Building a racecar from scratch sounds like an intimidating task, but if you start out with a solid plan, the process isn’t nearly as painful as you might think. There are some racers who have the skills to do this by creating their own plans, while others need a little bit of guidance to get the project going. S&W Race Cars manufactures a range of chassis kits to simplify the process for the end-user, from straightforward square-tube framerails to ready-to-assemble drag race chassis kits. We talked with S&W’s staff to get the lowdown on what it takes to build a chassis from scratch using one of their kits.
S&W Race Cars is a family owned and operated business that has been helping racers build their own cars for 60 years, with a large catalog of parts and full chassis kits. They cover the full spectrum of builds, from a Saturday night bracket car all the way to a five-second Top Alcohol Funny Car. Not only do they provide blueprints and parts to complete a build, but they can also construct a car for a customer in-house from a pile of tubes to a finished vehicle.
What To Look For In A Chassis Design
Before you even pick up the phone to place an order for parts to build your car, you need to have an idea of what kind of racing you plan to do. There is no one-size-fits-all chassis for drag racing if you want to be successful, so coming into the project with a plan and defined goals are important. If you try to build a car that is good at everything you won’t have the kind of success you hoped for.
John Burke is an engineer at S&W and has a wealth of experience helping racers build the best car possible for their style of racing. He adds some detail about what to consider when you’re beginning a new build.
“You want to build the car for the application it will be used for. With a dragster, if you’re going to run Top Dragster that will be different from a bracket car or Super Comp car. You want to hone in on what class it will be racing in. If you’re going to try and race in a Top Sportsman or a heads-up class, you want a light car made from chrome-moly. Bracket cars are a little easier to build, but you still have to take into consideration what kind of engine package you’ll be using.”
You know the car is the right fit for you when it feels as comfortable as a good pair of shoes to sit in. – John Burke, S&W
Being comfortable inside the car and within reach of all of the controls is another critical part of a car’s design. You should fit snuggly inside the car, but still, be able to get in and out without any issues. You should also be able to put on your helmet and other safety gear inside the cockpit easily if the chassis has been constructed correctly. A car can also be too big for a driver — you don’t want too much room inside where you aren’t secure in the seat or there’s too much room around you.
“If you’re a big guy and you want an Opel GT or Vega, that might not be the best option for you because it will be way too tight of a fit. Your knees won’t be in a good position, you’ll be close to the driveshaft, or if you’re taller, your head will be dangerously close to the roofline. The dragster guys want to build the biggest car they can for resale, or people will buy a big car for their child coming out of Jr. Dragsters, and that’s just not safe. You don’t want the fit to be so tight you can’t turn the wheel, but you also don’t want so much room you don’t feel secure in the car,” Burke says.
When you know what kind of racing you want to do and have a chassis style selected that fits you, the type of track you will be racing on needs to be taken into consideration. Not every track is as smooth as glass or has the best prep laid down. Let’s say you plan on racing a dragster in Super Comp or bracket racing: you have the choice between a hardtail or suspended-style chassis.
Burke and the team at S&W recommend if you will be racing on bumpy tracks to go with a dragster that has a suspension. The reason is that if you run a hardtail dragster on a bumpy surface, especially in the shutdown area, the car will tend to bounce a lot more. Door-car racers don’t have to worry about this issue since their cars have dampeners at all four corners, but Burke recommends a longer wheelbase car if the track surface is bumpy. In the end, it’s all about driver comfort, safety, and the consistency of how the car will perform.
One of the final things you want to look at when selecting a chassis is the SFI specification. If you don’t have the right SFI rating from the start, you’ll run into issues trying to get the car to certify for the type of racing or elapsed time you want to run.
“There can be a lot of confusion when it comes to SFI specs due to the number of them, especially for door-cars, because it’s based on the elapsed time and weight of the car. A lot of people want to build a mild-steel car because they have a Mig welder, but that limits you to how quick the car can go. You need to look into that before you start to build. Our chassis, whether you get them in mild-steel or chrome-moly, are the same — the only difference is the size of the tubing based on the specs,” Burke says.
Part of what plays into the SFI rating of a chassis are the materials used in its construction. S&W takes great care in ensuring all of its chassis kits are offered in the correct material for the intended application. For all of its dragster, altered, Funny Car, and roadster chassis, S&W only uses chrome-moly tubing. Door-cars are available in both chrome-moly and mild-steel based on the determined elapsed time and weight of the vehicle.
Burke offers some additional insight into the materials that are used in a door-car chassis kit.
“Almost all the tubing is going to be mild-steel DOM. Our kits use the larger 1-5/8-inch tube. We run a .134-inch sized wall because during the manufacturing process, when you bend the tube, there can be stretching that might cause thin spots. With .134-inch you won’t get any spots that are so thin the sonic tester will read it as failing. With the straight tubing, we go with .120-inch wall because it covers the mil-spec that SFI requires. Chrome-moly is all formed with a mandrel bend so there aren’t any issues with that becoming too thin.”
The S&W Approach And Build Tips
S&W has been in business for 60 years, and many staff members are racers and/or they serve a crew, and the more than 200 years of combined racing experienced gives the company unique insight into building a car. Since the company was part of the team that helped SFI develop its safety standards, its designs meet the accepted construction practices that are required. S&W begins every chassis design or new car build with those requirements in mind.
“We have a set way we like to hook our rear suspension components to the chassis that we use. The rear of the car we generally try to have it as wide as we can to get the biggest tire under the car as possible. We have a set design how the front suspension is added to the chassis and that’s based on the struts being used. The fronts of our cars are all about the same width because of the rack and pinion steering system we use,” Burke explains.
Looking beyond the build, S&W tries to create chassis designs that, when finished, are easy to maintain. Their goal is to ensure all of the major driveline components can be easily reached without having to disassemble the car. This ideology comes from working with customers and listening to their feedback on how to improve designs and keep up with current technology.
We want to make things where they aren’t confusing and the customer can have the confidence to build the kit because it’s user-friendly. – John Burke, S&W
When you order a chassis from S&W you won’t just get a box of random tubes taped together and some cryptic instructions. With a dragster kit, you receive a neat package that includes the tubing, mid plate, front motor plates, spindle bosses, bill of materials, general arrangement drawings, setup notes, and a chassis tag.
The bill of materials is cross-referenced to the drawings so it matches the supplied materials. This goes with the cut sheet that the shop uses to cut all of the tubing and is numbered before it’s packaged.
“When the customer gets their bundle of tube, the numbers on each tube will match what’s on the bill of materials and drawings. This is done so they can see what they have and where it goes. Everything is numbered and they’re given quantities so they can figure it out easier. If someone calls us and there’s an issue where tubes were missing, they can let us know what they need. It also makes it easier to figure out which tube is which if the number is rubbed off, because all the sizing is on the drawings, too,” Burke explains.
It’s an exciting moment when you receive a box of parts for a build from S&W. Before you tear into the box and fire up your welder, it’s best to ensure you have all of the right tools for the job. Things like a tape measure, a saw to trim tubing, a belt sander, tube notcher, grinder, and plenty of clamps are a good start.
“You can build a jig with materials from a scrap yard by making two parallel rails leveled off a garage floor. That is for the roadsters, altered, and dragsters. Guys who build door-cars will build the chassis inside the steel shell after making sure it’s square. They can also build a chassis jig if they want to,” Burke says.
After you have all the tools and have studied the directions, it’s time to start putting the car together. One thing that S&W recommends is to tack the car together before you begin any final welding. If that isn’t going well, you might want to consider taking it to a professional welder to have it done correctly.
Burke offers up the method S&W uses to build cars in-house and a good example of how to go about the process.
“We lightly tack everything in here when we’re building a car, so if someone bumps it that won’t cause parts to move. After the car is done we go through and add more tack welds before we pull it off the jig to be sure it doesn’t move out of shape. After that, we will then fully weld it when we’re happy how it all fits and looks. When you do that final welding you want to weld most of the bottom first, but we don’t start on one end and move to the other. We go back and forth from the front and rear so we don’t make an area too hot from welding on it. That spreads the heat out and will keep it from getting too twisted.
Building a car at home from raw materials doesn’t have to be an intimidating process. S&W Race Cars makes it easier for a savvy home builder to do it with a well-laid-out set of directions and quality materials. If you’re thinking of tackling a build of your own, talk to the team at S&W Race Cars to see what they can do to help you make your dream build a reality.