How do you aim a newly installed headlight?

Dear Car Talk | Jul 01, 1992
Dear Tom and Ray:
Mary
TOM: Well Mary, you don't need to readjust the headlights just because you changed the bulb. There are two different sets of screws in the headlight assembly. One holds the bulb in place, and another completely independent set aims the light. So if you did the job right, the aim should be exactly where it was before.
RAY: But unfortunately, most people don't do the job right. Most people just start turning screws til they find the right ones...the ones that holds the headlight in place. And by that time, they usually have the beam pointing at their neighbor's bedroom window (come to think of it, maybe they do this intentionally).
TOM: So my guess is that you DO need to have the aim adjusted, Mary. And there are two ways to do it. The best way is to just take the car to a garage that has a grid for adjusting headlights. It'll take a mechanic all of three minutes to set them correctly, and he'd be hard pressed to charge you more than five bucks to do it.
RAY: Or, you could use my brother's method. After he changes a bulb, he purposely sets it way too high. Then he goes out driving at night, and over a period of a couple of weeks, he gradually adjusts the beam downward...til the hand signals and gestures of oncoming motorists subside. Then he knows it's pretty close.
Mary
TOM: Well Mary, you don't need to readjust the headlights just because you changed the bulb. There are two different sets of screws in the headlight assembly. One holds the bulb in place, and another completely independent set aims the light. So if you did the job right, the aim should be exactly where it was before.
RAY: But unfortunately, most people don't do the job right. Most people just start turning screws til they find the right ones...the ones that holds the headlight in place. And by that time, they usually have the beam pointing at their neighbor's bedroom window (come to think of it, maybe they do this intentionally).
TOM: So my guess is that you DO need to have the aim adjusted, Mary. And there are two ways to do it. The best way is to just take the car to a garage that has a grid for adjusting headlights. It'll take a mechanic all of three minutes to set them correctly, and he'd be hard pressed to charge you more than five bucks to do it.
RAY: Or, you could use my brother's method. After he changes a bulb, he purposely sets it way too high. Then he goes out driving at night, and over a period of a couple of weeks, he gradually adjusts the beam downward...til the hand signals and gestures of oncoming motorists subside. Then he knows it's pretty close.
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