How to Build a Rat Rod

Last Updated: February 27, 2020 References Approved

Usually a backyard or garage project, Rat Rods often start entirely from scratch, or by combining the parts from two junkers to make little engines that could. The ideal Rat Rod looks like it shouldn't be able to hold together, much less move. Revered as much for aesthetic as for practical value, Rat Rods are in constant need of adjustment and tweaking, making them a fun project for garage hounds with extra parts and time.

Part 1

Part 1 of 3:

Prepping the Frame

1
Procure an old car. Visit a local junkyard to check out the oldest cars that are still intact, which might make good candidates. Several Rat-Rodding websites also exist with links to possibilities.^{[1]
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Research source} Look for one that is not especially rusted, and has its essential shape is still intact. Typically, Rats are made from American cars, often pick-ups, manufactured pre-1960. Popular models for Rat Rods include:
- Mid-century Chevrolet pick-up trucks
- '30s-era Fords, esp. the "Model A"^{[2]
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- Early Chrysler hemi engines are popular, as well as flathead V-8s
2
Remove all interior elements from the car. To strip it down and start fresh, that means you'll need to remove all the seats, fixtures and other accessories from the car. Typically, cars used for Rat Rods are in pretty bad shape to begin with, in terms of the interior, making this step somewhat necessary.

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3
Drain all gasoline from the gas tank. Position a container under the drain cock, or remove one of the fuel lines and collect any gas remaining in the gas tank. This is an essential step in prepping the car for Rodding, as you're going to be doing a lot of welding and any remaining traces of gasoline will be dangerous. Keep a fire extinguisher ready in your shop or garage at all times while you're working.
4
Size the frame however you want it. Measure and mark where you want the vehicle's new axles and wheels to go, then cut the frame up to the desired length using a reciprocating saw. Since a Rat Rod is mostly about the look of the car, you'll mostly be flying by the seat of your pants anyway.
- It's usually common to shorten the rear of the vehicle somewhat to accommodate the axle and eliminate any elements, such as roofs or hoods, that you no longer want. Make any cuts to accommodate the drivetrain.
5
Improvise. It's also possible to build your own frame, using about 20 feet (6.1 m) of rectangular 2x4 steel tubing in the early stages, cut into two equal sections. Weld them together, patterned like a ladder, as square and as level as possible. Use one cross member toward the front, one in the back, and a crossing pattern in the middle to support the body. Match the width of the frame to the body you intend to use.

Part 2

Part 2 of 3:

Building From the Ground Up

1
Aim to keep it under $3,000. Among Rat-Rodders, it's a common goal to try to keep the total price-tag somewhere under $3,000 as a badge of your ability to work with limited materials. If you're up for a challenge, put your skills and your resourcefulness to the test and try to keep the project as cheap as possible by scrounging for a mishmash of parts in the junkyard, or on eBay.^{[3]
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2
Install new axles, shocks and suspension system. You can customize your suspension using the latest in modern suspension technology, making the Rat a hybrid of old and new. Having a Model A that turns on a rail? Yes, please.
- Start by measuring the rear width or rear body width and finding axles of the appropriate size. The axle should be somewhat longer than the width, and Leaf Spring rear axles are typically popular options because of their possibility for modification. Anything from the 60s and 70s is also popular, depending on the price.
- Install coil springs in a side-to-side or parallel pattern by welding the upper mounts on the cross member in the rear and the lower mounts to the axle housing. To keep it cheap, use a straight axle in the front, salvaged or new.
- The suspension from a Mustang II/ Pinto, AMC Pacer or Corvair are popular and useful choices, though ready-to-weld suspension kits are also available, sometimes for as little as a few hundred bucks, complete with frame and axle brackets, as well as template guides. It's a good investment, if you need new parts.
3
Mount the body on the frame. Old truck bodies are by far the most popular choice, but you can also make use of more modern fiberglass, which is forgiving and easy to work with. Customize your body and make the rod you want, cutting it for the crude-style and swagger you want from a good Rat Rod, then weld it to the frame.
4
Rebuild the existing engine, or install a new engine. try to remember: a Rat Rod is a semi-legal and wonky glorified go-kart, so don't break the bank with the drive train. An old Chevy 350 or a Ford 302 are both super-common and usually-cheap options that you could get and rebuild however you want.^{[4]
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Research source} Just get the thing running. The great thing about hot-rodding is that if you want to use an engine that really doesn't fit in the body, there's nothing stopping you from doing it but your own creativity and ingenuity. Make it fit. Leave the hood off and do what you want.
- You might consider selling the block from the car you got initially, especially if the heads are worn out, then using the extra money you got from the sale to get something from the same era that actually runs.
- Install any new starters or alternators as you install the engine into the frame. Make sure you have removed as much grease as you can from the engine before installing, then install the transmission and mount the drive shaft and the radiator. Hook up the steering linkage and install the pedals, welding any additional joints that will be necessary to keep the thing together.
5
Finish the job. You'll be close to running at this point, but you'll still need to install the brakes and tires to try to make the Rod as safe as possible. It might not be street legal, eventually, but you'll have to make the thing stop. Put in a seat, or cut up a couch and use something bootleg and hilarious. Rat Rods are amenable to any weird ideas you've got about cars aesthetically. Have fun with it!^{[5]
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Part 3

Part 3 of 3:

Styling Your Rat

1
Mount a windshield, side-view mirrors, and the rear-view mirror as necessary. Rat Rods will often go without typical car accessories. Windows, covered seats, and even doors are purely optional. Keep your tools handy so that you can continue to tweak your rat rod even after you've taken it out for its first ride. Customize it creatively.
2
Paint the body of the rat rod using matte or spray paint.^{[6]
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Research source} Some Rat Rodders like to leave the rusty exterior basically as-is, to show how tough and lasting the original was and remains to be. If you want a slightly more polished look, but want to retain some of the grit, go for a matte base coat with some brownish spray highlights that might resemble rust, but also seal the exterior and protect it some.
3
Give it a theme.^{[7]
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Research source} Popular at parades and fairs, Rat Rods styled with unique themes will often draw a crowd. Using unusual objects instead of a steering wheel, for example, might be a fun project that'll get people chuckling. Check out other Rat Rods for inspiration and do something unique and fun to make it worth your while.
4
Be original. Unlike hot rods, rat rods are customized cars that are not meant to resemble an antiquated original. Spice up your vehicle with odd adjustments and a colorful body, or dramatically alter the original frame to create an entirely new shape.

Community Q&A

Question

How much would this project cost me?

Community Answer

That depends entirely on your budget, but a common goal is to keep it under $3,000.
Question

Can I fit a V10 or V12 into a Rat Rod?

Community Answer

Of course you could! Many trucks and cars of old came with V10 and V12. You could also just completely build your own frame.
Question

Can I use any kind of frame to build a rat rod?

Community Answer

Yes, however, some frames look weird and clunky inside a rat rod, unless they are heavily modified to fit. Also, you need to make sure that your frame is strong enough to support the power generated by the engine. A large blown motor on a Miata frame for example, can twist it and destroy your ride.

Warnings

When making a rat rod, always keep a fire extinguisher nearby. Even if you drain all the gasoline, explosions are possible while welding.

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Take care when cutting and welding old metal. Surfaces can often be weaker than they appear, and the risk of contracting tetanus if old metal cuts the skin is great.^{[8]
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Mayo Clinic
Educational website from one of the world's leading hospitals
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