1993 Ford Mustang Notchback - Captain Hook - PHR Project Car
What Does It Take To Hook 775 Hp On 10-Inch Drag Radials And A Stock Suspension? Just Some Good Parts And A Sharp Chassis Man.
From the November, 2009 issue of Popular Hot Rodding
By Stephen Kim
Photography by Stephen Kim
The Fox Mustang's factory...
The Fox Mustang's factory triangulated four-link rear suspension is an extremely capable setup. With the addition of quality aftermarket components from Competition Engineering, the stock design can rival the performance of ladder bars or aftermarket four-links at a fraction of the cost.
Muscle car magazines have rarely been advocates for progressive and socially responsible behavior, but our past transgressions of apathy are about to change with Project Fox. PHR's '93 Mustang notchback is very green-Ford Calypso Green Metallic to be exact-and with a 532ci big-block Ford mated to a GM TH400 trans, it boasts the latest in hybrid technology. Making power is only half the battle, however, and getting Project Fox's 775 ponies to hook on skinny 10-inch-wide drag radials and a stock-style suspension is no easy feat. Or is it?
Sanctioning bodies such as ORSCA, PSCA, and others have made the Fox Mustang one of the most popular platforms for small-tire class drag racing in existence. Without the assistance of ladder bars or aftermarket four-links, Fox Mustangs have run as quick as mid 7s at 185 mph on 275/60R15 drag radials, which works out to just 28x10 inches. Since these pioneers have already done the dirty work for us, emulating their suspension setups and bolting on the same Mickey Thompson meats they rely on is a great place to start in our quest for 9-second e.t.'s. Most importantly, by putting the power down instead of helplessly spinning the tires in a stationary stupor, we'll be doing our part to reduce our Mustang's carbon footprint.
To make everything hook on such a limited contact patch, we ordered a heavy-duty rear suspension setup from Competition Engineering. The goodies include adjustable upper and lower control arms, springs, adjustable shocks, and a beefy drag-spec sway bar. Getting Project Fox's underpinnings track ready, however, is a bit more involved than simply bolting on some new parts. Since the Mustang's unibody was designed to handle just a hair over 200 hp, it needs reinforcement in several key areas to prevent the suspension pickup points from separating from the body. Manning the wrenches once again is expert chassis man Bill Buck of Bill Buck Race Cars in Austin, Texas. Before heading out to Route 66 Raceway to tune on Mike Murillo's 6-second Outlaw 10.5 Mustang last July, Buck showed us what it takes to get hooked even when packing only a quarter of the horsepower he's accustomed to.
9s For $25K
In our haste to get crackin' on Project Fox, we've neglected to formally introduce you to the newest member of PHR's project car garage. The plan is simple: Stuff a 775hp big-block into a 3,000-pound car, and run 9s. To make things more interesting and spice up the charismatically challenged nature of late models in general, our goal is to run single digits on a stock-style suspension and Mickey Thompson 275/60R15 drag radials. To top it all off, the budget has been set at $25,000, and the car will retain a full interior, real glass, stereo, power windows and door locks. Did we mention that it's going to be completely street legal, and drive to and from the track without a trailer? In order to keep things simple and minimize costs, we've already built a 532ci big-block Ford engine, a Phoenix TH400 trans, and an 8.8-inch rear end. Likewise, the factory EFI has been tossed in favor of a carb, and running small tires will eliminate the need for mini-tubbing. Although the car will see occasional street duty, we won't kid ourselves or question your intelligence by claiming it will be used as a daily driver. And that's exactly the point. By establishing a realistic purpose for the car, stuff like fuel injection, overdrive, rear disc brakes, and locking diffs are now pricey and frivolous doohickeys. In future issues, we'll tackle the fuel system, front suspension, rollcage, interior, cooling system, exhaust, engine and trans swap, and chassis tuning before finally running Project Fox at the track. Sure, our Mustang falls well outside the '64-'72 sweet spot, but it's too new to be rusty, and the principles of building a hard-core street/strip drag car are universal. And who can argue with cheap speed? -Stephen Kim
|THE COST SO FAR |
|Story: ||PHR Issue: ||Price: |
|'93 notchback Mustang ||Nov. 2009 ||$3,000 |
|Sold old wheels, tires, engine, trans ||N/A ||-$1,000 |
|532 big-block Ford ||June 2009 ||$9,644 |
|Phoenix TH400 trans ||Sept. 2009 ||$1,645 |
|Strange 8.8 rear end ||Oct. 2009 ||$1,759 |
|Comp Engineering rear suspension ||Nov. 2009 ||$1,708 |
|Total: || ||$16,756 |
|WHERE THE MONEY WENT |
|Item: ||Part No: ||Price: |
|Comp Engineering upper control arms ||C8005 ||$210 |
|Comp Engineering lower control arms ||C8007 ||$255 |
|Comp Engineering spherical bearings ||C3168 ||$140 |
|Comp Engineering coilovers ||C2055 || $596 |
|Comp Engineering sway bar ||C2020 ||$280 |
|Comp Engineering torque box plates ||C8015 ||$25 |
|Rock Auto brake drums ||2604R ||$52 |
|Custom reinforcement welding ||N/A ||$150 |
|Total: ||$1,708 |
Before bolting on any new...
Before bolting on any new parts, the control arm anchor points must be reinforced rigidly to the body. The factory spot welds hold up fine for a stock 205hp motor and street tires, but are subject to breaking loose once e.t.'s dip into the 11s. At this stage, Project Fox's stock suspension and rear end have already been removed for the 8.8 buildup that was featured last month.
Using a sanding disc, Buck...
Using a sanding disc, Buck removed the paint, primer, and top layer of metal around the areas needing reinforcement. Attempting to TIG weld factory-galvanized steel increases the potential of contaminating the welds with air pockets. Consequently, Buck prefers MIG welding these spots instead.
When subjected to lots of...
When subjected to lots of power and grip, the upper control arm brackets have a tendency to separate from the body. Adding welds around the entire perimeter of the bracket makes them plenty strong for 9-second e.t.'s. Beyond that point, Buck recommends tying the control arm anchors directly to the rollcage.
Reducing flex in the control...
Reducing flex in the control arm brackets can put additional stress on the boltholes and cause them to elongate. To prevent them from becoming egg-shaped, Buck welded washers to both sides of each bolthole.
Unlike the upper control arm...
Unlike the upper control arm brackets, the lower control arms push their anchor points into the body. Under heavy stress, this area will cave in and buckle. To combat this, Buck not only beefs up the factory spot welds, but also welds in torque box reinforcement plates provided by Competition Engineering.
Much stronger and lighter...
Much stronger and lighter than the factory pieces, Competition Engineering's upper control arms are built from mild steel. Their spherical bearings won't do much for NVH, but they dramatically reduce deflection and binding compared to the stock rubber bushings. The length of the arms can also be altered to fine-tune the pinion angle.
Competition Engineering's coilover conversion kit moves the spring mounting point from the lower control arm to the rear-end housing. This enables brisk ride height changes, and the single-adjustable shocks feature 12 different stiffness settings. Some sanctioning bodies forbid relocating the springs, but since Project Fox isn't being built to compete in a specific class, this arrangement is stock enough for us.
Lowering the ride height adversely...
Lowering the ride height adversely affects lower control arm geometry and compromises traction. Competition Engineering's setup features bolt-in brackets with three adjustment points that allow altering the instant center. The bars are finished in satin black, and the brackets are zinc-plated for durability.
One of the most important...
One of the most important links in the entire rear suspension is the heavy-duty drag sway bar. It consists of a chrome-moly torsion tube, 6061-T6 billet aluminum swing arms, and adjustable endlinks. Like a street or road race sway bar, a drag sway bar controls the weight transfer of a car from side to side. Unlike a road race sway bar, however, a drag unit is used to preload the suspension. Not only does this prevent excessive body twisting at launch, it also drives the rear end into the ground as weight transfers rearward at launch for maximum traction. As a result, a drag sway bar has no free-play whatsoever, and is far too stiff for a road race application.
After spraying down the exposed...
After spraying down the exposed bare metal with undercoating, the coilovers were bolted into position. They attach to the rear end and body at the factory shock mounting locations using adapters provided in the kit.
The Competition Engineering...
The Competition Engineering lower control arm brackets mount to the rear-end housing using the stock bracket and boltholes. For added insurance, Buck chose to weld them as well. MIG welding is more forgiving when attaching two pieces of metal with a large gap between them. To help locate the bracket, the lower control arm was installed before welding it all together.
The angle of the lower control...
The angle of the lower control arms determines the instant center. Pointing them farther upward moves the instant center rearward, which transfers weight from front to back more quickly. The ideal setup is a compromise, however, since this also unloads the rear tires more quickly as a car progresses down the track.
The factory rubber bushings...
The factory rubber bushings pressed into the rear-end housing were replaced with spherical bearings before installing the new upper control arms. Buck suggests heating them up with a torch and cutting them out with a Sawzall, since using an air chisel is too time consuming. After applying anti-seize to the adjuster links, Buck lined up the bolthole locations of the new arms with the stock pieces to establish a baseline length. This will be changed when it comes time to fine-tune the chassis for track duty.
After attaching the billet...
After attaching the billet endlinks to the torsion tube portion of the sway bar, it was slid inside the side mounts on each end before the entire assembly was welded to the body. To prevent the rear-end pumpkin from hitting the bar at launch, the bar must be pushed as far forward and upward as possible. Before throwing sparks, Buck made sure that the bar was completely flat using a level.
In order to avoid complications...
In order to avoid complications during final setup, it's imperative to square the rear end beneath the car before attaching the endlink mounting tabs. Buck took several measurements between the center of the pumpkin and the body to ensure proper alignment. Afterwards, the tabs were TIG-welded before attaching the endlinks.
From Buck's experience, positioning...
From Buck's experience, positioning the endlinks at 10 degrees from horizontal is a good baseline setting. Depending on whether the car pulls to the left or to the right, it can be straightened out by adjusting the preload on the endlinks. Incremental adjustments can yield big changes on the track. Buck says that a 1/3-turn, or "two flats" in chassis guy lingo, is the most the endlinks should be adjusted at one time.
To maximize weight transfer...
To maximize weight transfer and consistency, the Competition Engineering springs feature a linear 150 lb/in rate. Relocating the springs directly to the rear-end housing yields a spring rate that's the exact same as the effecting wheel rate. The stock setup, which mounts the springs on the lower control arms, throws linkage ratios into the equation. As a result, the stock arrangement would require springs much stiffer than the one's we're using to achieve a 150 lb/in wheel rate.
With the Competition Engineering...
With the Competition Engineering rear suspension and the built 8.8 rear end in position, we finished it off with a set of five-lug brake drums from Rock Auto. Project Fox was equipped with wimpy four-lug axles in stock trim, so it only made sense to upgrade to five-lug axles. The least expensive way to complete the four-to-five lug swap is with a set of stock replacement drums off of a mid-'80s to mid-'90s Ford Ranger pickup. They're only $26 a pop from Rock Auto, which was half the going rate at the local parts stores. If you can plan your projects far enough ahead, shopping at Rock Auto can save loads of money.