Why Suspension and Brakes Matter Just as Much as Your Engine

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Throwing a massive, powerful engine under the hood does not a performance car make. A hot rod, sure, but a performance car? Not so much. Of course, this depends heavily on your definition of “performance,” but a true performance car can do more than just blast down straightaways at mind-blowing speeds. It can also carry that speed eloquently into a corner, negotiate an apex, and carve through to the other side of it without making the driver feel as if he or she needs an FIA Super License. Power is one thing; getting that power to the ground is even more important. That’s where the chassis and suspension come in. Without the right combination of chassis rigidity, suspension tuning, tire selection, and braking ability, all that power your beefcake engine sends through your jewel of a transmission won’t mean much, as only a small portion of it will make it to the pavement.

Each vehicle in the Lexus F performance line comes equipped with a naturally aspirated V-8 engine that can rocket the cars to 60 mph in under five seconds. But to help translate all that grunt to the ground, a car needs a chassis that’s up to the task of making sure the driver doesn’t completely lose control when the right pedal is depressed all the way. For example, when we tested the Lexus GS F, we noted that the “handling isn’t just predictable; it’s accessible—a trait that’s become rare as these expensive sports sedans blend attributes of intercontinental ballistic missiles and roller coasters.” In addition to the unequal-length control arm front and multilink rear suspension, the GS F and RC F now employ a new-for-2017 Linear Adaptive Variable Suspension system, which features high-resolution linear solenoid electronically adjustable shock absorbers, to improve their ride and handling even further.

The Lexus RC F’s front control arms are made from forged aluminum.

A suspension that is too firm will make for a bone-jarring ride and skittish handling on all but the most pristinely paved circuits; one that’s too pillowy will have the car wallowing around corners as if it’s suspended on marshmallows. Suspension engineers spend most of their waking hours working to find the right balance between the two. The Lexus F performance line allows the driver to tailor the suspension via Drive Mode Select, but it’s also capable of additional automatic adjustability within the selected drive mode, based on driver input and road conditions. In all, damping force in the new Linear Adaptive Variable Suspension is adjustable over a range of 30 steps, allowing suspension compliance that’s suitable both for comfortable trips and composed jaunts on back roads.

But the dampers are not working on their own. One of the most important characteristics of a well-sorted performance car is predictability. To extract the most out of a car on a track or a nice road, you want to know that, barring any unfortunate mishaps, the car will respond to driver input—be it a squeeze of the brake pedal or throttle or a quick cut of the steering wheel—the same way every time.

The Lexus GS F’s torque-vectoring differential can help quell understeer when driving in Track mode.

Another tool automakers employ to help with predictability is a differential. A conventional limited-slip differential essentially works to distribute power to the wheels equitably. So, say you’re entering a sweeping left corner and, as the inside rear wheel starts to lose grip, the differential ensures power continues to flow to both wheels, including the outside wheel that has greater traction. But it’s passive, in that it simply limits the amount of slip between the drive wheels; it can’t be tasked with sending more power to the right or left independently of the available traction.

For the F performance cars, Lexus designed a user-adjustable torque-vectoring differential (TVD) that uses electronic actuators to engage a speed-multiplying planetary gear. The TVD has a response time of a thousandth of a second and can actively “overdrive” the outside rear wheel in a corner, which works to rotate the car in the direction of the turn. It can do this proactively, not just in response to a loss in traction. The TVD has three different settings: Standard, Slalom, and the most extreme, Track mode. When in Track mode, the differential is optimized for high-speed circuit driving, where stability and corner-exit acceleration are the focus.

A hallmark of modern performance cars is all the action happening behind the scenes to make the driver comfortable. But a performance car is not supposed to completely detach the driver from the road. It’s supposed to do the opposite. The great ones are able to communicate clearly what is happening at all four corners of the car. You’ve probably heard critics complain of a car’s steering being too numb or dull. What they mean is they can’t for the life of them feel any information on the road surface or grip level streaming up through the steering wheel.

As more cars move away from mechanical systems and toward digital apparatuses, it’s gotten increasingly difficult to create communicative steering systems. This is mainly due to some people perhaps not wanting all of that information when simply taking the car down the street to grab a cup of coffee. In an attempt to offset that and keep enthusiasts happy, Lexus tweaks the steering settings based on the selected drive mode.

Capping off all of these features is perhaps the most important: brakes. No matter how fast a car is able to go, how many g’s it’s able to pull on the skidpad, or how much you’re able to feel the road through the steering, if your car is not able to brake when you need it to in the way you need it to, it all falls apart. The main parameters with performance braking are swept area and heat. You want large rotors to maximize the swept area (where the pads contact the rotor), and you want a way to dissipate the heat generated from slowing the car. And, of course, the harder the brakes are used, the hotter they get. That’s why, when you watch a race at night, you see red glowing discs on each of the cars. But this heat has to go somewhere. The solution to this issue is to run the largest ventilated brakes you can fit onto the car. Lexus teamed with Brembo for a package that includes high-friction brake pads paired with six-piston, ultrastiff monoblock calipers and 15.0-inch slotted and ventilated discs in the front, and four-piston, ultrastiff monoblock calipers with 13.6-inch slotted discs in the rear. To put this in perspective: Some Lexus cars of the early 1990s had 15-inch wheels as standard. Today’s GS F runs brake rotors that size.

But that’s the way it goes. As the years have gone by and power figures have risen, suspension and brakes have proven to be just as important as, if not more important than, the engine powering the vehicle. Luckily, Lexus understands that.

Brembo supplies the RC F’s massive front and rear brakes.

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