Head light adjustment - The 1947 - Present Chevrolet & GMC Truck Message Board Network

grs · 11-07-2011, 12:14 PM

How far back from a wall should the truck be to adjust the head lights? And how high up from the floor should the light shine on low beam. And should the lights go to the left, and right a little? That is how we adjusted them when I was a VW mechanic.

piecesparts · 11-07-2011, 02:59 PM

Unless you are really anal about using the wall as a source for headlight adjustment, my suggestion is to take the truck to a dry gravel road or chip seal. You want the light reflection back to you from the lighter colored rock in the road. I adjust my lights to where I think that I would like to have them and then turn them down a 1/2 turn. I use this as my way of lighting deer at night. THis will usually put your low beams at the license plate level on a car in front of you when you drive two to three car lengths behind them. You want to be able to light the white line on the passenger side of the road, so a slight angle to the right for the RH headlight works. I have mine more to the center of the driving lane, for my comfort. I don't get flashed for being out of adjustment, so my judgment apparently is working to everyone else's taste.

njlimbaugh · 11-07-2011, 04:15 PM

Usually park the car about 20 feet from the wall. Measure the height of the headlight bulb center from the floor and the distance between bulb centers. Mark the center of the bulbs on the wall, same height and distance apart. Put beams on "HI" and adjust the bulbs so the 'hot spot' centers on the wall markings. The low beams will automatically be where they should be.

TheApocalyptican · 11-07-2011, 05:11 PM

When I do mine, I get the lights pretty much level horizontally and vertically, and pull up to a wall, and put a + on the wall with tape that is at the center of the hotspot of the light. Then back up to 25ft, and get the vertical line matched up perfectly, and then get the horizontal one so that the hotspot is 2 inches below the center of the tape. Since I have dual headlights, and run a hi/lo in one, and a hi only in the other, I do the 2 inch drop with the hi/lo, and I do only like a half inch drop with the hi beam.

The "accepted" practice is 2 to 2.5 inches drop at 25ft. Some in bigger trucks aim them down more to be nice to other drivers, but, that's just personal preference.

grs · 11-07-2011, 06:11 PM

Thanks men. I want to adjust it correctly so I don't blind the on coming drivers. And I want to do it right the first time.

11-07-2011, 12:14 PM	#1
grs Registered User Join Date: Jan 2010 Location: Roanoke, Tx. Posts: 1,561	Head light adjustment How far back from a wall should the truck be to adjust the head lights? And how high up from the floor should the light shine on low beam. And should the lights go to the left, and right a little? That is how we adjusted them when I was a VW mechanic.

11-07-2011, 02:59 PM	#2
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: Head light adjustment Unless you are really anal about using the wall as a source for headlight adjustment, my suggestion is to take the truck to a dry gravel road or chip seal. You want the light reflection back to you from the lighter colored rock in the road. I adjust my lights to where I think that I would like to have them and then turn them down a 1/2 turn. I use this as my way of lighting deer at night. THis will usually put your low beams at the license plate level on a car in front of you when you drive two to three car lengths behind them. You want to be able to light the white line on the passenger side of the road, so a slight angle to the right for the RH headlight works. I have mine more to the center of the driving lane, for my comfort. I don't get flashed for being out of adjustment, so my judgment apparently is working to everyone else's taste. __________________ Frank

11-07-2011, 04:15 PM	#3
njlimbaugh Registered User Join Date: Jun 2011 Location: LaFayette GA Posts: 111	Re: Head light adjustment Usually park the car about 20 feet from the wall. Measure the height of the headlight bulb center from the floor and the distance between bulb centers. Mark the center of the bulbs on the wall, same height and distance apart. Put beams on "HI" and adjust the bulbs so the 'hot spot' centers on the wall markings. The low beams will automatically be where they should be.

11-07-2011, 05:11 PM	#4
TheApocalyptican Registered User Join Date: Jun 2010 Location: Las Vegas, Nv Posts: 312	Re: Head light adjustment When I do mine, I get the lights pretty much level horizontally and vertically, and pull up to a wall, and put a + on the wall with tape that is at the center of the hotspot of the light. Then back up to 25ft, and get the vertical line matched up perfectly, and then get the horizontal one so that the hotspot is 2 inches below the center of the tape. Since I have dual headlights, and run a hi/lo in one, and a hi only in the other, I do the 2 inch drop with the hi/lo, and I do only like a half inch drop with the hi beam. The "accepted" practice is 2 to 2.5 inches drop at 25ft. Some in bigger trucks aim them down more to be nice to other drivers, but, that's just personal preference. __________________ 1995 Suburban K2500 454.....off road & towing 1999 Astro, work van 2006 Silverado 2wd 5.3 w/4.5" lift and 33s Last edited by TheApocalyptican; 11-07-2011 at 05:17 PM.

11-07-2011, 06:11 PM	#5
grs Registered User Join Date: Jan 2010 Location: Roanoke, Tx. Posts: 1,561	Re: Head light adjustment Thanks men. I want to adjust it correctly so I don't blind the on coming drivers. And I want to do it right the first time.

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