Driving vs. Fog Lamps

[AdamsCherokee]

I'm really having trouble grasping the difference between driving and fog lamps.

Basically, I'm in need of replacing the lights on my cherokee's brush guard, and I'd like to put some up on the roof rack.

I'm pretty sure that driving lamps are a longer more focused beam, whereas fog lamps provide a less focused beam of the general area.

I was wondering which was which though. I have a set of lights that were on my jeep's brushguard/bumper when I bought it that are basically crap. They're basically just $20 round lights from walmart... (I've actually gone and priced them for $23) Would I want foglamps or driving lamps.

What about up on the roofrack, are those driving lamps or fog lamps. Or does it really matter?

[madrabbitt]

up top, driving.
down below, probably driving, unless you NEED a fog pattern.

Lets steal some images from hella's site, ok?
This is a fog pattern from the FF75 lamp.

Note the short wide coverage.

Now this is a driving beam patter, same series of lamp.

See how its longer and narrower?

You want those types of lights up top.
As for bottom, it depends on the type of usage you have.

I installed Hella 500 series on my grille, and FF50's under the bumper.
You can see pictures of them on and their patterns at www.madrabbitt.com/jeep/freeform50.htm

hope this helps.

[jfw432]

Stick with fog lights unless you like driving 100 mph at midnight on back roads. I have the 20/20 lights that have driving and fog lights in them. Same 55 watt Hella bulb with a different lens on each side. I can't even tell when the driving lights are on. My high beams from the cheap cherokee headlights are better than the driving lights. Fog lights do make a huge difference though. Shoot out farther than my low beams and light up everything else around me.

[bmartini]

Originally Posted by jfw432

Stick with fog lights unless you like driving 100 mph at midnight on back roads. I have the 20/20 lights that have driving and fog lights in them. Same 55 watt Hella bulb with a different lens on each side. I can't even tell when the driving lights are on. My high beams from the cheap cherokee headlights are better than the driving lights. Fog lights do make a huge difference though. Shoot out farther than my low beams and light up everything else around me.

any possiblilty that you wired these lights backwards? because they are supposed to work in the oppostie way...just a thought...

[madrabbitt]

Originally Posted by jfw432

Stick with fog lights unless you like driving 100 mph at midnight on back roads. I have the 20/20 lights that have driving and fog lights in them. Same 55 watt Hella bulb with a different lens on each side. I can't even tell when the driving lights are on. My high beams from the cheap cherokee headlights are better than the driving lights. Fog lights do make a huge difference though. Shoot out farther than my low beams and light up everything else around me.

Chances are you dont have them aimed properly.
This is what a properly aimed driving light should look like.
(btw, the wall is 100 feet away)

[madrabbitt]

Comparitivly speaking, this is the low beams alone, same spot.

[KB8UDE]

Originally Posted by AdamsCherokee

I'm really having trouble grasping the difference between driving and fog lamps.

Basically, I'm in need of replacing the lights on my cherokee's brush guard, and I'd like to put some up on the roof rack.

I'm pretty sure that driving lamps are a longer more focused beam, whereas fog lamps provide a less focused beam of the general area.

I was wondering which was which though. I have a set of lights that were on my jeep's brushguard/bumper when I bought it that are basically crap. They're basically just $20 round lights from walmart... (I've actually gone and priced them for $23) Would I want foglamps or driving lamps.

What about up on the roofrack, are those driving lamps or fog lamps. Or does it really matter?

Besides the beam pattern which has been correctly shown already, I think that true fog lamps are also amber in color. The amber light has less reflection off of rain, snow, and fog than a white light does. For example, the exact reason that you don't run your high beams in bad weather...it's harder too see with all the light bouncing back at you.

I think that depending on which state you are in you can actually turn off your headlights and just run marker lights and fog lights in bad weather.

I have a set of KC lights to wire up that came with amber lenses that I can snap on or leave off depending on what I need. I'm not sure how well that will work but i'll find out soon.

[madrabbitt]

Its more of the beam pattern then the color.
Amber cuts thru wet fog well, but the problem with amber is you lose alot of light intensity the closer you get to red on the spectrum. Deep ambers will probably reduce the usable light by about 25%.

Blue actually cuts thru drier fog and smoke well, but in most states, you cant exactly run blue on the front of a vehicle.

The crystal ion amber actually gives you a nice bright amber color without losing too much light intesity. I've seen some nice PIAA ones that put out a good color. I'm also fond of the hellas that have the slightly amber tinted lenses.

[denverd0n]

Fog lights throw a wide beam, close to the ground, with a sharp cutoff at the top so that they won't reflect off the fog and reduce the drivers visibility. Driving lights throw a narrower beam further down the road and without the sharp cutoff.

As for the amber color, it can help, but the problem is that a lot of cheap companies will take any old lens, tint it amber, and then call it a "fog light." If the lens isn't designed to throw a low, wide beam with a sharp cutoff, though, it will be lousy in the fog and the amber tint won't help. So, if you're going to get amber tinted fog lights make sure they come from one of the top-quality companies like Hella, Cibie, or the like.

[jfw432]

Well the lights say top on them so I'm assuming that they're mounted properly. The fog lights are aimed slightly below my headlights and the driving lights are just a little higher.

[madrabbitt]

They arent mounted correct.
Driving lights should be mounted so the middle of the beam is just below the headlights at 100 feet or so