When you're driving your
Jaguar down some desolate two-lane blacktop road at 140 mph on a
moonless night, it's helpful to be able to see where you're going.
Unfortunately, not all headlight systems are up to the task. If you
have the older US-spec XJ-S with four round headlights with the
original sealed beam units in place, I suggest you slow down.
Even if you obey all posted speed limits, you will be amazed at
what an adequate set of headlights will do for the pleasure and
enjoyment of nighttime motoring. Where you used to have to squint and
stare in hopes of seeing things in time to avoid hitting them, you
can now sit back and relax; the eyes of a deer or a dog are visible
from a long way away. In fact, you may come to fully
appreciate the advantages of nighttime driving, with the reduced
traffic and cooler temperatures.
US Headlight Laws
Before I delve into how to make things
better however, I'd like to explain a little about the evolution
of headlight laws here in the U.S. Back in the 1950's and 1960's,
automobile headlights seemed like fertile ground for government
control. Laws had been established requiring all cars to have one of
two types of headlight systems: two 7" round headlights or four
5-3/4" round headlights. It was this requirement that ruined the
appearance of the Jaguar
XJ6, designed to have two 7" bulbs and two 5-3/4"; for the U.S.
market the two 7" had to be replaced with 5-3/4" with a filler ring
around them. It also is the reason the early XJ-S has two round
headlights on each side instead of the
Euro-style single lamp
assemblies.
Also, the wattage of headlights was limited to 55/60W on the
high/low bulbs and 55W on the high-only units, regardless of size; as
a result, the four-headlight system produced far more light than the
two, since it had 230W operating on high beam instead of only 120W.
And all headlights were required to be "sealed beam", meaning that
the entire headlight was the bulb itself, when it burned out you had
to replace the whole thing. On top of all this was a general
prohibition on more than four headlights on a car.
Sometime in the 1960's they prohibited glass covers on the
headlights. This changed the appearance of the Jaguar E-type and the
Volkswagen Beetle. In the early 1970's, they added rectangular
headlight systems to the approved list.
With the advent of energy conservation concerns, the automotive
manufacturers were finally able to convince legislators in the mid
1980's to drop the requirements for using standardized sealed beam
headlights and permit the use of custom headlight assemblies in the
name of better aerodynamics. Since cars in other countries had
already been using such systems for many years, it also helped
companies like Jaguar not have to design two different front ends for
their cars. In some countries in Europe headlight wipers are required
by law, and wipers don't work well on the US standardized bulbs.
With the new custom headlights came replaceable elements, but
rather than using the H4 halogen bulbs that were already in use
elsewhere, the new headlight systems generally use a new 9000-series
bulb with an O-ring on the base. Perhaps the requirement that the
headlight system be "sealed" persists in this form.
Now, on to enlightenment.
Brighter Lights
While the Euro-style
headlights are now legal in the US it is probable that several
laws are still in force regarding headlights. It is probable that the
55/60W limit is still there in some form or another. Before jumping
in and modifying your headlight system, you might want to check the
regulations in your state. Or, you might want to simply note how many
citations are handed out annually for illegal headlight assemblies
and decide whether or not you want to chance it.
Note that all of the headlights described are stipulated in the
J. C. Whitney catalog as "for
off-road use." That is how they can sell headlights that may,
technically, be prohibited on public highways in some areas; why the
upper left cutoff on low beam would be helpful in an off-road
application is never explained. There are a couple other tricks
available. At one time, J. C.
Whitney sold some "sealed beam" H4 headlights for street use; a
rubber boot had been glued on over the bulb socket making the whole
thing sealed. When the H4 bulb burned out, you just cut the boot away
and put in a new one.
For readers of this book who drive on the wrong side of the road
(UK, "downunder", Japan), note that you must get headlights with low
beams that cutoff the upper right. I'm sorry,
J. C. Whitney doesn't appear to
offer any headlights for RHD cars. But I'm sure there are suppliers
of suitable units in your countries, and the same type of
improvements should be possible.
H3 Halogen Lights
If your XJ-S is fitted with driving lights instead of fog lights,
it is probable that the driving lights use H3 halogen bulbs. These
bulbs are normally 55W and can be purchased just about anywhere that
sells auto parts. However, for a little more visibility, replacement
H3 bulbs are available from J. C. Whitney in 100W and 130W versions.
H4 High/Low Beam Units
Another possibility is to replace the high/low sealed beams (the
outer two bulbs) with the far superior non-sealed units using H4
halogen bulbs. The standard H4 bulb is 55/60W, so it is the same
wattage as the sealed beam and meets any legal limit there. But the
H4 units have much better focusing patterns; on low beam, you can
pull the car up to a wall and see that the pattern provides a
distinct cutoff to the upper left (on LHD cars), while still
providing plenty of illumination down and to the right. The result is
that oncoming traffic gets blinded much less on low beam -- a good
result, since the H4 bulbs produce a brilliant white light even when
the wattage is the same as conventional sealed beams.
H1 High Beam Units
You can also replace the sealed high beam units (the inner units
on each side) with assemblies that use H1 halogen bulbs. The standard
H1 is 55W to meet that limit, but J.
C. Whitney sells 100W and 130W versions.
High-Power H4 Bulbs
For serious illumination, J. C.
Whitney also offers H4 bulbs in 80/100W, 90/130W, and 100/165W.
Note that the light output of light bulbs is not necessarily
proportional to wattage; usually the higher wattages are more
efficient. In household bulbs, for example, a single 100W bulb
produces more light than two 60W bulbs. Suffice it to say that these
high-wattage H4 bulbs will definitely do the trick. I have a pair of
90/130W on a car with only two headlights, and on high beam sometimes
the reflection from a brand-new speed limit sign can be a little
blinding. The little reflectors on the road are lit up for a mile at
least. And when you flash at someone to move over, they move over!
By the way, the H4 bulbs are very common, and the 55/60W versions
can be purchased in local department stores. The high power versions,
of course, are harder to find -- but if you buy a spare or two, they
don't take up much space in the trunk or glovebox since they are very
tiny.
Also note that the H4 assemblies are nothing resembling sealed; in
fact, the back end is open enough you might consider it ventilated. I
cannot imagine why this would be a problem; if you get the car
that far under water, you've got more to worry about than the
headlights! If you are concerned about moisture (or anything else)
getting in, there are rubber boots available that fit over the back
end of any headlight and are held in place by the plug. Some such
boots might even be included with the H4 assemblies. Note, however,
that installing this boot will keep the assembly warmer; this doesn't
normally pose a problem, but if you're using the big-wattage bulbs
you might consider the tradeoffs between how hot the bulb gets and
how big a problem moisture is.
Driving Lights
Beyond this, you can add more driving lights, but it would be hard
to imagine why it would be necessary.
Euro-Style Headlights
With all that, we haven't changed the outward appearance of the
car. If you have the four round headlights, you might consider
replacing the whole assembly with the Euro-style single lamps; they
are legal now, and reportedly do a better job of lighting the road
than the four sealed beams. This is an expensive fix, however, and
would probably only be considered by XJ-S owners who prefer the
appearance of the Euro style lights.
Hella Headlights
There are other possibilities. J.
C. Whitney also offers Hella headlights, which are highly rated
and claim to be perfectly legal. They are more expensive, though.
Handling Halogen Bulbs
Keep your grimy paws off any of those tiny halogen bulbs. The oil
from your fingers on the surface of the quartz insulates it and
prevents it from dissipating heat as it should. The result is that
the bulb burns out very quickly, whereas normally an H4 bulb will
last considerably longer than a sealed beam. If you accidentally
finger the bulb, clean the surface with some alcohol before
installing.
Alternator Capacity
Since W = A x V and automotive bulbs are 12V, a 130W bulb will
draw nearly 11 amps. Four of them will draw over 43 amps, or about 24
amps more than the stock lights did. You might want to consider the
capability of your alternator; the later XJ-S was fitted with a
115-amp unit, but the earlier ones had 66-amp or 75-amp Lucas units
-- and you've still got electronic fuel injection, windshield wipers,
A/C system fans, etc., etc. to provide power for. Still, this usually
doesn't present a problem, perhaps because you can't use high beams
too much due to oncoming traffic, there's usually no point to using
high beams in the rain when the wipers are going, and since it's cool
after dark the A/C fans are always on low speed.
Fuses and Wiring
You also need to consider the wiring and fuses. The XJ-S provides
a 25-amp fuse for both high-beam headlights on each side of the car
in a fusebox on the left side of the engine compartment. If you go
with four high-wattage bulbs, this fuse size will be marginal at
best.
Line Loss
If the wires providing power to high-wattage headlights are too
long and too small to carry the current, the resulting line losses
can rob you of some of the light you've paid for. In some cases the
resulting losses from long lengths (the wiring goes through the
dashboard area to the headlight switch) of thin wire can result in
the high-power headlights being dimmer than the originals. The
way to check is to measure the voltage right at the back of the
headlight while it's on; if it is more than a couple of tenths of a
volt less than battery voltage (12V), you have too much loss in the
wiring.
Relays
If this is the case, the solution is to disconnect the wires from
the headlights and connect them to the coils of relays, run a massive
power wire from the battery to the common contacts on the relays, and
run substantial wires (with suitable in-line fuses) from the contacts
on the relays to the headlights. Thus, you operate the relays with
the original wiring for the headlights themselves, and the serious
current takes a much more direct route to the bulbs.
Since there is a main bus on the firewall of the XJ-S, this only
requires running a serious cable from there to the front of the car.
The relays should be mounted up close to the headlights to minimize
wire length. Technically, you can do all this with only two relays,
one for low beam and one for high beam, but it may be necessary to
use two for high beam to keep from overloading the contacts on a
standard 30-amp relay. Be sure to provide suitably massive ground
wires on the headlights as well.
On to the Stereo
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