Sponsored by HUMAN Speakers Headlight aiming

(courtesy Lee Levitt, 10/5/94)


Actual aiming instructions.

[Ed. note: All my comments are set off with square brackets just like this one- Huw]

General (European) Lighting Information

Since I'm a confirmed quartz halogen junkie, I've been asked to discuss the specifics of European headlamp aiming. It is an art rather than a science, but anyone can do it with a flat parking lot, a little time on their hands and some darkness. True European headlamps (H4, H1, etc.) typically do not have the appropriate mounting points for American headlamp aiming machines so they must be aimed by hand.

H1, H2, H3, H4 all refer to a specific style of bulb. They are quite different and not interchangeable. The H4 is the only style that has a dual filament.

The lens and reflector may be unique to a specific style of car - 1994 Volvo 850, for instance. Or it may be a common shape, 7 inch round or quad rectangular... Most systems sold in the US are sealed, that is the lens, reflector and bulb are a single integrated unit, just like a 70 watt lightbulb for your reading lamp.

Others have replaceable bulbs, like your Bosch or Hella fog lights and virtually all European headlamp systems. The rational behind this is that the lens and reflector don't wear nearly as quickly as the bulb, so the high quality optical lens/reflector is reusable [while] the cheap part (the bulb), which wears out, is replaceable. In addition, this allows manufacturers to design aerodynamic lenses if desired (early Saab 9000, Audi 5000, Porsche 911, etc.)

Most of these cars have different headlamp configurations in the US and Europe (older Saab 900, Audi 4000) although some manufacturers are trying to standardize (late Saab 9000, Land Rover Discovery, BMW), which may mean that European lighting is getting poorer or US lighting is getting better. ... By the way, I believe that most of Canada now follows the more restrictive US lighting codes.

Usually lamp assemblies are referred to by their style - Volvo 240 aero, or Volvo 240 quad rectangular, not H4. In fact the quad rectangular takes two different bulbs, the H4 for the outboard combo lo/hi and H1 (if memory serves) for the inboard high beam. [this is correct]

But the quad rectangular (lo/hi) or 7 inch round could either be US sealed beam or European lamps, which would take H4 bulbs. So some people may say 7 inch round H4, meaning 7 inch round Euro...

Bulb Availability

I buy my bulbs from Imparts. They seem to offer the best prices on bulbs at about $11 or so per high powered bulb 90/100 or 100/130. They also have high powered 9004s, for late model Saabs, Volvos, and a variety of other cars and trucks. You can reach them at 800 325-9043.

I've run 80/100s in H4 quad setups on an '82 Volvo 244T. No problem with wiring or blinding people. OTOH, I have fried several wiring connectors on my wife's Saab 9000 with 70/80 and 80/100 watt bulbs, but it uses a 9004 bulb with a very poorly designed connector. I recently upgraded the connectors with new heavy-duty ones from Competition Limited. These use a much more robust female connector. Haven't had any problems since.

I'm currently (ahem) running 90/100s in my '88 Volvo 745T and have used these wattage bulbs since the car was new. I run my headlights day and night and typically get about a year! out of a bulb. I've got a set of 100/130s in the toolkit just waiting to be installed when the last of the 90/100s goes.

Aiming Instructions

Proper aiming of the lamps will help keep you from blinding people, but the fact is that in some circumstances, coming over the crest of a hill for instance, the concentrated light from the H4 will bother people no matter whether you've got 55 watts or 130. Passing can also be a problem. Don't linger behind someone as you're passing them. The "hot spot" of your beam pattern shines right on their mirrors and into their eyes. Makes them rather cranky. If you see your beam pattern heading toward their mirror, just pick up the pace a bit. By the way, trucks can be particularly sensitive to this and may take countermeasures you won't like. So be careful when passing.

Low Beam Aiming

Aiming is straightforward. [oh, you're so funny, Lee - Huw] First, find a completely level area that borders a wall. Drive right up to the wall and mark a spot on the wall directly opposite the center of each lowbeam. Then back up about 10 feet. You want the hot spot to hit just below and to the right of that mark, about 3 inches down and to the right. [I would say more like one inch for a one degree drop - I run two degrees on my car, and that's a bit on the low side - Huw]

Here's what the pattern will look like:
[I created this diagram to replace the incredible ASCII art in the original document - Huw]

H4 Headlight Cut Off Pattern
The X is your mark. The hot spot is where the diagonal and horizontal lines meet. This will ensure that as traffic approaches, the hot spot won't be pointing up into their eyes.

I've been asked why I run such high-powered lights on my cars. Personally, I think that most people vastly overdrive their lowbeams in anything but ideal conditions. So I like that extra margin of the additional light on the road.

Aiming High Beams

The procedure for aiming high beams is a little different than that for aiming low beams. The goal of aiming low beams is to ensure that the hot spot stays on the road in front of you and away from oncoming drivers, that's why you want the hot spot to gradually drop off the further away you get, with the top of the hot spot falling onto the road some 50 or 100 feet away from the car and to the right.

With high beams you don't care about oncoming traffic, unless of course you're trying to fry retinas. Instead you care about maximum beam dispersion. So you trust the lamp designer to provide a good pattern with good light control and dispersion and simply aim them directly ahead or perhaps angled outward just slightly. It's a little difficult to do this using the low beam aiming technique because of the size of the high beam hot spot, but a modified version works.

By the way, you do not need to re-aim the high beams of an H4 (single reflector) setup. Once the low beams have been aimed, the high beams are also properly set. The dual filament bulb casts low and high beams onto different portions of the lens, providing discrete beam patterns for each setting.

Keep in mind that a quad setup has 4 lamps firing on high beam, since the low beams have a secondary pattern on high. Don't re-aim the outer lamps for their high beam pattern. In fact whil you're aiming the high beams, it is probably wise to unplug the low beams and deal only with the inner lamps.

For the high beams, move right up to the wall described earlier. Make sure you're on absolutely level ground or the aiming will be thrown off. Mark an X directly opposite the center of each high beam. Now very slowly back away from the wall, taking care not to pitch the car with acceleration or to run into anything behind you...

The high beam hot spot should grow around that X, but not move away from being centered on it. If anything, it should come up just slightly. Readjust as necessary.

Fog lights

Contrary to popular opinion, fog lamps are not designed to be aimed directly at the ground for maximum illumination or directly up into the air to illuminate low-flying aircraft. Fog lamps have a broad flat beam pattern with a sharp cutoff.

They should be aimed directly ahead for maximum coverage, with a 5 degree or so downward slope to the beam pattern. For best road coverage they should be mounted below the bumper...for maximum protection they should be above the bumper...you choose. Aiming methodology is similar to that for low beams.

On older lights I've had snow and ice create a thermal inversion that's cracked the lens. Hasn't happened recently though to either Bosch fogs on my Volvo or Hella fogs on the Saab (both factory supplied), but you should clear them of all snow and ice before you turn them on. And don't use snow to clean a lamp that's hot (learned that the hard way!)

Other Auxiliary Lamps If you're adding driving or pencil beams, you know what you're doing. [Then why do most owner added, and even factory, auxiliary lights seem to be so poorly set up? Maybe because people drive with them on in traffic! - Huw]

Checking Patterns

Once all of your lights are properly aimed, you can run a couple of simple tests to verify. First, find a *very* level road. Turn your low beams on and walk about 75 feet away from the car. If you bend down, the hot spot of the light should strongly intensify as your head gets closer to the ground. The lamps should look lit but not blindingly so from normal height. Once you get to about a foot from the ground you should see the hot spot.

You should also be able to see the beam cutoff on cars in front of you. As you move further away from the car in front of you, the cutoff should drop slightly. On level ground it should not be above taillight or trunk level.

Aiming Mechanics

There are two adjustments on each headlamp, one dictating left/right aiming, the other controlling up/down. These are little knurled knobs or similar, usually accessible from behind the lamp. These adjust how the entire lamp assembly is pointed in the assembly mounting structure, not the position of the bulb within the reflector, which is fixed.

In addition, when you replace a bulb in a European style lamp (H4, etc.), you do not need to re-aim the lamp. In fact, when you replace a sealed beam unit, you should not have to re-aim that lamp either. (BTW, I had a set of Euro lamps that did have two separate bulbs in one housing with an adjustable high beam reflector, but that's a different story...)

American specification [DOT] lights all have fittings for a headlight aiming machine which aim them using bubble scopes rather than beam pattern. Some European lamps also have this fitting, but I'd trust my 15 years of aiming these things over a machine which would not be designed for European beam patterns. (Unless of course your parts place which sold you the lights does have a Euro lamp machine. I think the Tire Buying Place in Elmsford NY did at one point.)

Also, by the way, if you are changing bulbs, make sure you don't touch the bulb portion of a headlight bulb with your finger. The grease from your finger on the glass of the bulb will cause it to overheat and fail prematurely. I believe isopropyl alcohol will clean it safely. [I recommend always carefully cleaning new bulbs with alcohol prior to installation. You never know how they've been handled befreo you get them! - Huw]

The Law

Legally, most European lamps are to be used for offroad purposes only. Sure! (big grin) Replacement headlamps come with a sticker right over the lens that says so. I have never had a problem with either New York or Masachusetts inspection or police regarding any lamp I've run. (Keep the 8" rally lights covered) Other states and jurisdictions may be somewhat more restrictive, Pennsylvania and Maryland particularly. So you may need to swap out lamps when you go to get your car inspected in these states. Or worse. Again, your mileage may vary. I am not a lawyer nor do I play one on the Internet. You get in trouble, you're on your own...

BTW, with enough lights on the front of your car, you may not need snow tires. Flip the lights on and instant dry pavement!

Hope this helps. Please feel free to repost all or part of this anyplace you see fit. If you make any money with it, just send me half.

Graciously provided by: Lee Levitt

"Disclaimer? I don't need no stinkin' disclaimer!"