What Is Chassis Welding? Is It Legal and Is It Safe?


Source: Eduardo Cabrera

When it comes to your vehicle’s chassis, especially if you are an avid off-roader you are bound to encounter some sort of chassis damage along the way. There are several factors to consider when opting to make repairs to your chassis and while welding may be your only repair option we looked into whether this is a safe and or legal option.

Depending on which state you are in, Chassis Welding is legal if its carried out by a qualified welder and inspected and certified by an engineer and a modification plate installed. In some states, you may also need a roadworthy certificate.

We delved deeper into the subject to understand the fundamentals and basic requirements you need to follow to ensure your repair is deemed safe and legal. We also discuss why your chassis may need welding and what you can do to prevent it from happening again.

What Is The Chassis And Why May It Need Repairing?

Fundamentally, the chassis is the backbone of any vehicle and its primary function is to support and carry the maximum load safely in all conditions. The chassis is designed to flex and absorb the engine and driveline torque even more so when navigating uneven road surfaces.

At some point, your chassis may need to be repaired by means of welding which is the structural fusing of the metal to repair, alter or reinforce the integrity of your vehicles’ chassis. This process is regarded as safe and legal as long as the required guidelines are followed, and a proper inspection is done upon completion.

Is Welding A Chassis Legal?

A direct answer would be Yes, chassis welding is legal provided you follow the guidelines correctly. The 6 points below are the general requirements to follow.

  1. Any structural welding, modifications, fabrications or repairs need to be carried out by a qualified welder.
  2. You will require a modification permit before making any alterations to your chassis
  3. The recommended repair or welding procedure must follow the manufacturer’s protocol. In the case of an older vehicle without a Vehicle’s Manufacturer guidelines the welding must be compliant with the Australian Standards.
  4. All repairs must be inspected and certified by an engineer. This guideline is first to ensure the safety of the occupants can be reasonably guaranteed and that the integrity of the vehicle has not been compromised due to the modification of the chassis.
  5. You will be required to have a roadworthy test done. The vehicle is tested and inspected to ensure the modification or repair has not rendered the vehicle unsafe to be on the road and lastly
  6. You will need to have a modification plate installed

Check Your States Legal Requirements

Just like every state has different licencing requirements its best to check your local legal requirements related to vehicle repairs. These details can usually be found on the roads departments website.

Is Chassis Welding Safe?

Chassis welding can pose several safety issues if the repair and procedures are is not carried out correctly and the appropriate guidelines are not followed. A chassis absorbs a tremendous amount of stress that is distributed throughout the lateral beams and if the welding is not done correctly this can lead to chassis failure or wear and tear of other integral components.

Some of the issues and damages that can result from poor chassis welding techniques and repairs include

Electrical System(s) Damage – If your welding is not carried out by a professional with the correct precautions in place, you could cause damage to your vehicles electrics such as the in-car entertainment system, car alarm, sensors etc. A professional welder will disconnect the positive terminal on your battery system to prevent any voltage pulses which may cause electrical damage to your 12v systems.

Uneven Tyre Wearing -It is possible to wear down your tyres unevenly due to incorrect weight distribution caused by any poor chassis repairs.

Incorrect Alignment – Your chassis repair can alter the alignment of your vehicle and result in what is commonly known as ‘crabbing’. Poor chassis welding repairs can also cause stress points when they are not able to disperse the load evenly.

The real possibility exists that once you have your chassis repaired it is essentially a structural modification and if not done correctly you may end up replacing the chassis in its entirety. Be sure to engage with a professional company that understand the procedures, legal requirements, has the correct tools and experience to safely repair a chassis.

Your chassis may need repair, strengthening or replacing for different reasons. The most common reasons involve damage and wear caused by cracks and rust. Rust is usually caused by salt water that is not washed off the vehicle and the salt slowly corrodes the metal until it is week and brittle. Vehicles that are used on unpaved roads often have the undercarriage literally sandblasted resulting in areas of bare steel exposed to the elements which also causes corrosion making the metal vulnerable to splitting.

Common Mistakes That Lead to Chassis Repairs

• Do not drill holes in chassis rail flanges or too close to other holes it results in perforation tares.
• Incorrect welding procedures ie undercutting, no preheat, slag inclusions, transverse welding of flanges etc
• An abrupt change of section ie square end on a reinforcement or body sub-frame
• Overloading of chassis ie vehicle loaded beyond its designed capacity
• Insufficient reinforcement
• Incorrect cross members ie torsion-ally stiff cross members
• Suspension too stiff (capacity of the suspension is greater than chassis capacity)
• Incorrect body mounting ie rigidly mounted tanker
• Excessive chassis cutouts, even grinding a notch on a flange can induce a crack
• Accident damage

Remember that a repair to your chassis should not be considered as a quick fix this needs to be done by a professional, repaired correctly and result in a legal and structurally sound job.

Early Warning Signs That May Indicate Chassis Failure

If you have had a repair done to your chassis be mindful of your vehicle’s capabilities and the way your vehicle handles. While not all chassis issues are noticeable it may be worth taking a closer look at the chassis repair if you recognize any of the below issues a closer inspection may well prevent further damage.

• Unusual suspension noise
• Rapid or uneven tyre wear
• Change in the way the vehicle rides, corners, handles etc
• Wheels misaligned
• Vehicle drifts at highway speeds
• Vehicle feels unstable

Related questions

How Much Is A Chassis Welding Job Going To Cost?

The costs of welding can vary widely anything from $20 – $200+. It ultimately depends on what needs repairing, the extent of the damage, materials required and perhaps the greatest cost is related to labour, whether the repair requires several hours labour or is just a quick patch. It also varies depending on who you get to complete the job and where you are located. The only way to get a definite price is to get someone out and get a quote. Remember you want to make sure you are using a reputable company that produces quality workmanship.

When To Repair And When To Replace?

This really depends on the extent of the repair and viability and costs associated with repair. If the repair consists of minor rust then it makes sense to fix the chassis extending its life for a reasonable financial input. If the repair is extensive and involves structural fabrication it may not be worth the effort and costs compared to the benefits of a new chassis that you gain an extended life out of and in doing so you ensure your safety and the vehicles integrity.

James Mitchell

Hi, I’m Jimmy Mitchell and I love exploring the off beaten tracks hopefully you’ll enjoy my 4 Wheel Driving Blog about my 4×4 adventures and looking at my photos. And hopefully you’ll be inspired to get out there and enjoy yourself in our great outdoors. We love being out on the open road. Exploring this vast country and all it has to offer. As an avid 4 wheel driver, I’m very keen to share my experiences and adventures. Through my blog, you’ll read about my personal take on 4 wheel driving, my experiences, my travels and adventures. My family and I are based in Western Australia so the majority of my adventures will be in the vast wilderness that makes up a huge percentage of this state. I drive a 2010 Nissan Navara ST that I am slowly building into a family tourer. I also own a 2015 PMX Stirling LX Camper.

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