AO

I just got a set of H4s. They are awesome. People are flicking their lights at me even though I have them aimed down considerably . Then I flick back !

But I was wondering if these come as right and left? If I were to guess I'd say I have 2 left ones as the light is cast slightly to the left on both of them - plus the mounting brackets/aiming bolts are the same for both. Any one else have this or am I the lucky one?

hacker-pschorr

Don't right had drive cars aim the opposite direction as left hand drive cars?

cobalt

The lenses on the H4's and H1's are identical to both sides. Although the RHD versions are oposite of the LHD. Yes they are far superior to the H5's

jpitman2

The H4 8" lenses, as with other sizes, come in LHD and RHD, with different offsets and cutoff lines. With LHD lenses you should see the same pattern from both - flat cutoff to the left to avoid dazzling oncoming traffic, rising to the right to cover the roadside better. The reverse with a RHD lens. If you put RHD lenses on a LHD car, you would have a low flat cut off on the right, and a badly glaring beam into oncoming traffic.
RHD beams, not correct scale, but you get the idea:

\
\
\
\__________

LHD:-

/
/
/
________/


hth
jp 83 Euro S AT 49k, RHD that spent half its life in a LHD country....

Rich9928p

H4 headlamps are far superior to US DOT headlamps. However, you may have discovered why H4s were deemed too dangerous for the US ... your H4 lights are dangerous when improperly aimed. This may be why oncoming cars are blinking at you, you're blinding them! H4s have a knife edge line, where the focused light is on the bottom half of the beam and no light is transmitted in the top portion - there is a is a "hokey stick bend" at the right side of the beam to light the side of the road for left hand drive cars.

DOT headlamps do not have a focused beam, the pattern is an unfocused blob that spreads light but a great deal of the intensity is lost.

The basic goal is to get the beams parallel to your direction of travel, low enough that they don't blind oncoming traffic, and the same height. You should see the low beam cutoff on the cars in front of you.

This process works for me. First, find a level stretch of driveway or parking lot that is adjacent to a wall or garage door which will be the aiming screen. Load up your car normal travel trim, fuel and passenger load simulated if you can't find a passenger. Drive the car close up to the wall. Mark the headlight centers both vertically and horizontally with a heavy felt tip (you might want to use a large piece of cardboard and save it to be re-used on the same car or stick a couple of Post-Its on the wall if you have a an indoor wall, this makes it easier for easy rechecks.) Mark the center of any auxiliary lights as well. Now, roll the car straight back, 25 feet. Scribe a straight line between the headlight centers (line B). This is the important step - Measure down 3" and draw another horizontal line (D). Do the same for your auxiliary lights. One at a time, aim the lights as follows (turn off or cover the lights not being aimed, I draped a black towel over the other lamps). Be sure the knife edge focus is aimed at line D.

AO

Wow! Thanks for the tips. I'll have to re-check which I have LHD or RHD lights? Also, I think I'll re-aim them downward just a bit.

SharkSkin

Take a look at the attached pic. The wedge that you see to the right of the "4" in "H4" is what throws the beam upward on the right side of the road for use on RHD roads(US). If that wedge is on the other side, the lenses are designed for LHD roads.

Vilhuer

It might be possible to install them upside down but I quess it would be easy to notice when low beams would light up road far ahead only.

jpitman2

I thought it was the CAR that was LHD or RHD, NOT the road! It relates to the driver seat position, not which side of the road you drive on doesnt it? UK, Oz, NZ etc are RHD countries, who drive on the LHS of the road!!!
jp 83 Euro S AT 49k, RHD

AO

Dave,
Unfortunately, you've just confused me even more. You said that the wedge to the right of the 4 (as you face it) casts its light to the right side of the road. This seems counter intuitive. Based on your description, this is what happens (see pic below). I would have thought that the wedge would reflect the light to the the side that it's on - not accross.

Again, I'll have to look at my setup when I get home tonight, but I think my setup is the same as yours. Hmmmm.....

Garth S

Dave's pic is correct for LHD lights - the projected light above the sharp cutoff line will be to the right: the assymetry has 'something' to do with a rearward projecting bulb into a parabolic reflector....and the prismatic cut of the lens ...
I have a set of each type of 8" H4's - the S4 arrived with RHD lights in an LHD car - as is req'd in Japan. I adjusted them lower - and had not received any signals of annoyance from oncomming traffic: hopefully, this will work for you.
Some knowing seller did not offer full disclosure on this sale ...

sublimate

Someone had a great post about aiming H4s, complete with pictures of the patterns on a garage wall. I can't seem to find it - anyone remember where it is?

Vilhuer

Whole purpose of cut on lens is to make sharp horizontal line to light where it ends so it lights up road near car but do not blind oncoming traffic. As this would leave right side ditch and possible signs etc in there dark until car is some 50 meters from them lights have angled cut that allows light to go much further in that side (all this on LHD cars). This is good to have as moose and other animals could come in front from ditch. Light pattern these lamps provide has quite interesting shape. It's like long elongated oval with top left 1/4 left out.

Euro lights should be aimed so that sharp horizontal light border drops about one centimeter for each meter it travels. This can be done by driving car 5 meters away from wallon even groung and measuring that light border is 5 cm lower than what is measured height from ground to cut line in center of headlamp. Angled part takes care itself and how far ahead ditch side is lights up depends on what shape lamp is. If there is adjustment **** next to drivers seat it need to be set to correct position reflecting loading status of car when adjustment is done. This way **** has correct effect when loading changes.

BrianG

The aiming process is actually quite simple.

From a level surface, with one light either off or covered, aim the other to a mark on a wall that is at or slightly below the height measured from the ground to the center of the H4's lens, on the car. Obviously this will result in a parallel-to-the-ground low-beam cutoff plane. This plane will be substantially lower than the eye level of pretty much every vehicle on the road.

The lateral location of the beam is far less critical, but I simply stand behind the car, straight aft of the headlight, and locate the cut-off "angle" straight ahead of the car.

I am curious about how to identify a LHD H4 lens as opposed to a RHD unit, because, unlike Garth, I don't think Andrew's picture is accurate. The angle-of incidence rule is not appropriately reflected (ha ha ha) in the diagram.

hacker-pschorr

Andrew - where did you get these?