Improving Classic’s Lighting

Many classic cars suffer from poor lighting by modern standards, half a century ago it may well have been sufficient, when road speeds were lower, traffic density was much less and fewer people drove in the dark anyway. Not only have standards moved on but some older cars’ lighting circuits have degraded to such an extent that you would get more light out of electrifying a mummified mouse. But on today’s roads it is becoming ever more important to get a good clear view of the road far ahead, combating the perils of faster roads and the glare of oncoming traffic with dazzling HID lighting. The temptation is to add more lights, possibly by bolting on some ugly auxiliary lights, but this would ruin the classic lines that we love so much. Luckily there is usually something fairly simple that can be done to solve this conundrum.
Let me start by de-mystifying the available lighting technology. Modern bulb and lamp construction can harness the light output more efficiently, making the beam brighter and stretch to greater distances. Original bulbs used a tungsten filament in an inert gas such as argon, passing electrical current through it causes it to heat up and emit light, but the atoms on the surface of the filament evaporate and condense on the cold glass surface of the bulb, that’s why they turn silver/grey over time, eventually the filament is so eroded that it burns out. But even before it burns out its’ performance is significantly reduced because of the grey tungsten deposits on the glass, blocking the light.
This problem was cunningly solved with the halogen bulb, it is basically the same design but the halogen gas conveys evaporating tungsten back to the filament in a constant cycle of evaporation and replacement. Because filament erosion is much less of a problem it can be run at much higher temperatures and so produce more light for the same electrical power, in fact it has to run at high temperatures to work properly. It is because of the very high operating temperature that it is vital to keep the glass clean, any grease or dirt will cause it to become porous, you can tell if this is happening because the glass turns milky, and very soon it goes pop.
The best modern headlight bulbs can increase light output by up to 90% compared to halogens of 10 years ago, and extend the length of the beam on the road by over 30m, which is a very welcome improvement for very little outlay.

Here’s a bit of top trivia, halogen headlight bulbs are made in two varieties, quartz glass and hard glass. Quartz has the advantage that it can run at higher temperatures and so make brighter bulbs, the low thermal expansion rate means it can even cope with the occasional water splash, worth knowing if your lamps are prone to condensation.
You can tell if it’s a quarts glass bulb if you look at the wires as they go into the glass as they will be attached via a thin strip of molybdenum metal foil in order to cope with the very different expansion rates. Hard glass bulbs tend to be a bit cheaper, because the wires just go straight in without the need for foil.

Not content with the performance of the halogen bulb, cunning engineers developed the ultra bright high intensity gas discharge systems, so popular on modern cars. This is basically and arc lamp similar to Humphry Davys’ design of 1802, nothing is really new. A very high voltage is generated, in the region of 10kv, in the control unit and an arc is struck in the bulb, usually in Xenon gas. High frequency starting allows the arc to be struck very quickly so that you can flash the lights without having to wait a few seconds. These offer very high outputs at significantly lower power consumption, typically light output equivalent to a 100W halogen but consuming only 35W of electrical power. The beam is much bluer too, although it is often claimed to be closer to daylight the actual spectrum is more fragmented, but that’s a bit academic and needn’t worry us.
Another allegedly modern innovation, although it actually first appeared in 1911, is the use of a projector lens instead of a conventional lamp lens, the beam pattern is formed by a shaped reflector. The advantage is that much more of the bulbs’ light is focused into the intended beam area, making it much brighter and extend further but with a very highly defined cut off to the front and sides of the beam pattern. In one spot its very bright, in another its pitch dark, there is very little graduation. This has two problems, firstly it ruins the night vision of the driver so objects just outside the beam area are much harder to see, secondly the edge of the beam has a variety of colours which flash blue, white and orange to other road users as the car moves over irregularities in the road, which can be both dazzling and distracting.
The most recent development has been the use of LEDs for headlights, previously they simply haven’t had enough power to do the job but now cars such as the Audi R8 sport them.
Options for classic cars.
The first step is to upgrade to a halogen bulb, in many cases this is a simple plug in replacement, but if you have a sealed beam unit you have the choice of using a halogen sealed beam or replacing it with a conventional unit which will make subsequent bulb replacement cheaper. It’s also worth noting that if you take your classic touring on the continent some countries require you to carry spare bulbs, and carrying spare sealed beam units may not be your preferred option.

Many classics use a ‘standard’ 7 inch or sometimes the 5.75 inch round lamp, and there are many replacement units available to up the performance. But beware, there are some cheap 7 inch units and there are some good units, but you can’t have both. The more expensive units have a much better beam pattern, the cheaper units scatter more light and whilst still creating a legal beam pattern they loose a significant proportion of the light in less useful directions. This is due to manufacturing precision in making both reflector and lens, so for best performance go for the quality makes.

Swaps.
The real beauty of cars with 7 and 5.75 inch lamps is that you can swap them with items from other cars, for instance if you fancy a set of projector lamp main beams on your Jaguar XJ6 then why not pop down to your friendly local scrappy and get a set off a late BMW E30 3 Series?
Upgrading the optics on other headlights is also sometimes possible, where the unit has been in production for a long time there may be later units with better performance than can be retro fitted, check with owners clubs and forums for specific models.
Another way of using modern lamps to replace unusual shaped classic units, such as an Allegro or Ami 6, is to cut out the original unit and make a frame to accept a modern, small, headlight unit. By then finishing the conversion with a shaped clear plastic outer cover, it is possible to create a modern lighting system that looks similar to the original. It is obviously a big job, not least because forming the plastic cover can be tricky, so it is probably best left to a professional engineer.

Approvals.
Any headlight for use in the EU should have been tested by a suitably accredited body, then it will have an ‘e’mark. A capital E, followed by a number, in a circle denotes ECE approval administered from Geneva, where as a lower case ‘e’, again followed by a number, in a square denotes EC approval administered from Brussels. In both cases the number refers to the country in which the test was done. Armed with this info you can check up that the ‘e’ mark is genuine and hopefully avoid some of the many fake parts that sometimes slip into the country.
A bit more top trivia; the USA had some curious headlight regulations, until 1983 only round lamps were allowed, which is why many US versions of European cars had to have a special light pods made, such as the quad light set up on cars such as SD1s, Opal Mantas and Jaguar XJ-S.

Handling the power.
Most upgrade options will actually reduce the power consumption, but if you are adding lights then the wiring must be up rated to suit to avoid burnt out looms.
In fact, it’s worth checking the wiring anyway, poor connections and corroded wires increase the overall resistance and reduce the voltage available at the bulb, reducing brightness as a result. Most types of classic connectors are still available, so if yours are oxidized then it’s a really good idea to get them replaced. Wires have a tendency to corrode from the ends, under the insulation, turning the conductors black and in extreme cases rotting the wire strands, which again increases resistance and reduces performance, so running new wires from the switch or relay may be necessary.
Another thing to check is the running voltage of the car, most 12v bulbs are tested at about 13.5v and designed to run on modern cars running at 14.5v, but many classic cars only manage 13v and if the alternator/dynamo is not at its best then it could even be lower when the lights are switched on. Upgrading to a better alternator/dynamo can make a significant difference to the lighting performance.
In all of the above cases, the critical thing is the actual voltage at the connectors on the bulbs. To get a genuine reading its worth testing the voltage with a good quality meter, and not forgetting good quality leads, on the terminals of each of the cars bulbs when the lights are switched on and the engine is running. Anything less then 13.5v and you might well be loosing out.
If your car is a 6v or a 24v system then ideally you would have 6.75v and 28v when the engine is running respectively.

Adding lights.
When the cars standard lighting is a little weak, it is always tempting to add a few extra lights to pep things up.
But beware of masking a fault with the original system, if after going through all the above checks and upgrades you discover that your classic really does have genuinely poor lighting then maybe bolting on a few extra units is the only option.
With any modification the first question to ask is ‘what problem are you trying to solve?’ If dipped beam is fine but main beam is too narrow for twisty lanes then a set of driving lights set to point at the dark zones may be ideal, but if dipped beam is too feeble then a little more work is needed to ensure the beam can be accurately positioned, this might involve a steady bar being attached to the lamp to stop it moving in use and to allow some angle adjustment.
Some classics suffer from having the lights so low that it is very difficult to get any useful range out of them, cars like the Midget, Lancia Stratos and TR7 can use the lighting pods designed for rally cars, if the cars has sporting pretensions then this can complement the overall look, but on an ordinary road car it just looks terrible.
Generally though, it is very rare for a car to actually need extra headlights, upgrading the standard units as detailed above is a far better idea. The one exception is fog lights, which are designed to be fitted very low and have a flat but broad beam to minimise the reflected glare from the fog. Fitting these below the front bumper is essential, but this can make them prone to damage. For this reason its best to fit them with a hinge or bendable mounting at the top so if you nudge a kerb when parking the lamps fold up rather than shatter. Also a plastic or metal lamp grill will help protect hem from large objects, and a clear plastic cover will prevent stone chips cracking the glass.
At the rear of the car there are often some useful auxiliary light options. First let me say something about high level brake lights, although they generally look a bit naf they are proven to drastically reduce the chance of someone piling into the back of your beloved car, fitted carefully to the top of the rear screen they can be made almost factory fit and LED units take very little power so the existing wiring might be able to cope, if it’s in good condition.
Many Classics have no reversing light which is a pain when reversing at night into a tight parking space. Retro fitting one is fairly straight forward, usually bolted under the rear bumper, but operating it can be tricky. If the gearbox has provision for a reverse switch then so much the better, but if not then you will have to fabricate a mounting plate and fit your own switch.
Rear high visibility fog lights are an excellent safety aid too, fitting is again a matter of attaching it to the bumper on most cars and then wiring it to either a switch that can take the current or else using a relay. Either way it will need its own fuse and a warning light on the dash somewhere.

Indicators and side lights.
Some classic cars have notoriously feeble rear lights and indicators, so much so that they can become all but invisible with obvious safety problems as a result.
Luckily there are things that can be done to significantly improve matters, but without ruining the beautiful classic style.
Modern filament bulbs offer a reasonable increase in visibility, but by far and away the best improvement is from LED clusters which are much brighter and have a sort of sparkly appearance that usefully improves contrast. But beware of cheap LEDs, as with many things quality costs, cheap LEDs will fail early where as quality units will last for many decades, and rather than suddenly blowing they will gradually get a little dimmer.

Leave a Reply

Your email address will not be published. Required fields are marked *