All About Flashback

Alec R

Member
Sep 9, 2014
50
eLightbars
What is Flashback? How do I prevent it? 

Discuss!

Please keep it clean and organized, this forum section is heavily moderated to keep information organized. We're going to use content from these discussions to compile a helpful guide for users seeking information about products in this industry.
 

Alovebaby41

Member
May 23, 2010
354
Texas
Flashback occurs when lights placed inside of vehicle either are placed to far away from the glass or are not protected with a shield or housing. Thus creating room for the flashing light to reflect on glass and other interior parts. 

Flashback during the daytime can be ok, however during night time operation it can become very hazardous. Especially if the operator is attempting to drive emergent with flashback. 

Flashback can be eliminated or reduced by using vehicle specific interior lights and or lights with flashback shields. Such as the Whelen Inner Edge XLP are made to contour to the glass, producing no flashback. Another example would be the Whelen Avenger which comes with a flashback shield, but because it is not made specific to any vehicle, it will help to reduce flashback, but it will not eliminate it. 

Something else to keep in mind, I have found if lights are being placed behind tinted windows the flashback is greater than windows without tint. I am not sure if there is a direct correlation, just my experience. 
 

bpollard

Member
Jun 13, 2010
422
USA, SC
I would add that flashback is not only a nuisance and safety issue to the occupants inside, it is the result of some of the light output being kept inside the vehicle instead of projecting out.  This reduces the amount of visible light output from the exterior.

It seems to me that it varies from vehicle to vehicle.   I assume the angle of the glass and the amount of tint impacts this.

This is not something that you can stop, but I bring it up to keep in mind, that any interior light is going to appear brighter sitting on the shelf, or even outdoors sitting on the roof or hood, than it will when mounted behind the windshield. 
 

cabunty

Member
Sep 21, 2014
135
New England
i was wondering if people could share some of the solutions they have used to prevent flashback. i have the feniex apollo 2x and the flashback escaping from the sides is very bad. due to the contoured surface i am having a hard time coming up with a solution that works. i have put a piece of vacuum hose, split on one side, on the leading edge or windscreen side of the light which eliminated that problem. now i just need to come up for something for the sides.

any ideas?

apologies in advance if this is not the correct forum. 
 

Doug

Member
May 23, 2010
1,151
Maryland
I have found that flashback diminishes the closer the light head is to the windshield. I have a DashMiser 3 on the dash which is not more than a quarter inch from the windshield. Because of this, I have very minimal (if any) flashback.
 
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dovy6

Member
May 18, 2011
206
Brooklyn
Does anyone have any tips on creating custom flashback shields? Sometimes there is no choice but to mount a light with some space between the head and the glass. What could be done in this situation to help?

I have a PowerArc light that came with some cardboard you are supposed to cut into a shield. Let me tell you, if you've never tried, it's very difficult! 

Anyone have any ideas? I'm thinking maybe 1/8" or thinner sheet metal might work. Anyone else?

Thanks
 

Mattdecker

Member
Mar 16, 2013
1,172
Barren County, Kentucky
I have found that flashback diminishes the closer the light head is to the windshield. I have a DashMiser 3 on the dash which is not more than a quarter inch from the windshield. Because of this, I have very minimal (if any) flashback.
I have a dual Dashmiser in the windshield and it has flashback but nothing overly blinding or distracting to me.
 

rwo978

Member
May 21, 2010
5,196
ND, USA
Does anyone have any tips on creating custom flashback shields? Sometimes there is no choice but to mount a light with some space between the head and the glass. What could be done in this situation to help?

I have a PowerArc light that came with some cardboard you are supposed to cut into a shield. Let me tell you, if you've never tried, it's very difficult! 

Anyone have any ideas? I'm thinking maybe 1/8" or thinner sheet metal might work. Anyone else?

Thanks

ABS plastic can be bought in various sizes. I bought several black sheets a couple years ago that were intended for speaker boxes and had various sized markings on the back for speaker cutouts. However, they also had checkerboard squares for cutting. cut to size and use a torch to heat the ABS, then bend.... if needed. I've used them for several various needs.
 

rwo978

Member
May 21, 2010
5,196
ND, USA
yes
 

sheazle

Member
May 31, 2013
185
Missouri
I get the flashback shield as close to the window as possible, and then use a narrow strip of adhesive black vinyl to bridge the gap. I am not a fan of the rubber gaskets that ship with some lightbars as I have had trouble getting them to work reliably. This is especially true with "universal" interior lightbars.

I bought some black striping vinyl at the auto parts store and cut a strip about 3/4" wide. The only flashback I have now is due to the internal reflection of the windshield.
 
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2015-Impala

Member
Jun 4, 2015
206
NJ
1 solution from whelen that i gor from the tech about my avenger trio is hes had other complaints also since its a universal shield and plastic and windshields are different. He told me if enough called and expressed their concern about it they would make something fairly quickly for us so the problem can be resolved


Also the z style rubber stripping seems best suited for dash lights as it would mount under and have a slight curve against the windshield. Just search z style rubber and it should pop up.
 
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