This isn’t my first encounter with a Ford Mustang Shelby GT500. I used to be as soon as lucky sufficient to put fingers on a spanking new 2013 Shelby GT500 for the categorical function of unleashing it on a cross-country road trip from Atlanta to Los Angeles. That automotive was a 662-horsepower blunt instrument that was made all of the extra beastly by a balky six-speed guide gearbox that would full a Zero-to-60 mph pace run in first gear.
However the powertrain was not probably the most knuckle-dragging facet of that automotive. No, that will be the solid-axle rear suspension, which solely jogged my memory how a lot I resented the Mustang for its cussed reliance on such truckish underpinnings. Oh certain, the 1999-2004 SVT Cobra had unbiased rear suspension, however that was a low-volume particular with a slipshod IRS adaptation. It hardly counts.
My opinion totally modified when the Mustang underwent its sixth-generation redesign. The 2015 Ford Mustang got here customary with a well-conceived IRS system that was equally spectacular on autocross programs and high-speed circuits alike. Now, lastly, this newest technology positive aspects its personal GT500, full with IRS, plus 760 horsepower, a seven-speed DCT and an non-obligatory Carbon Fiber Monitor Pack suspension and tire improve. I can’t wait to take a look.
This preliminary view of the GT500’s entrance suspension is basically hidden behind a large set of brakes, however a strut suspension (yellow) remains to be discernible excessive.
At simply over 16.5 inches in diameter, these pizza-sized entrance rotors are a full inch larger than these discovered on a GT350. These are composite rotors made by German supplier SHW, so named as a result of the 40mm-thick cast-iron friction ring is related to the central aluminum hub through a collection of stainless-steel pins. This development permits the rotor to drift considerably to curb vibration, however the aluminum middle part additionally trims unsprung weight. That’s going to be a theme with this automotive.
All sixth-generation Mustangs have a dual-pivot decrease linkage as an alternative of a single decrease management arm, however I noticed nothing however forged iron and metal the final time I crawled below a 2015 Mustang GT. Right here it’s plain to see that the GT500’s knuckle (yellow) and the ahead hyperlink (inexperienced) have switched to aluminum. As for the lateral hyperlink (purple), it’s nonetheless product of metal.
The metal lateral hyperlink takes up the lion’s share of the cornering hundreds. These can be immense in a performance-focused automotive just like the GT500, so this hyperlink’s internal pivot (inexperienced) employs a ball joint for optimum lateral stiffness. However the world isn’t easy, so the angled aluminum stress hyperlink has a excessive quantity rubber bushing (purple) at its internal connection level. Pothole strikes and different huge hits will are inclined to shove the hub rearward, and this bushing is there to take the sting off.
However the central concept behind a twin ball joint association is to maneuver the decrease steering pivot level outward to a spot that will in any other case be bodily inconceivable with a wishbone and a single ball joint. The steering pivot level here’s a digital one which resides on the intersection of traces drawn via the middle of every hyperlink’s bushings. If you happen to mission that time right down to the tire’s contact patch you’ll get a small scrub radius that enhances steering precision and direct really feel.
I scrubbed the steering backwards and forwards earlier than I acquired began, and these marks are the end result. They converge at a degree that’s barely inboard of the midpoint of the tire’s contact patch. The scrub radius isn’t zero, however it’s fairly small — which is not any imply feat contemplating the GT500’s huge 305 mm-wide entrance tires. A Ford engineer jogged my memory that the digital pivot level does migrate considerably as the 2 hyperlinks transfer about one another, and that makes it necessary to not get too grasping in your makes an attempt to create a zero-scrub radius. You don’t need the scrub radius to modify from optimistic to adverse because the digital level strikes about.
The GT500 makes use of magnetorheological dampers entrance and rear. This patented adjustable damping system seems on a number of high-end autos below the identify MagneRide, and its idea of operation differs from different adjustable dampers in a basic method. Right here the damper valving is fastened whereas the viscosity of the particular magnetorheological damper fluid is altered. MagneRide does this by repeatedly adjusting an electromagnet throughout the damper through this enter wire.
However there’s one thing odder nonetheless about all of this. Why is the wire popping out the underside?
The wire comes out the underside as a result of the Mustang’s MagneRide entrance struts are inverted struts. Not following me? Consider a daily monotube shock absorber. It must be a monotube shock so it’ll work within the inverted place. Let’s make it a Bilstein, too, as a result of their monotube shock our bodies are well-known for being yellow. A MagneRide damper is most positively not a Bilstein, however stick with me.
Flip your shock the other way up so the yellow physique is on high as an alternative of down beneath. Drop your upside-down shock shaft-first into the strut housing and join the shaft to the underside. As a result of that is an electronically-controlled damper, the management wire that runs via the shaft will exit out the underside. The polyurethane bump cease can be hidden down towards the underside, too.
Why do that? Inverted struts are immensely sturdy. You may immediately SEE how they’re in a position to deal with heroic cornering hundreds. However the GT500 isn’t the one Mustang that has them. Any Mustang with the MagneRide choice will use inverted struts. The GT500’s are tuned in a different way, however they’ll look the identical up below the mud boot.
Magnetorheological dampers are repeatedly variable dampers, so the pc that controls them wants to observe the place of the wheels with suspension peak sensors (yellow) in any respect 4 wheels, in addition to just a few g sensors.
Excessive cornering hundreds demand a stiff strut mounting construction, and this elaborate Ok-shaped strut tower brace offers that by tying each shock towers to the firewall, in addition to one another.
The GT500’s hole entrance stabilizer bar (inexperienced) is bigger than what’s fitted to some other Mustang. It has a 36 mm-diameter bar with four.eight mm wall thickness whether or not you purchase the Carbon Fiber Monitor Pack or not. The automotive delivers all of that, too, as a result of its ends are related on to the strut housing through a drop hyperlink, a well-recognized setup that produces a 1-to-1 movement ratio.
The GT500’s six-piston Brembo calipers have a set bridge for further stiffness, so that you’ll be eradicating them solely to vary brake pads. That’s executed by eradicating these “radial mount” bolts (yellow), which is a brake engineering alternative that emphasizes caliper mounting stiffness.
Other than that, you will have observed that the GT500’s wheel studs are uncommonly lengthy. I wasn’t in a position to verify it, however I feel they’re right here as a result of the Carbon Fiber Monitor Pack’s carbon fiber wheels have an uncommonly thick hub middle part.
These wheels don’t weigh a lot in any respect, which represents a big discount in unsprung mass. That’s clearly a powerful level, however a Ford engineer I spoke with stated that wheel stiffness is the extra vital profit. You might not notice it, however wheels can flex below excessive cornering hundreds, a state of affairs that reduces camber and alters the load throughout the tire’s contact patch. These carbon wheels are far more inflexible in that regard, and that permits the GT500 to take finest benefit of its very sticky (and really huge) 305 mm entrance tires.
These entrance wheels are 11-inches huge, and but the whole meeting weighs simply 50.5 kilos. How good is that? Terribly good. I as soon as measured a Mustang GT of the identical technology. Its 255/45ZR19 entrance tires had been mounted on 19-by-9 inch wheels, and that mixture weighed 56.2 kilos. This GT500’s carbon entrance wheel meeting is sort of 6 kilos lighter DESPITE having 2 inches extra tread width, one further inch of rim diameter and a couple of further inches of rim width.
The entrance rim does have a coating inside, nevertheless it’s not structural within the least. It’s a deposition coating that’s been utilized on high of the carbon to guard adjoining surfaces from the immense warmth generated by the brakes. The fabric is much like what you’d discover on susceptible spacecraft re-entry surfaces.
In the meantime, on the rear, brakes as soon as once more dominate the scene and block our view. This time it’s as a result of the difficult composite rotors are gripped by two calipers. The GT500 is the one Mustang arrange this fashion, and it required extra modifications we’ll see in a while.
Like all sixth-generation Mustangs, the GT500 makes use of what’s known as Integral Hyperlink rear suspension, a kind of multilink suspension that’s uncommonly good at enabling excessive lateral cornering stiffness and torque resistance whereas nonetheless providing a good bit of longitudinal compliance.
The primary part that attracts your eye is the large decrease arm (yellow) that operates like a decrease wishbone. From right here it seems like an A-shaped arm, however we’ll see later that it’s extra difficult than that. Simply in entrance is a shorter toe hyperlink (inexperienced) that has an eccentric for toe changes at its internal finish. Each are hooked up to an enormous aluminum knuckle (purple) that carries the rear wheel bearing and drive flange.
I’m making an attempt to point out how the forces move via these hyperlinks. Inexperienced represents cornering forces, whereas yellow represents the longitudinal backward pulse of sharp impacts. You may see how the bushings on the inexperienced paths may be optimized for cornering, whereas the decrease arm’s elevated internal pivot may be optimized to soak up the backward pulse as a diagonal tug throughout the arm.
In comparison with what’s occurring down beneath, the higher hyperlink (yellow) lives a relatively boring existence. It’s there to brace the camber angle on the higher reaches of the suspension, which isn’t a very troublesome job as a result of the contact patch is way sufficient away that it may get away with a single-shear mount (inexperienced). The dip in its form is there to clear the physique construction at full compression.
However there’s a problem. How does the higher finish of the suspension resist torque hundreds? Wouldn’t this simply flop about once you stood on the gasoline?
It really works as a result of our decrease A-arm is actually an H-arm. It has this further extension (yellow) that’s there to offer a mounting level for the integral hyperlink (inexperienced) that provides this suspension sort its identify. And that is how this suspension takes up torque hundreds, it’s why the higher camber hyperlink can function independently as a mere camber hyperlink.
Sharp-eyed sixth-gen Mustang followers might discover an even bigger distinction. Do not forget that second brake caliper we noticed just a few photos again? Nicely, the knuckle needed to be remade so the second brake caliper (purple) had one thing to mount to. However that led to extra modifications. Mustangs with out the second brake caliper have an extended integral hyperlink that extends up from the H-arm. However right here the secondary brake caliper eats up that area, so the GT500 has a shorter aluminum integral hyperlink that extends down from its H-arm. The knuckle isn’t simply completely different as a result of it should present caliper mounting factors, it additionally should present a decrease integral hyperlink anchor level.
The GT500 monitor pack’s coil spring has very comfortable higher coils that are supposed to go into bind (yellow) to primarily enable the automotive to take a seat decrease on stiff springs whereas nonetheless sustaining the “regular” free size frequent to all Mustangs. Notably, this nook of the automotive is jacked up on this picture and is even drooping considerably in comparison with what it seems like sitting on the bottom.
However it’s not dropping all that a lot as a result of the Monitor Pack model of the GT500 has a really giant 1-inch hole stabilizer bar (inexperienced) with hole part partitions which are four.5 mm thick.
The rear finish’s magnetorheological damper just isn’t inverted, and so its voltage management wire (yellow) comes down from the highest. There’s a urethane bump cease hidden behind the mud boot (inexperienced) however you’ll need to belief me on that.
Just like the entrance, the rear suspension has a peak measurement sensor that feeds into the MR damper ECU.
The picture angle is lower than excellent to make any concrete estimates, however you may at the least see that our H-arm has much more work to do. It should shoulder each load related to vertical suspension motion. Evaluating its innermost pivot on the suitable to its final attachment level on the left, the spring settles in about 45% of the way in which out, give or take. The stabilizer bar linkage is subsequent in line at about 65% of the way in which out, adopted by the shock absorber (inexperienced) at round 75% of the way in which out. These *very approximate* movement ratios characterize how a lot much less the assorted elements will compress for a given quantity of wheel journey.
The GT500’s rear brake hub is uncommonly skinny, and I’m going to guess that’s as a result of the carbon fiber wheel hubs are so thick. The carbon fiber wheel’s design isn’t precisely deep-dish, so the additional thickness of the difficult wheels needed to mission inward. This wheel thickness enterprise could also be why the second caliper was wanted within the first place as a result of the GT350 has a normal-looking rotor hat with a drum parking brake in-built. No room for that right here.
The rear wheel and tire meeting weighs 51 kilos, which is barely a half-pound greater than the fronts regardless of wider 315/30ZR20 tires and wider 11.5-inch rims. Why is the distinction so small? At first I assumed it is perhaps the coating, however the Ford engineer I spoke with stated that didn’t quantity to a lot. He advised that the entrance tires is perhaps heavier than the rears as a result of they’re constructed to steer the automotive and are subjected to increased cornering hundreds.
As for my 2015 Mustang GT comparability, its 275/40ZR19 tires and 9.5-inch wheels weighed 60.eight kilos again within the day. These a lot larger sneakers weigh virtually 10 kilos much less as a result of they use carbon fiber.
You may see why the 2020 Ford Mustang Shelby GT500 impresses me excess of the 2013 instance I drove cross nation seven years in the past. This automotive isn’t only a huge honking engine enveloped by skunk stripes and Shelby badges. It nonetheless is that, however the GT500 is now ALSO a critical well-rounded monitor weapon that maximizes the complete potential of the sixth technology Mustang’s lengthy overdue shift to unbiased rear suspension.
Contributing author Dan Edmunds is a veteran automotive engineer and journalist. He labored as a automobile growth engineer for Toyota and Hyundai with an emphasis on chassis tuning, and was the director of auto testing at Edmunds.com (no relation) for 14 years.
You will discover all of his Suspension Deep Dives right here on Autoblog.