1993 Ford Mustang Notchback - Shift of Power
In Order To Transfer The Weight And Put The Power Down, We Install A Tubular Front Suspension From AJE On Project Fox.
From the November, 2009 issue of Popular Hot Rodding
By Stephen Kim
Photography by Stephen Kim
AJE's front suspension kit...
AJE's front suspension kit for '79-93 Mustangs includes a tubular K-member, control arms, camber/caster adjustment plates, motor mounts, and springs for $799. It was matched up with Strange single-adjustable shocks ($119 each) and a Unisteer manual steering rack ($430) for a simple yet cost-effective front suspension combo.
When it comes to extracting ridiculous power out of a big-block, it's so easy a Wall Street CEO could do it. Nevertheless, that easy grunt comes with the penalty of extra mass, which makes transferring all that power and weight to the rear tires even more difficult. The trick is to offset the increased heft over the front tires with lightweight suspension components, and to optimize the spring rates to facilitate quick and efficient weight transfer. By installing a complete tubular front suspension system from Anthony Jones Engineering on Project Fox, our goal is to accomplish just that.
So far, Project Fox has been...
So far, Project Fox has been fitted with a built 8.8-inch rearend, a Competition Engineering rear suspension, and an AJE front suspension. Its 532ci big-block and Phoenix TH400 trans are sitting in our garage waiting to be installed. Next month, we'll walk you through installing a custom 10-point rollcage.
For those coming late to the party, the goal with our '93 Mustang project car is to run 9s in street-legal trim on a budget of $25,000. To prevent Project Fox's 775hp big-block Ford from pulverizing its 275/60R15 drag radials, we installed a complete Competition Engineering rear suspension system last month. That said, planting the rear meats is impossible unless the front suspension pulls (or shifts) its own weight, so on this go-around, we'll be installing an AJE tubular K-member and lower control arms, coilovers, and adjustable camber/caster plates. Further assisting with shifting the power rearward are Strange single-adjustable shocks, and a lightweight Unisteer manual steering rack. Together, these components will help shed nearly 100 pounds off the nose of the car. That's definitely a good thing, since we estimate that our aluminum-headed 532 big-block weighs roughly 150 pounds more than the stock iron-headed 302 small-block.
Removing the stock K-member...
Removing the stock K-member and front suspension assembly as a single unit is a straightforward and rather uninteresting affair. After disconnecting the brake lines, steering shaft, power steering lines, and upper shock and K-member bolts, the entire cradle drops right out. Since it serves no purpose on a straight-line machine, the stock sway bar got chucked in the trash.
Transferring weight, however, is just the first part of a front suspension's multiple roles. As soon as the car leaves the gate, the front underpinnings are also responsible for directing man and machine in as straight of a path as possible. Light steering feel and side-to-side wandering are the bane of a well-handling drag car, but fortunately AJE's suspension features a wide range of alignment adjustments to dial out any potential drama. Showing us how to set it all up once again are the generous folks at Bill Buck Race Cars in Austin, Texas. Since Project Fox's stock motor and trans had been pulled long ago, the entire aftermarket suspension bolted right up in half an afternoon.
|THE COST SO FAR
|'93 notchback Mustang
|Sold old wheels, tires, engine, trans
|532 big-block Ford
|Phoenix TH400 trans
|Strange 8.8-inch rearend
|Comp Engineering rear suspension
|AJE front suspension
|WHERE THE MONEY WENT
|AJE K-frame, control arms, coilovers, camber plate
|Strange adjustable shocks
|Unisteer manual steering rack kit
|Comp Engineering bumpsteer adjusters
|Rock Auto brake rotors
The difference in header and...
The difference in header and oil pan clearance between the stock and AJE K-member is substantial, as it frees up an additional 2.5 inches of space in the A-arm section alone. AJE's K-member is built from mild steel, and weighs 34 pounds less than the stocker. One of its most unique features is its modular motor-mount design, which means that anything from big- and small-block Fords, to big- and small-block Chevys, to LS1s and mod motors can be positioned perfectly in the Fox engine bay by simply swapping out the motor mounts. The mounts are available from AJE, and the company also offers suspension components for third- and fourth-gen Camaros, Mopars, and '05-and-up Mustangs.
Although the stock control...
Although the stock control arms can be reused, we opted for AJE's tubular units in order to drop an extra 16 pounds of mass. The lower ball joints are attached to a separate mounting plate, which enables camber and caster adjustments by pushing it inward or outward. The polyurethane bushings reduce deflection over the stock rubber pieces. As with the K-member, the control arms are powdercoated black from AJE for good looks and corrosion resistance.
AJE's billet sleeves slip...
AJE's billet sleeves slip over just about any aftermarket shock to transform it into a coilover. The springs are offered in a variety of rates ranging from 150 to 225 lb/in. Factoring in the additional weight of the big-block, we went with 200 lb/in springs. The billet camber/caster plates are essential for dialing in the alignment settings for maximum straight-line stability.
Granted, double-adjustable shocks would add some wow factor, but Buck says they're overkill for a 9-second street car. He prefers the tuning simplicity of a single-adjustable shock, and notes that plenty of cars run single-digit e.t.'s with old-school 90/10 shocks. These units from Strange feature rugged steel construction and 10 rebound settings. At just $119 each, they're a fraction of the price compared to double-adjustable shocks.
Since the 17-year-old stock...
Since the 17-year-old stock steering assembly was on its last leg, we used it as a good excuse to install a lighter manual rack. This $430 Unisteer conversion kit includes the rack, steering shaft, and urethane bushings. Installing these components and removing the power steering pump drops another 35 pounds off the front end.
Bumpsteer is just as undesirable...
Bumpsteer is just as undesirable in a drag car as in a road race machine, so we ordered up a set of adjusters from Competition Engineering. They're built from 6061-T6 billet aluminum, and allow minimizing changes in toe as the suspension moves through its range of travel.
Drag vs. Street Caster
Caster is simply the angle of the front spindle when viewed from the side of the car, and straight-line machines and corner carvers call for vastly different caster settings. A spindle that tilts rearward has positive caster, while a spindle that tilts forward has negative caster. Since light steering and wandering is a consequence of negative caster, almost all production cars have a few degrees of positive caster built-in from the factory. Where road cars and drag cars differ is in the amount of positive caster that's desirable. "The greater the positive caster, the better the car's straight-line stability and the more effort it requires to move the steering wheel," Bill Buck says. "These aren't necessarily bad things in a drag car, so I like to set caster at 5 to 7 degrees in straight-line applications, however, heavy steering effort isn't ideal for a street or road race car, and the wheel can have a tendency to jolt when you hit a bump with too much positive caster. Consequently, you want to limit positive caster to about 2 degrees in these types of applications, which makes the car feel more agile while still providing enough straight-line stability."
Drag cars are notorious for...
Drag cars are notorious for bending camber plates due to the abuse they endure after landing from a wheelie. To solve this problem, AJE's plates mount to the underside of the shock tower instead of the top. In order to dial in maximum positive caster, Buck enlarged the shock tower opening with a grinder to angle the top of the spring/shock assembly as far back as possible. Adjusting camber and caster is as easy as loosening up two Allen bolts, and sliding the shock to the desired location.
After assembling the coilovers,...
After assembling the coilovers, they were bolted to the camber plates prior to installing the K-member. This requires long arms or a helper since the shock piston must be slid into the camber plate from the bottom, and cinched down from the top.
The AJE K-member is far lighter...
The AJE K-member is far lighter than stock, but anchoring it into position is much easier with an extra set of hands. It attaches to the car at eight points using the stock bolts.
Before hitting the bolts with...
Before hitting the bolts with an impact wrench, Buck cinched them down finger tight to allow squaring the K-member to the frame-rails. Fortunately, the process is hard to mess up. Buck suggests wiggling the K-member around until the mounting tabs are parallel to the car's framerails.
The AJE K-member is shipped...
The AJE K-member is shipped with the control arms already attached to it, but they must be torqued by hand for the final install. Buck says the lock nuts should be tightened until all the slack is removed, but the control arm should still move up and down freely with minimal effort.
With the ball joint attached...
With the ball joint attached to a separate mounting plate, it can be moved inward and outward to adjust camber by removing the four retaining bolts. Unlike a road race car, since a drag application requires very little negative camber, Buck set the retaining plate on the middle setting. Final camber will be dialed-in using the camber/caster plates.
Regardless of how fancy a rear suspension setup may be, without the correct front spring rate it will never put the power down. Bill Buck says the ideal front spring rate for a drag car is just enough to hold the front end up in the air. From there, it's up to the shocks to fine-tune the rate of weight transfer. Furthermore, choosing the correct front rate is far more important than choosing the correct rear rate. "The lighter the front spring, the more weight it will transfer rearward when you hit the gas. Since springs with lower rates squish down more when loaded than stiff springs, they store more potential energy," he explains. "You can use stiffer springs to prevent the suspension from bottoming out, but that can hurt weight transfer, so I prefer using softer springs and travel limiters. If a car transfers too much weight and does violent wheelstands, then it might be necessary to use stiffer springs. If Project Fox was a track-only car, it could get away with 170 lb/in springs, but since it will see some street time a 200 lb/in spring is a better compromise. AJE's coilover conversion relocates the spring right on top of the ball joints. That means that the spring rates and wheel rates are very similar, which allows running a relatively soft spring."
The Unisteer manual rack attaches...
The Unisteer manual rack attaches to the K-member using two bolts supplied with the kit. Before attaching the steering shaft, it's very important to make sure that the steering wheel is centered.
With tubbed cars running very...
With tubbed cars running very large rear tires, Buck says that lowering the front end with drop spindles is a good way to reduce aerodynamic drag without adversely affecting handling. However, since Project Fox is set up for small 10-inch-wide tires, we reused the stock spindles to keep things simple and minimize costs. After sliding them on the ball joints, Buck torqued down the castle nuts and attached the spindles to the coilover assemblies.
The final links in the front...
The final links in the front suspension install are the tie rods, to which Buck attached the Competition Engineering bumpsteer kit. Since the lower control arms and tie rods travel in different arcs, the tires tend to toe-in when compressed, and toe out during wheelies. Not only does this compromise handling, the friction of the tires scrubbing on the pavement can actually slow the car down. Bumpsteer adjusters allow the Heim joints on the tie rods to be moved inward and outward by simply turning a wrench. This enables the tie rods and lower control arms to move as close to parallel as possible to minimize the effects of bumpsteer.
Our Mustang came equipped...
Our Mustang came equipped with wimpy four-lug hubs from the factory. There are several ways to convert to a five-lug arrangement, but the cheapest method is with a set of stock replacement rotors off of a mid-'80s Lincoln Continental. Rock Auto set us up with a pair of fresh rotors for $36 a pop, which was far cheaper than at the local parts store.
Unisteer's manual steering...
Unisteer's manual steering rack kit includes a steering shaft with rugged universal joints. It attaches to the stock Ford steering column, which features an integrated slider intended to absorb shock in a frontal impact. Buck says that it's a great safety feature, so he left it in place. Since the slider retracts into the firewall after the stock steering shaft is removed, it must be pulled out before bolting it to the Unisteer piece.
With the tubular suspension...
With the tubular suspension bolted into place, the additional real estate it opens up is quite evident, which will help tremendously when shoehorning the big-block into place. AJE also offers K-members in a drop-rack configuration for additional oil pan clearance, but we skipped on that option as our 532's Moroso pan was designed specifically for big-block swaps. Compared to stock, the lightweight components shave roughly 100 pounds off the front end.