How do you aim a newly installed headlight?

Dear Car Talk

Dear Car Talk | Jul 01, 1992

Dear Tom and Ray:

Recently I replaced a burned out low beam headlight, but could not find any information in either my owner's manual or on the headlight box about how to aim the new light properly. I remember years ago, the owner's manual in my old Beetle told you how to mark a spot on the garage wall at a certain height, and then back the car up a certain number of feet. You kept adjusting the headlight beam until it was on the spot marked on the wall. Unfortunately, I don't recall the distances. I'd appreciate any suggestions you may have about methods of aiming headlights since I don't want to annoy other drivers and I'd like to see where I'm going.

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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