Is It Legal to Weld a Truck Frame?

by WeldingWatch

Is It Legal to Weld a Truck Frame

A vehicle’s frame, also known as its chassis, is like a vehicular skeleton. It’s the underneath and keeps the car strong enough to do what it needs to. Sometimes, there are situations where welding the chassis can seem like the best solution, but the legal waters can be a bit murkier in places.

Federal law hasn’t made it illegal to weld the frame or chassis of a vehicle. They do state however, that any welding repairs should be in accordance with manufacturer’s recommendations. Local law can be a mite trickier, and it’s always recommended to get legal advice from a qualified professional before conducting any irreversible repairs or modifications.

Unlike some other countries, the US government tends to be pretty liberal when it comes to laws surrounding welding the chassis/frame. The rules surrounding welding frames can be found here. The only time welding the frame can be a problem is if either of the donor cars are listed as stolen or destroyed on the VIN registry. These cars are known as “cut-and-shuts”.

What’s a Cut and Shut?

A cut and shut is a car that has seen two or more cars used and welded together to make one functional car. The cut and shut relies on at least two cars that most of the time have had one end destroyed in a collision. A welder will cut the two cars in half and salvage the half that wasn’t impacted in the collision.

This is still a highly dangerous vehicle, even when attended to by a welder. This is because when a frame has been welded back together after being cut vertically by a welder, that car isn’t going to stand up to the required amount of force resistance during a high-speed collision.

In collisions, cut and shuts tend to fall apart quite quickly and injuries are a lot more common. The easiest way to check for a cut and shut is to check all the VIN points you can find on the car. If they don’t all match up, then it’s time to start asking questions.

What’s the Best Type of Weld for Truck Frames?

For auto work in general, frame or body, people tend to be divided between two main types of welding. The first is MIG welding and the second is Tig welding. Both are arc welding processes, but they aren’t exactly the same.

Tungsten Inert Gas (TIG) – This method of welding uses rods two directly bond two metals together. It would come less recommended for something like a truck frame. The reason for this is that TIG welding tends to work better on thinner metal pieces than thicker ones. The upside is that it doesn’t require a consumable filler, but you should definitely use one if you’re trying to weld a truck frame.

Metal Inert Gas (MIG) – MIG welding tends to be easier to use, easier to correct, and better for bigger welds. It uses a filler material to bond two pieces of metal together, creating a weld out of the wire filler being fed through the welder.

If you’re going to weld the frame of your truck at any point, it’s definitely advisable to use MIG over TIG. The ability to work with thicker welds, as well as being able     to fix minor errors with a lot more ease make it easy to understand why the more experienced tend to opt for MIG when it comes to auto-repair.

Who Is the FMCSA?

The Federal Motor Carrier Safety Administration (FMCSA) are the government body who are responsible for setting out rules to be followed regarding vehicular safety. The link above leads to the 393.201 rules that set out standards to be followed regarding frame welding.

Here’s a summary of them below:

  1. The frame or chassis of each commercial motor vehicle shall not be cracked, loose, sagging or broken.
  2. Bolts or brackets securing the cab or the body of the vehicle to the frame must not be loose, broken or missing.
  3. The frame rail flanges shall not be bent, cut or notched, except as specified by the manufacturer.
  4. Parts and accessories shall not be welded to the frame or chassis of a commercial motor vehicle except in accordance with the vehicle manufacturer’s recommendations. Any welded repair of the frame must also be in accordance with the vehicle manufacturer’s recommendations.
  5. No holes shall be drilled in the top or bottom rail flanges, except as specified by the manufacturer.

The rules they make are actual federal regulations. This means vehicles can be seized if they aren’t followed and passenger-carrying businesses can see fines which, left unpaid, can see enforcement action intensify.

What Equipment Will I Need for Auto Welding?

Chances are that if you’re reading this post, you’re likely thinking about welding your truck frame. Provided you’re not welding a commercial truck, you’re not going to invalidate your car’s eligibility to be on public highways.

If you’re just starting out, or are relatively new and want to know exactly what equipment you’ll need to make sure you’re in a good position to tackle whatever welds you need to, then take a look at our list below:

  • An Angle Grinder – When welding, you won’t be able to get your welds clean and flush all the time every time, so you’ll want an angle grinder to be able to grind away any excess filler and keep your weld sites clean and flush.
  • Pneumatic Saw – Lining up your fits when welding is important. A pneumatic saw will help you make very precise cuts and will help you line up the finer welds you’ll be making on the frame.
  • Aviation Snips – There’ll be times where you’ll need to cut patches out of sheet metal, and the easiest way to do this is with aviation snips. Good ones can cut out cold rolled steel at 18 gauge and stainless at 23. Useful for many welding disciplines.
  • Welding Clamps – Welding clamps that lock are the best option among clamps. They’re used for keeping metal in place while you weld. They’re especially useful when you’re welding from below.
  • Dolly Set – Used for shaping sheet metal, a hammer and dolly set can be essential to certain projects where you need to shape bodywork.
  • Body Hammers – As mentioned above, hammers are the tool of choice for body work provided they’re the right type of hammer.
  • Sheet Metal Gauge – Being able to gauge your sheet metal is invaluable, especially for MIG welders. This is because by being able to gauge thickness, you’re going to be able to get more accurate MIG settings working.

Safety Equipment

When you’re doing anything that exposes you to extreme heat, safety first is truer than ever. Make sure you get yourself welding gloves, a welding helmet and a welding coat. This may seem basic, but people have foregone them in the past and that’s the stuff campfire horror stories are made of.

How Can I Practice Welding When Starting Out?

When you’re just starting out, practicing welding can be daunting. You won’t want to practice on your car because you’re smart enough to know that’s a bad idea, so how are you going to practice and get good enough to confidently tackle your truck?

Your best bet to start is to undertake a course at your local community college if you can. It’ll set you up with a potential career if you’ve got certifications, and it’s the best way to learn if you’re not a self-starter.

If you are a self-starter but don’t know where to begin, then books and YouTube videos should be where you start your journey. If you learn all you can from books and videos first, and focus on the basics and fundamentals, you’ll pick them up a lot quicker when you do start practicing.

If you’ve done either of the above for long enough but need to actually practice now, then you’ll want to make a trip to the scrapyard. There’s no substitute for welding metal, but a scrapyard will have cheap materials you can pick up and practice on.

When you start practicing welding, start with the basics and learn from the bottom up. When you start practicing, you’ll want to practice breaking each weld you make to make it easier to correct mistakes and replace welds too.


It’s not illegal to weld a vehicle unless it’s a passenger-carrying vehicle, and even then commercial vehicles can have weld repairs made as long as they adhere to manufacturer recommendations. If you’re new to welding, don’t start on your truck. It’s best to work your way up to your truck by starting on scrap metal. It’s important that you consult legal advice on local laws about making welding repairs or adjustments to your vehicle, as local laws will differ. If it’s feasible, you’ll want to start a welding course to learn, and if not then pick up some books and watch videos to familiarise yourself with the basics.

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