Project Fox Body Update 2 | Suspension, Wheels, Tires, Brakes
Thanks for tuning back in! Last time we shared the exciting news announcing our Foxbody project. If you haven’t seen that article, click here to catch up. For everyone else that wasn’t tardy to the party, let’s dive in!
In our previous installment we briefly touched on the continued innovation our Ridetech team continues to display in their newest suspension products. Not to downplay the performance of old cars back when they were new, but the lingering effects of OPEC and stringent EPA regulations were impacting muscle and sports cars of the day. In addition to that, the suspensions they put under these cars were equally lazy, especially by today’s standards. A lot of cars, including our Mustang, negotiated corners with Mcpherson strut-type designs, and the rear end struggled to keep up with the front tires with their limited stick/solid axle rear ends, with no alignment adjustment capabilities.
Many enthusiasts tend to build “me too” cars from time to time. Kind of a “if it was good enough for so-and-so, it’s good enough for me” vibe. However, we wanted to pull out all the stops with our Foxbody’s suspension. The aged McPherson struts were chucked into the nearest bin, and the OE solid stick axle? We know it’s not as tough as a burly 9-inch, but does anyone need a spare 8.8?
Many enthusiasts tend to build “me too” cars from time to time. Kind of a “if it was good enough for so-and-so, it’s good enough for me” vibe. However, we wanted to pull out all the stops with our Foxbody’s suspension. The aged McPherson struts were chucked into the nearest bin, and the OE solid stick axle? We know it’s not as tough as a burly 9-inch, but does anyone need a spare 8.8 to go drag racing?
Our team ultimately came up with a double wishbone design that we call our Foxbody Front SLA suspension. Installing it in place of the prior setup, it employs a short A-arm up top, a longer A-arm below. A Ridetech coilover locates inside the lower A-arm and mounts to the frame up top. This design enjoys a more desirable camber curve as it articulates through its travel. In addition, caster, roll center, and Ackerman angles were optimized, making for better handling and steering feel. The stock steering rack is retained along with the factory track width. Maximum front tire width improved a bit as well (our car is sporting 275mm, but we’ve done some massaging of the fender wells, etc. It is compatible with stock subframes, but we also have a version that is compatible with most aftermarket front K-members. Both upper and lower ball joints accept a Ford-bearing style version of our Ridetech’s AFX hub spindle.
This cast iron hub spindle allows for the installation of newer SN95 brakes or, newer still, S550/S650 brake packages. The latter series brakes translate to modern braking technology including bigger six-piston calipers and larger rotors. If you’re keen to keep an eye on car-part.com or similar auction type sites, you should be able to score some factory Brembos on the cheap, but we went ahead and tapped the shoulder of our friends at Wilwood for braking duties.
Since we were going with S550 brakes, Wilwood recommended their S550 AERO series brakes package. That system is comprised of six piston brake calipers mated to 14’’ slotted rotors up front, and out back a set of four piston calipers and 14’’ rotors round things out. We’re doing our best to document all the weights of components as we install them on the car. A standard Ford Mustang rear rotor weighs 28.2 pounds, whereas Wilwood’s Aerolite rotor comes in at 20 with the rotor hat installed, netting an 8.2 lb. savings on each rear corner (16.4lbs). Each caliper comes in at 14 lbs. One of the primary benefits of being able to lower weight with brake components is that we are reducing the unsprung weight of the vehicle.
Unsprung weight simply refers to any components of the vehicle that aren’t carried by the weight of the springs. Generally speaking reducing unspung weight reduces the amount of work required by a spring and shock to maintain a tire’s contact with the road surface. Furthermore, a car with reduced unsprung weight will typically handle cornering, braking, acceleration events, much better all while having improved ride quality.
Wilwood stainless braided brake lines are responsible for hydraulic fluid transfer of the EXP 600 Plus brake fluid, reducing flex in the system and helping maintain positive pedal feel. And when it comes to pedals, a S550 drive by wire accelerator pedal and Wilwood pedal box replaced the factory pedal set.
Shifting toward the back, the live rear axle is no longer with the living and has been replaced with a complete Ridetech developed bolt-in IRS conversion. Like the front suspension it is designed to work with S550 drivetrain components, including shortened S550 axles (street and race versions will be available), the center chunk, and the same high tensile strength ductile iron hub spindles we’re using in our front kit which accepts the later gen brake package. The ball joints that will come with the system are Moog variants, guaranteeing serviceability over the use of the car, as well as maximum strength, consistent braking, and reduced maintenance.
While the installation of this IRS system does add around 50 pounds to the car, we’re unconcerned as that weight accumulates at a low point in the rear of the vehicle, keeping the weight controllable and helping the overall weight bias front to rear. With the amount of weight we’re saving by switching to a fiberglass hatch, we’ll easily make up for the additional pounds out back.
Each corner of the car will utilize lightweight one-piece forged Monoblock Forgeline GS1R wheels measuring 18 x 10’’ and weighing in at 19.90 lbs. per wheel. Sticky 200 treadwear Kumho V730 Ecsta tires measuring 275/35/18 and weighing 28.4 lbs. per tire provide a square tire setup, providing a much wider contact patch over stock at both ends of the car.
Shifting on to exterior bodywork, we mentioned that Foxes were light from the start. But when you’re building out a racecar, necessary additions to the car, i.e., the roll cage, inevitably add some weight back into the car. That said, we wanted to make sure that we were able to make up for lost ground for those needed additions by saving lbs. in other areas. A set of fiberglass fenders, doors, and rear hatch will go a long way in removing some weight across the entire car compared to the factory metal.
We fully expect to add a splitter and partially flat bottom to the front of the car to keep it from feeling too light at higher speeds along with a chassis mounted rear wing adjustable rear downforce. More to come on that in a future update.
That about sums it up for this installment of the development of the Ridetech Fox Body race car. Stay tuned for the next one!
