How do I add a leaf spring to the suspension of my 2010 Mitsubishi Triton?

The short answer is that this can be done, and, in fact, there are kits available to allow you to add a leaf to a suspension spring-pack. The broad idea is to make the spring stiffer, increasing theoretical load-carrying ability as well as giving more ground clearance (as the modified spring will usually make the vehicle sit higher).

The trick is finding the correct extra-leaf kit for your specific vehicle, and this is where a specialist supplier comes in. The kit should include the extra two spring leaves as well as longer centre bolts (as the spring-pack is now thicker). And as with any suspension -related equipment, quality is hugely important to safety and the actual performance of the new set-up.

But there are other issues. The first is a legal one. While the new, thicker spring-pack might tempt you to increase the loads you carry, legally, the vehicle retains its original loading and towing limits until it has been certified otherwise by an accredited engineer. Some kits are supplied with this paperwork all sorted for you ready to simply lodge with the authorities, but some aren’t. And consulting engineers don’t generally come cheap. You would also need to inform your insurance provider of the change to the vehicle’s specification. There are also absolute limits to how much higher your vehicle can sit compared with a standard one. This varies from state to state, but in your home state of NSW at the moment, a vehicle can legally be raised by 75mm over its standard ride height. The catch is that only 50mm of this can be from suspension modifications, and the other 25mm of lift through bigger tyres. But if you stick within those limits and don’t intend to increase the vehicle’s load or towing ability, then the raised suspension doesn’t need to be certified by an engineer for the vehicle to remain legal.