"When the phone rings and it’s someone building a brake system from scratch, that’s actually a really fun time for me,” says Michael Hamrick, one of Wilwood’s top tech specialists. “That’s when we get to really form a relationship with someone and talk to them, ultimately, about what is going to make their car more satisfying to drive.”
What Are Our Needs?
Let’s start with the subject of this inquiry: a former ASA stock car chassis, No. 404 to be precise, built in 2004 for the now-defunct American Speed Association racing series. It’s one of our latest project car acquisitions.
ASA offered a NASCAR alternative, one that welcomed a lot of big names and cutting-edge technology to stock car racing–well, cutting-edge technology for that venue, like fuel injection.
[Learning more about tube-frame race cars | ASA tube-frame racer]
Our car, like every car in the series, started with a center section–the part of the chassis between the front and rear firewalls–constructed by Howe Racing. In some cases, a few different builders then finished out these center sections with their own front and rear subframes that met the ASA specifications. Our car was completed by Lefthander Chassis and features symmetrical front and rear subframes, although some of the suspension bits are asymmetrical and biased for oval track use.
Our chassis also came with a lot of Wilwood braking components, although they’re mostly period-correct for 20 years ago and designed for oval tracks. We went in knowing some updating would be required, as we plan to reorient the car for road course use. So we needed brakes that could handle a 2700-ish-pound, 500-ish-horsepower car on foot-wide slicks. And they had to be able to do it at places like Daytona and Sebring.
Let’s Chat About It
“When someone calls up who’s staring from square one, I almost treat it like a first date,” Hamrick explains. “It’s all about getting to know each other and understanding the needs, skills and habits of the driver so we can design around them.
“When it comes to the hardware,” he continues, “there are almost infinite options, although there are some limitations occasionally. So really the first thing I want to know is what does the driver like?”
If that all sounds a little touchy-feely, well, brakes are kind of like that. As we’ve beaten half to death in every piece of brake editorial, brakes are the most effective speed-changing device on your car, so maximizing their effectiveness is paramount to lowering lap times–and to building a car that’s more satisfying to drive.
A good supplier will want to know about your experience. What have you driven in the past, and what did you like–or not like–about the brakes? The supplier might also ask about your general driving tendencies–neat and tidy or toss and catch?–as well as your goals for the build.
“Even non-automotive background info can help us build a mental profile of what we’re trying to achieve,” Hamrick says. “Do you ride horses or motorcycles? Did you build your last computer or buy it? Ever do any dancing or play soccer? All of this stuff can give us insight into factors like how you relate to mechanical devices as a user, how technically inclined you are, and even how developed and how much sensitivity your leg and foot muscles have. All of that goes into our brake system equation.”
Our conversation opener focused on our most recent mount–a 550-horsepower C5 Corvette fitted with power-assisted brakes–and how we were moving into a car that would easily be the equal or better of the Vette but at a much lower level of sophistication.
Armed with that info, Hamrick could start making some generalizations, although we still weren’t in the realm of specifics yet. “So the brake setup that’s on the car now is probably fairly rear-biased,” he figured of our ASA car. “That was typical of oval track cars, as they use the brake for corner entry as much as they do speed adjustment. So it probably has equally sized front and rear rotors [diameter, yes, but width, no] and some older, fairly small four-piston calipers [also correct].”
With those generalizations out of the way, we discussed our particular braking philosophy, which mostly consists of “Give us all the brakes.”
Knowing that, Hamrick then moved to one of the next elephants in the room: “Coming out of that C5, you had 14-plus-inch rotors and power-assisted brakes. And here you’ll have a car that’s maybe a bit lighter but is probably going to have more grip on true slicks and be capable of speeds just as fast, if not faster, in a straight line. So I’m guessing you’re used to a relatively light pedal?”
Yeah, nailed it.
“So what we’ll have to do is work backward from the corners and try to tune the hydraulics to your liking,” Hamrick said. “And I think you’ll be pleasantly surprised with the effort. We can spec manual brakes to have fairly light actuation.”
This new setup wouldn’t feel exactly like power brakes, but we’d pick up superior feel and complete independence from engine vacuum. “Manual brakes are going to be exactly the same every time you hit them at any speed,” he noted.
Now to Discuss Hardware
At this point, we’d already learned a lot about what we wanted and needed before any mention of specific parts. As we’d learn, that’s an important part of the process.
When discussing a new build, Hamrick explains, he’d rather start with goals than part numbers. “Our customers tend to be knowledgeable and technically savvy,” he explains, “but they also might not have up-to-the minute info on the latest technology that we might be offering, or know how to mix and match bits from disparate parts of our catalog that may not be grouped together on the website.”
For us, that meant leading into some suggestions. The cool thing about our new car, Hamrick said, is that it’s basically a budget-friendlier version of a TA2-class Trans Am racer: 550 horsepower, tube-frame chassis, solid axle and 15-inch wheels. “So we can start by leaning on the known quantities from that series and adapt from there to suit your specific desires,” Hamrick told us.
His first recommendation was to replace our old bracket-mounted calipers with radial-mounted calipers. This, he explained, would allow us to fit a larger rotor inside those 15-inch wheels–basically, we’d be able run the TA2 setup that matches a 12.375-inch rotor with six-piston calipers.
And, he continued, those same radial-mount calipers would allow us to run even larger rotors should we decide to move to 18-inch wheels paired with IMSA-spec slicks. “With a radial-mount caliper,” he explained, “you have some leeway to space out that caliper from the hub and fit a larger rotor that can be used with your larger wheel package.” Options are always nice.
Floating rotors–where the rotor and center hat are joined via sliding fasteners–were also mentioned as a necessity. Per Hamrick: “This car is never going to the grocery store. The only time the brakes will ever be used will be in high-demand situations, which means lots of fast heating followed by hard cooling due to high speeds followed by fast heating, and so on.”
Our car came sporting two-piece rotors, but the outers were fixed to the hats. Floating rotors, which allow the iron rotor to expand and contract independently of the aluminum rotor hat, should lead to less warping and cracking.
The floating-rotor setup would let us run lightweight, aluminum center hats with traditional iron rotors. The sliding fasteners allow the two dissimilar metals to expand and contract at their own rates. If those two components are solidly bounded together, Hamrick explained, they could warp and then crack near the fastener junctions.
Homework Assignment
When our call concluded, we still didn’t have a comprehensive list of parts, but we had a solid plan of action. And that’s also something Hamrick wanted to drive home.
“When you’re starting from essentially nothing–and sometimes even when you’re upgrading an existing car without a lot of prior development–remember that it’s a process, not a product,” he cautioned. Your ideal setup might not involve a simple SKU; you might need to mix and match.
At this point, we had homework: Fully detail our current setup, including measurements, part numbers (if possible), and photos showing equipment both off and on the chassis so space clearances can be determined.
And it’s not about the calipers and rotors. How do our pedals mount? Where will all the lines and master cylinders go? It’s a fairly comprehensive assignment, but in the end we’ll have a system tailored to our very needs.
We feel this experience is a microcosm of everything else to come regarding this car: lots of research, lots of discussion, lots of options, lots of technology and lots of leaning on experts. To get the most out of that last item on the list, communication is as important as parts.
