Jay
09-24-2008, 03:33 PM
Understanding the Mustang chassis and suspension and how they relate to drag racing.
Drag racing is one of most basic yet most exciting forms of motor sport.The concept is simple to understand and virtually anyone can get involved.
It doesn't matter if you're driving a stock street car, a slightly modified boulevard bruiser, or a purpose-built drag race machine--there's a class for everyone. Fortunately, many Ford products--especially the late-model Mustang--lend themselves to the dragracing arena. And if you modify your machine to run quicker elapsed times with a greater trap speed, you'll quickly realize you must also modify the chassis and suspension to get the power to the ground.
There's a science to applying horsepower. To do it you'll need traction--and lots of it. But you can't sacrifice control or stability in the process. You'll learn early on that the quickest way to the finish line is a straight line. You'll also learn those who make wild runs are not the good drivers; they're the ones who end up with slow e.t.'s. Even worse, they sometimes end up in the wall. Maximizing performance takes a basic understanding of chassis and suspension, and with that knowledge you'll be on the fast track to low e.t.'s.
-
The Chassis
When it comes to building a quick, reliable, and safe Mustang,you should begin with the chassis. As it's the foundation, it must be sturdy.
Late-model Mustangs utilize a unibody chassis (also called the frame). A unibody chassis is built from a thick, sheetmetal floorpan with most of the body structure welded to the floor. This creates a rigid platform to which you can mount the suspension components. It differs from a full-frame chassis (which resembles a ladder) that uses framerails supported with cross bracing to which a body and suspension are bolted.
There are many benefits to unibody construction, including lighter weight and reduced construction costs. It also allows for the floor of the vehicle to be lower. These factors make unibody cars greatfor racing, but there are some important modifications that should be done to prepare a unibody car.
First and foremost, you must strengthen the chassis. When it comes to Mustangs, the unibody structure was not originally designed to handle the torque loads of a racing engine or slick tires. Simply stated, when the power is increased or slick tires are added, you increase the load on the suspension components, the pick-up (or attachment) points, and the actual unibody structure.
It is therefore critical to install bracing that will increase the overall rigidity of the unibody and the pick-up points. If this isn't done--and done properly--the unibody will flex, the suspension pick-up points may move, and the suspension can't work as designed. The car will be unpredictable and it may handle poorly.
Because of this, we also now know to add a set of frame connectors. These are necessary because they tie together the front and rear subframes of the vehicle, and they rein-force the unibody chassis structure.
Next on the list for any serious racer should be a rollbar or rollcage. This type of structure will add crash protection for the driver and strength to the unibody. It is important to have the structure tie in to critical points in the car that will enhance the strength. Simply welding it to the floorpan is not as good as having it welded to the stronger bracing points, namely the main floorboard crossmember, the rocker panels, and the rear shock towers. With the engine applying torque to the K-member and the suspension prying on the floor in the back, it becomes increasingly important to also add kicker bars connecting to the torque boxes where the suspension parts mount.
-
Launch Control
During launch, maximum power is applied to accelerate the vehicle in the most efficient manner. This means you must be able to use all the power to accelerate forward, while not giving up traction and while maximizing all the variables, of which there are many, including track conditions, weather, horsepower and torque output, launch rpm/converter stall speed, trans-mission and rear axle gearing, suspension type and adjustment, and tire size and type.And let's not forget about the weight of the vehicle, available traction, and driver skill.
In that first moment of launch, power is transferred from the engine to the transmission, either through a clutch or a torque converter. Torque is multiplied by the transmission gearing,and the flow of power is sent to the driveshaft and to the rearend. The ring-and-pinion gears further multiply torque. Then the differential orspool directs the torque to the axles in order to drive the wheels.Finally, the tires rotate and the car begins forward motion.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_20_s.jpg
After many years, Mustang racers have learned a lot about making the four-bar rear suspension work at the track.
If the rear housing was bolted or welded solidly to the chassis, as in a dragster,you would rely solely on the tires for traction. But in the case of late-model Mustangs, the suspension allows the four wheels and tires to move up and down independently of the chassis structure. And because the chassis is suspended, force applied to the sprung weight causes weight transfer. Generally, when accelerating, the weight moves rear-ward; when braking, it transfers forward.
But what many don't realize is the act of weight transfer is actually caused by engine torque and gearing. Because every action has an opposite and equal reaction, the rear housing, which is attached to the axles, will rotate in the opposite direction of the wheels. Because of this reaction, force is applied to the upper and lower control arms, which are attached to the housing.
Under acceleration, the upper arms are pulled rearward, while the lower arms are forced forward. This force is applied directly to the vehicle's chassis at the control-arm attachment points.
Since the control arms are attached directly to the chassis of the car, it is this force, or torque, that causes the nose to rise and the weight to transfer rearward. The upper control arms pull the chassis or unibody up and the lower arms drive it forward and up.
Meanwhile, the front springs, which have been compressed, possess stored energy. When the nose begins to rise, the springs release this energy and force the nose up quicker than it could be lifted on its own.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_22_s.jpg
It may be a challenge getting the '05 Mustang GT suspension to work at the strip, with three control arms and a single Panhard bar. Notice how the coil springs are located on the rear housing rather than on the control arms.
The sprung weight will be supported by the springs. Springs separate the wheels and tires from the chassis and allow the tires to remain in compliance with the road or racing surface.Springs also allow the wheels and tires to absorb bumps and vibration without transferring them fully to the vehicle's occupants.
If the car has enough power or enough gearing, it will lift the nose off the ground. This lifting can be further enhanced with front struts that have little resistance on extension. Naturally, a tighter strut will slow the rise of the nose. Many racers use an adjustable strut to control front-end rise. A properly designed strut should also be engineered to be stiffer on the compression side so the car doesn't slam down and bottom out the suspension.
Racers can also alter the rate or damping effect of the rear shocks to change the rate at which the rear housing reacts when acted upon. Ultimately, it is the tuning of these two areas that make up a good suspension. Of course, you can alter the way your car launches by moving weight, or by changing the launch rpm, the gearing, and sometimes tire pressure, too.
Ford Mustang Rear View At Track
One of the best chassis-tuning tools is a good crew chief using a video camera. This not only allows you to have a seat-of-the-pants perspective, but also that of the crew chief and the video replay.
As power is increased or stiffer gearing is installed, the load or force applied to the control arms, the bushings, and the chassis is also increased. Therefore, it should be noted that the first thing any Mustang owner does before hitting the track is beef up the chassis, the suspension attachment points, and the control arms and bushings.
As you can see, altering anything relating to the engine, chassis, suspension, gearing, and so on will affect how the car hooks and drives down the track. That's why it's important to understand what each part does and to buy only parts that will complement the entire package.
-
Airbag
In some applications, racers will install a specially designed bag inside the rear spring(s). This bag can be inflated to increase the spring rate of that particular spring. In most cases, increasing the rate of the right-side rear spring can help limit roll rotation onlaunch, which helps the vehicle drive straight. A drag race-style, rear antiroll bar, however, is the preferred method of limiting and controlling roll rotation.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_02_s.jpg
AntiRoll Bar (rear)
Many chassis builders and aftermarket suspensionsuppliers offer rear antiroll bar kits to enhance dragstrip performance.Antiroll bars (also called sway bars) are actually torsion springs, and when applied to the rear suspension they can limit roll rota-tion (seen as twisting) and enhance vehicle stability as well. The drag-style rear antiroll bar features two bushings or bearings that are mounted betweenthe chassis rails at a location above the rear housing. A torsion bar isthen located between the bushings or bearings, and the bar is connected with links that drop down and attach to the rearend housing. When launch is viewed from the back of the car, you'd see that the body rolls to the right and the rear housing actually rolls to the left. The antiroll bar,which is connected between the body and the rear, works to resist this opposite loading and keep the rear and body from twisting apart. The result is equal loading to both sides of the rear housing, which also means more equal traction to each tire.
AntiRoll Bar (front)
Most vehicles will be equipped from the factory with a front antiroll bar. This bar works under the same principle asthe rear bar, but it is connected to the chassis and to the front A-arms via end links. Since the front antiroll bar ties the lower A-arms to the chassis, it has a tendency to limit front-end lift on launch. That's because the antiroll bar prevents full extension of the lower A-arms.For the purpose of drag racing, therefore, it is beneficial to remove the front antiroll bar as this will result in more rapid and increased pitch rotation of the front end.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_03_s.jpg
Bearings/Bushings
At points where moving parts meet or touch there willbe a certain amount of resistance or friction. It is necessary to install a material softer than those touching each other to reduce this friction. To accomplish this, bearings or bushings are installed. These can be found between suspension links, inside the wheels, and inside the engine. Shown above are polyurethane bushings used on various suspension components. These generally replace softer rubber bushings, which tend to flex or distort more than polyurethane.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_04_s.jpg
Coilover shocks/struts
Any shock or strut that is fitted directly with a coil spring is considered to be a coil- over shock. Most coilovers are more compact and lighter in weight than stand-alone spring and shock, or strut combinations. This allows them to fit neatly between wide rear tires commonly found in dragracing. It also allows racers to change springs more easily.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_05_s.jpg
http://images.musclemustangfastfords.com/tech/mm_0503_drag_06_s.jpg
Control Arms
Late-model Mustangs from 1979 to 2004 (excluding'99-present Cobras and Cobra Rs) utilize a four-link rear suspension,with two springs, four shocks, and a small antiroll bar that links between the two lower arms. This system incorporates two upper and two lower control arms (also called trailing arms). The arms connect to the rear housing and to the vehicle on the opposite end. Stock arms areformed from stamped steel and use rubber bushings at each end. The soft rubber limits noise and vibration, but it is not optimum for racing applications because rubber tends to deflect excessively. The aftermarket produces quite a few variations of the upper and lowercontrol arms. Some are made from billet aluminum, some from round-tube aluminum, and others from boxed aluminum or steel.
Driveshaft Safety Loop
A driveshaft safety loop is a device made of steel that surrounds the driveshaft 360 degrees and is designed tocapture the driveshaft in the case of driveshaft or U-joint failure. The NHRA and IHRA have specific requirements for size, type, and placement of the driveshaft safety loop.
-
Frame/Unibody
Most automobiles utilize one of two types of frames--ladder or unitized body. The late-model Mustang incorporates a unibody design, which is lighter than a full-frame car and more cost-effective to build. The unibody consists of the floorpan, the bodypanels, the front radiator support, and the front and rear subframes,all of which are welded together during original vehicle construction.
Frame Connectors
Because the Mustang uses a unibody frame, it is necessary to install aftermarket frame connectors to link the front subframe with the rear subframe, thus strengthening the entire structure. Installing frame connectors increases the stiffness of the floorboard and chassis and greatly reduces flexing of the structure,resulting in better performance from the suspension and increased longevity from the chassis. Frame connectors come in many shapes and forms and they can be either bolted in or welded. For the ultimate in strength, chassis builders will section the floorboard of the vehicle and drop in custom connectors, which are then welded directly to the floor of the vehicle.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_08_s.jpg
Heim Joints
These double-adjustable upper controlarms use Heim joints at the front mounting point. A Heim joint is acaptured bearing that provides movement for the suspension link without any bind or deflection.
K-member
The K-member in a late-model Mustang is used to support the engine, along with the lower control arms. It gets its name from the K-shaped design. The stock unit is a steel member that attaches to the front subframe of the body and provides attachment points for the lower A-arms and the engine mounts. Aftermarket K-members are usually built from tubular or boxed steel and therefore can be built lighter than the stock stamped-steel K-member.
Ford Mustang 5.0 Front Driver Side View
Pitch Rotation
Simply stated, pitch rotation is the technical term for weight transfer. It is beneficial to have sufficient pitch rotation to help hook, but excessive weight transfer can cause giant wheelstands--which don't necessarily make you go fast, but they do get you on magazine covers.
Roll Rotation
This is noticed as a twisting movement seen on some dragcars during launch. A car that roll rotates badly will lift the left front tire on launch much further than the right front. You will also notice on Mustangs that roll rotate badly there is a lot of chassis separation between the left rear tire and the wheelwell, and little separation on the opposite side. Excessive roll rotation is wasted energy that could otherwise be used to drive the car forward. This also can upset the geometry of the suspension and lead to poor handling characteristics. Excessive roll rotation can be caused by a number of things, including a lack of frame connectors, lack of a rear anti rollbar, or mismatched springs. It can even occur from an abundance of torque or gearing. It can also be caused by worn bushings, a bent chassis, or broken/tweaked torque boxes. Generally, you can solve this problem by installing a rear antiroll bar, a stiffer right rear spring(or an airbag), and a rollbar or rollcage to stiffen the chassis.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_11_s.jpg
Rollbar/Rollcage
Most drag cars are equipped with a rollbar or rollcage.The rollbar/cage is a steel structure made from mild steel or lighte rchrome-moly tubing built into the car's interior to provide rollover protection and to increase the stiffness and/or rigidity of the chassis/frame. A rollbar generally incorporates a main hoop that sitsdirectly behind the driver and is supported with forward and rearwardbars. A rollcage is similar to a rollbar, but it incorporates additional bars that are placed above and forward of the driver. In addition to driver protection, the rollcage adds strength to the chassis--and in some cases is used as the chassis--to which all the suspension members are attached. This type of vehicle is termed as a "tube chassis" car.Modern door slammers (shown) incorporate a Funny Car-style cage to add extra protection for the driver.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_12_s.jpg
Shocks/Struts
Shocks or struts are damping devices that are mounted a teach corner of the vehicle and control the rate at which the wheels oscillate. For the purpose of drag racing, it is beneficial to have front struts that are loose on extension because this allows for a rapid rise rate of the front end, which assists weight transfer.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_14_s.jpg
Springs
Springs act to provide a cushion between the wheels and tires,and the body of the vehicle. Drag racers will vary the size, shape, and rate of the springs to alter the effect of weight transfer during launch. A tall, thin-wire front spring can be compressed quite a bit and will possess a great amount of stored energy, whereas a short, thick spring will be much harder to compress. A short spring is therefore better suited for handling because it can resist compression. Common spring types are coil springs and leaf springs.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_15_s.jpg
Torque Boxes
Torque boxes are specially designed components on a stock Mustang that are welded to the unibody. They provide an attachment point for the rear trailing arms (also called control arms). In factory trim,the torque boxes (upper and lower) are tack welded to the body of thecar, and under abuse they tend to tear away from the body. For racing or heavy street use, it is necessary to reinforce the torque boxes. This can be done by welding the seams of the boxes directly to the unibody,or by installing an aftermarket reinforcing kit such as the Battle Boxes sold by Wild Rides Race Cars.
Drag racing is one of most basic yet most exciting forms of motor sport.The concept is simple to understand and virtually anyone can get involved.
It doesn't matter if you're driving a stock street car, a slightly modified boulevard bruiser, or a purpose-built drag race machine--there's a class for everyone. Fortunately, many Ford products--especially the late-model Mustang--lend themselves to the dragracing arena. And if you modify your machine to run quicker elapsed times with a greater trap speed, you'll quickly realize you must also modify the chassis and suspension to get the power to the ground.
There's a science to applying horsepower. To do it you'll need traction--and lots of it. But you can't sacrifice control or stability in the process. You'll learn early on that the quickest way to the finish line is a straight line. You'll also learn those who make wild runs are not the good drivers; they're the ones who end up with slow e.t.'s. Even worse, they sometimes end up in the wall. Maximizing performance takes a basic understanding of chassis and suspension, and with that knowledge you'll be on the fast track to low e.t.'s.
-
The Chassis
When it comes to building a quick, reliable, and safe Mustang,you should begin with the chassis. As it's the foundation, it must be sturdy.
Late-model Mustangs utilize a unibody chassis (also called the frame). A unibody chassis is built from a thick, sheetmetal floorpan with most of the body structure welded to the floor. This creates a rigid platform to which you can mount the suspension components. It differs from a full-frame chassis (which resembles a ladder) that uses framerails supported with cross bracing to which a body and suspension are bolted.
There are many benefits to unibody construction, including lighter weight and reduced construction costs. It also allows for the floor of the vehicle to be lower. These factors make unibody cars greatfor racing, but there are some important modifications that should be done to prepare a unibody car.
First and foremost, you must strengthen the chassis. When it comes to Mustangs, the unibody structure was not originally designed to handle the torque loads of a racing engine or slick tires. Simply stated, when the power is increased or slick tires are added, you increase the load on the suspension components, the pick-up (or attachment) points, and the actual unibody structure.
It is therefore critical to install bracing that will increase the overall rigidity of the unibody and the pick-up points. If this isn't done--and done properly--the unibody will flex, the suspension pick-up points may move, and the suspension can't work as designed. The car will be unpredictable and it may handle poorly.
Because of this, we also now know to add a set of frame connectors. These are necessary because they tie together the front and rear subframes of the vehicle, and they rein-force the unibody chassis structure.
Next on the list for any serious racer should be a rollbar or rollcage. This type of structure will add crash protection for the driver and strength to the unibody. It is important to have the structure tie in to critical points in the car that will enhance the strength. Simply welding it to the floorpan is not as good as having it welded to the stronger bracing points, namely the main floorboard crossmember, the rocker panels, and the rear shock towers. With the engine applying torque to the K-member and the suspension prying on the floor in the back, it becomes increasingly important to also add kicker bars connecting to the torque boxes where the suspension parts mount.
-
Launch Control
During launch, maximum power is applied to accelerate the vehicle in the most efficient manner. This means you must be able to use all the power to accelerate forward, while not giving up traction and while maximizing all the variables, of which there are many, including track conditions, weather, horsepower and torque output, launch rpm/converter stall speed, trans-mission and rear axle gearing, suspension type and adjustment, and tire size and type.And let's not forget about the weight of the vehicle, available traction, and driver skill.
In that first moment of launch, power is transferred from the engine to the transmission, either through a clutch or a torque converter. Torque is multiplied by the transmission gearing,and the flow of power is sent to the driveshaft and to the rearend. The ring-and-pinion gears further multiply torque. Then the differential orspool directs the torque to the axles in order to drive the wheels.Finally, the tires rotate and the car begins forward motion.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_20_s.jpg
After many years, Mustang racers have learned a lot about making the four-bar rear suspension work at the track.
If the rear housing was bolted or welded solidly to the chassis, as in a dragster,you would rely solely on the tires for traction. But in the case of late-model Mustangs, the suspension allows the four wheels and tires to move up and down independently of the chassis structure. And because the chassis is suspended, force applied to the sprung weight causes weight transfer. Generally, when accelerating, the weight moves rear-ward; when braking, it transfers forward.
But what many don't realize is the act of weight transfer is actually caused by engine torque and gearing. Because every action has an opposite and equal reaction, the rear housing, which is attached to the axles, will rotate in the opposite direction of the wheels. Because of this reaction, force is applied to the upper and lower control arms, which are attached to the housing.
Under acceleration, the upper arms are pulled rearward, while the lower arms are forced forward. This force is applied directly to the vehicle's chassis at the control-arm attachment points.
Since the control arms are attached directly to the chassis of the car, it is this force, or torque, that causes the nose to rise and the weight to transfer rearward. The upper control arms pull the chassis or unibody up and the lower arms drive it forward and up.
Meanwhile, the front springs, which have been compressed, possess stored energy. When the nose begins to rise, the springs release this energy and force the nose up quicker than it could be lifted on its own.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_22_s.jpg
It may be a challenge getting the '05 Mustang GT suspension to work at the strip, with three control arms and a single Panhard bar. Notice how the coil springs are located on the rear housing rather than on the control arms.
The sprung weight will be supported by the springs. Springs separate the wheels and tires from the chassis and allow the tires to remain in compliance with the road or racing surface.Springs also allow the wheels and tires to absorb bumps and vibration without transferring them fully to the vehicle's occupants.
If the car has enough power or enough gearing, it will lift the nose off the ground. This lifting can be further enhanced with front struts that have little resistance on extension. Naturally, a tighter strut will slow the rise of the nose. Many racers use an adjustable strut to control front-end rise. A properly designed strut should also be engineered to be stiffer on the compression side so the car doesn't slam down and bottom out the suspension.
Racers can also alter the rate or damping effect of the rear shocks to change the rate at which the rear housing reacts when acted upon. Ultimately, it is the tuning of these two areas that make up a good suspension. Of course, you can alter the way your car launches by moving weight, or by changing the launch rpm, the gearing, and sometimes tire pressure, too.
Ford Mustang Rear View At Track
One of the best chassis-tuning tools is a good crew chief using a video camera. This not only allows you to have a seat-of-the-pants perspective, but also that of the crew chief and the video replay.
As power is increased or stiffer gearing is installed, the load or force applied to the control arms, the bushings, and the chassis is also increased. Therefore, it should be noted that the first thing any Mustang owner does before hitting the track is beef up the chassis, the suspension attachment points, and the control arms and bushings.
As you can see, altering anything relating to the engine, chassis, suspension, gearing, and so on will affect how the car hooks and drives down the track. That's why it's important to understand what each part does and to buy only parts that will complement the entire package.
-
Airbag
In some applications, racers will install a specially designed bag inside the rear spring(s). This bag can be inflated to increase the spring rate of that particular spring. In most cases, increasing the rate of the right-side rear spring can help limit roll rotation onlaunch, which helps the vehicle drive straight. A drag race-style, rear antiroll bar, however, is the preferred method of limiting and controlling roll rotation.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_02_s.jpg
AntiRoll Bar (rear)
Many chassis builders and aftermarket suspensionsuppliers offer rear antiroll bar kits to enhance dragstrip performance.Antiroll bars (also called sway bars) are actually torsion springs, and when applied to the rear suspension they can limit roll rota-tion (seen as twisting) and enhance vehicle stability as well. The drag-style rear antiroll bar features two bushings or bearings that are mounted betweenthe chassis rails at a location above the rear housing. A torsion bar isthen located between the bushings or bearings, and the bar is connected with links that drop down and attach to the rearend housing. When launch is viewed from the back of the car, you'd see that the body rolls to the right and the rear housing actually rolls to the left. The antiroll bar,which is connected between the body and the rear, works to resist this opposite loading and keep the rear and body from twisting apart. The result is equal loading to both sides of the rear housing, which also means more equal traction to each tire.
AntiRoll Bar (front)
Most vehicles will be equipped from the factory with a front antiroll bar. This bar works under the same principle asthe rear bar, but it is connected to the chassis and to the front A-arms via end links. Since the front antiroll bar ties the lower A-arms to the chassis, it has a tendency to limit front-end lift on launch. That's because the antiroll bar prevents full extension of the lower A-arms.For the purpose of drag racing, therefore, it is beneficial to remove the front antiroll bar as this will result in more rapid and increased pitch rotation of the front end.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_03_s.jpg
Bearings/Bushings
At points where moving parts meet or touch there willbe a certain amount of resistance or friction. It is necessary to install a material softer than those touching each other to reduce this friction. To accomplish this, bearings or bushings are installed. These can be found between suspension links, inside the wheels, and inside the engine. Shown above are polyurethane bushings used on various suspension components. These generally replace softer rubber bushings, which tend to flex or distort more than polyurethane.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_04_s.jpg
Coilover shocks/struts
Any shock or strut that is fitted directly with a coil spring is considered to be a coil- over shock. Most coilovers are more compact and lighter in weight than stand-alone spring and shock, or strut combinations. This allows them to fit neatly between wide rear tires commonly found in dragracing. It also allows racers to change springs more easily.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_05_s.jpg
http://images.musclemustangfastfords.com/tech/mm_0503_drag_06_s.jpg
Control Arms
Late-model Mustangs from 1979 to 2004 (excluding'99-present Cobras and Cobra Rs) utilize a four-link rear suspension,with two springs, four shocks, and a small antiroll bar that links between the two lower arms. This system incorporates two upper and two lower control arms (also called trailing arms). The arms connect to the rear housing and to the vehicle on the opposite end. Stock arms areformed from stamped steel and use rubber bushings at each end. The soft rubber limits noise and vibration, but it is not optimum for racing applications because rubber tends to deflect excessively. The aftermarket produces quite a few variations of the upper and lowercontrol arms. Some are made from billet aluminum, some from round-tube aluminum, and others from boxed aluminum or steel.
Driveshaft Safety Loop
A driveshaft safety loop is a device made of steel that surrounds the driveshaft 360 degrees and is designed tocapture the driveshaft in the case of driveshaft or U-joint failure. The NHRA and IHRA have specific requirements for size, type, and placement of the driveshaft safety loop.
-
Frame/Unibody
Most automobiles utilize one of two types of frames--ladder or unitized body. The late-model Mustang incorporates a unibody design, which is lighter than a full-frame car and more cost-effective to build. The unibody consists of the floorpan, the bodypanels, the front radiator support, and the front and rear subframes,all of which are welded together during original vehicle construction.
Frame Connectors
Because the Mustang uses a unibody frame, it is necessary to install aftermarket frame connectors to link the front subframe with the rear subframe, thus strengthening the entire structure. Installing frame connectors increases the stiffness of the floorboard and chassis and greatly reduces flexing of the structure,resulting in better performance from the suspension and increased longevity from the chassis. Frame connectors come in many shapes and forms and they can be either bolted in or welded. For the ultimate in strength, chassis builders will section the floorboard of the vehicle and drop in custom connectors, which are then welded directly to the floor of the vehicle.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_08_s.jpg
Heim Joints
These double-adjustable upper controlarms use Heim joints at the front mounting point. A Heim joint is acaptured bearing that provides movement for the suspension link without any bind or deflection.
K-member
The K-member in a late-model Mustang is used to support the engine, along with the lower control arms. It gets its name from the K-shaped design. The stock unit is a steel member that attaches to the front subframe of the body and provides attachment points for the lower A-arms and the engine mounts. Aftermarket K-members are usually built from tubular or boxed steel and therefore can be built lighter than the stock stamped-steel K-member.
Ford Mustang 5.0 Front Driver Side View
Pitch Rotation
Simply stated, pitch rotation is the technical term for weight transfer. It is beneficial to have sufficient pitch rotation to help hook, but excessive weight transfer can cause giant wheelstands--which don't necessarily make you go fast, but they do get you on magazine covers.
Roll Rotation
This is noticed as a twisting movement seen on some dragcars during launch. A car that roll rotates badly will lift the left front tire on launch much further than the right front. You will also notice on Mustangs that roll rotate badly there is a lot of chassis separation between the left rear tire and the wheelwell, and little separation on the opposite side. Excessive roll rotation is wasted energy that could otherwise be used to drive the car forward. This also can upset the geometry of the suspension and lead to poor handling characteristics. Excessive roll rotation can be caused by a number of things, including a lack of frame connectors, lack of a rear anti rollbar, or mismatched springs. It can even occur from an abundance of torque or gearing. It can also be caused by worn bushings, a bent chassis, or broken/tweaked torque boxes. Generally, you can solve this problem by installing a rear antiroll bar, a stiffer right rear spring(or an airbag), and a rollbar or rollcage to stiffen the chassis.
http://images.musclemustangfastfords.com/tech/mm_0503_drag_11_s.jpg
Rollbar/Rollcage
Most drag cars are equipped with a rollbar or rollcage.The rollbar/cage is a steel structure made from mild steel or lighte rchrome-moly tubing built into the car's interior to provide rollover protection and to increase the stiffness and/or rigidity of the chassis/frame. A rollbar generally incorporates a main hoop that sitsdirectly behind the driver and is supported with forward and rearwardbars. A rollcage is similar to a rollbar, but it incorporates additional bars that are placed above and forward of the driver. In addition to driver protection, the rollcage adds strength to the chassis--and in some cases is used as the chassis--to which all the suspension members are attached. This type of vehicle is termed as a "tube chassis" car.Modern door slammers (shown) incorporate a Funny Car-style cage to add extra protection for the driver.
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Shocks/Struts
Shocks or struts are damping devices that are mounted a teach corner of the vehicle and control the rate at which the wheels oscillate. For the purpose of drag racing, it is beneficial to have front struts that are loose on extension because this allows for a rapid rise rate of the front end, which assists weight transfer.
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Springs
Springs act to provide a cushion between the wheels and tires,and the body of the vehicle. Drag racers will vary the size, shape, and rate of the springs to alter the effect of weight transfer during launch. A tall, thin-wire front spring can be compressed quite a bit and will possess a great amount of stored energy, whereas a short, thick spring will be much harder to compress. A short spring is therefore better suited for handling because it can resist compression. Common spring types are coil springs and leaf springs.
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Torque Boxes
Torque boxes are specially designed components on a stock Mustang that are welded to the unibody. They provide an attachment point for the rear trailing arms (also called control arms). In factory trim,the torque boxes (upper and lower) are tack welded to the body of thecar, and under abuse they tend to tear away from the body. For racing or heavy street use, it is necessary to reinforce the torque boxes. This can be done by welding the seams of the boxes directly to the unibody,or by installing an aftermarket reinforcing kit such as the Battle Boxes sold by Wild Rides Race Cars.