5.0 Mustang & Super FordsHow To Chassis Suspension
Prepare for Open Tracking, Part I
At Speed on a Track Without Competition Promises Nonstop Fun--if You're Prepared
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Open track. You've probably heard the term but aren't quite sure what it is.
Gushed by adrenaline-jazzed participants three days after their last on-track escapade, "open track" isn't exactly a self-explanatory term and hasn't been in street lingo long enough to conjure up an accurate mental image the way "drag racing" does. But that's changing, as 5.0 fans discover road-course joy.
Open track, as the name somewhat suggests, is a free day at a road-racing track. There is no racing, no trophies, no winning, no losing, just all-out, around-the-track driving. Cars are loosely assigned to run groups based on speed or lap times, most often determined by the aggressiveness and skill of the driver and somewhat by car preparation. Typically, four groups cover the range--from novice drivers in nearly stock daily drivers to old hands in their thundering, no-rules-required, open-track toys.
The run groups take sequential turns on track, typically for 20 minutes at a time. This puts about half an hour from the first hot lap of one group to the next hot lap of the following group, meaning you'll go on track for 20 minutes every hour and a half. That may not sound like much at first, but it's more than enough track time for your body and wallet, especially given the normal two-day format.
On the track itself, passing is typically limited to designated areas on the straights, and any sort of fender-kissing is hugely frowned upon. Open tracking was largely started by Shelby Cobra, Pantera, Ferrari, and other owner clubs looking for safe, legal places to exercise their equipment, and that has meant an emphasis on going home with the sheetmetal straight. That does not mean the action is limited to pouring tea and discussing the weather, however. In the faster groups the pace is full-race, and the driving thrills unmatched anywhere short of all-out road racing.
As Mustang enthusiasts, we have an excellent start in revving up an open-track program. Our 5.0- and 4.6-powered machines are powerful enough off the showroom floor to provide excellent triple-digit speed thrills, the chassis are nimble enough to make it around a corner, and the whole unit has the robustness needed to stand a day of track punishment. That said, you have three challenges when launching an open-track career. The first is finding a place to run, the second is outfitting the chassis with highly desirable handling improvements, and finally there is the inevitable need for speed, as addressed by powertrain upgrades.
In this article we'll jump right to the most vital Mustang improvements--those found on the chassis, then next month we'll return to examine the powertrain.
Politely put, the late-model Mustang chassis is definitely not the ponycar's strongest point. Luckily, chassis help is readily available and arguably affordable. Furthermore, the powertrain is practically ready to go in dead-stock form, so whatever money is spent on the chassis can be partially offset by the money that need not be spent on the engine--at least until speed-greed gets hold of you!
To start with the nuts and bolts, what's wrong with the Mustang chassis is a lack of rigidity. This is surely the case with the '79-'93 Fox-chassis cars. The center section of the unibody is weak, so the stiffest subframe connectors you can afford should top your list of must-have modifications. While the minimal open-track rules don't normally require a rollbar in the slower groups, rollbars--or better yet, a rollcage--are excellent chassis stiffeners as well as safety devices. Thus, they should be next on your list of chassis-stiffening devices. The traditional strut tower and g-load braces don't offer the huge help you need on track because they don't stiffen the middle of the chassis, but every little bit helps.
Hatchback and coupe Fox chassis are equally limber, while the convertibles are horrible--the absolute worst. These positively must be reinforced with extensive, through-the-floor subframe connectors and rollcages. In fact, while the better chassis shops can make convertibles work well, their flexibility and inherent lack of protection keeps them a distant third in open-track desirability.
The '94-and-later SN-95 chassis are much improved over the Foxes, but still benefit from, and need, subframe connectors and 'cages. Offsetting their natural stiffness, the SN-95 cars are heavier, so if you're building a dedicated open-track car, you might as well start with a Fox and add the necessary stiffeners--you'll end up with a lighter car.
Beefy is better when it comes to chassis stiffeners. There is a fair amount of cosmetic-grade bracing and chassis fluff on the market. Avoid it and go with the locomotive-grade stuff. Also, watch where the bracing attaches. It should weld-in over a large area; bolting into sheetmetal is too flimsy.
We'll just come out and say it: The stock Mustang suspension positively blows chunks on track.
Chunks of your tires, that is.
The rear suspension is arthritically bound by Ford's dumb-but-cheap 20-plus-year-old suspension geometry and has a lousy roll-center height to boot. The front suspension has poor camber gain and carries anti-Ackermann. The two suspensions working together do only one thing well, and that's promote tire-grinding understeer (push), followed by snap oversteer (loose, fishtailing). Nearly impossible to consistently take to the limit, the Mustang suspension is known for its ability to grind off the front tires in two laps of hard road-course work, all the while providing the driver with a nervous, fishtailing ride that's big on adrenaline but woefully short on letting the driver use all the tires have to offer.
The cure comes in two basic forms. For casual, cost-effective street action, bolt-on methods will do. This means adding camber plates to gain caster, hard bushings to reduce deflection, aftermarket rear control arms to reduce flex in the arms themselves, and other detail improvements. For open tracking, this bolt-on method is OK, but it is more cost effective than effective.
Method number two is considerably more extensive, but in the end far more satisfying. That is, you essentially replace your suspension with an aftermarket system. Yes, this is expensive, but it really works. Lord knows, you have plenty of suspensions to choose from. Kenny Brown, Global West, Griggs Racing, HP Motorsport, Maximum Motorsport, and Steeda all offer complete or nearly complete suspensions.
Our advice: Read up on the various offerings, then buy into the program you like and stick with it. Because there is more than one way to build a suspension that works, do not cherry-pick suspension parts piecemeal from multiple manufacturers. You'll only end up spending plenty of money and getting less than you should for it.
Danger zone number three for a Mustang on a road course is braking. Good for about three laps before fading into uselessness, the stock brakes on LX and GT Mustangs must be dumped immediately. Otherwise, you'll go diving into turn five only to find the pedal mushing to the floor while the scenery continues to rush up through the windshield. This makes for great stories at the post-event beer bust, but is the hard way to obtain social prominence, and gets old fast.
More than anything, non-Cobra Mustangs need larger front brakes. Again, the aftermarket choices are huge, from moving up to Cobra PBR-based sliding calipers all the way out to IndyCar brakes if you have money to burn. The Cobra gear is workable for most drivers and comes as part of a somewhat monetarily modest package that works with 17-inch wheels. Baer Racing also has several versions of the PBR brake optimized for various Mustang uses and budgets.
Brake-system "small" parts to keep in mind are braided-steel hoses, ducting, and plenty of DOT-3 brake fluid. Avoid silicone fluid; it's great for restorations but is spongy in performance applications. Instead, plan on bleeding the brake system often (at least once a weekend) using Ford Heavy Duty or Performance Friction's Z-Rated DOT-3 fluids. Both are recommended by aftermarket brake experts Baer Racing.
We mentioned brake ducting; plan on it. It's the only way to keep the hot-running front brakes cool enough during track workouts. Without ducting you'll bake your expensive binders needlessly. The tighter the track, the more vital brake cooling becomes.
Keep in mind the braking system will require some maintenance once in heavy use. Track layout and driving style come into play here, but you can bet on several brake-pad changes and front rotors on a seasonal basis. The discs are best replaced--not turned--when warped, as turning the discs only makes them thinner and more prone to warping. Big, heavy discs are often a necessary evil when considering rotating inertia, unsprung weight, and all those other road-racing niceties; but they can really pay off in increased brake life. Don't skimp on the brakes.
Wheels and Tires
Wide, large-diameter wheels and short-sidewall tires are needed on a road course to obtain the maximum possible footprint, a rapidly responding tire sidewall for quicker response in left-right-left transitions, and a larger package to fit the brakes into. Those are the primary requirements.
Secondarily, you want a light wheel and tire package both to hold total vehicle weight down and to keep unsprung weight low. Unsprung weight is the vehicle weight not supported by the vehicle's springs, namely the wheels, tires, brakes, hubs, and about half of the suspension arms on a Mustang. The lower the unsprung weight, the faster the suspension can react to pavement irregularities. You can go broke writing one check for state-of-the-art wheels and not go that much faster--especially as a beginner--so don't go too crazy with lightweight wheels to start with.
As for tires, there hangs the financial crux of the entire exercise because generous track time and hard cornering mean tires are consumed like so much sandwich bread. Good road-race tires are what you want, and they are expensive and tend not to last long. With a stock suspension they won't last an afternoon, so you can rationalize the cost of your torque arm and tubular K-member as a money/tire-saving tactic.
Certainly, to get started you can run on premium street tires, then move up to the specialty DOT-legal road racing rubber as talent and finances permit. Someday you may even move up to full-on road-racing slicks to match your OZ wheels, but with no money or tin cup to win, why bother?
As for size, the popular 245/45-17 is a smart choice. Larger tires could be a hair faster, but at great cost, not only monetarily, but also in rolled fender lips labor, larger wheels, hassles finding a replacement tire at the track, and so on.
You'll also want a good dial-type, tire-pressure gauge with a bleed-off valve. Work with your tire shop to find the correct tire pressures and monitor them before every on-track session (expect around 32 psi with radials). As heat builds in the tire during the day you'll need to bleed out a bit of air.
Open tracking is as safe as houses, with the exception of random mechanical failure or, much more likely, some form of brain fade on your or another driver's part. So, by far the most important safety feature is a relaxed, focused driver. That means general car preparation, a good night's rest, and a mature attitude are truly important safety precautions.
In fact, these aspects are so important that open-track promoters and underwriters have found a bare minimum of safety requirements necessary with street-prepared cars. A Snell-approved helmet, long pants, and stock seatbelts are all that is typically mandatory. Costs are thus held low, and the lack of hassle in dealing with more than $1,000 in helmet, shoes, gloves, and driver suit, along with a small notebook of paperwork as is done in road racing, is not missed.
Of course, things can go wrong, and if they do you'll want steel-tube protection against cartwheeling the old bus or getting center-punched-out by another 3,200-pound participant. Thoroughly consider a rollbar or 'cage. Your 'cage thoughts should include seatbelts and seat as well as the 'cage. Robust seat mounts, a proper road-racing seat, and correctly routed seatbelts are must-haves as you start going fast. The seat is vital--both for safety and to support you against cornering loads. It's amazing how important good seat support is in achieving fast lap times. Spend a little time with an SCCA rule book (General Competition Rules) figuring out the proper angles for seatbelt mounting if you aren't familiar with how they should go.
For the 'cage, a custom one done locally or through mail-order can work equally well. Make sure the welder knows what he's doing (not a good place to teach yourself), and make doubly sure the 'cage is fully covered with closed-cell foam rollbar padding anywhere you could possibly contact it, especially near your head. You should be able to modestly punch the rollbar padding with your bare fist and not feel the tube lying underneath.
'Cage specialist Autopower has several options for the Mustang, while Dave Turner Motorsports offers the Dual Sport. That's a nifty bar with removable diagonal and cross-hoop braces that combines good protection and harness attach points during weekend events with superior interior access (including the rear seat) during the week.
Get Out There
Above all, just get out there on track. Open tracking is a world ahead of goofing off on the street. It's a full-on automotive riot, and you'll find the participants friendly and eager to help the newcomer who asks for guidance. Teaming up with a buddy can really save money and get you to make the most important decision of all--the Go Decision.
A performance alignment works fine for open tracking. For fresh-off-the-street Mustangs, Dario Orlando at Steeda says to try 1.4 to 1.7 degrees of negative camber, 4 to 5 degrees of positive caster, and 3/32 toe-in. Any more negative camber gives more inner tire wear than anything else, and doesn't aid braking stability. More caster helps handling but is hard on the steering rack, so leave the big caster gains to when you've modified the entire suspension.