The basic job of the shock absorber is to control or dampen the movement of the springs. A shock absorber that is too soft will have a hard time controlling the suspension, causing the ride to be bouncy and inefficient while cornering. If the shock is too stiff, the ride will be harsh and cause the vehicle to slide too easily.
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Shocks have two functions: compression and rebound. Compression is defined as the collapsing of the shock absorber. This occurs when the car hits a bump and the suspension moves upward, pushing the piston rod into the shock body. Rebound is when the shock extends. Most people associate this with their car hitting a dip in the road, causing the suspension to drop and the shock to extend, but rebound does much more than that. When you drive your car into a hard left turn, the right front (outside) shock compresses, the left front (inside) shock extends. If you have the right shock valving, the inside shock will resist extending (rebound) and the outside shock will resist compression. In this way, the shocks assist the springs and sway bar to limit body roll and increase cornering (lateral) traction.
Most factory replacement shocks do not have adjustable compression or rebound. Some aftermarket performance shocks are available with internal valves that allow you to adjust them for preferred compression and rebound. Those two settings are different for each application, due to many factors, including vehicle weight, tires, and spring rates. In the past, drag car front shock absorbers were marketed as 90/10 shocks. This generally meant that they were valved for 90 percent compression and 10 percent rebound. Shock experts say that 90/10 shocks are more of a marketing term and a pair of actual 90/10 shocks would be very dangerous. Marketing shocks based on percentages is an old trick that won’t seem to go away. They are better measured in terms of how much force it takes to compress or extend the shock. Drag shocks are set up to allow the front of the car to lift easily during the launch (the shock has very little resistance to extension), but come down slow (more resistance on the compression), which transfers more weight to the rear wheels for off-the-line traction. While this type of set-up is great for drag racing, it is not safe for the street. A Restomod would be better with a shock valved with the compression and rebound resistance much closer to equal.
Most conventional shocks are not rebuildable. The more expensive race shocks are rebuildable and can also be revalved for fine-tuning your suspension. These shocks are usually adjustable in some way. Some shocks have a knob at the bottom or top to adjust them from soft to firm. Other shocks have to be compressed in order to adjust the firmness.
A mono-tube shock has a single chamber inside the shock body. A single valve at the end of the piston modulates dampening. Mono-tube shocks are typically of high-pressure gas design, ranging from 250 to 400 psi. The pressure inhibits cavitation caused by foaming or aeration if air gets drawn through the valve. Since they only have a single chamber, mono-tube shocks dissipate heat faster than twin-tube designs. They can be mounted upright or upside down.
A twin-tube shock has two chambers inside the shock body: an inner and outer chamber. The inner chamber contains the piston and the oil. On the end of the piston is a valve. There is also a valve at the bottom of the inner chamber, which modulates the amount of fluid forced into the outer chamber.
There are two different ways to build twin-tube shocks. The more expensive way is to use a cellular bag (also known as a “gas bag”). The bag is typically filled with Freon gas to 10 to 20 psi. Other designs also include a foam material inside the gas bag. Some sources say non-gas bag designs are more efficient. Unlike high-pressure twin-tube shocks, twin-tube gas-bag shocks don’t rely on gravity. They can be mounted upright, upside down, or even sideways.
Coil-over shocks are similar to conventional shocks, except for the threaded body or threaded adapter collar. A coil-over shock replaces the factory shock and spring. The spring rate is determined by the vehicle weight and intended ride quality. The coil is placed on the shock and allows vehicle height adjustment. Both mono- and twin-tube shocks are available as coil-over shocks.
A sway bar or anti-roll bar is one of many parts that play a role in reducing body roll. The body-roll elements are: spring rate, wheel center rate, tire rate, ride rate, and roll rate. The springs, shocks, bushings, wheels, tires, chassis, and sway bars are all key parts in the car’s ability to corner well. Obviously, a car would operate without a sway bar, but it would not be very safe or fun to drive. The typical front sway bar ends attach to the left and right lower control arms. The main center section of the bar is mounted to the frame rail on the left and right side of the front of the car. The typical (non-IRS equipped car) rear sway bar ends mount to the left and right rear frame rails, and the main center section of the sway bar mounts to the differential housing.
The main center section of the sway bar is horizontally attached to the right and left frame rail, and it is able to pivot on a single axis. If the right end of the sway bar acts, the left end of the sway bar reacts, and vice versa. This means if the right end of the bar moves upward, the left end of the sway bar also wants to move upward. The same is true for downward motion.
In really basic terms, when a car is driven into a left-hand turn, the right (outside) control arm wants to push the right end of the sway bar upward, which in turn makes the left end of the sway bar want to lift the left (inside) control arm. At that same time, the left (inside) control arm is pulling the left end of the sway bar downward, which in turn makes the right (outside) end of the sway bar force the outside control arm downward. The action of the forces of both of the ends of the sway bar counteract each other and are coupled to the frame, which causes the frame to attempt to stay level to the ground, reducing body roll. A sway bar with a bigger diameter reduces more body roll. Body roll affects lateral (cornering) traction of the tires by planting or forcing the tire down onto the asphalt. Some body roll is necessary to increase the traction of the outside tire. If the suspension does not have any body roll, the tires will tend to slide instead of biting for traction with the outside tire.
The front and rear (if your car has one) sway bars can work together or against each other. A rule of thumb: If your car has understeer, you can decrease the diameter of the front bar and increase the diameter of the rear bar. If your car suffers from oversteer, you should increase the size of the front bar and decrease or remove the rear bar.
Aftermarket Sway Bars and Accessories
There are two types of aftermarket sway bars – conventional and racing. Conventional aftermarket bars typically resemble the shape of a stock bar, with the exception of the increased diameter. They even usually bolt into the stock bar locations. Conventional aftermarket sway bars were only offered as solid units until 2000. In 2000, Hotchkis Performance started processing hollow bars. These units are hollow, large-diameter bars that are as strong as their solid counterparts, but only a fraction of the weight. As of the original release of this book, Hotchkis only offers hollow bars for the late- 1990 Ford models.
Quickor Suspensions and Addco offer a full line of solid sway bars for Ford and Mercury cars. Stam-Bar Stabilizers offer adjustable front and rear sway bars strictly for the 1965 through 1973 Mustangs. The custom sliding adjustable end link system was derived from racing car technology and it works great for tuning the suspension on your Mustang. Easy adjustments can be made at the track or in your garage. If you are going to race on a track that has 85 percent right turns and 15 percent left turns, the StamBar can be adjusted to increase bias and get more traction from the outside tires.
Gun-drilled racing sway bars are completely different from conventional sway bars in appearance, but they do the same job. Typically, this type of sway bar consists of a straight-splined solid or gundrilled (hollow) bar with adjustable aluminum or steel arms. They are mounted with solid bearings or Delrin inserts. The aluminum or steel arms are available in many lengths, and they are usually straight. The installer can then bend them to the desired shape, so that they clear the tires and suspension pieces. These bars are used on circle- and dirt-track racing cars, but they also have been showing up on full-tilt Restomods. At the time of this book’s publication, these types of bars were only available from Griggs Racing for their 1965 through 1970 Mustang GR- 350 custom front suspension systems.
You can also engineer your own racing-style sway bars. You can pick up different width, diameter, and wall thickness bars; different length and shaped arms; and the necessary hardware from Speedway Engineering.
Sway bar bushings and end-links come in a few different types. The bushings are available in rubber and polyurethane. The end-links are available in the standard rubber and polyurethane through-bolt type, the solid rod-end type, or with studtype rod ends.
The standard through-bolt endlinks are the most common way to attach your sway bar to the control arms. These end-links come in different lengths. To determine the length you will need for your application, the car will need to be sitting at rest with the sway bar installed (with the exception of the end links). If you pivot the sway bar so the ends are parallel to the ground, there should be a gap between the end of your sway bar and the locating hole in the control arm. Measure that distance; it will be the length of the end-link that you will need. The solid rod-end style end-links work well on the track because they offer non-binding, fluid motion. On the street, most car builders prefer the longer life of bolt-through types over the solid rod-ends. Once the solid rodends wear, they will start making noise. As with any rod ends, installing safety washers will ensure the rod ends will not totally separate if the ball wears out. Automotive engineers are constantly coming up with new ways to mount the ends of the sway bars to control arms.
Keep your eyes out on the higher performance cars for new end links and other hardware. Always keep your eyes and your mind open for new designs when you are around racetracks and new car dealerships. You never know when you might see something that would work great on your Restomod. This goes for every aspect of your car, not just the suspension.
Sway bar, upper control arm, and lower control arm bushings on most Ford and Mercury front suspensions are made of rubber. Aftermarket companies offer replacement bushings made from polyurethane, which is a stronger compound that offers performance benefits. For even more performance and a more road-ready feel, solid bushings are another option. Solids are either a combination of Delrin and metal, or just metal.
Keep in mind that the stiffer bushing you use, the more precise your suspension geometry will be. Flexible factory bushings distort under load, altering your alignment to the point of reducing the effectiveness of your steering and suspension. Read further to help make your decision on what is best for your application.
Most stock front suspension bushings are rubber, especially in Ford cars built before the late 1980s. That’s when manufacturers started introducing polyurethane in some applications. The rubber bushings create a comfortable ride for the average driver by absorbing shock from imperfections in the road. Unfortunately, rubber bushings do have a drawback—they also flex and distort. When a car is driven hard into a corner, the control arm bushings distort enough to completely change the alignment settings. The changes in geometry can create unpredictable handling.
There are benefits of using poly – urethane over rubber bushings. Poly – urethane has a higher load-bearing capacity, greater tear strength, and superior resistance to oils, depending on the formulation. Polyurethane bushings don’t distort like rubber bushings. For instance, when the control arms are under load while cornering, the polyurethane bushings will keep your alignment closer to where it’s supposed to be. This is a great advantage to creating a more predictable and controllable Restomod, especially if you take it to the track. Of course, polyurethane bushings also increase road feel in comparison to rubber bushings.
There is a big urban legend about polyurethane. People say it squeaks. Polyurethane does not squeak. The squeak you hear is caused by the lack of proper lubrication between the bushings and the surface of the surrounding part. Not all polyurethane bushings are created equal. Each company has different theories, designs, and compounds to achieve its idea of a superior bushing. Each polyurethane manufacturer has its own blend of materials for urethane and lubricant. For best results, use the lubricant supplied by the manufacturer and follow the provided instructions to fully clean the surrounding parts.
Polygraphite bushings, available from Performance Suspension Technology (PST), are an alternative to the regular rubber and polyurethane bushings. PST’s graphiteimpregnated Polygraphite bushings offer good road manners, but they do not allow suspension deflection. PST also claims its bushings don’t squeak because of the naturally lubricating quality of the graphite.
Delrin and Aluminum
In some cases, control arm and leaf spring bushings on Fords, Lincolns, and Mercurys can be replaced with Delrin and aluminum bushings. They consist of a steel inner crush sleeve, an outer aluminum housing, and a Delrin bearing sleeve to keep the two different metals from binding. Since the materials don’t flex, they offer precise suspension geometry. They also give the driver a little more road feel than the polyurethane bushings. The bushings you can replace with these types of solid bushings are in upper control arms, lower control arms (in non-strut rod equipped cars), leaf spring eyes, and IRS control arms.
Unfortunately, these bushings are only produced for a select few of these applications, due to popularity or the lack of it in the Ford Restomod hobby. Global West offers Del-A-Lum for 1979 and newer Mustang control arms, 1980 through 1988 T-birds, and in leaf-spring shackle kits on 1964-1973 Mustangs.
Delrin and Steel
Many stock-car racing companies offer Delrin and steel control-arm bushings for custom applications. Stock-car products are heavy-duty, but not always best for street use. I have seen Delrin and steel bushings with extremely loose tolerances, which work well, but they can generate some loud clunking in the front suspension when loaded and unloaded. It’s great for low-buck racers, but not great for a street car.
Metal and Metal — Spherical Too
Stock-car racing companies offer bushings with steel housings and inserts. They are also available in aluminum versions. These bushings are not forgiving. They transfer all road feel to the chassis and steering wheel. If you are building an extreme Restomod and only plan to drive it on the street about 50 miles per year, you could get away with using these. They are equipped with grease fittings, and it is necessary to keep solid bushings lubricated to minimize galling. You have to remember that the only thing preventing the two pieces of metal from binding is that thin layer of grease
The other type of metal-to-metal bushing is the spherical aircraft bushing. Global West and other companies offer these for specific applications that require the movement offered by these bushings. Global West offers these bushings in its tubular, lower front control arms for many shock-towerequipped Fords. Where the lower control arm meets the frame, the rubber bushings can be replaced with these inflexible, full-range-of-motion, spherical aircraft bushings. They will increase road feel, but also improve the handling with more precise, consistent suspension geometry.
Handling – Understeer and Oversteer
When I was at a driver meeting for a high-speed open-road racing event, I was given a simple explanation for understeer and oversteer. Understeer is when your front end hits the wall. Oversteer is when your rear end hits the wall. That is about as simple as it gets. Understeer and oversteer can be caused by many things: road conditions, tire compounds, spring rates, shock compression and rebound ratios, sway bar choices, alignment, acceleration, braking too hard, and much more.
Understeer condition is described as a loss of traction in the front tires, which n turn causes the front end to push. That push can be very dangerous since steering ability is usually non-existent. Not being able to control the direction that your car is traveling in can be dangerous and costly.
Oversteer is described as a loss of traction in the rear tires during cornering, which in turn causes the rear end to slide. Many drivers prefer oversteer rather than understeer. In oversteer conditions, the car can at least be corrected by steering into the slide, unless extreme oversteer is experienced. Controlled oversteer can be helpful to get the car around a tight corner more easily, but any loss of traction can be detrimental if you are shooting for fast lap times at the racetrack.
Drifting, or a four-wheel drift, is caused when traction is lost in the front and rear tires. Both understeer and oversteer conditions are present. Experienced, highly skilled drivers pilot their cars in controlled drifting conditions in almost every corner. Track experience and in-depth knowledge regarding your car’s set-up are important when pushing your car to the edge.
Why Upgrade Brakes?
A car is made from thousands of different parts. A few of those items have more importance than others, especially when it comes to safety. The highest on this safety list is probably the brakes. Drum brakes and disc brakes are the two brake systems used on cars today. Brakes build up heat every time you use them, and disk brakes disperse heat better than drum brakes. Less efficient drum brake systems slow the car using brake shoes pushing outward against the inside of the brake drum. Disc brake systems are more efficient and have brake pads that work together to pinch the brake rotor. You may ask, “My car came factory-equipped with disc brakes; why should I upgrade them?”
If you plan on driving hard around corners and your engine is pumping out extra horsepower, you are going to need some extra stopping power to be safe. If you are planning on ever driving a road course, you will definitely need to upgrade to bigger rotors and better calipers. The stock drum and disc brakes are fine for stopping a vehicle under normal driving conditions, but on a road course, you are forced to use the brakes more than they were ever designed for. This is especially true if you race the correct way, which is to slow your car down with the brakes, not the engine and transmission.
After a few hard stops, the stock brakes start to lose their effectiveness because of the heat caused by the excessive friction. Stock brakes don’t cool off very well, and heat in the stock brake material causes outgassing. Outgassing results in gas pockets forming between the pad and rotor surface. This is even more pronounced with drum brakes, because the brake lining has even more surface area. When the lining doesn’t completely contact the rotor surface, it cannot effectively slow or stop the vehicle. This problem is known as brake fade. Installing a brake cooling system (covered later in this chapter) may combat brake fade, but it doesn’t eliminate the problem. Aftermarket brake pads made for racing or high-performance driving use newer-technology materials that minimize or eliminate outgassing problems. Look for pads that advertise with terms like “race ready” and “dynamic surface treatment.”
The best improvement you can make to your braking system is to upgrade to large-diameter rotors that have more contact surface area for braking and for cooling, along with more brake torque (increased leverage). Upgrading to performance pads, along with rotors and calipers, will also give you more braking power (or cowbell, if you get my Christopher Walken reference). With a properly balanced system (explained later in this chapter), the upgraded system will shorten your stopping distances and greatly improve the vehicle’s ability to make repeated stops on a road course. With better brakes, you’ll be able to drive faster around the course. You can drive deeper into a corner without braking, since you can wait longer before applying the brakes. You will leave lesserequipped cars in the dust.
I could write a whole book on performance brakes, but I’ll just scratch the surface regarding the types of performance brakes, balancing your system, and brake cooling. To make things simple, only four-wheel disc brake systems will be covered in this chapter.
Most of the brakes covered in this chapter are Baer Brakes. Due to experience with brakes and kits from five different brake companies, I have found Baer Brakes kits to have the highest overall quality. They are the most likely to have all the necessary parts included and the parts fit correctly without the need to next-day-air a replacement part. Baer Alcon calipers have a superior internal design that makes them easier to bleed than some other comparable bigname calipers. You might have other experiences, but these are my recommendations.
To save a few bucks, some industrious enthusiasts have found ways to adapt disc brakes to their Restomods from Granadas, Lincoln Versailles, Lincoln Mark VIIs, or other vehicles. These brake conversions can work great when installed with the correct parts, but people don’t always get the system balanced (covered later in this chapter) by installing the correct master cylinder with the correct bore size. There is quite a bit more to upgrading your brakes than bolting on a set of disc brakes from another car.
Low-buck Granada 11-inch Brake Upgrade
Adding Granada brakes is one of the most popular and longest-standing front disc brake upgrades for V-8-models of 1965 to 1973 Mustangs and 1963 to 1969 Falcons and Rancheros. If you are working on a non-V-8 car, you will need to upgrade to V-8 steering components when performing the Granada brake upgrade. The V-8-equipped Granada is equipped with 11-inch rotors, while the 6-cylinder Granada is equipped with 10- inch rotors. If you’re going to go through the trouble, you might as well go for the 11-inch rotors. You’ll need the following parts from the front of a 1976 to 1979 V-8 Granada: spindles, rotors, brake brackets, and brake calipers. These parts can be obtained at your local wrecking yard. You can acquire the other parts needed to complete this job from an auto parts store. These (Granada) parts include: inner and outer wheel bearings and races, wheel seals, rubber brake hoses, remanufactured calipers, new brake pads, and rotors (if your donor rotors are in rough shape).
Replacing the master cylinder is suggested. Each application is different, so it’s impossible to suggest a master cylinder from a certain vehicle. If your car is equipped with a single-reservoir master cylinder, I highly suggest replacing it with a dual-reservoir master cylinder. A single-reservoir unit is unsafe. If brake fluid was to leak out of any portion of a single reservoir system, you would lose all braking pressure. A dualreservoir master is safer because if the fluid were to leak out of the rear of your brake system, you would still have pressure in the front system, and vice-versa. In the case of replacing your singlereservoir master with a dual-reservoir unit, you should expect to spend some time bending and flaring some brake tubing to plumb in the new set-up. If you’re changing master cylinders from a dual to another dual master, you may not need to spend as much time on it, but don’t think it will be a simple boltin. You will need to do some careful research to help you choose the proper master cylinder for your specific application. It is very probable that you won’t find a “brake expert” at your local car parts chain store. Choose your sources wisely; the ability to safely stop your car is a matter of life or death.
When choosing a master cylinder, also take into consideration which side of the master cylinder the brake lines exit the unit. If they exit toward the engine, you may have clearance problems with the valve covers. Choosing the bore size is the most important aspect of the quest for a new master cylinder. You’ll most likely need to install a brake-proportioning valve to balance the brake system.
Once you have all the necessary parts, you can start the brake swap. With the exception of choosing and plumbing the master cylinder and locating the correct tie-rod ends for your application, performing this swap can be fairly easy. For your safety, once you’ve swapped all the parts, you should have a shop align your front suspension.
There are a couple of items you should be aware of before starting the installation.
- The snout on the Granada rotors are larger in diameter than the early Mustang drum brakes, which means most early stock wheels will not fit. Even some aftermarket wheels do not fit over the Granada rotor snout.
- The outer tie-rod ends will not fit either, so you’ll need to purchase some specific units to have the correct fit. Manual and power steering set-ups require different tie-rod combinations. These specific parts are available from Mustangs Plus.
- Granada brake hoses are too short and will require adapter lines to fit the 19641 ⁄2 through 1967 Mustangs. These are also available from Mustangs Plus.
- The spindle height is different on the Granada. Sometimes it can raise the vehicle as much as 1 inch.
- The master cylinder on your car will need to be replaced with a dual master cylinder from a newer car with the proper brake set-up. For instance, if you are upgrading to Granada front disc brakes and you are keeping your stock drum brakes, you will need a 7 ⁄8- to 1- inch master cylinder designed for a car with front disc brakes and rear drum brakes. If you are installing four-wheel disc brakes, you’ll need a master cylinder designed for a car with four-wheel discs. Read the section in this chapter on balancing your brake system.
- To help balance the brakes, you’ll probably need to install a brake-proportioning valve.
- Obtain all the correct torque specs from a repair manual so all the parts can be installed to the correct specifications.
- If you have any doubts about your mechanical skill level, have a shop perform the Granada brake upgrade for you. There is absolutely nothing wrong with having a trained professional work on any part of your car. It’s always better to be safe than sorry.
BRAD FAGAN’S 1972 PINTO PANGRA
Back in the early 1970s, the smallcar market was filled with sporty cars like the 914 Porsche, Opel GT, and Datsun 240Z. Jack Stratton of Huntington Ford in Arcadia, California, had visions of taking a small production car and modifying it to a level in which it could compete with the previously mentioned sports cars. When the Pinto was introduced in 1971, Jack finally had the perfect candidate for his vision.
Jack started tracing the Pinto body lines from photos and modifying them. He first contacted Kustom-car guru Gene Winfield to help implement his ideas, but Gene was bogged down with other projects and didn’t have the time. So Jack enlisted Bob Crowe, who had experience with all sorts of fiberglass ventures from boat hulls to camper tops. With Jack’s passion and Bob’s experience, they came up with a solid design. The whole external package flowed well with the Pinto’s original body lines. It’s tough not to notice the Pangra’s menacing sloped front fenders and pop-up headlights that look unmistakably like the Pantera.
All body changes were applied to the Pinto’s front end. The original front fenders, hood, and lower valance were discarded. The completely redesigned front end consisted of extended fiberglass fenders, which housed pop-up headlights, an extended fiberglass hood, and a fiberglass cowl cover to hide the windshield wipers. The original bumper and grill were cleanly incorporated into the design. In rare photographs of the Pangra being test driven by magazines, a sizable spoiler was attached to the body at the top of the rear window.
Jack’s all-encompassing vision didn’t stop at modifying the body. The next step was the suspension, tires, and wheels. The Pangra “Can Am” suspension consisted of lowered front coil springs, front and rear sway bars, lowering blocks for the rear, and Koni shocks on every corner. The Koni shocks weren’t off-the-shelf parts. Jack worked closely with Koni to get just the right compression and rebound valving for optimum cornering performance. The tires and wheels were important to the handling, too, so Jack upgraded to 7- inch mag wheels and Continental radial tires. The chosen wheels, tires, suspension parts, and completely different caster, camber, and toe settings resulted in a 0.874 g pull on a 200-ft skid pad. Those skid pad numbers were better than 0.740 g pulled by the expensive sports cars available at that time.
Jack also made upgrades under the hood. The original 122-ci engine needed some added power, so Jack worked with Ak Miller to design the correct power for this project. They came up with a turbocharger, exhaust manifold, header pipe, intake manifold, and water injection (to control detonation). With forged pistons to increase compression, the combination of parts produced approximately 175 to 200 hp. The Pangra’s zero-to-60- mph time was 7.5 seconds, the quartermile time was 15.4 seconds @ 92 mph, and it had a top speed of 125 mph.
To round out the Pangra package, Jack also changed the interior. He added a custom dashboard, additional gauges, and Recaro front seats. All these changes made a well-rounded car that definitely gave all the early 1970s sports cars a run for their money.
These Pangras were available from the dealer between August 1972 and sometime in 1973. The selling price off the showroom floor was $4,600 (with a stock Pinto selling for about $2,200). The dealer-assembled Pangra came with a two-year warranty. There were approximately 50 dealer-assembled Pangras sold off the showroom floor. Only four are known to still exist as of 2004—one wagon and three sedans. If you didn’t want to purchase a Pinto Pangra (back in 1972 and 1973) as a complete car, you could purchase kits to perform your own Pinto modification the Pangra specs. Kit number one was the Pangra front-body assembly, which retailed for $595. Kit number two was the “Can Am” suspension package, which retailed for $951. Kit number three was the Ak Miller turbocharger kit along, with kits numbers one and two, and it retailed for $1,691.
The 1972 Pangra in the photos belongs to Brad Fagan. He has been a Pinto fanatic since 1976. He’s swapped V-8s and 2.3-liter SVO turbo powerplants in the past. The red 1972 Pangra is mostly stock, and he plans to keep it that way. For more information on Pintos and Pangras, go to www.fordpinto.com. The website has stock and modified Pintos, tons of great information on Pinto history, and a community of people who can answer your questions.
Aftermarket Brake Upgrades
Performance rotors come in a few different types. They come machined from a single cast piece, a cast outer ring with an aluminum hat, or a carbon fiber outer ring (for racing only) with an aluminum hat.
Different manufacturers offer different options with their rotors. Baer Brakes offers cross-drilling, slotting, and zinc washing. Cross-drilling allows gasses to disperse from the pad surface, so the pad has better contact on the rotor surface. Brake-pad technology has almost eliminated outgassing, so these days cross-drilling and slotting are more for visual appearance. Crossdrilling creates the potential for stressrisers that can lead to cracks in the rotor, so Baer casts its rotors with the cooling vanes in a specific pattern to lower the potential of crack migration. For full-on racing applications, Baer Brakes suggests rotor slotting, but not cross-drilling.
Zinc washing is great for rotor appearance. The zinc coat comes off the rotor surface where the brake pad rides, but the coating stays on the rest of the rotor. If you coat the rotor, it protects all other surfaces from ugly rust that builds up on the part of the rotor surface that is visible through most of the aftermarket wheels used on Restomod vehicles.
There are two types of calipers: floating and fixed. The floating caliper relies on pressure applied to the rotor from its single inboard piston to pull the outboard pad into the outside face of the rotor. This design is much more forgiving in production tolerances, and it is used on almost all production vehicles on the market today. Fixed calipers are solidly mounted to the spindle or axle housing with opposing inner and outer pistons. When brake pressure is applied, the pistons squeeze the rotor equally and simultaneously. This creates a better pedal feel, and a much quicker braking response than floating calipers can produce. The tolerances on mounting the fixed caliper over the rotor needs to be precise. In the mid to late 1960s, the big three (Ford, GM, and Chrysler) were heavy into Trans-Am racing. This involvement influenced some of the factory-option, four-piston, fixed-caliper brakes available to the public. When floating calipers were introduced, factories switched to using them on production vehicles to keep assembly lines moving faster and the cost of parts down. Fixed calipers are now only used on racing applications.
Today, aftermarket fixed calipers are available in standard or staggered piston bore configurations. Standard bore calipers have symmetrical bore sizes from side to side and front to rear on each caliper. Staggered bore calipers have a different size of bores coinciding with the turning direction of the rotor. In the direction of rotation, the smaller bore is first in the rotation of the rotor. This applies the pad to the rotor more evenly. With standard bore calipers, the pistons are equally sized, so they push the pad against the rotor face at the same time. The pushing causes the leading edge of the pad to dig in a fraction of a second sooner than the trailing edge of the pad, resulting in increased wear on the leading edge of the pad.
The key to running cool brakes is to have cooling ducts running to the center of the rotor, where the air can cool the internal rotor vanes and evenly cool the rotor. If you run the air duct to the inboard face of the rotor, you will be cooling the inboard face, but the outward face will run extremely hot. This will cause the inboard and outboard pads and rotor faces will wear unevenly.
Air intake ducts and hose can be purchased from racing supply stores. The heavy-duty plastic ducts come in different shapes and sizes. The intake duct should be placed in a high-pressure location, such as a front air dam or an opening in the front valance panel. It is a good idea to install wire mesh over the inlet to keep rocks and debris from entering the duct and hose. The brake duct hose comes in different diameters and temperature ranges. Typically, you have to fabricate your own duct/backing-plate to mount to the caliper bracket of spindle. You want to leave very little room for air to escape without going through the rotor vents. This will ensure that you are getting all the cooling possible. Attach the hose to the back of the intake duct, and attach the other end of the hose to the backing plate/duct on your rotor. A few plastic zip ties are good for affixing the duct hose to stationary items in the engine compartment. Be careful not to mount the hose where it will contact a tire, moving engine, or suspension part. A spinning tire can rip the hose out of its position in a split-second, and possibly damage the tire or cause the hose to bind the suspension.
Brakes don’t like heat. It shortens the life and effectiveness of the pads. In racing and extreme driving conditions, the rotor can warp and/or crack from excessive heat. Most Restomods won’t be driven hard enough to require brake ducts, but if you take yours to an open track day, you may want to consider them to protect you and your car. For the most part, brake cooling is for frequent and full-time racers.
If you don’t want manual brakes, you will need to boost your brakes in one of two ways. You can choose to install either a vacuum- or hydro-style brake booster. Vacuum-assist brake boosters work great for stock and moderate applications. When increasing your horsepower, you can adversely affect your engine’s vacuum output, which can limit your brake boosting to an unsafe level. Large-diameter, vacuum-assist boosters can crowd engine accessories, like valve covers. They can also limit frame bracing. Smaller vacuum boosters might give you more clearance, but they still rely on vacuum that you may not be able to supply. You can try to hook up an electric vacuum pump, but they rarely work as well as the installer hopes.
To increase braking on trucks, manufacturers started offering hydroboost braking systems. The booster bolts between the firewall and the brake master cylinder. The hydrobooster does not rely on vacuum. The boosting comes from fluid pressure that is plumbed in between the power-steering pump and steering box. The pressure operates the brakes during any driving condition. This system is known to work better than any vacuum booster on the market. An aftermarket company named Hydratech Braking Systems offers complete kits that include the booster and hoses.
Balancing a Braking System
Standard brake systems are broken down into two separate systems joined by one link – the master cylinder. The front and rear systems need to be balanced. An average car needs about 70 percent of its braking ability in the front brakes and 30 percent in the rear. If you notice, cars with factory four-wheel disc brakes have smaller brake calipers in the rear than in the front. If the rear system had the same braking power as the front system, the brakes would be unbalanced, and the car would be very dangerous to drive. The rear brakes could lock up before the front brakes have a chance to slow the car down. The same goes for having too much braking in the front. The correct caliper bore size in both the front and rear is also very important. To explain this, I will give you a detailed account of my own experience balancing a brake system.
I started with a generic 1968 sixcylinder car equipped with four-wheel drum brakes. I converted it to a set of front disc brakes from a newer production car, and put a Ford 9-inch rear end from a ’76 Lincoln Mark IV with the stock Mark IV rear disc brakes. I put in a later model master cylinder and brake booster on the firewall. It turns out I was extremely lucky; for my normal street driving, the system was well balanced from front to rear. Then I took the car out on Sears Point road course for a day. After a few laps, the brakes started to fade, so I would let them cool off in the pits and run again. When I upgraded my engine from 350 to 483 hp, I decided it was time to upgrade the brakes. I put money down on a Baer Brakes Track kit for the front. Due to some engine compartment constraint issues with my bigblock, I removed the power brakes and converted back to a manual brake system. Against Baer Brakes suggestions, I left the Mark IV disc brakes in the rear. What did they know? Disc brakes are disc brakes. They probably just want me to spend more money on their brakes. I showed them!
The Baer Track kit had some huge 13-inch rotors and two-piston PBR calipers. I installed a master cylinder with a 1-inch bore. The front brakes looked great, but the system didn’t work. The system was unbalanced. I had switched the large, single-piston calipers to a pair of Baer PBR calipers that had two pistons much smaller in diameter. Coupled with the large, single-piston Mark IV calipers in the rear, I could not push the brake pedal hard enough to actuate the master cylinder in order to the stop the car in a timely fashion. In fact, I couldn’t get the front or rear brakes to lock up even if I put the pedal through the firewall – the amount of fluid it took the master cylinder to move the rear caliper pistons was too much. The front brakes were doing all the work, but they were not doing their job, and the car was unsafe to drive.
To band-aid the system into getting more fluid to the rear brakes, I would have to install a proportioning valve in the front brake system to restrict the fluid and force the rear system to operate sooner. This was not an option I was willing to take. I was already not getting enough braking force in the front, and there was no way I was going to limit it even further. At this point, I tested my stopping distance from 60 to 0 mph. As hard as I tried, I could not lock the brakes. The stopping distance was 177 feet.
I called Baer to find out what to do. They told me to get smaller piston rear calipers. I figured, since I was going to change the brakes, I might as well get the suggested system. I bought a Baer rear Touring kit with 12-inch rotors and single-piston PBR calipers. They were equipped with parking brakes, which was a big plus, since I could never get the parking brake mechanism in the Mark IV calipers to work. I had Vic DeLeon at Speed Merchant install the kit, since the bearings had to be pressed off my axles to remove the Ford backing plates. The system worked great after that. The new caliper bore sizes were much smaller than the ones from the Mark IV. The front and rear brakes could safely stop my car, and the system was finally balanced. Baer had also suggested switching my master cylinder to a 15⁄16-inch bore size for even better braking, but I had not done that yet. I tested the braking distance from 60 to 0 mph again. The car stopped in 148 feet; it was a huge improvement over the previous 177.
I had a chance to pick up a used Baer Pro front kit from my friend, Karl Chicca. He was upgrading, and had these left over. I installed the four-piston fixed Alcon calipers onto my Track kit rotors. This further improved the brake feel and the balance of the system. The feel of a fixed caliper over a floating caliper was a night-and-day difference. The fixed calipers actually gave the brakes a power-brake feel at the pedal, since they react so much faster than the floating caliper. I ran one braking test from 60 to 0 mph. The stopping distance was reduced to 137 feet. On that one test, my 137-foot stopping distance was identical to what it took to stop an ABS-equipped ’99 SVT Mustang Cobra in the April 1999 issue of Road & Track. Not bad for an iron-headed big-block car. Just imagine what will happen when I change the master cylinder to a different bore size.
Since changing a standard dualreservoir master cylinder and the bore size affects both the front and rear brake system (except in rare occasions), you can either install a brake-proportioning valve or change to a dual master cylinder set-up.
The proportioning valve is hooked inline between the master cylinder and the rear brakes to help balance the front and rear systems. If the rear brakes are locking before the front brakes, the proportioning valve restricts pressure to the rear brakes, which allows the front brakes to come on stronger before the rear brakes fully activate. Most street cars equipped with proportioning valves have them located in the engine compartment near the master cylinder. Some racing cars prefer to have the proportioning valve located within reach of the driver’s seat, so the brake bias can be adjusted while on the track to compensate for tire, chassis, and track conditions.
A more invasive (opposed to using a proportioning valve) balanced system can be achieved using a dual master cylinder set-up with a balance bar. A balance bar system allows you to customize your master cylinder bore size for the front and rear brake circuits separately. The front and rear brake circuits become their own systems. If your front brakes would work best with a 7 ⁄8-inch bore master, and the rear brakes would work best with a 3 ⁄4-inch bore master cylinder, or any different combination, the balance bar system is for you. Once you have installed both master cylinders and the balance bar system, you can make slight adjustments to the balance bar to change the front and rear brake bias. Most brake bias systems are available with an optional knob so you can adjust the bias on the fly. Putting in a balance bar system usually requires installing a new brake pedal assembly. If you go through the trouble of installing the pedal assembly, it only makes sense to install the adjustable bias knob.
There are a few things to keep in mind when picking your tires. Tire companies measure their tires from sidewall to sidewall, not the width of the tread. Generally, a 275/45ZR17 is 275 mm from sidewall to sidewall. Not all tire manufacturers abide by the same standards of measurement. A 275 tire by one manufacturer may be wider than a 275 by another. A wider tire will increase traction during forward acceleration and cornering. Moving up from a 275/40ZR17 to a 335/30ZR17 can lower your quarter-mile times and increase lateral bite of the rear suspension, which could increase understeer (or decrease oversteer). Wider tires up front can decrease understeer (or increase oversteer). The compound of the rubber used to make a tire plays a big part in the traction of specific tires. A soft compound tire gives your car more traction, but wears it out faster than a harder compound tire.
Your outer tire diameter changes the final gear ratio. A smaller-diameter tire will increase gear ratio and speed up your speedometer, while a larger-diameter tire will react exactly opposite. Large-diameter, ultra low-profile tires can give your Restomod a lifted, fourwheel-drive look. For a good look, Kevin Long, tire specialist from Campbell Auto Restoration, says his general rule is to have about 1.5 to 2 times more tire sidewall than space between the top of the tire and the fender opening. This can keep you from going overboard with wheels that are way too big, or tires that are way too thin.
Your driving habits should be taken into consideration when choosing a tire. Are you: driving strictly on the street, auto-crossing, open tracking, or periodically hitting the drag strip? Kevin Long provides good insight regarding tire choices. For mainly street driving, he suggests ultra-high-performance street tires such as: Michelin Pilot Sports, Goodyear F-1, BFG G-Force KD, Bridgestone S-02/S-03, or Yokohama AVS Sport. For auto-crossing and open track: Yokohama A-032, Michelin Pilot Club Sport, or Hoosier. For drag racing: BFG Drag Radials, Nitto 555R, or Mickey Thompson ET Streets. All these options are DOT street legal. He warns that street-legal racing tires will not last long for street use, and drag radials are not designed to go around corners.
There are many different wheel companies on the market. There are also different types of material used to build wheels. The most common wheels used on Restomods are the cast-center with spun-aluminum outer, cast aluminum, billet aluminum, and forged aluminum.
Forged wheels are the strongest wheels available. Most forged wheels built today are three-piece designs. The rim is assembled of two pieces, and the center piece is bolted in with highstrength bolts. There are also two-piece forged wheels available. Forged wheels are much stronger and lighter than cast wheels. The strength of the forged wheel offers high durability for street use. I’ve seen many less expensive, large-diameter wheels bent from hitting potholes and road debris. It’s especially easy to damage the large-diameter wheels because guys typically run low-profile tires with them. The tire’s sidewall normally takes the road shock, but with a small sidewall, there is nothing to take the shock.
Large-diameter wheels and tires can be much heavier than stock wheels and tires. They increase the rotating mass, which means they require more braking force to slow them down and more power to speed them up. Wheels are measured between the inner wheel lips, not the outside edges of the wheel lips. An actual 8-inch-wide wheel might be 9 or more inches wide when measured from outside lip to outside lip.
Fitting Tires and Wheels
Going by the basic rule of bigger is better, most people want the widest tire and wheel combination they can cram in the fenderwells. Wider tires help increase lateral and straight-line traction during dry driving conditions, but typically decrease traction in wet driving conditions. A wider tire tends to hydroplane more easily because the water can’t get out from underneath the contact patch of the tire fast enough.
When picking tires and wheels, there are a few more things to take into consideration. Are the tires going to fit within the wheel housing (wheelwell)? Are the wheels going to be the right backspacing (or offset) to clear the suspension components? Measuring for correct fitment is critical.
Too much backspacing can move the wheel and tire inward and cause interference with the control arms, ball joints, outer tie-rod ends, brake hardware, brake calipers, shocks, brackets, inner-wheel housing, frame, and more. Too little backspacing will move the tire and wheel outward, causing the tire to interfere with the fender lip and outer wheel housing. Measuring for proper backspacing is important when you want the biggest tire and wheel package on the front or rear of your car.
The first order of business in getting the correct backspacing is to find the narrowest width of the inner-wheel housing. Measure the wheel housing in many different locations because wheel housings are not always equal widths from front to rear. Keep in mind that the tire needs space to travel upward in the wheel housing during suspension compression. If your car is lowered and the outer wheel housing is shallow and curved inward, like the ’67 Mustang wheel housing, you could be limited to a narrower tire than if you made some modifications to the wheel housing. After measuring the width of the wheel housing, subtract 1 to 11 ⁄2 inches. This will give you necessary 1 ⁄2 to 3 ⁄4 inch on the inside and outside of your tire for ample suspension movement. Some extra clearance may be necessary for steering the front wheels. This measurement will be the maximum width of the tire you can run in your wheel housing. Tire manufacturers measure their tires from sidewall to sidewall (when mounted on suggested wheel widths), not tread width.
The next step is to measure backspacing. Safely support your car with jack stands and mock the ride height. With your brake rotors installed, put a straight edge across the mounting face of the brake rotor. With a tape measure or a ruler, measure 1 ⁄2-the distance between the straight edge and the inner wheel housing. Taking the 1 ⁄2-to 3 ⁄4-inch tire clearance into consideration, the remaining measurement will be your backspacing. Keep in mind that the backspace for a wheel is measured from the back edge of the wheel lip to the back of the mounting surface. Do not measure from the tire bead mounting surface on the inside edges of the wheel. Measure both sides of the car for proper backspacing because auto manufacturers don’t build square cars. I’ve seen cars with as much as a 7 ⁄8-inch difference from side to side.
If you don’t want to spend the time doing all this work, for a fee, some performance tire shops offer services to test-fit wheels and tires on your car or to measure it.
Written by Tony Huntimer and Posted with Permission of CarTechBooks