Ford muscle cars have always been very popular. The Mustang, especially, is an American icon. When it comes to performance handling, drivers such as Parnelli Jones showed that the blue oval could be a force to be reckoned with on a road course too. While classic Fords generally don’t enjoy the type of after-market support the GM cars do, there are still some really excellent parts available to address the unique needs of Ford muscle cars.
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One very cool thing when it comes to Ford muscle cars is that along with their good and bad points, almost all of them share very similar suspension components. That means the topics I cover here apply to everything from 1960 Comets to 1973 Mustangs, including 1966 to 1971 Fairlanes and 1968 to 1971 Torinos. But the Mustang/Cougar gets the majority of the aftermarket attention because the parts start to get a little mo re exotic.
If you read Chapter 8 on GM muscle cars you noticed some common themes. If not, go back and read it, there’s good information there and it’s always fun to know the other owner’s car better than he or she does.
Front Suspension Options
Again, the worst factory design elements are in the front end and this is where you see the biggest gains for the least time and money. Unlike most other cars of the era, traditional Ford muscle cars have the springs on top of the upper A-arms and use them as the weight-bearing arms. That means that the geometry solutions are Ford specific. As on many of their contemporaries, the suspension geometry is very backward. Camber curves are positive in bump, especially in 1960 to 1964 cars.
Thanks to Ford suspension engineer Klaus Arning and Carroll Shelby, things improved in 1965 and later, when they included a modification similar to the Camaro G-Mod covered earlier. The upper/inner A-arm mounts are dropped to change the angle of the upper A-arms and the inner pickup points are moved for improved camber gain and a higher roll center. This was a step in the right direction, but a more aggressive version can be employed on 1965+ cars for further gains. Because the upper A-arms mount the springs, Fords also received a 1-inch drop in ride height. Several companies, including Total Control and Pro Motorsports Engineering, offer templates to do this conversion.
As always, when you make one change you have to change other things too. Dropping the cross shaft with stock upper A-arms can lead to angular ball-joint bind in bump, especially if the car is also lowered with springs. There is a “negative wedge” kit available to change the installed angle of the ball joints, but you may still run into issues trying to get a decent performance alignment. After-market arms, designed to work with this geometry modification, are strongly advised.
Total Control Performance (TCP) also offers another option with its adjustable, tubular upper A-arms—a vertically offset cross shaft. This cross shaft mounts in the typical location, but lowers the pivots at the ends of the cross shaft to achieve the same modified geometry without templates, measuring, or drilling new holes. It’s clever and works very well. The adjustable turn-buckle feature of the arms also makes them very quick and easy to adjust.
Bushing selection for Fords is pretty easy because they came with greaseable steel bushings in the upper A-arms. These worked very well, so replacement arms usually continue to use either Teflon-lined or greaseable steel bushings as well.
The lower A-arms are comprised of two separate units: an arm and a strut rod. The arm handles inboard/outboard loads and the strut rod primarily manages fore/aft loads. These parts are load bearing, but not weight bearing.
There are some issues with the stock parts. The lower arm doesn’t need to be as beefy as arms with a spring seat but, even so, they are really flimsy. The stock rubber bushings also have a lot of deflection. The strut arms are sturdy enough but the huge bushing that mounts the front of the strut allows excessive caster change under load and contributes to quirky handling. Replacing the bushings with harder compounds helps this issue, but increases binding, so there’s no real net gain. The solution to the flexible lower arms is simple. You can box the arm for a low-buck solution, or you can step up to aftermarket tubular lower arms. The strut rod bushings require a more complicated fix.
In order to get the range of motion necessary, you really need some kind of spherical joint. The easiest and cheapest method is a bolt-on bracket, which mounts where the strut rod used to go into the bushing. A Heim joint bolts into the bracket and screws into the end of a tubular strut rod. This solution works, but you have all the street durability and NVH issues of the Heim to deal with. This method also has apparent caster adjustment built into the strut rod. That’s a cool feature to have, but if you change the length of the strut rod to get more positive caster, it also pivots the lower arm forward on its inner bushing. You have a little room to play with here if the bushing is rubber, but poly begins to bind almost immediately and Delrin or aluminum binds badly.
The ideal solution would use enclosed greaseable spherical joints in both the strut and the arm, so the whole assembly can pivot freely regardless of caster adjustment. Total Control used the older Heim joint system years ago, but refined it further to use Delrin race True-Center flex joints. That makes for a very slick package with crisp handling and easy caster adjustment. They are not the least expensive alternative, but they’re the best lower arm solution I’ve worked with for the traditional Ford platform.
The “spring on the upper A-arm” design format has some pros and cons. It transfers a lot of load up high into the car’s structure, making beefy shock towers a must and engine access a bit tighter. This load also means that underhood structural reinforcements are a very good idea. One of the good points is how you have additional options when mounting coil-overs and springs. Most coil-overs still mount to the upper A-arms, which requires a compact unit. There are also packages that change things and mount the coil-over to the lower arm. Doing this requires a beefy tubular lower arm purpose-built for the task, but doing so allows ample room for the coil-over. It’s one of the few conversions with more room to work than it even needs.
You can also run conventional performance coil springs, which are available from many sources. If you order lowering springs, take a 1-inch drop for the Shelby mod or the vertically offset cross shafts into account (if you use one of them) when determining your final ride height. There are also options from Total Control and RideTech to use air springs if you prefer them.
Once again, shocks are critical. I’ve covered a lot of territory on shocks already so I’ll just say it again and then move on: Don’t skimp on shocks! There are plenty of good options and adjustable shocks always offer the most tuning range.
There are some replacement front clips available for Fords, but because they don’t use factory subframes or even K-members, there’s a lot of cutting and welding involved. The complexity of the Ford aftermarket front clips means they’re best installed by a good chassis shop. Because they are Mustang II–based (that’s Pinto to anyone who doesn’t sell them), they’re generally much better than stock and can be tuned for good handling performance. But whether they’re good enough to merit all of the extra fabrication work required to install them is debatable.
Rear Suspension Options
The rear suspension offers a lot of options, from performance leaf springs (and all the ways they can be augmented) to all-out torque-arm and four-link systems. There’s even a bolt-in independent rear suspension based on an original-period Ford design. So, what to choose? That’s going to depend on your goals and your budget.
The cumulative technology discussed previously certainly applies. You want springs designed for performance handling. They are likely to be lowering springs, so decide how much you want to lower the car and head in that direction. The cumulative technology discussed previously certainly applies. You want springs designed for performance handling. They are likely to be lowering springs, so decide how much you want to lower the car and head in that direction.
There are cool features available on some replacement springs that I haven’t seen as aftermarket offerings for any other brand. One is a choice of vertically offset spring eyes. The eye is the end of the spring where the bushings are. Typically, the ends roll upward to form the eye, putting the mounting bolts above the main leaf. Total Control offers a choice of this standard configuration, including a mid-eye arrangement and a reverse-eye.
On a mid-eye spring, the main leaf dips down before it curls upward, putting the mounting bolts in line with the top of the main leaf. This lowers the car about 1 inch without sacrificing any spring arch.
The reverse-eye spring just curls down and around the bushings, putting the mounting bolts below the main leaf, which lowers the car about 11⁄2 inches. They are available in 4-, 41⁄2 -, or 5-leaf configurations, which basically translate into firm, firm plus better traction, and firmer. The half leaf is added on top of the main leaf, and only on the front half of the spring to prevent spring wrap and improve straight-line traction. Traction aids (with the usual caveats) and add-on Watts-link setups are possible means of augmentation.
An additional means of improvement is Total Control’s torque arm for 1964 to 1970 and 1967 to 1970 Mustangs. This unit is intended for use in conjunction with leaf springs. It’s adjustable for angle and uses a shackle at the front end to prevent binding with the leaf spring’s arcs of movement. It’s a great way to improve traction without hindering handling in the least. Combined with good springs and a Watts link, it should rival the performance of some of the higher-end multi-link/coil-over packages.
That brings us to the higher-end multi-link systems used to replace the leaf springs altogether. Again, you have a number of choices. Use the technology discussed earlier to look them over and consider the pluses and minuses of each one before you buy. As always, some are better suited than others for certain uses. The G-Link is a great multitasker in this category, just as it is for the Camaro. It may interest some Ford fans to know that the G-Link was designed and sold for the Mustang first.
For the hardcore handling enthusiast and racer, TCP has an outrageous torque-arm package complete with a Watts link and pushrod-actuated lay-down coil-overs. Practically designed on the race track, this system uses Teflon-lined Heim joints on the arms and a Watts link with billet-aluminum bell-cranks to transfer motion from the pushrods to the coil-overs. It may not be the best option for a street cruiser, but it surely impresses all who see it.
Outrageous in a totally different way is the rebirth of the prototype T-5 independent rear suspension package, now available from CTM Engineering. It’s a faithful copy of Klaus Arning’s baby from 1964. It’s a Jaguar-esque IRS with stressed halfshafts for upper arms and trailing arms on each side. This type of suspension was state of the art in its day. I don’t think I’d use it on a hard-core performance car today, but it would make a great conversation piece and probably work really well in a sporty street/touring car.
Sway bars aren’t an option with some of the more exotic rear suspension packages and some of them may not need them. But, on more typical cars, they’re generally a good idea. Keep the same general concepts of balance and tuning in mind when selecting bars for your Ford muscle car. Don’t overdo it with a huge front bar, especially if you’ve done geometry modifications. An adjustable-rate rear bar is always a handy tuning aid.
Chassis rigidity is a big issue with these cars, just as it is with many cars from this era. They don’t have a true front subframe, so you can’t technically use subframe connectors. But, the center span of the chassis is still torsionally weak and could really benefit from some reinforcement. Several companies offer parts to do this, ranging from Mustangs Plus’ weld-in structure kit (made from heavy-gauge sheetmetal pieces) to beefy tubular structure kits like those from TCP, which incorporate an X-brace for additional rigidity. These structural add-ons can yield huge reductions in chassis and body flex. They make the car feel much more solid and help everything from ride quality and handling to body panel fit and window sealing. If you’re serious about performance, this is a must-have part of your build.
As always, a roll cage of some kind is also a great way to add chassis stiffness and safety. All the normal pros and cons of running a cage in a street-based car still apply.
Ford Fox Body 1974 to 1978
I don’t mean to offend anyone who owns a Mustang II King Cobra, but let’s face it; it’s a dressed-up Pinto. Yeah, due to that lineage, they typically get no respect. However, there are lots of performance parts available for the Pinto, or rather, Mustang II front end. Use the methodology covered earlier in the book to select upgrades that actually improve performance. Tubular front upper A-arms with screw-in Chrysler-style ball joints yield a nice improvement in camber gain due to their taller ball-joint studs. Sway bars, shocks, and springs are plentiful, but many of them are tailored to heavily modified versions of this front end and may not be a direct fit to the original cars. The rear end is a simple leaf-spring design, so all the information covered already applies.
Overall, these cars are actually a pretty good platform for performance handling, combining light weight, a decent stock front end (with plenty of aftermarket support), and a simple, easy-to-upgrade rear suspension.
Ford Fox Body 1979 to 1993
Sharing the Fox platform used on many mid-size Ford cars, the Mustang began to really assert itself in the performance world. Initially low on both power and handling (as were most vehicles billed as performance cars in 1979), the Mustang really blossomed into a great performance car throughout the 1980s. The strut front end design has decent geometry, and performance modifications center mostly around alignment aids such as camber plates, and tuning parts such as performance rate lowering springs and sway bars. The information in this section also applies to Fairmonts, Thunderbirds, and any other Ford built on the Fox platform.
The rear suspension is a typical triangulated four-link design. The only unusual thing is that the spring seats are on the lower trailing arms rather than on the axle. That doesn’t make much difference except for changing the motion ratio of the springs, so don’t try to compare Mustang spring rates with those of other triangulated four-link cars with their springs mounted on the axle. The Mustang requires stiffer springs to attain the same wheel rates.
As is typical with factory triangulated four-link suspensions, the principal issues are poor axle locating and binding. The flimsy factory trailing arms use very compliant rubber bushings. This is especially apparent when you consider how many of these cars were fitted with horizontally mounted quadra shocks to limit wheel hop and aid traction. These kicker shocks (as they are sometimes called) dampen the rotational movement of the axle (when viewed from the side). More rigid arms and harder, less-compliant bushings prevent this problem, but they can also increase binding, especially in torsion. This adversely affects handling. This is especially true on uneven surfaces (like the streets in most of North America).
There are a few ways to go about fixing them. The first and easiest is to swap on a set of arms with greaseable flex joints or spherical pivots of some kind, such as Currie Currectracs or Maximum Motorsports (MM) HD/Extreme arms. The MMs also have an option for adjustable rear ride height. These are all a compromise, of course, but can be a pretty good one.
You can alter the dynamics of the rear suspension with an add-on Watts link, like the one sold by Fays2. This stabilizes and affixes the roll center as well as doing a great job of lateral axle location. Leave the rubber bushings in at least one end of the upper trailing arms to allow the Watts link to do its job unhindered.
Or you can swap in any one of a number of aftermarket rear suspension packages. There are lots of choices here, from torque arms to three-links and four-links, but keep in mind that most are designed for serious road racing, and as a result may have minimal ground clearance and little or no NVH isolation. Torque arm and Panhard bar systems are particularly popular with Fox-body Mustang road racers, and systems from Maximum Motorsports and Griggs are both good choices.
Maximum Motorsports also has adjustable-rate rear sway bars available. Steeda Autosports offers a five-link package, which is actually a four-link with Panhard bar. This package could theoretically provide better anti-squat than a torque arm is capable of. Tailpipe clearance with any of these systems is going to be compromised in some way, so expect to have to at least modify the tailpipes or plan on going to a custom exhaust system—maybe with side exits.
Again, chassis rigidity is lacking and should be improved. Subframe connectors and strut tower braces are available from a host of different manufacturers, which should give you some idea of how important they are.
Good shocks and struts are of vital importance, as always. The Fox body is also better suited than some cars for coil-over conversions, and there are several available from aftermarket manufacturers such as Griggs, Steeda, and Chassisworks/Varishock for both front and rear.
Correctly outfitted, the Fox-body Mustangs and their kin are formidable performance cars with extremely capable handling.
Written by Mark Savitske and Posted with Permission of CarTechBooks