Because power is useless without control you need to understand how the suspension helps the force at the tires be transformed into motion while the steering (for the most part) determines what direction the motion is in. This chapter concentrates on street and highway (including high-speed events) use and covers some road course applications. A pure drag race suspension isnât well suited to street use so I briefly address it in the high-performance street and streetable track-day sections. I also cover steering options for the three vehicle types.
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Suspension Upgrades
The daily driver focuses on minor modifications with a limited budget based on the factory-style suspension. The high-performance street car takes things up a notch by using upgraded components at the front and eliminating the leaf springs at the rear. The track-day car utilizes a more-robust design at the front and rear plus more radical options when there are no budgetary or other constraints. In each section I consider the tradeoffs among cost, handling, ride comfort, installation, streetability, and reliability
Vehicle Type 1: Daily Driver
In its time the suspension of the first-generation Mustang was as advanced as any pony or muscle car suspension from Detroit. The doublestamped control arm, coil springs, and shock suspension provided good road-holding and handling characteristics for its day, but it is certainly antiquated by todayâs standards and must be replaced to reach modern high-performance standards. The live-axle rear suspension with shocks and leaf springs also provided competent traction and damping duties, and certainly was much better than the single-leaf rear suspension on the Camaro, which had tramping and wheel-hop problems.
Although the ride and handling were not very refined, it was a capable suspension. With some modifications, however, the basic design even proved to be race worthy. The basic suspension was developed and refined for use in SCCA Trans-Am road racing. In 1970 Parnelli Jones took the Boss 302 to the Trans-Am Championship. The suspension is crude by todayâs standards but it had pretty high limits and capability. It was very strong too.
Because making any major changes to the stock design of my project car would inevitably exceed my budget, I profile certain targeted upgrades that yield the biggest performance increase for a reasonable investment.
I try to do so in a way that also helps make up for 40 or more years of wear and aging by replacing worn or damaged parts with cost-effective upgrades rather than installing direct-replacement parts. The majority of these upgrades involves eliminating excessive compliance/play in the suspension so that the movement of the parts is limited to a smaller range and is thus more predictable.
Ride Comfort
When you upgrade the suspension there is generally a very small tradeoff in a slightly harsher ride and the possibility of a feeling bit more vibration in the cabin but the improvement in dynamic response compensates for it. The cost of most of the parts is relatively low plus their durability usually exceeds that of the OEM parts. The lower control arm with a strut rod has some pretty large (and soft) rubber bushings. Like any OEM suspension design, the rubber is intended to improve ride comfort plus reduce vibration and road noise. Unfortunately, these bushings tend to allow too much unwanted movement and, over time, they fail.
Perhaps the worst offender of the many rubber bushings in the stock suspension are those for the strut rods. These are also where the most improvement is possible, mainly because they play such a major role under hard braking. The elimination of excess movement/compliance stabilizes the lower arm and greatly improves vehicle handling, braking, and stability.
The stock rear suspension is a model of simplicity but soft rubber bushings produce greater compliance. Because there are far fewer of these bushings their effect is less.
Using leaf springs also introduces some unique issues. A harsher ride is one of them plus things like spring wrap-up also come into play. Still, there are a few things you can do to the stock suspension to improve it enough for street and moderate performance use. (For extreme/track use more radical modifications are needed.)
Upper Control Arm
The front suspension design of first-generation Mustangs didnât change much. It consisted of an upper control arm, a lower control arm, and a strut rod on each side combined with an anti-sway bar, springs, shocks, etc. You can upgrade the parts and make substantial improvements in performance.
The stock upper control arms are generally suitable for a daily driver but they still can benefit from a few modifications. These Global West arms are the stronger four-bolt variety plus they utilize a revised bushing design with harder durometer rubber to reduce excessive and unwanted movement of the arm.
The stock upper control arm is adequate for many high-performance street applications and does not need much improvement. However, you can install four-bolt ball joints and not drill new mounting holes 1 inch lower in the shock towers for a Shelby mod. Global West Suspension, Mustangs Plus, and others make upgraded upper arms that are stronger and have revised geometry to take advantage of a dropped location.
Global West offers negative-roll components for road racing; those optimized for drag racing are fine for street use. These OEM-style arms feature slightly revised mounting nuts and cross shafts to reduce play via more precise threads. Harder bushings help minimize slight fore and aft movement. Tubular, non-OEM arms are also available.
The OEM design utilizes a spring perch that positions the spring on the upper control arm. A centering ring inside the shock tower locates the top end of the spring while the shock absorber passes through the center of it and the spring. A special mount secures the top of the shock. The spring and shock capably handle the suspension loads but itâs not optimal because most of the load is placed on the upper control arm. In addition the OEM spring perch uses a relatively compliant rubber bushing, which isnât the best for performance or durability. Â
An easy and inexpensive way to fix this is to replace the OEM perches with ones using polyurethane. This significantly reduces the amount of unwanted movement while providing some cushioning. For maximum performance and handling, perches with roller bearings virtually eliminate all play and friction. They can even improve the ride due to less initial impact friction (âstictionâ).
Koni offers a line of âclassicâ shocks that are an excellent choice for a simple, non-adjustable shock likely to be used in a daily driver. There are many more sophisticated and expensive options, which may be adjustable, but they are not really needed at this level of modification or its cost criteria.
A quick and relatively easy way to remove some of the squishiness of the stock suspension is to replace the OEM rubber-bushed spring perches. Polyurethane perches cushion the ride, allow less movement, and last longer. Perches using bearings instead of bushings provide the maximum reduction in unwanted movement. They donât compress to any noticeable degree and they reduce friction and impact harshness.
Global West, Total Control Products, and others offer direct-replacement springs with various rates and ride heights to suit various situations. When combined with the better arms, bushings, shocks, etc., they very noticeably improve the dynamics of the vehicle.
When going to a higher spring rate itâs also advisable to replace the OEM rubber spring isolators with polyurethane components from Energy Suspension or a similar manufacturer. These better tolerate higher spring rates and further reduce unwanted compliance.
Lower Control Arm
Upgraded aftermarket lower control arms provide significant performance improvement over stock. Global West offers a significantly reinforced stock-type lower arm that is âboxedâ on the underside to greatly improve strength. Spherical bearings replace the OEM rubber bushings, provide lower stiction, and virtually eliminate unwanted compliance. They accept all other OEM components and are a very good choice for drag race vehicles where the need for lighter weight is more important than the need to handle higher cornering. To get the full benefit of them you should also replace the OEM eccentric âcamâ bolts with Global Westâs lockout kit.
These stronger square plates are held in place by the factory flanges and donât move out of adjustment under heavy loading as the OEM cam bolts often do. They have six settings covering a wider adjustment range than the OEM bolts. This is a simple and inexpensive way to improve the stability and consistency of suspension alignment.
Strut Rods
The strut rods are an often overlooked component in the front suspension. They greatly affect the stability of the car, especially under hard braking. In addition to locating the lower control arm front-to-back, strut rods are responsible for absorbing the majority of the braking forces transferred to the suspension.
If the strut rods are improperly adjusted the wheel alignment may be off and there can be a high possibility of the car pulling to one side under braking or acceleration. If a strut rod bushing fails you can be sure that happens, severely and quickly. A worn/failing bushing usually causes the car to pull to one side when trying to drive straight. Itâs a good idea to replace OEM strut rod bushings on any vehicle with high mileage because rubber deteriorates over time, even if the car has been sitting.
For a daily driver that sees lots of potholes and other road hazards itâs best to use rubber bushings. You can inexpensively upgrade to a higher durometer/stiffer rubber to reduce movement yet still have cushioning so the benefits are significant. Polyurethane should never be used for a street car because it can restrict and bind the arc of suspension travel. A sudden suspension jolt or impact can cause the strut rod to bend (or even break off) at the base of the threads.
First-generation Mustangs were equipped with mundane hydraulic shocks at the factory, which faded after severe acceleration, hard braking, and aggressive cornering. These twin-tube, steel-bodied, gas-charged Koni Sport shocks provide excellent damping and are an affordable alternative to high-end aluminum-bodied shocks. These shocks provide a significant dampening improvement over the stock shocks and more consistent dampening at high speeds while providing decent levels of comfort. A Mustangâs cornering ability is improved while body roll is limited. (Photo Courtesy Koni)
Upgrading the lower control arms follows the same theme as the uppers but takes things a bit further. The reinforcement of this Global West arm (top) is more obvious because it is boxed to significantly improve strength while keeping weight and cost fairly low. It eliminates the OEM rubber bushing in favor of a spherical bearing. This almost fully eliminates any compliance or friction while helping to reinforce the mounting box.
Eliminating compliance and flexing of the lower arm is of little benefit if the arm is not kept in proper alignment/ adjustment. The stock eccentric adjusters can loosen and/or shift under hard use, thus causing the alignment to be out of spec. Replacing them with thicker, square lockout plates eliminates this possibility because they are held firmly in place yet still allow for a wide range of adjustment (in six steps versus continuously).
Bars and Braces
Most remaining front suspension components can also be costeffectively upgraded in a daily driver to provide very noticeable benefits. You can replace the various bushings associated with the anti-sway bars (end links, mounts) with highquality polyurethane parts, such as those from Energy Suspension. This provides increased firmness for high-performance applications.
To avoid potential noise and squeaks over time Energy Suspension includes grease fittings to allow for additional lubrication as necessary. The anti-sway bars themselves can also be upgraded with thicker/stiffer parts to reduce body roll. This isnât necessary in a drag race situation where the front bar may be removed (at least at the strip) to reduce weight. Even on a road course car a stiffer bar may not always be best if it throws the handling balance off, especially with lighter small-blocks.
No suspension system can work to its full potential unless itâs connected to a stable platform/vehicle. Early Mustangs were never known for having great torsional strength or chassis rigidity. Like many other cars that rolled out of Detroit the Mustang is a unibody car and, unless the body and suspension have been recently restored, time has most likely taken its toll. These cars tend to sag a bit due to a combination of metal fatigue, corrosion, rust, loose or missing fasteners, and broken welds.
The most common example is that the shock towers tend to bend inward toward the engine. The Mustang had this issue from the beginning so âexport bracesâ and Monte Carlo bars were offered. An export brace bolts between the firewall and the shock towers to brace them under hard cornering. A Monte Carlo bar provides additional support by connecting to the shock towers across the engine bay to further reduce their movement relative to each other.
The OEM parts arenât very strong so itâs best to use good aftermarket components such as those sold by Mustangs Plus and Global West. The best export brace designs have thick flanges and welded joints to minimize movement. Theyâre non-adjustable and may require some effort to install because every car ages and moves differently.
Versions that provide greater adjustability are easier to install but do not provide as much torsional rigidity once theyâre in. The best Monte Carlo bar designs use thick, straight tubing with thick brackets and adjustable rod ends with opposing threads to allow adjustment by simply rotating the bar (versus having to adjust each side separately). A curved bar may be necessary to clear a larger distributor or other obstruction but these are not as strong unless they use thicker-wall tubes.
The strut bar bushings are an area where great improvement is possible. For a daily driver the most costeffective thing to do is to replace the existing bushings with firmer/higher durometer versions such as these available through Global West. They significantly reduce the amount of movement yet still provide some isolation from noise and vibration, etc. Do not use polyurethane bushings here; they can cause strut rod failure. Replace or upgrade the strut rods if theyâre bent.
A front bar with a different torsional stiffness is usually included in a sway-bar kit to better balance the front and rear roll stiffness. Such bars may be smaller or larger in diameter than the stock bar depending on differences in materials, design (solid versus hollow), shape, and adjustability (extra holes, etc.). You canât always judge stiffness by its appearance.
Subframe Connectors
One of most effective and affordable methods for improving chassis strength and ridgity is to use subframe connectors. When building a high-performance or restomod Mustang, installing subframe connectors is an absolute must. These tie the front subframe to the rear frame rails to supplement the stiffness provided by the body and the floorpan. Bolt-in designs are generally not as effective as weld-in designs but welding them after theyâre bolted in usually helps.
A simple, inexpensive upgrade is to replace the OEM anti-sway bar bushings and links with polyurethane-based parts such as these from Energy Suspension. They reduce the amount of body roll and improve the overall response of the suspension. They do, however, require periodic lubrication to prevent noise.
The best designs have fully welded tubes and large, thick attachment brackets that contact the frame stubs on three sides. Even for cars not driven aggressively the installation of subframe connectors with an export brace and a Monte Carlo bar stiffen the car so that squeaks and rattles are greatly reduced.
Other than cost, the only possible negative to subframe connectors is the potential loss of ground clearance, especially with a lowered car, and maybe a small weight increase.
Leaf Springs
For a daily driver the factory leaf spring-style suspension is usually retained. This is somewhat of a performance limitation but there is no inexpensive alternative. Having said that, the stock leaf-spring suspension can be vastly improved, even to the point where it is acceptable for daily use as well as limited track use.
As with the front, the goal is the minimization of unwanted compliance/movement along with general spring and shock firming. The starting point is the elimination of the stock rubber spring eye and shackle bushings because theyâre probably worn out anyway. Using direct-fit polyurethane bushings is okay if you want to keep costs to a minimum. They reduce movement and provide more cushioning compared to their rubber counterparts but they can squeak if not greased.
A better solution is to use DelA-Lum bushings from Global West. Although these cost more than rubber bushings, they substantially improve performance. Their design is unique in that the spring and shackle bolts ride inside a plated steel sleeve that is inside precisely machined cylindrical Delrin bushings. These bushings rest inside anodized aluminum housings, which are inserted into the spring and/or frame rail. This construction accomplishes several things.
This front suspension uses reinforced stock-type control arms and strut rods and upgraded bushings. The springs and shocks have been replaced with more performance-oriented parts plus the spring perches were replaced with polyurethane parts. Even though much more radical (and costly) options are available, this simple level of upgrading still makes a dramatic improvement in vehicle performance.
Early Mustangs benefit greatly from a Monte Carlo bar (the straight, adjustable bar between the shock towers) and an export brace (the fixed bars running between the firewall and the shock towers). These can be adapted to work with most engine swaps such as this 5.0L EFI engine. They should both be used whenever possible.
Perhaps the most common method of stiffening up the body is to use subframe connectors, such as these weld-in units from Global West. The design of these components is critical if they are to provide any noticeable benefit and not have ground-clearance issues.
First, there is virtually no compliance in any direction. The springs cannot move sideways to any degree, thus enhancing stability while allowing for slightly more effective tire clearance and/or wider tires.
Second, because there are no bushings that compress, the springs only rotate in the vertical plane; they donât twist or cock at an angle under load. Again, there is better leaf stability due to more precise, consistent, and restrained motion.
Finally, because this design has such inherently low internal friction there is a reduction in impact harshness and an improved ability for the spring to move through the desired range of motion. Extra strong, plated, steel shackles and Delrin side bushings further ensure accurate movement of each spring. Grease fittings for each Del-A-Lum bushing ensure they can stay properly lubricated throughout their very long life.
The springs themselves are available in various configurations and rates to suit different needs. Once you determine the correct spring rate you can finalize the type of spring to determine the rear ride height. Global West offers normal, reverse-eye, and mid-eye springs, which can drop the rear of the vehicle up to 11â2 to 2 inches below stock while preserving the correct spring shape/arc (some others alter the spring shape).
The guidelines for the front apply to shock absorbers: Stick with a premium brand such as Koni (Classic line) for simple and nonadjustable versions. Thereâs little point in upgrading to a more expensive, adjustable shock in a daily driver unless you intend to stay with leaf springs for the foreseeable future.
Global West advises against using anti-sway bars when their complete suspension system is used. They claim itâs not necessary due to their choice of springs, shocks, and geometry. In higher-performance situations a rear bar may prove to be beneficial if it helps balance the car but this probably isnât an issue with a daily driver.
The rear spring eye receives the same type of Del-A-Lum bushing and enjoys the same benefits. In addition, the frame bushing is also replaced with a Del-A-Lum bushing to eliminate another source of unwanted compliance and instability. This firming up of the leaf spring mounts requires stronger shackles to ensure the springs stay properly located.
The simple design of leaf springs doesnât offer many possibilities for change but they provide very dramatic results. The springs can be replaced with others having a different spring rate and revised construction, which can alter the vehicle height. These reverse-eye springs lower the car (at the same spring rate). Global Westâs Del-A-Lum bushings replace the OEM rubber bushings and eliminate unwanted movement, compliance, and friction by keeping the springs properly and consistently located. The spring shackles are also reinforced.
Del-A-Lum bushings fit where the OEM rubber mounts go. Side-to-side movement is almost completely eliminated through the use of Delrin thrust surfaces. The internal structure of these bushings is such that the spring eye can only rotate around the mounting bolt; it cannot cock sideways or move back and forth as is possible with a compressible bushing. This greatly stabilizes the spring and produces much more accurate, consistent, and limited motion.
Vehicle Type 2: High-Performance Street Car
To take handling performance to the next level, be sure the subframe and the suspension are strong and sound. This is because highperformance applications place greater loads on the car, which means that achieving greater torsional rigidity in the frame and suspension is imperative.
Reinforcements
For the daily driver you can reinforce the basic body structure to provide a more stable foundation for the suspension. For this vehicle type, the chassis should receive additional stiffening for higher cornering forces.
Each shock tower should be fully welded along each seam to enhance their overall strength. Even higher spring loads and cornering forces place a greater load on the body and chassis and cracks tend to develop in the thin sheet metal of the towers. This degrades performance and destabilizes the car under hard cornering and braking. In extreme cases, enough cracks can lead to suspension failure, which obviously is dangerous.
Another modification is to supplement the existing subframe connectors with side rails that extend out to the sills to further stiffen the floorpan. The increase in weight is minimal plus itâs located low and centrally in the car, thus helping to improve handling. The real benefit, however, is the greatly improved stiffness and torsional bending. The front and rear suspensions are tied together so the chassis and suspension system respond as a single unit.
The design of the Del-A-Lum frame bushing eliminates the potential for any significant lateral movement (while only allowing the rotation of the mounting bolt) but not its movement in other directions.
The extra rails also can provide a more convenient jacking point for lowered cars.
Hybrid Front Suspension
To keep the overall cost down for this level of build, a âhybridâ front suspension keeps the stock suspension layout and geometry but uses many high-performance upgraded parts. This configuration is well suited as a transition from a daily driver because the main components are completely suitable for daily street use yet allow maximum performance when additional upgrades are installed.
You need to install tubular upper control arms as the first step in this upgrade. Global West offers top-quality chrome-moly tubular arms that provide superior strength and torsional rigidity over the stock stamped-steel arms. These arms also offer several degrees of positive caster adjustment for improved handling characteristics and specialized suspension setups. The caster is adjusted on the strut rods that have jam nuts.
These are not only much, much stronger than OEM arms but they also incorporate revised geometry and use Del-A-Lum bushings instead of rubber or polyurethane on the cross shaft. This greatly reduces friction and virtually eliminates unwanted movement. These arms can use the stock spring perches, etc., or a simple, bolt-on coil-over kit.
Coil-Overs
The Total Control Products (TCP) Econo Bolt-On Coil-Over spring and shock combination is a great way to upgrade the stock front suspension. The shocks provide 71 â2 inches of travel. These coil-overs easily replace the existing springs, perches, and shocks with simple, modular units that provide far greater tunability and adjustment potential. They simply bolt onto the existing factory or aftermarket (preferred) upper arms and require only minimal adaptation on top of the shock towers. Single/16-step and double/256 combination shocks are available along with numerous spring rates. The ease of replacement makes it feasible to have extra springs to swap as needed for different uses.
If you change the leaf springs and/ or the rear axle assembly make sure to use compatible parts that locate and retain the springs on the axle. Incompatible designs could result in the locating peg on the springs not reaching the corresponding hole on the axle mounting plate. When an axle assembly with a recessed locating hole is used special metal inserts such as these from Global West are likely to be needed. They simply drop in but can also be epoxied.
This upgraded daily driver rear suspension doesnât look much different than the original suspension unless you look closely. The upgraded Koni shocks are obvious but the better springs and Del-A-Lum bushings donât stand out very much. The difference they make in terms of vehicle performance, however, is extremely obvious.
These Global West tubular upper control arms are stout enough to handle even the most extreme loads. They can come with revised geometry to further improve handling in street or road race use. They allow use of all stock components but, realistically, these parts should also be upgraded to achieve the best result. Note the use of Del-A-Lum bushings (no rubber), the reinforced spring perch mounts, and the extra bar.
One way to help ensure proper handling balance for a given vehicle is to source all components from a single supplier as a matched kit for a particular type of driving. This kit from Chris Alstonâs Chassisworks is one example. Kits from other suppliers can include new rear springs and/or other components as well. (Photo Courtesy Chris Alstonâs Chassisworks)
These direct-bolt-in Varishock coilover shocks from TCP provide easily adjustable ride height and shock valving with the OEM front suspension design. They are also lighter than the components they replace. These can be used with stock or aftermarket upper control arms, though the latter is really best. (Photo Courtesy Global West Suspension)
Various upper mounts are available to lower the front ride height as much as 2 inches even before the adjustability of the coil-over is considered. These units are lighter than stock parts, require minimal maintenance (just a grease fitting on top), and provide virtually the same adjustability as more-expensive systems with easier installation.
The lower arms also should be upgraded to stronger tubular units for this application. Global West again has the answer with their extremely strong tubular arms. They feature the same spherical bearings as the boxed OEM arms while providing far more strength and an extra mounting point for the strut rods.
Combining Global Westâs upper and lower tubular control arms virtually eliminates friction over the entire range of movement. You can easily and smoothly move either one through its full arc with just your fingers after itâs been installed.
To achieve the ultimate in front-suspension performance while still retaining the factory shock towers a full coil-over conversion system is necessary. This relocates the mounting point of the coil-over assembly to the lower control arm to better distribute forces. In addition, it provides even more beneficial geometry while still using the basic OEM design.
Such designs are more costly than a hybrid setup yet they can provide a bit better performance under the most demanding conditions. They provide at least as much tunability with superior geometry plus theyâre still far less costly than a full Mustang II subframe system.
Leaf Springs versus Coil Springs
Leaf springs serve their purpose well as a good, simple, safe, durable, and relatively inexpensive form of rear suspension when using a solid axle. You cannot precisely tune spring rate for the best compromise between road holding and ride comfort.
For a high-performance application a higher spring rate is needed and this produces a harsher ride and fails to maintain as stable a total rear tire contact patch. This is mainly due to the inherent friction between the leaves of each spring along with the more-random motion of each spring (and thus the axle and tires) due to bushing compliance, spring wrap up, etc.
Coil springs lack the internal friction of leaf springs. Well-tuned shocks are able to dampen the springs and thus the loads placed on a coil-over suspension are easier to control and distribute and are more consistently dampened.
You rarely see leaf springs on new cars. The ride and behavior on rough surfaces and/or with high loading is simply better and more predictable and consistent with coil springs, even in drag racing.
Air Springs
Air springs are able to change damping characteristics on demand for increased ground clearance and performance at various speeds and applications. However, they have a higher cost and progressive âspringâ rate. They also are much more complicated to install (and tune) due to the need for an air compressor, tank, lines, etc. Air springs add weight and take up space.
Three- and Four-Links
Straight four-link and some three-link designs are often low in cost and relatively easy to install. They suffer from having a panhard rod that creates lateral movement of the rear axle due to the arc the panhard rod swings through. Panhard rods can be advantageous in some situations where most of the turns on a track are in the same direction. In most cases a Wattâs linkage offers superior performance but costs more. Lower-cost systems tend to use polyurethane bushings and other less-costly components to keep the price down. Theyâre usually bolt-in designs, which may be fine on the street but often are not suited to more extreme use. In most cases, however, such systems can still outperform OEM leaf springs.
G-Links
TCPâs âg-linkâ system is a canted four-link design. Itâs typical of similar mid-priced and more-capable systems. Based on 1979â2004 Mustangs, itâs a direct bolt-in with only minimal welding required. TCP offers this particular system in three types: polyurethane bushings, spherical bearings, and billet aluminum arms with spherical bearings. All have the same basic geometry and installation. The polyurethane version has a little more compliance than the others but may require a bit more maintenance in terms of lubrication but itâs also less costly.
The mid-priced g-link system has steel lower links versus the lighter, more-obvious, and more-costly billet aluminum links of the highest-cost system but it is otherwise identical. Three different versions of coil-over shock are also available for each configuration: 16-step single-adjustable (bump and rebound together), 16-step dual-adjustable (bump and rebound independently), and 16-step four-way adjustable (bump and rebound independently adjustable at high- and low-piston speed settings) with remote reservoirs for optimal performance.
The TCP system has high-quality components, a modular design, and many adjustments, so you can set it up for high-performance street use or for a day at the track. The upper and lower links can be installed in multiple positions and are also adjustable in length. This provides firm or soft roll control. Instead of having to change the length of a link you may just need to change to a different hole.
Similarly, ride height can be changed by adjusting the collars on the shocks or by moving the upper shock mount to a different hole in the cradle. This added flexibility can be very convenient plus it can be a competitive advantage with quicker adjustments.
Provisions are made for all the optional features TCP offers for these systems. Whether you go with no rear anti-sway bar, a sliding-link solid bar, or a splined tubular bar it bolts right up to the g-link system whether youâre using the OEM axle or one of TCPâs FAB9 axle housings.
These tubular lower control arms from Global West provide exceptional strength and performance for a stockstyle front suspension. The extra reinforcement is obvious at the end where the tubes come together at the chassis mount, across the tubes, and even right up to the ball joint. The OEM rubber bushing has been replaced with a spherical bearing. These arms offer additional strut rod mounting holes plus revised geometry for potentially better performance, especially when used as part of a complete negativeroll kit. The anti-sway bar bushing mounts are even radiused for stability and durability! (Photo Courtesy Global West Suspension)
A final feature of the g-link is its exceptional provision for ongoing maintenance. All spherical bearings have grease fittings and are capable of being readjusted and even rebuilt if necessary. A simple adjustment ring and set screw provide the ability to compensate for any excess wear by reducing the internal clearances.
Strut Bars
The far greater handling and braking forces of high-performance use require a significant redesign of the strut bars. A rubber bushing is no longer suitable for such use and must be eliminated. A rod end or spherical bearing is normally used in place of the rubber bushing, along with a much stronger and adjustable rod.
Global West developed these revised strut rods to virtually eliminate any movement along the centerline of the rod, thus maintaining a much more consistent rod location/alignment and minimizing the effects of hard braking and cornering. By using adjustablelength rods with rod ends that index to the frame (to ensure proper alignment) these strut rods also provide additional adjustment capability for a more precise alignment. Friction and wear are greatly reduced so they last longer. The ride can be a bit harsher. (Photo Courtesy Global West Suspension)
These designs completely eliminate any excessive for-and-aft movement of the strut rod while greatly reducing friction and strength. The location of the true pivot point is held stable and constant (it moves around with rubber), thus minimizing random variations in the caster change throughout the full arc of movement.
Anti-Sway Bar
Further front anti-sway bar modifications may not be needed if you already did some. Generally, when you make significant changes to the springs and/or shocks you also need to change, or at least readjust, the anti-sway bar(s). Remember, the suspension is a system, not just a combination of parts. Everything needs to be compatible to get the best result.
For a high-performance street car, you probably donât need adjustable anti-sway bars.You still must, how ever, ensure the bar(s) is matched to the rest of the suspension. Itâs a question of achieving the proper balance. You probably wonât be changing the parts out much so you just need to get things right at first and then you can rely on shock settings, tire pressures, and so on for any tuning you might need to do.
Underbody subframe connectors can be supplemented for higher-performance use. Adding additional bars and tying them into the side sills reinforces the main tubes of the subframe connectors and the floorpan. The loads are also more widely distributed, minimizing concentrations, which can cause problems at weak spots. The new bars also make great jacking points.
When the additional loads of high-performance driving are to be the norm, additional strengthening measures are needed for the body structure. A simple but critical upgrade is to fully weld the shock towers. The majority of the front suspension loads are imposed on the shock towers yet theyâre only partially welded from the factory. Over time even normal loads can lead to cracks in the towers. Full welds do a much better job of distributing these loads across the entirety of the shock tower, thus avoiding the concentrated stress that causes cracks.
Vehicle Type 3: Streetable Track-Day Car
A vehicle in this category sees a lot of extreme use so it needs even more chassis stiffening than the other types. I discuss roll bars and cages in Chapter 12 but there are other modifications you can make to the basic body structure. Mustangs Plus offers a chassis-strengthening kit that provides weld-on reinforcement panels primarily for the floorpan area. These panels box off the bottom of the car while better tying together and reinforcing the major structures. This involves significant cost and complexity including some major modification of the basic vehicle. If much higher power levels and cornering loads will be generated such modifications are likely necessary.
When combined with a proper roll bar/roll cage structure you have as stable (and safe) a platform as possible (without a full tube chassis) when starting with an early Mustang body. Some upgrades may also be required by sanctioning bodies and/ or event organizers before they let you run.
The suspension solution for this vehicle type builds on the highperformance street type and itâs basically an upgrade with greater emphasis on strength and tunability: a coil-over system from Ridetech. Ridetech offers three levels of coil-over, or ShockWave/air-spring, configurations.
An elaborate (and costly) strut rod design is from TCP. The concentricpivot assembly utilizes two preloaded Delrin bushings inside billet aluminum housings to relocate the effective pivot point farther forward, thus effectively lengthening the strut rod while also eliminating unwanted compliance/movement. The longer rod reduces the alignment change throughout the range of travel, thus allowing less of a compromise in setting the caster, etc. (Photo Courtesy Total Control Products)
With this Global West complete coil-over conversion system, the OEM spring/shock setup is replaced by a coil-over setup, which mounts to the revised lower control arm to better direct/distribute the spring forces. This geometry is inherently superior to the OEM design for a number of reasons yet the same basic control arms and strut rods can be used. An adapter is added to the lower arm to accept the bottom mount of the coil-over unit. The upper arms are modified to allow the coilover to pass through plus there is a special mounting scheme for the coilover to the shock tower.
The Level 1 system comes with non-adjustable shocks and no front anti-sway bar. The Level 2 coil-over system is the same except for the shocks (single adjustable for rebound) and the inclusion of the optional MUSCLEbar with PosiLinks front antisway bar. The Level 3 system includes the front bar along with the best shocks (single adjustment for rebound with dual-stage high- and low-speed adjustments for compression, plus remote reservoirs) and is the preferred choice for this vehicle type.
Steering Upgrades
No suspension system is of much value if your steering system also isnât up to the task. The steering is responsible for the cornering loads the suspension has to deal with but, more importantly, it takes you where you want to go (most of the time). The standard steering systems on early Mustangs left quite a bit to be desired. Even right off the showroom floor they were vague, void of any real communication from the road, and not very responsive to inputs. They were usable enough and safe enough for normal street use but, other than perhaps in drag racing, they were not really feasible for use during any type of highspeed high-performance driving.
The main reason is their complexity. The use of a hydraulic cylinder/ ram to provide power assist wasnât a very elegant solution; it introduced many more joints where excess wear and play could develop. The system weighed more and was prone to leaks. It presented a challenge for packaging when you wanted to install headers.
Vehicle Type 1: Daily Driver
For a daily driver that sees mostly street use and a minimal modification budget itâs only practical to minimally repair the stock system to the extent itâs necessary. Tie rod ends, ball joints, and so forth arenât especially expensive and should be the first things to get replaced if theyâre worn or damaged with excessive play.
Another prime candidate for replacement is the rag joint between the steering column and the steering box. Even if this looks okay itâs a good idea to replace it if itâs been on for a long time because the rubber deteriorates over time, thus creating more play and slower steering response. In some cases the joint could actually fail under extreme use. Even though you likely wonât lose steering altogether youâll probably end up someplace you donât want to, fast. Replacing the rag joint is cheap insurance against that. The steering box usually doesnât need much attention other than perhaps a slight adjustment of the worm gear clearance if itâs excessive. This is easily done by loosening the locknut on the steering box and adjusting the screw per factory instructions. In extreme cases and/or where the box is leaking or otherwise damaged you can have it rebuilt or buy one that already has been rebuilt. If the cost of doing this proves to be too high you can perform an upgrade instead.
The power steering pump rarely has any problems other than perhaps a leaking seal or hose. These should be replaced unless you plan on upgrading. The problem with these systems is usually the hydraulic ram/cylinder and/or the associated control valve. They tend to leak due to wear of the seals. Their rubber bushings at the frame rail mount also tend to disintegrate over time, thus allowing the ram to move more than it should. This quickly makes the steering more vague and slow.
Inexpensive rebuild kits with superior materials reduce the tendency for leaks or excessive play after the rebuild. If the various rubber components are cracked or otherwise deteriorated they too can be replaced for little cost. Rebuilt rams are available, though theyâre not cheap. If youâre thinking of buying a complete replacement you probably should just save your money and upgrade to a better system instead. If you have no need to keep the original components for judging at a show, for example, it just doesnât pay to keep the stock system unless itâs in good shape and you donât want to put much money into a daily driver. Basically, keep the stock system healthy until you can afford to toss it. Otherwise, wait to upgrade it.
Vehicle Type 2: High-Performance Street Car
For any type of high-performance use you should toss the original steering system and replace it with a modern and effective solution. A prime example of this is the integral power steering conversion kit from Borgeson Universal. Kits are available for the 19641 â2â1970 models whether they came with manual or power steering. There may be clearance issues if youâre using the factory Z-bar on a manual transmission car; you may need to change to a cable or hydraulic clutch release system to make things work.
The Borgeson system completely eliminates the hydraulic ram/cylinder and control valve because all of their functionality has been incorporated into the new steering box. A higher-output pump is required so one is supplied with the necessary mounting bracket, hoses, steering link adaptor (if needed), and even a new rag joint. You may need to modify the stock steering column a bit but itâs a small price to pay for the benefits you receive. The steering is much more direct and responsive while also being much more durable and reliable with minimal risk of leaks.
To make things even stronger, you can weld the mounting plates wherever you can get to them. This further reduces flexing and adds strength by tying much of the rear of the car together to absorb the suspension loads. Proper weld penetration is critical. (These welds arenât pretty but theyâre deep enough and donât show.)
Ridetech provides these fixtures to help ensure the axle tabs are welded in the right place. After the axle has been verified as being correctly located and centered these adjustable fixtures are run between the axle and the upper link mounts on the cradle. The tabs to be welded are bolted to the other end before the fixtures are adjusted to rest the tabs in the proper place for welding. The tabs almost surely need to be trimmed a bit before welding to minimize gaps between the tabs and the housing. Once the tabs have been welded on and painted, the fixtures can be removed and replaced by the upper links.
The installation of the upper links is by far the most difficult aspect of installing this suspension. The reason is the tabs to be welded to the axle housing must be precisely located to ensure the axle is properly located in all directions. These tabs are critical for setting proper pinion angle. The upper links are adjustable in length to allow the proper setting to be reached but this may not be possible if the tabs are not located properly. If the cradle and axle tabs are properly placed the length of the upper links should be nearly identical. Be sure to paint all welds.
Considering all the new parts you get, this is one of the best upgrades you can make for the money. You experience better steering every time you drive the car. If your old/OEM system needs any significant amount of investment for your daily driver or high-performance street car this Borgeson setup is the better way to go. Itâs also fine for a street/strip car that just drag races.
The following is an installation overview of a Borgeson powersteering conversion. It is not a step-by-step guide because there are too many differences among cars.
The mounting brackets for the lower links are simple to bolt on because they are located by the spring pad pegs on the axle. Ensure the nuts on the U-bolts are evenly tightened and not overtightened to the point of warping the flanges. Some of the provided locknuts are fairly thin so itâs easy to strip them; thicker ones are easy to find.
The finished installation shows these coil-overs, which allow the usual adjustment to ride height and valving (via the adjustment knobs at the top of each coil-over). Non-adjustable and doubleadjustable versions plus other springs are available. The lower links can be mounted in any of three locations to optimize the geometry for different purposes.
Vehicle Type 3: Streetable Track-Day Car
For a streetable track-day car that sees more that just the drag strip you want to take things a bit further for maximum performance. This means converting to a rack-and-pinion steering system. The advantages of doing so are many, whether you go power or manual. The system is simpler, and there are a lot fewer joints. You simply have the rack and a means for mounting tie rods and U-joints plus a means for connecting to the steering column. It almost always weighs less than a regular system when you consider all the links, joints, and so forth it doesnât have.
In a powered system you also need a pump and hoses because the power assist is usually integral to the rack, if you want it to be. Manual racks are sometimes preferable, however, where lightweight is a priority and high cornering (or parking) forces are rarely, if ever, encountered. Think drag racing.
Add-on electric power assist kits can significantly reduce steering effort on just about any vehicle and do so without the need for a pump or hoses. They are usually installed under the dash, either with a new steering column or through modifications to the existing steering column. Some units integrate the assist motor directly onto the rack, though that can be a packaging problem. Electric-assist systems generally donât have the same direct feel as a hydraulic system. If you donât need that last bit of communication with the road this may be an acceptable option, though not necessarily an inexpensive or easily installed one.
Better rack-and-pinion systems such as the TCP conversion kit mount the rack in such a way that itâs not bearing any load other than that of the steering forces. Designs that allow the rack to be loaded in other ways can be prone to premature wear, sticking, resistance while moving, and even the risk of failure. Those that remove the tubular factory crossmember and replace it with an unbraced/unreinforced rack can be problematic. Those with proper reinforcement, however, can actually help stiffen the lower control arm mounts and the frame rails in general, thus providing some handling benefit.
Look for a system that uses existing factory mounting points for installation and has a vehicle-specific mounting bracket to ensure proper fit and clearance with the road and oil pan. The mounting location should also minimize the need for any corrective measures such as the installation of a bump steer kit or making exhaust modifications.
The TCP kit meets all these criteria while also having an exceptionally quick ratio (three turns lock-to-lock versus four or more for OEM racks), straight-cut gears, a large-diameter rack for strength, and the correct geometry. TCP includes specific mounting hardware for each car.
An interesting and effective rear suspension upgrade for early Mustangs is from TCP. This torque-arm/pushrod system does an incredible job of improving handling performance and traction under acceleration and braking. The long torque arm mounted directly to the front of the axle housing (and also to the body near the transmission) uses the axle forces generated to help plant the tires under acceleration and greatly reduce dive under braking. A Wattâs linkage virtually eliminates lateral movement (versus the inherent arcing path of panhard rods). The support cradle is reinforced by gussets and links, which extend forward to attach to the original leaf-spring mounts. The cradle may interfere with large exhausts. (Photo Courtesy Total Control Products)
Installation of a new steering box is pretty simple; itâs a direct bolt-in. Its larger size, however, requires some modification of the steering shaft. For 1968 and later models with a collapsible column (shown) the column can simply be âpersuadedâ back into the firewall with a suitable mallet. In some cases you may need to further trim the column housing. For earlier cars you need to cut the column and use the included shorter, solid shaft.
A very effective and reasonably priced way to dramatically improve steering performance is to replace it with a more contemporary system such as this one from Borgeson (left). It has far fewer system components. More importantly, the integration of the power assist directly into the steering box greatly improves steering feel and response. Weight and the number of potential leaks are also reduced plus additional header clearance is provided. This setup is absolutely the minimum that should be considered for any kind of performance driving and even for strip use if youâre drag racing.
Written by Frank Bohanan and Posted with Permission of CarTechBooks
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