

I'm wondering if any of you have experience stopping the horrible whistle that occurs on an MX7000 lightbar once you reach speeds of 60-65mph or so? On our search team, we have a couple of vehicles equipped with these lightbars and when you're going down the highway it's almost like clockwork that once you hit 65mph, the thing lets out the most annoying whilstle imaginable. It's REALLY loud and we have tried FOREVER to stop it with no luck. Any experience in this area would be very much appreciated.

Jack
http://www.nccert.org

Are they all light models or do they have the speaker housing?

They are the "all light" models. I've attached a picture of the truck so you can see....

Good luck finding the problem and correcting it. The whistle could be from the lightbar itself such as a small gap in the domes or something similar.

I tend to think this is more of a disruption of air flow issue since you have a cap on the truck as well. Short of putting it in a wind tunnel and running smoke over it I doubt you'll track the problem down.

I have that same bar, and never had a whistle- make sure the gap between each lens section is minimal, and that they are all screwed down tight. It looks like all the clips are on there on the front, which was my other thought... Worst case, try putting packaging tape around the seams between each section of lens on the front side and see if it still does it, then you'll know if t's coming from there.

Just a side thought, is the window on the front of the truck cap closed all the way?

Thanks for the suggestions. I haven't tried the tape as you mentioned. I think one of our folks may have tried it a little bit but I will do it again just to make sure. The cap window is shut tight as well as the back window on the truck. We have to take off the cap here in and there to pull trailers or put equipment in the back. It still whistles without the cap. I was almost thinking it could have been one of the orange marker lamps on the roof as well. The other trucks don't make this noise as far as I know.

I'm thinking that lip mount....or can u say for sure it's right above you??

also keep in mind, that those "grommets" that they install for the lightbar wiring, are sometimes hard plastic, and not rubber, and are NOT sealed properly, creating a concave area... try dabbing some silicone where the lightbar cable enters the roof... IF thats the problem...

We had 6 Federal Signal Vista bars do the samething, we found it was a little piece of styrofoam on the mounting strap to protect the cars paint, replaced it with a little rubber and it was fine

Did you put the plastic tubing in the channels for the mounting bolts on the lightbar? I haven't used an MX7000 in years but they used to come with the tubing that you cut to length after you tightened up the feet on the bar. They will whistle if you don't put it in there.

I'm not sure about the tubing. none of us mounted the lightbar as the vehicle has been with the team for a number of years. I have just gotten sick of the noise and decided I would ask about it. I'm wondering if it's possible to get this tubing from the manufacturer as a single part?

It's the tubing, you can buy it at any hardware store, just clear platisc tubing, like you would use on a fish tank. I believe it is either 3/16 or 1/4 OD.

SG

I've heard the same whistle before...

1998ish Expedition. MX7000 lightbar.

Comes in around 65-75mph... disappears around 75... comes back at 100 I think.

I haven't bothered to look at fixing it since I don't drive the vehicle all that often - and everyone kinda laughs at it because it's used as a pretty reliable speed indicator.

-Alex

1998ish Expedition. MX7000 lightbar.

Comes in around 65-75mph... disappears around 75... comes back at 100 I think.

having fun alex??

wouldn't want to push a 98 Expo that high anyway! i like having all four on the ground.

i have to agree with 2-way Guy, we had one doing the same thing and the Tubing was the problem, person installing the lightbar didn't know what the tubing was for and threw it away. After installing tubing in Mounting track, the whistle almost disappeared. I'd check to see if that is your problem.


Mikey

You can contact CODE 3 with your complaint and they will send you out the wind kit for free.

One of the first responders over here in Canada has a lightbar like that on their truck. They get the same annoying whistle at those speeds you are, The company that installed it said its where on the roof it is mounted; wind is getting compressed betwen the bottom of the lightbar and the top of the roof, causing the whistle. They moved the lightbar back about 8 inches and the whistle disappeared. I didn't know there was a kit to prevent this, I'll pass that info on.

Thanks for the tips guys. I will let you know what works.

HAD THE SAME PROBLEM ON A 97 EXPEDITION, WE SHIMMED UP THE FRONT OF THE BAR ABOUT 1/8 INCH AND IT WENT AWAY

[quote="tiawah466"]HAD THE SAME PROBLEM ON A 97 EXPEDITION, WE SHIMMED UP THE FRONT OF THE BAR ABOUT 1/8 INCH AND IT WENT AWAY[/quote]

Had same problem on a 99 F-150, and same solution.

When you mean shimmed up, you raised the whole bar up?

Frank

On my truck, I used 2 thick plastic washers to raise the front half of the bar up.

THAT IS WHAT WE USED ALSO.