Thread: Isuzu Dmax Suspension upgrades

If you go 50mm front and rear you will just achieve a slightly higher saggy bum. Controversial statement, but what you want over the factory leafs at the rear is more, more compliant individual leaf sections forming the leaf spring pack. Each leaf deflects under a set amount of weight, so for a greater range of loading before the overload plate at the bottom of the pack is in play you need more leaves. Once the overload plate is engaged, the next stop is just that, the rubber bump stop hitting the chassis. The danger there is creating a pogo stick at the back with many leaves loading and unloading and most factory oil filled nitrogen pressurized shocks won't like that work rate - buggers will fade young. It's not a fault of the product its the design of the suspension system is setup for urban soccer mums carting a bag of soccer balls and three kids to sports...

What you want at the back is a compliant multi-leaf spring pack with heavy duty foam cell shocks - rated to a stiff ride unloaded and then slightly baggy when fully loaded. That means you're at the extreme end of the load range when fully loaded or towing heavy, in the middle at your normal mid range load and then unloaded is stiff but not unmanageable. If your bump stops are engaging every bump when fully loaded, your springs are crud and aren't up to the task... I'm not a major fan of airbags, having been involved with one cracked chassis but that was due to the vehicle having quite a range from empty load to full load and the supplementary bags not getting adjusted according to recommendations.

Now the fronts - minimum lift to get the alignment and caster angles back into manufacturer's specs. Using the example of the ranger, with a 7-leaf high load pack and foam cell shocks in the arse, the fronts stayed on factory springs but foam cell struts. I needed a 20mm lift on the front wheels, with the Ranger's design 20mm of lift = 10mm extra compression on the factory springs. I achieved that by a foam cell strut with a removable floating lower spring cup and fitting a 10mm spacer ring under it. With the strut assembled on factory springs and dropped back into the vehicle this gave the required 20mm lift at the front end to get the adjustment range back into factory specs. Any higher than that, and the arse would have been drooping with a load on...

Hope that makes sense, but setting up a ute for towing with a 50mm lift all around will likely lead to disappointment - it's different if you are going for ground clearance or clearing wheel arches for bigger boots etc etc where you want the vehicle sitting flat but for towing you want the vehicle sitting flat with the trailer on which means that it needs to be up at the back when unloaded. Otherwise the stability goes to the pack when you have a heavy trailer on and the arse is dragging...