Lightbar Mounting Question for Installers

Jman423

Administrator
Sep 10, 2010
3,391
United States
On a late model F-150 (09-11), there is a support that spans between the B-Posts, is it common to still mount the bar there and drill the cable through it? We have other trucks that have the bar mounted directly over the B-Posts, but mine was mounted pretty far forward of the B-Posts. Not only does it look "wrong", but I am having all kinds of wind noise that I've never had before. Recently, this same exact bar was on my earlier model F-150 (2008) for three years and I could hardly hear any noise.


I don't know if the mounting location has anything to do with the noise, but I can say that there is a TON of silicone sitting on top of the grommet. There is so much that it actually tapers just about all the way up to the bottom of the extrusion. With this much bulk added to the cable, I am wondering if that is where the excess wind noise is coming from. We aren't just talking about a little bit of noise that you would expect from a lightbar, this sounds almost like the window is cracked (wind is NOT coming in from the doors).


So anyway, I am trying to figure out what to do. The installer has claimed that nothing is wrong and there is nothing that can be done to correct the issues. I did check above the headliner and there is no wind (or water) coming through the cable entry point, which is what I originally thought the problem was.


Anyway, I would just like to hear from any installers that may have input on this.


Thanks
 
May 25, 2010
7,072
Tunkhannock, PA, USA
The only thing I can think of is the change in aerodynamics with the NBS trucks... It might be the way that the air comes off of the front edge of the hood and hits the top of the roof...
 
Last edited by a moderator:

k9cop116

Member
May 31, 2010
139
Southeast Texas
I mount all ours directly above the B-pillar....we run Freedoms, and I havent noticed any significant wind noise. My wires enter the cab just behind the lightbar....your bar sure seems to be mounted farther forward than any I've seen....
 

EVModules

Member
May 16, 2010
864
Deer Park, WA
That's a typical position for lightbars. This is highly favored because you want the alley lights directly over the operator's head.


I can't tell but does that lightbar have mounting channels underneath the bar? Code 3 bars had them and they make noise when the wind passes under the bar, hence the strips of plastic tubing fillers to negate that effect.
 

HILO

Member
May 20, 2010
2,781
Grand Prairie Texas
side2.JPG


Mine you, this is very rough, but you will get the idea. The green is a good air flow, passing over the bar if it was at the b-post. The red shows the stream dows not catch enough up draft to clear the bar at its present location. Instead of pushing the air over the bar, most of the stream it is hitting the front, and going into rotation, and then under the bar, producing lift, and forcing the air through the samll space between the roof and light bar. This causes your wind noise. I would say this also affects your fuel economy as well. At the b-post is the ideal place to mount anything across the roof as it is usually provides the highest arch of stream. An easy way to check your stream is to go to a hand car wash or other wise use a pressure washer, have someone hold the wand about 3/4 inches from the windshiled with the center of the spray aimed at the windshiled seal. The spary pattern should be verticle. You wil be able to see the mist flows over the roof line. This works best with the bar off the roof of course. Or find another vehicle that is a match for year, body, and external accessories. If re position is not an option, you could try a bug deflector which will push all the air running ove the hood/windshiled up about an inch and give you a different stream, and reduce wind noise.
 

Jman423

Administrator
Sep 10, 2010
3,391
United States
HILO said:
View attachment 18418

Mine you, this is very rough, but you will get the idea. The green is a good air flow, passing over the bar if it was at the b-post. The red shows the stream dows not catch enough up draft to clear the bar at its present location. Instead of pushing the air over the bar, most of the stream it is hitting the front, and going into rotation, and then under the bar, producing lift, and forcing the air through the samll space between the roof and light bar. This causes your wind noise. I would say this also affects your fuel economy as well. At the b-post is the ideal place to mount anything across the roof as it is usually provides the highest arch of stream. An easy way to check your stream is to go to a hand car wash or other wise use a pressure washer, have someone hold the wand about 3/4 inches from the windshiled with the center of the spray aimed at the windshiled seal. The spary pattern should be verticle. You wil be able to see the mist flows over the roof line. This works best with the bar off the roof of course. Or find another vehicle that is a match for year, body, and external accessories. If re position is not an option, you could try a bug deflector which will push all the air running ove the hood/windshiled up about an inch and give you a different stream, and reduce wind noise.

Well, thank you for that fine forensic explanation. It makes sense... my co-worker has the same truck with the same lightbar and he doesn't have this problem. My only other concern would be drilling through that cross-member to get he cable to enter the cabin when the bar is moved to over the B-Posts, which I will probably do myself. I'm assuming that's how it was done in his truck.
 

k9cop116

Member
May 31, 2010
139
Southeast Texas
Jman423 said:
Well, thank you for that fine forensic explanation. It makes sense... my co-worker has the same truck with the same lightbar and he doesn't have this problem. My only other concern would be drilling through that cross-member to get he cable to enter the cabin when the bar is moved to over the B-Posts, which I will probably do myself. I'm assuming that's how it was done in his truck.



Unless you are just looking for an uber-clean install....just make the hole for the wires just behind the bar....you wont have to punch thru the support, and you can seal the hole using much less sealer. If you want...I'll take a pic of how I did mine and post it later tonight when I get to work........tp
 

Jman423

Administrator
Sep 10, 2010
3,391
United States
k9cop116 said:
Unless you are just looking for an uber-clean install....just make the hole for the wires just behind the bar....you wont have to punch thru the support, and you can seal the hole using much less sealer. If you want...I'll take a pic of how I did mine and post it later tonight when I get to work........tp

As long as the cable isn't out from under the bar, I don't really care.


Pictures would be appreciated though. I'll probably tackle this sometime this week.
 

k9cop116

Member
May 31, 2010
139
Southeast Texas

Jman423

Administrator
Sep 10, 2010
3,391
United States
Well, problem solved... I think. I moved the bar, but I haven't had a chance to drive it to see if the wind noise has subsided. I still have to do some more work to it tomorrow before I can drive it, but relocating the bar went pretty smoothly. I did discover that the installer had the lightbar cable routed with the side curtain airbags in the A-Post, I am sure that would not have ended well if there was a deployment. Oh, and the bar was held on with one screw on each gutter strap... :rolleyes:


bar_moved.jpg
 
May 25, 2010
7,072
Tunkhannock, PA, USA
Holy Hell!!! 1 screw per side!!! Thats nuts... And the running of the cable along the side curtain air bag is just laziness and dangerous to boot... Glad you're fixing it Jim...
 

EVModules

Member
May 16, 2010
864
Deer Park, WA
It goes to prove that there is such thing as life & death when choosing your installer. A few bucks saved is NOT worth your life or another!


I'd have dragged that installer out of his hole and pointed it out! He/she has no place in the installation business.
 

Jman423

Administrator
Sep 10, 2010
3,391
United States
Well, the way I see it... If they did it wrong the first time, what says that won't do it wrong again, or do something else wrong. With all of the things that I found, I'd rather just do it myself so I know it was done right. It was inconvenient, but while I had the headliner down to move the lightbar, I was able to move the dashlight dead-center where it belonged, allowing me to adjust my mirror. So it all worked out.


And, HILO was correct with his diagram, as soon as I got on the road this morning, I noticed the wind noise that was bothering me was completely gone. There is still the typical wind noise which I expect, but the wind that was rushing around under the bar was gone. It sounds exactly the same as it did on my old truck. So this was a good experiment to prove that mounting a bar too far forward will cause a lot more wind noise, and probably less fuel efficiency, than if the bar was mounted properly. I would guess that most of the people that have SUV's with a roof rack that prevented them from properly mounting a bar are experiencing lots of noise that would likely be cut down considerably if the roof rails were removed and the bar was mounted over the B-Posts.
 

HILO

Member
May 20, 2010
2,781
Grand Prairie Texas
I used to have a Chevy Venture van with a Streethawk all light mounted past the b-post, no wind noise, and no real noticable drag. I switched to an edge, mounted abit closer to the b-post again with no problems. When I swtiched from a Vista to a MX7000 on my 2000 Explorer, mounted at the same place right at the b-post, I could tell the difference as soon as I got over 50! Lost the wind noise and the truck handled better. Glad it worked out for you!
 

medic75

New Member
Mar 30, 2014
8
NW Pennsylvania
I realize I am posting in a thread that has been dead for a few years, but I didn't want to start a new discussion when this has already been covered.


This truck was delivered late last summer. Up until last month the truck never left the city. Now, I am driving all over Pennsylvania. It took me about 10 seconds of highway driving to realize that the wind noise is more than I have ever heard in other vehicles (Tahoes and Explorers) with larger MX-7000 light bars at similar speeds. The wind noise is so bad that, after a 4-5 hour trip, I feel like I may have damaged my hearing.


Do you think that this problem could be solved by simply moving the light bar back to the B-post? The light bar is a Whelen Justice, which I thought would be quiet because of it's low profile.


ai891.photobucket.com_albums_ac119_mscffp_2013_08_26_16_55_40_660.jpg
 

eckart59-23

New Member
Sep 6, 2018
1
Cleveland, OH
I think this thread is dead, but I am having a similar issue on a 2018 RAM 2500 with a Whelen Liberty DUO. I have moved it to about an inch or two behind the B pillar to 3-4 inches behind the B pillar and both are bad, especially with two plus hours of highway driving each day it gets annoying.
 

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