If you’re building a car for competition, it can be hard to figure out where to start aiding in your question to shave down lap times. Tires and brakes are great starting points, and you can only go so far with the engine and drivetrain components. What then, is your next step? That, fine Car Bibles reader, is tightening up the chassis.
Chassis bracing can help improve handling and performance by strengthening the car’s chassis, keeping all four wheels grounded to the ground, and pointed in the right direction. Car Bibles’ editors have driven enough loose-chassis cars around a track to know when it’s time for bracing, so stick with us as we dive into the basics.
Let’s get rolling.
What Is a Car’s Chassis?
A vehicle’s chassis forms the basis for every other part strapped to it. The engine, suspension, and body (the thing that gives a car its shape) are all mounted to the chassis. Chassis design can vary greatly from vehicle to vehicle, depending on the make/model and how it’s used.
Most passenger cars today are unibody design, which incorporates the frame and body into a single unit. Trucks and large SUVs utilize a body-on-frame system, which is when the body is mounted onto a ladder-style frame for high strength and stability under heavy loads.
What Is Chassis Bracing?
Because the chassis is the basis upon which all other parts of a vehicle are built, it’s crucial that it not only provides strength and support, but that it also be rigid enough to provide a stable ride. Automakers do focus on chassis geometry and stiffness, but sometimes it’s not enough. Chassis bracing, at least in the aftermarket, helps pick up the slack and can come in a variety of shapes, sizes, and applications.
Here are just a few types of chassis bracing:
- Strut tower bracing—Prevents strut tower movement and chassis flex in corners.
- Lower front bracing—Improves handling by amplifying the effects of a strut tower brace.
- Lower rear brace—Improves stability at high speeds and improves understeer.
- Rear cross brace—Tightens up rear end and improves understeer in cornering.
- Side bracing—Helps with vehicle weight transfer and works to improve the performance of other chassis bracing.
It’s also important to talk about roll cages. Beyond saving your life in a crash, cages act as chassis bracing by adding significant stiffness to a vehicle due to either being bolted directly to the chassis or welded to it. Think of the cage as an extra stiff skeleton that brings safety and rigidity to your performance car.
How Do Chassis Braces Work?
Chassis braces are designed to provide extra rigidity and strength to various parts of the vehicle. By reducing the amount of flex across the car’s width, bracing improves handling, grip, and predictability when pushing a vehicle hard. Strut tower braces, for example, improve handling by decreasing alignment shifts while driving, and rear strut braces can improve understeer in a front-drive car.
The whole goal here is to keep all four tires on the ground and pointed in the right direction. In performance cars or any vehicle with significant power, the engine and transmission alone can exert quite a bit of stress on the chassis, so it’s important to reinforce the base as much as possible.
What Happens When a Car Has Too Much Chassis Flex?
Too much chassis flex works against a car’s suspension system, and may allow wheel alignment and other issues to creep in. There may be more body roll and lean in corners, wheels may come off the ground, and the vehicle’s tires may wear unevenly.
Car Bible’s Glossary for Chassis Bracing
Welcome to bible school!
If you’re looking to go all-out with chassis bracing, seam welds are where it’s at. Where the automaker had robots to apply hundreds or thousands of welds to hold a car together, seam welding takes that to the next level by welding every damn seam together to hold body panels more tightly in place.
Alignment refers to a vehicle’s wheel positioning and the wheels’ ability to keep the vehicle traveling in a straight line. Alignment is measured with:
The angle of the wheel/tire in relation to the ground. Imagine looking at a car head-on or tail-on. Camber is the angle, or lean, that each wheel exhibits from these angles. Zero degrees of camber, then, would mean that each wheel is perfectly perpendicular to the ground.
The angle at which a wheel is turned relative to a straight-ahead position (think about french fry-pizza feet angles when skiing). Using the head-on viewing angle again, imagine that the two wheels on each side have a straight line drawn through them, front to back. Toe represents the inward or outward angle for each wheel.
These days, handling can be used as a term to describe everything from ride quality to performance on a race track, but its most basic and correct usage is to describe how a car performs in turns. In other words: Does it lean, does it understeer or oversteer, how much body movement is there under heavy braking, and how stable is it at high speeds?
The Car Bibles Questionnaire
Car Bibles answers all your burning questions!
Q: How do I know if my car has chassis bracing?
A. Some vehicles leave the factory with performance mods, such as chassis bracing. The most common forms of this are strut tower braces, which you can see by opening your car’s hood.
On top of the wheel arches, you’ll see the strut tower mounts. If there’s a bar connected to both sides, that’s a chassis brace. Since other forms of bracing are under the vehicle, you’ll need to check with your vehicle manufacturer to find specifics. We’re saying all of this with the assumption that you don’t drive a street car with a full cage installed.
Q: Do I need chassis bracing if I don’t track my car?
A. Chassis bracing, while certainly not a requirement, can greatly improve the handling of a street car. That said, adding chassis braces to a car that won’t be driven hard isn’t the best use of your money. Tires and brakes are a great way to improve handling prior to stepping up to chassis braces.
Q: How much do chassis braces cost?
A. It’s been said that car mods and racing are a great way to turn a large fortune into a small one, but some forms of chassis bracing aren’t all that expensive. A simple strut tower brace can be as cheap as $100, while the cost for a full roll cage can be $4,000- $5,000 or more, depending on the application and custom work needed.
Q: Can I make my own chassis braces?
A. You certainly can, but you should know more than a thing or two about your vehicle’s design and how it will react to the extra rigidity of bracing. If you’re looking to seam weld or add permanent modifications to the chassis, make sure you’ve done your research to add strength in the right places.
Q:Do I need chassis braces for my off-road rig?
A. Chassis braces can be a necessity for off-roaders, especially if you’re using a unibody vehicle like a Subaru or a crossover.
Q: Does chassis bracing add weight?
A. Depending on the type of bracing you choose, the answer will vary, but will always be “yes.” Adding structural rigidity will improve your lap times, however, so there’s a tradeoff between weight and handling.
Q: I don’t want chassis braces. What else can I do to improve handling?
A. The two most impactful “mods” you can do to improve your vehicle’s handling are tires and brakes. Upgrading to a dedicated summer or track tire will greatly improve your car’s grip and ability to remain stable in corners, while upgrading your brakes will allow you to approach corners at higher speeds and brake later.
The Chassis Bracing Video Tutorial
Car Bible’s Favorite Chassis Brace-Related Products
If you’ve added, or are looking to add, chassis braces to your car, it can be tough to figure out where to start looking for products to help you with your project. That’s why Car Bibles’ editors grabbed a few of their favorite products to get you started on the right foot. They include the Megan Racing Front Upper Strut Tower Brace, Mechanix Gloves, and Pro-Lift Jack Stands.
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