Question 1

Source Reference List:

Accepted Answer

[1] WA Department of Transport and Major Infrastructure, GVM and GCM FAQs.

[2] WA Department of Transport and Major Infrastructure, VTB-180A: Gross Vehicle Mass Re-rating.

[3] Road Traffic (Vehicles) Regulations 2014 (WA), regulation 160.

[4] Australian Government Department of Infrastructure, Transport, Regional Development, Communications, Sport and the Arts, Second Stage of Manufacture.

Question 2

Is an upgraded suspension enough to legally increase my GVM?

Accepted Answer

No. Fitting heavier-duty suspension does not automatically increase your vehicle’s legal GVM. In WA, the upgrade must follow the appropriate approval process. For an in-service vehicle, this includes DTMI approval and a modification permit.

See Transport WA’s requirements for GVM upgrades.

Question 3

How does wheel alignment affect fuel economy?

Accepted Answer

Yes. The approval process depends on when the upgrade is completed. Pre-registration upgrades must be completed under the federal Second Stage Manufacturer approval pathway, while post-registration upgrades must be approved by WA’s Department of Transport and Major Infrastructure, with a modification permit issued.

Read Transport WA’s GVM approval and certification guidance.

Question 4

Can poor wheel alignment damage tyres?

Accepted Answer

You can, but be careful what you change. Transport WA states that replacing components that formed part of the approved GVM upgrade kit with different components can invalidate the GVM approval. Before making changes, check whether the component forms part of your certified setup.

See Transport WA’s advice on changing approved GVM components.

Question 5

Can a GVM upgrade affect my insurance or vehicle warranty?

Accepted Answer

Potentially. Transport WA advises that vehicle modifications can affect both warranty and insurance coverage. It recommends checking with your vehicle manufacturer and insurer before carrying out a modification.

Read Transport WA’s advice on warranty and insurance.

Question 6

Will a GVM upgrade in WA be recognised interstate?

Accepted Answer

Generally, yes while you are travelling interstate, provided the re-rating has been properly certified in the state where the vehicle is licensed. Transport WA states that certified re-ratings are recognised in other jurisdictions while travelling. If you are permanently moving interstate and re-registering the vehicle, however, you should check the requirements of that state or territory, as registration and modification rules can differ between jurisdictions.

See Transport WA’s guidance on interstate GVM re-ratings.

Question 7

Can wet roads make suspension problems more noticeable?

Accepted Answer

Yes. Wet roads reduce tyre grip, so worn shock absorbers, bushes or other suspension components can make the vehicle feel less stable, particularly when braking, cornering or travelling over uneven surfaces.

Question 8

Do potholes cause damage to 4WD suspension?

Accepted Answer

Potholes can place sudden impact loads on the tyres, wheels, steering and suspension. A severe impact, or repeated smaller impacts, may damage components, affect wheel alignment or contribute to uneven tyre wear.

Question 9

How can mud and water affect suspension components?

Accepted Answer

Mud, water and road grime can collect around suspension and underbody components, concealing leaks, loose fasteners or early corrosion. Repeated exposure may also contribute to deterioration if the build-up is not cleaned away.

Question 10

What are the common signs of worn 4WD suspension?

Accepted Answer

Common signs include excessive bouncing, increased body roll, uneven ride height, unusual noises, fluid leaking from shock absorbers, uneven tyre wear and changes in steering or handling.

Question 11

Why does my 4WD feel unstable on wet roads?

Accepted Answer

Reduced tyre grip can make existing tyre, wheel alignment or suspension issues more noticeable. Worn shock absorbers may also reduce how consistently the tyres remain in contact with the road.

Question 12

How should I clean my suspension after driving through mud?

Accepted Answer

Rinse mud and debris from the underbody and suspension using low to moderate water pressure. Avoid directing high-pressure water closely at seals, electrical components and sensitive fittings, then inspect the area for visible damage, leaks or loose parts.

Question 13

What are the signs that a 4WD is carrying too much weight?

Accepted Answer

Common signs your vehicle may be carrying too much weight include rear suspension sag, excessive body roll, vague steering, bottoming out over bumps, uneven tyre wear and changes in braking performance. The vehicle may also feel less stable when cornering, towing or travelling on rough roads.

Question 14

Why is my 4WD sagging at the rear?

Accepted Answer

Rear sag often occurs when the springs are carrying more weight than they are designed to support. Constant loads from canopies, drawers, tools, fuel tanks, touring gear or tow-ball weight can all contribute.

Question 15

How does extra weight affect 4WD braking performance?

Accepted Answer

Extra weight generally increases stopping distance and places more demand on the tyres, brakes and suspension. It can also cause excessive nose-diving or make the vehicle feel less stable during hard or emergency braking.

Question 16

Can suspension problems cause uneven tyre wear?

Accepted Answer

Yes. Worn suspension components, sagging springs and changes in ride height can affect wheel alignment and how evenly the tyres contact the road. This may cause edge wear, cupping, scalloping or different wear patterns across the same axle.

Question 17

How can poor load distribution affect driving?

Accepted Answer

Weight carried too high, too far behind the rear axle or unevenly across the vehicle can affect steering, cornering and braking stability. It may also increase body roll, reduce traction and make the vehicle less predictable when towing or changing direction.

Question 18

When should I consider a certified GVM upgrade?

Accepted Answer

A certified GVM upgrade may be worth considering if your 4WD regularly carries accessories, tools, passengers or touring gear that brings it close to its factory GVM. The vehicle should first be weighed and professionally assessed to determine whether a GVM upgrade is suitable for its setup and intended use.

Question 19

What is the difference between constant load and variable load suspension?

Accepted Answer

Constant load suspension is designed for vehicles that carry a fixed amount of weight all the time, using heavier-duty springs to keep the vehicle level and stable under that load. Variable load suspension is designed for vehicles where the weight changes, offering a more comfortable ride when unloaded while still supporting extra weight when needed.

Question 20

Can I tow a caravan with variable load suspension?

Accepted Answer

Yes, you can tow a caravan with variable load suspension, especially if towing is occasional. However, if you’re towing regularly or carrying heavy loads, you may notice rear sag or reduced stability, which is where a more tailored setup or additional support like airbags may be needed.

Question 21

How does towing affect my suspension choice?

Accepted Answer

Towing adds extra weight to the rear of the vehicle through tow ball download, which can impact ride height, handling, and braking. If you tow regularly, your suspension needs to be set up to manage that load properly, whether that’s through constant load springs, a variable setup with support, or a custom solution.

Question 22

What are the signs my current suspension setup isn’t right for my load?

Accepted Answer

Common signs include the rear of the vehicle sagging when loaded, a harsh or uncomfortable ride when unloaded, poor handling or instability, especially when towing, and uneven tyre wear. If your 4WD doesn’t feel settled or controlled under your typical load, the setup likely isn’t matched correctly.

Question 23

Can my suspension be adjusted if my setup changes over time?

Accepted Answer

Yes, suspension can be adjusted or upgraded if your setup changes. This might involve changing spring rates, upgrading shocks, or adding components like airbags. If your vehicle use evolves over time, it’s worth reassessing your suspension to keep it performing properly.

Suspension

GVM Upgrades in WA, What’s Legal?

How Winter Driving Affects Your 4WD Suspension

6 GVM Warning Signs Your 4WD Is Overloaded

Constant vs Variable Load Suspension Explained

A Guide to Getting a GVM Upgrade for Your Landcruiser

How to Properly Load Your 4WD After a GVM Upgrade

Do Airbags Count Toward a GVM Upgrade?

What Is Camber, Caster and Toe in Wheel Alignment?

GVM Upgrades for Tradies

Why Shock Fade Happens and How to Prevent It