A good suspension upgrade isn’t just about height. It’s also about weight. Before choosing springs, shocks or a lift kit, it’s important to think about what your 4WD carries, how often it carries it, and whether that weight stays on the vehicle all the time or only gets added for trips.
For many WA drivers, that can vary a lot. Your 4WD might be lightly loaded during the week, then packed with a caravan, recovery gear and camping equipment for a trip down south or up north.
That’s where understanding constant load and variable load suspension becomes important. Go too heavy and your 4WD can feel harsh when unloaded. Go too light and it may sit low, handle poorly or feel unsettled once the caravan is hitched up.
In this guide, we’ll help explain the difference between constant and variable load suspension, and how to decide what’s right for your vehicle.
What Is Constant Load Suspension?
A constant load is the weight your 4WD carries all the time, not just occasionally. This usually includes fixed accessories or gear that stays in the vehicle day to day, such as canopies, toolboxes, drawer systems, fridges, dual battery systems, roof racks or work equipment.
Constant load suspension is designed to support that ongoing weight. It uses heavier-duty springs rated for a fixed load, commonly around 300kg, 500kg or 600kg, to help keep the vehicle sitting at the correct height and handling properly under load.
The key difference is that the weight is part of your everyday setup, not something you only carry now and then.
How a Constant Load Suspension works
With the right constant load springs fitted, the suspension is set up to support that weight from the start. Instead of sagging or sitting low in the rear, the vehicle stays level, controlled and predictable, even when fully loaded.
The trade-off is comfort when the vehicle is unloaded. Because the springs are designed to carry weight, they can feel stiff, harsh, or less forgiving around town and during everyday driving.
In Western Australia, constant load setups are common for vehicles doing serious work or long-distance touring, especially where reliability and load-carrying performance matter more than day to day comfort.
What Is Variable Load Suspension?
Variable load suspension is designed for 4WDs where the weight changes depending on how the vehicle is being used.
Instead of being set up for a fixed load, these systems use lighter or progressive-rate springs to provide a more comfortable ride when the vehicle is empty, while still offering support when extra weight is added.
It suits vehicles that don’t carry the same load every day. One day it might be used for daily driving, and the next it could be packed with camping gear, towing a caravan, or carrying extra weight for a weekend away.
It’s a flexible option for 4WD owners who need a setup that can handle changing loads, rather than permanent weight.
How Variable Load Suspension works
Variable load suspension is designed to be more flexible. When the vehicle is unloaded, it provides a smoother, more comfortable ride. As weight is added, the suspension helps support the extra load without feeling too harsh day-to-day.
It won’t feel as firm or “locked in” as a constant load setup under heavier weight, and if the vehicle is regularly pushed beyond what the springs are designed for, you may notice rear sag, reduced stability, or poorer performance.
For many 4WD owners, this is the most common setup, especially for those doing a mix of everyday driving, weekend trips down south, and or carrying heavy tools for work.
Constant vs Variable Load: What’s Right for Your 4WD?
When it comes down to it, the difference between constant and variable load suspension is how your vehicle carries weight day in, day out.
Both setups have their place. Constant load suspension is built for vehicles that carry the same weight all the time, while variable load suspension is designed for vehicles where the load changes regularly.
That one decision affects everything from ride comfort and handling to how your 4WD performs under load.
| Constant Load | Variable Load | |
|---|---|---|
| Best for | Fixed, permanent weight | Changing or occasional loads |
| Ride when empty | Firm, can feel stiff | Smooth and comfortable |
| Ride when loaded | Stable and controlled | Can sag if heavily loaded |
| Handing under weight | Predictable and planted | Less stable if pushing limits |
| Flexibility | Low | High |
What this means for your 4WD
If your vehicle is always loaded, constant load suspension keeps it sitting right, handling properly, and staying controlled, especially under heavy gear or long-distance touring conditions.
If your vehicle is only loaded some of the time, variable load suspension gives you a more comfortable ride day-to-day, without feeling overly stiff when you’re just driving around town.
Where Adjustable Suspension Fits In
Not every 4WD fits neatly into a constant or variable load setup. A lot of vehicles in WA sit somewhere in the middle, daily driving most of the time, then loaded up for trips, towing a caravan, or carrying extra gear when needed. That’s where adjustable and custom suspension setups come in handy.
Adjustable components don’t replace your springs, they fine-tune how your suspension performs. Common options include:
Airbags (airbag-assisted suspension)
- Help level the vehicle when carrying extra weight or towing
- Useful for managing temporary loads, like caravan tow ball weight
- Airbags can help support your suspension, but they don’t increase GVM or replace the need for the correct spring setup.
Adjustable shock absorbers
- Allow you to adjust firmness depending on conditions
- Useful for vehicles that switch between daily driving, corrugated roads and loaded touring.
- Improve control and comfort rather than load capacity
If your setup changes regularly, or sits somewhere between constant and variable load, a custom suspension setup is often the better option.
Many vehicles don’t fit neatly into one category. They might carry some weight all the time but not enough for a full constant load setup, tow regularly without being loaded every day, or need to balance comfort, load carrying and control.
A custom setup allows for this by matching spring rates to your typical load, using approved variations where applicable, and pairing the right shocks and springs to achieve a better balance of comfort and performance.
How to Choose the Right Suspension For Your 4WD
Choosing the right suspension setup comes down to how your 4WD is used most of the time. Not what your mate has or what it could be used for. Understanding this makes the decision a lot easier.
Before deciding on a setup, ask yourself:
- Is your vehicle always loaded or only sometimes loaded?
- What’s your typical load, not your maximum load?
- Do you tow regularly (caravan, trailer, boat)?
- Is it mainly a work vehicle or a lifestyle vehicle?
These answers will help point you in the right direction, but if you’re unsure, we can talk you through the best option for your vehicle.
A simple way to look at it:
- Always loaded = Constant load suspension
- Mixed use = Variable load suspension
If you match your suspension to your real usage you get better ride quality day-to-day, the vehicle handles properly under load, you avoid unnecessary wear and poor performance.
Suspension Setup for WA Driving Conditions
Suspension setup matters everywhere, but in Western Australia it becomes even more important. The distances are longer, the heat is harsher, and many 4WDs are regularly used for towing, touring, work, and off-road travel.
Long highway runs, corrugated tracks, heavy gear, caravan towing and hot conditions all place extra stress on your suspension. If your setup isn’t right for the way you use your vehicle, those issues can show up quickly through rear-end sag, poor handling, a harsh ride, or faster wear on components and tyres.
That’s why choosing between constant load, variable load or a custom setup is about more than comfort. In WA conditions, the right suspension helps your 4WD stay controlled, stable and reliable, whether you’re driving around Bunbury, heading down south, towing a caravan, or travelling further north.
Set Your 4WD Up for the Way You Use It
Choosing between constant load and variable load suspension comes down to how you use your 4WD. Having a suspension tailored to your setup improves ride quality, handling, and how your vehicle performs under load. That’s why it’s worth choosing an option that suits how your 4WD is actually used.
For a lot of vehicles, it’s not always a clear-cut choice. That’s where a custom setup makes all the difference, especially when you’re dealing with WA conditions, or a mix of daily driving and touring.
If you’re not sure what suspension setup is right for your vehicle, we can help. We’ll recommend a suspension package to suit how you use your vehicle. Contact us today to find out more.
