Last month we kicked off our Camaro-Mustang Challenge road race project with an introduction to the class and an overview of the selection and preparation of the donor '95 Mustang GT chassis. This month, we start building it. If you missed Part 1, you should know that the CMC is a bucks-down series designed as the ultimate grass-roots level of road racing. And even if you don't plan to build an all-out racer, most of the build will transfer to any Fox Stang. With that said, we'll get started.
Last month we did the deed of stripping and repainting the interior and front clip from the firewall forward, so now we can begin the fun part of bolting on the suspension and brakes.
The CMC rules make selection of chassis and braking components relatively simple, as the modifications allowed are minimal and require retaining mostly stock parts and geometry. Major components that can be upgraded are shocks, springs, and bushings, but suspension geometry and major control points and components must remain stock. With a few years of experience in the class with our previous car, we had a solid baseline setup already figured out and knew just where to turn for the needed parts-Maximum Motorsports.
Most readers are familiar with Maximum's full-on road and drag race suspension components consisting of tubular K-members, coilovers, and torque arms-but none of that stuff is legal in CMC. If you dig a little deeper into Maximum's catalog, though, you'll see that the company has a starter suspension kit called the Road & Track Box that is ideally suited to CMC. Consisting of upgraded shocks, springs, caster-camber plates, aluminum rack bushings, a bumpsteer kit, K-member braces, upgraded control arm bushings, a solid steering shaft, and rear lower control arms, these parts form a solid suspension foundation and are essentially a turnkey suspension system for a CMC Mustang.
You can tailor the spring rates and shock selections to the intended use of the car, and for our race-only setup, we selected MM's race-valved Bilstein front struts and Bilstein heavy-duty rear shocks to match our 1,000-pound front and 250-pound rear spring rates. Installing the parts is pretty straightforward, and the photos and captions hit the highlights. We'll get into suspension setup and tuning in future installments.
Mustang springs are available...
Mustang springs are available from numerous sources in a dizzying array of rates and heights. Given the limitations of the stock Mustang front suspension geometry, avoid the temptation to drop the car into the weeds. It may look cool, but it will place the front roll center too low and the car will handle poorly. As a general rule, Mustangs with stock K-members should not be lowered more than about 1.5 inches from stock ride height. We used 5x11-inch 1,000 lb/in linear-rate springs from Suspension Spring Specialists, trimmed a half coil to adjust the ride height, and matched them to a pair of Maximum Motorsports race-valved front struts. Note the reinforced strut mounting ears (arrow) that are a MM exclusive.
Adjustable caster/camber plates...
Adjustable caster/camber plates allow easy adjustment of the front suspension alignment settings. Maximum Motorsports' four-bolt plates for '94-'04 Mustangs require drilling one additional hole in the top of the strut tower to better distribute the load on the plates and eliminate bending the unsupported corner that can occur with other designs. The upper spherical bearing is strong enough to support the full weight of the car in coilover applications.
The CMC rules allow open choice...
The CMC rules allow open choice of bushing material, ranging from stock rubber to polyurethane to spherical bearings in the control arm pivot points. For the front lower arms, we selected Maximum Motorsports' offset delrin-aluminum bushings, which provide minimum deflection under high cornering loads. Offsetting the front LCAs forward about a half-inch improves caster and increases straight-line stability and steering feel.
In the rear, rules limit upgrades...
In the rear, rules limit upgrades to aftermarket rear lower control arms and alternate springs and shocks. Installing an aftermarket Panhard bar is also legal, but we chose not to use one on this car after considerable experience with one on our old car, preferring the higher rear roll center of the stock four-link suspension. Instead, we chose Maximum's Severe Duty lower control arms with spherical bearings on both ends to plant the rear axle, along with 250-pound linear rate rear coils from an '03 Mach 1 combined with Bilstein HD rear dampers.
There are two ways to fit...
There are two ways to fit a 12-inch front rotor under the Cobra/Bullitt/Mach 1 calipers: you can have OE 13-inch Cobra rotors machined down to 12-inch OD (shown) or use the front rotors from an '02-and-up Crown Victoria for a bolt-on solution. We've used both with about equal results, and although we prefer the quality of the OE Cobra Brembos, the Crown Vic rotors provide off-the-shelf availability at any auto parts store without any special machine work. To accommodate the smaller 12-inch rotor, the bolt-on caliper anchor brackets must be redrilled to locate the caliper closer to the spindle centerline. Again, you can tap a local machine shop to make the modification, or even easier, source pre-modified brackets from Baer Racing.
New Cobra twin 40mm piston...
New Cobra twin 40mm piston PBR calipers are still available from Ford Racing. Plain Mach 1 calipers are the best bargain going for about $200 for a new loaded pair complete with new anchor mounts and stock pads (sell them on eBay to offset the cost). Choosing among the numerous racing brake pad compounds available is largely a matter of driving style and personal preference. We've had excellent results with Hawk's DTC-70 pads, which combine excellent initial bite and modulation with good rotor and pad life.