A 4-Part Series to Clue you In before you Buy

Week 3 – Construction and Fitting, or ‘How it’s Built and How to Mount it’

This week we’re going to look at how your light bar or driving lights are actually put together, and explain what you need to know about their construction before you buy. Then we’ll move on to the many ways that you can attach the lights to your 4WD.

Firstly, let’s look into some of the different components you’re going to see mentioned when you’re reading up on which lights to fit to your 4WD.

How it’s Built

Breather Valves

As we talked about last week, wading in water with hot lamps causes pressure changes and a rapid decrease in temperature. This can cause the air in the lamp to condense. A breather valve uses a waterproof but breathable fabric (typically Goretex) to allow the pressure to equalise and

overcome this condensation issue.

If you plan to do regular water crossings, make sure your lights have a breather valve of some description. It’ll save you the heartache later. If they don’t have the valve, make sure your warranty covers condensation issues.

Lens Covers

Depending on the manufacturer, lens covers will come as part of the light, or will be sold as an accessory. Either way, you’re going to need them to keep your lamps in good condition.

Typically made from either acrylic or polycarbonate, each material has its benefits. Acrylic gives better clarity, is UV resistant, but tends to be more brittle. Polycarbonate needs to be UV treated but is tougher and more impact resistant.

Whichever you choose, it’s important to look for lens that are ‘hard-coated’ by the manufacturer to avoid scratches. If they don’t mention hard-coating, then they probably haven’t done it. Lens covers are essentially sacrificial, and will need replacing eventually, but the hard-coating helps to prolong their lifespan.


Nearly all LED lights use an aluminium housing, as it’s a great material for transmitting heat away from the lamps. Heat is the enemy of the LEDs central component, the LED chip, so manufacturers put a lot of time into helping the heat to dissipate. I’ll deal with LED chips in much more detail next week.

Driving lights generally use a process called casting where molten aluminium is poured or injected into a mould. Light bars, on the other hand, use a process called extrusion which uses higher pressure and is therefore more effective as a heat sink when comparing gram for gram of aluminium used. (Read our comparison of light bar vs driving lights)

Some manufacturers make a big  deal about the shape or direction of their ‘cooling fins’ which are supposed to aid cooling. This is largely marketing spin. The main cooling effect comes from driving. A 5-10km/h wind will be much more effective at cooling than the design of the fins.

Getting a balance between good heat transfer and having a lamp that’s not too heavy involves skilled engineering. Recent developments, along with higher efficiency LEDs, have helped reduce the overall weight and cost of housings drastically. As I mentioned in Week 1, all this innovation is great for the end consumer.

The final thing to look out for when looking at housings is the coating. Black powder-coating is the most common, and works very efficiently, however it’s important to check if the powder has a UV stabilising agent. If not, the housings will fade in the sun, something which will rarely be covered by warranty. If this does happen, you can always re-do them yourself at home.

Wiring Harnesses

This is an area where safety is the best policy. A dodgy wiring harness can not only damage your lights, it can potentially cause a fire and send your whole vehicle up in smoke. We definitely don’t want that.

The safest option here is to always stick to the harness that the manufacturer supplies with your lights or light bar. Using the wiring from the old set of lights that you’re replacing might sound like a good way to save a few dollars, but LED lights take a lot more wattage than your old HIDs.

If you can’t get the harness from the manufacturer, reputable lighting manufacturers sell harnesses, and are sure to have something to suit your wattage. Failing that, get a qualified auto-electrician on the case.They’ll make sure that the harness is robust enough to handle your power requirements.

How to Mount It

Next up, let’s look at what you can use to attach a light or light bar to your 4WD. Once you’ve decided where on the vehicle you want to mount it, you’ll need to look into what brackets to use. Finding the best lamp in the world and choosing the ideal lighting output for your needs is all well and good, but will be a total waste of time if the light falls off your truck after a week!

When picking where to mount your driving lights or light bar, keep in mind that you’ll want to drill as few holes as possible into your bull bar. Find a system that needs the least holes, or that will fit existing holes.

Each manufacturer has different mounting systems, often using different materials. The most common materials used are:

  • Mild Steel
  • Plastic
  • Die Cast Aluminium
  • Stainless Steel

First up, powder-coated mild steel. This is typically associated with cheaper lamps. These brackets have a tendency to break under pressure, especially at weak points. They can also tend to get scratched which leads to rust. Enough said.

Plastic is being used more commonly these days for LED light brackets. There’s no rust worries, but there is the risk of a ‘whip’ effect, as the plastic can flex. What that means is that you might notice a bounce at the end of the beams, especially with a pencil-beam lamp.

Die cast aluminium is a very common type of mounting bracket, because they’re cheap to make, lightweight and won’t rust. Depending on how heavy your lamp is and whether the bracket is on the side or base, the aluminium can fail and crack, especially on corrugated roads.

Leaving the best to last, we have stainless steel. It lasts the longest, and won’t rust. Brackets vary from 1mm to 4mm thick, and therefore vary in price and strength. A well engineered 2mm bracket should fare well in most conditions, and give you good value for money. It will also avoid rust dribbles around the holes and nuts.

When using any of the above materials it’s a good idea make sure the warranty covers the breaking of brackets and the corresponding damage to the lamps. At this point, a slight diversion is in order, to talk about warranties, as these are something you really should take into account when choosing your lighting setup.

A Note on Warranties

Warranties for LED light bars and driving lights usually range between one and seven years. An LED should operate for 50000 hours under normal conditions, so a 7 year warranty is reasonable.

The original cost of the lights will often dictate how watertight the warranty is. It’s worth your while really reading the fine print here to find out how covered you really are should an issue arise.

Often, the best warranties come from the companies who actually fit the lights, rather than the manufacturers. However, they should also be able to tell you how much support the light manufacturer will give, as well as their own warranty policy. If you’re fitting yourself, do your homework extra well! Read reviews by others and study the warranty page on the manufacturer’s website.

With that out of the way, it’s time to get back to the technical stuff. Next week, in our final installment, we’re going to go through some more of the terms and concepts that you need to swot up on to ensure you get the perfect setup for your 4WD. See you then!