Ask our Experts, we're here to help!
If you’re looking to take the performance aspirations of your vehicle from the street to the track, autocross is a great place to start. While some folks consider it to be simply a stepping stone into time trials or wheel-to-wheel racing, autocross is really a motorsport discipline unto itself; a format that requires specialized driving techniques as well as a vehicle that’s tuned to perform in this context.
“For a lot of folks, autocross is the migration from street use into more involved performance driving,” says Kyle Tucker, founder of Detroit Speed & Engineering (DSE). “I think that this really starts with the tires – tires are hugely important to a vehicle’s overall performance and for establishing the level of grip that you have to work with. I also think it makes sense to get a baseline of the vehicle’s performance before diving straight into suspension upgrades, by running it at a test-and-tune event or two. Getting an accurate baseline includes using tires that are in good condition with proper pressures, and having an appropriate alignment on the car. Alignment will have a big impact on a car’s handling as well.”
A great autocross suspension setup not only handles well, but also provides plenty of feedback and confidence-inspiring predictability. Experts recommend starting your upgrade program by first taking the car out and establishing a solid baseline for its performance at test-and-tune events.
Tucker says that the goal is to make the driver feel more connected to the car, and that’s accomplished not only by improving road-holding capability, but also by enhancing feedback and predictability. For those reasons, it’s important to establish a well-defined plan of attack for upgrades. As he points out, simply throwing parts at the problem and hoping for the best can actually do more harm than good.
“People have a tendency to go overboard with spring rates, or shock valving – or a combination of the two – and that can actually make the car handle worse rather than better. If the car is over-sprung for the car or the road surface, or the shock valving is off, the tire won’t be able to do its job as effectively. We want to maximize the contact patch, so the suspension needs to absorb road surface imperfections rather than bouncing off of them.”
Effective upgrades will not only improve cornering ability, and the car’s ability to handle predictably in a varied range of situations, it can also help to distribute loads more evenly between all of the tires. That balance will make it easier to utilize all of the braking capability on tap, and put power down when coming out of slower corners.
Here we’re going to take a closer look at suspension modification strategies for autocross-tuned vehicles. We’ll get the ball rolling with some basic upgrades that you can do to get an otherwise-stock vehicle prepped for your initial autocross sessions, then we’ll explore some of the more comprehensive upgrades you might want to consider if you’ve got some experience under your belt, and finally we’ll look at the upgrades that can help a seasoned autocrosser shave those elusive tenths off their run times.
Balance is one of the biggest keys to an effective autocross suspension setup. By distributing loads as evenly as possible between all four tires, you can get the most from your car's potential performance.
For those who are looking to get involved in autocross, there are a few suspension upgrades that will make a world of difference in an otherwise-stock vehicle without breaking the bank or dramatically altering the vehicle’s road-going drivability.
“After tires, my priorities at this level have always been sway bars and shocks,” Tucker says. “As much as the driver’s braking and acceleration inputs dictate weight transfer to the front or rear of the car, the sway bars, or anti-roll bars, dictate the lateral weight transfer. With a relatively stock vehicle, you only have so many knobs you can turn to affect handling and provide feedback to the driver. But bars will do that. They can turn a ‘loose’ [oversteer-biased] car to ‘tight’ [neutral, or understeer-biased] or vice-versa, depending on what you choose for front and rear bars.”
Experts say that improved shocks are one of the best values when starting to make autocross suspension upgrades on an otherwise stock vehicle, making them a great modification for anyone looking to try their hand at the sport for the first time.
Generally speaking, a stiffer rear sway bar is going to promote more oversteer in a rear-wheel drive car, while a softer bar will shift the vehicle’s character more toward understeer. A bit of rotation can be useful on tight autocross courses, though, so you’ll likely want to find the sweet spot that delivers ‘neutral’ behavior. While that can be tough to accomplish without some trial-and-error testing, sway bars with adjustable end links can provide the flexibility needed to fine-tune the car’s setup over time.
“If someone is planning to autocross regularly, I always recommend an adjustable bar,” Tucker says. “That fine tuning can also help dial in the car for a particular course and road surface, too.”
He adds that the front sway bar is even more important than the rear bar when it comes to adjusting a vehicle’s lateral behavior.
“If you use too soft of a bar up front, you’ll get too much body roll and too much weight transfer onto the tire, which can cause the front to push [understeer]. And if it’s too stiff, you don’t get enough weight transfer, and that can create an understeer condition as well. Typically you want a setup that minimizes roll but still allows for some weight transfer across the front axle.”
Click here now to see Detroit Speed's full line of sway bars.
Sway bars, or anti-roll bars, dictate the lateral weight transfer of a vehicle. Although many vintage vehicles came from the factory with sway bars, they're typically nowhere near adequate for the rigors of autocross. Aftermarket sway bars, like this one from Detroit Speed, are more effective and offer much greater adjustability.
When it comes to shocks, whether it’s an OE-style replacement or a coilover, at this level the main goal is to increase the suspension’s rebound response over stock to help keep the tire planted. “More rebound essentially equates to more suspension force pressing the tire down into the pavement,” says Tucker. “The greater force value you have in that shock curve, the harder that tire is going to be driven into the pavement.”
He also says that steering upgrades can make a big difference at this level, especially for vintage platforms. “Having a quicker steering ratio than stock can be really beneficial on an autocross course because it will require less rotation of the steering wheel to point the front end where you want to go. This, along with increased steering angle, can make it much easier to be precise on really tight courses.”
Check out Detroit Speed's quick-ratio steering box now.
Steering upgrades can make a significant difference in the way vintage cars drive and how successful they are on an autocross course. This Detroit Speed steering box is a bolt-in replacement for a wide array of popular General Motors vehicles. It has a quick 12.7:1 ratio, with a more direct feel and response than OEM units.
If you’ve been autocrossing for a while and you’re looking to take your car’s on-track capability to the next level, there are also some more comprehensive upgrades that can have a meaningful impact on a vehicle’s handling prowess. As Tucker explains, these upgrades tend to follow the same logic as the initial modifications mentioned above, but bring an emphasized focus on tuning.
“This is where you’re looking to dial in the setup a bit more – upgrades that will allow you to get more aggressive with the alignment, and coilovers that offer adjustability beyond rebound. It’s also where you might want to look at chassis upgrades that will increase rigidity.”
Click here now to see Detroit Speed's coilover kits.
All coilovers aren't created equally, even from the same manufacturer. Better coilovers allow adjustment of more parameters than entry-level units, making them a worthwhile upgrade as you start to get serious about laying down competitive times in autocross.
In terms of the latter, upgrades like subframe connectors don’t change the suspension setup itself, but they do improve the suspension’s performance. “Torsional rigidity is especially important on older cars – you need subframe connectors so the body doesn’t also become a tuning element of the car,” he says. “If the chassis is flexing, it actually affects the suspension geometry and its ability to function efficiently. So anything you can do to take flex out of the equation will improve suspension performance.”
More sophisticated coilovers also enter the picture at this level. While the ride height and rebound adjustability of a basic coilover allow for a significantly more tunable suspension than a stock setup, coilovers with both rebound and compression adjustability can allow a driver to really hone in on tuning that suits their vehicle, their driving style, and the characteristics of the course that they’re driving on.
“You would want something that’s at least two-way adjustable here,” Tucker tells us. “And you want the ability to tune the shock pressure. Shock pressure is, in effect, spring rate. That means that a quick shock pressure adjustment at the track is going to alter some of your spring rate as well.”
Click here now to see Detroit Speed's full line of subframe connectors and chassis stiffening components.
Most older cars aren't known for their rigidity and stiffness. The flex that they're prone to compromises the effectiveness of their suspension when faced with the high cornering loads typical of autocross. Fortunately, there are a number of relatively simple remedies, such as these Detroit Speed subframe connectors.
He also notes that most vehicles don’t see significant suspension travel in an autocross setting because the surface is relatively flat and smooth, so the shock tunability emphasis here is more about low-speed control rather than high-speed control.
“So here you dial in a lot of compression and a lot of rebound to press that tire into the pavement as hard as you can, but how far you can go really comes down to the pavement that you’re working with. One parking lot is going to be different from another when it comes to the mechanical grip levels, so being able to fine-tune the shocks for each situation is going to help.”
Autocross courses are flat, and driven at relatively low speeds. That said, pavement surfaces and the grip they provide vary considerably from course to course. For this reason, it's best to be able to tune your shocks for a wide range of conditions.
Tucker also offers some advice for those who autocross competitively and have noticed that their performance has plateaued.
“We’re assuming that the driver is being taken out of the equation,” he says with a laugh. “And that’s something you really need to take into consideration. As you go through this progression as an autocrosser, it’s common for people to enter into it cautiously, and really critique themselves. And as they get more experience, their driving style also gets more aggressive, and often times that aggression is the limiting factor for the car’s performance. Part of the goal, as a driver, is to really get to know the car and work with it rather than against it.”
See Detroit Speed's Speed Kit suspension systems now.
Factory suspension components were built for a very different mission than competitive autocross, and they were designed when vehicle dynamics weren't widely understood. Detroit Speed’s Speedkits are a modern, purpose-built suspension system that bolts onto your stock chassis, thereby overcoming most of these limitations.
He says that experimenting with brake pad options, alignment specs, and the aforementioned tuning options for adjustable sway bars and coilovers can often help a driver shave additional time off of their runs. That said, it’s also possible for a driver to simply reach the limits of a factory-style suspension setup.
“If you do feel like you’ve maximized everything you’ve currently got, you’re probably at a point where it’s going to take more than swapping bars and coilovers to make a meaningful difference. At this level, particularly with a vintage platform, a stiffer, more advanced front suspension system with aggressive camber and caster curves, and more overall adjustability is your next stop.”
Check out Detroit Speed's QUADRALink rear suspension systems now
When you're upgrading your vehicle's suspension, don't forget about the back end. This Detroit Speed QUADRAlink rear suspension system is a vast improvement over the stock setup, offering improved geometry and much greater adjustability.
Packages like Detroit Speed’s Speedkit systems can provide a holistic approach to suspension upgrades that minimize the customary legwork required and ensure that all of the components you’re selecting will work well together. Meanwhile, systems like DSE’s subframe assemblies – which serve as complete front suspension system replacements – can change a vehicle’s handling behavior on a truly fundamental level while also improving packaging for wider wheels and tires.
“With the independent front suspension on an early muscle car, you’re limited by the factory geometry and the adjustability that comes along with it,” says Tucker. “But a well-designed aftermarket system is going to give you new geometry, which typically means a more aggressive camber curve and more aggressive caster settings, along with more adjustability for both of those attributes.” DSE’s QUADRAlink and DECAlink systems offer a similarly comprehensive solution for vintage rear suspension systems that delivers revamped geometry, improved tire packaging, and far more tunability than the factory-style setups for vintage platforms.
Click here now to see Detroit Speed's full line of subframe assemblies.
The best way to overcome the limitations of your stock suspension and chassis is by replacing them altogether. This Detroit Speed subframe suspension assembly features hydroformed frame rails, compromise-free suspension geometry, and premium components, making it an excellent autocross upgrade.
Tucker also has a few reading recommendations for those who are looking to get a better understanding of how to approach suspension tuning. “Some of the books I learned the most from were Engineer to Win, Tune to Win, and Drive to Win by Carroll Smith. Carroll was an engineer, but he had a way of approaching things with a racer’s mentality while making it easy to understand.”
In the meantime, Tucker suggests that folks who have questions about their projects can simply give the folks at Detroit Speed a buzz at (704) 662-3272 to get knowledgeable insight from experts in this specialized field.
“Our guys can help troubleshoot parts, and even help troubleshoot some setups. At times they’ll come to me, too, and I’ll share some of the setup books that I’ve raced with over the years. That’s all available; it really just comes down to how serious a customer is about getting that type of information.”
SEE THE FULL LINE OF DETROIT SPEED CHASSIS and SUSPENSION COMPONENTS AT: DetroitSpeed.com
.
