Automotive News

Service Advisor: ‘Going Over’ the Edge

The Ford Edge is an SUV based on a the CD3 platform. The brakes on these vehicles are straightforward and do not break any new ground. The brake systems on all variants have disc brakes at all corners.

There are no major changes to the brakes system from 2007 to 2009. For the 2008 model year, ABS became a standard feature, as did a direct tire pressure monitoring system.

The worst brake component to service is the master cylinder. Getting to the unit requires removal of the trunking for the air intake, battery tray and other components.


Unfortunately, the rotors on the Edge do not have too much material. It might be difficult to get at least one turn out of the rotors before they are under spec. Overall runout and thickness variation should be less than 0.001.”

Front Rotors:
• New thickness: 28 mm (1.10”)
• Min. thickness: 26 mm (1.02”)
• Min. thickness to machine: 27.1 mm (1.01”)

Rear Rotors:
• New thickness: 18 mm (0.78”)
• Min thickness: 16 mm (0.63”)
• Min thickness to machine: 9.1 mm (0.35”)

Front Brake Pads:
1. Retract the piston. Do not pry in the caliper sight hole to retract the pistons as this can damage the pistons and boots. Remove the two brake caliper guide pin bolts and position the caliper aside. Support the caliper using mechanic’s wire.

2. Remove the brake pads, brake pad shims and stainless steel shims. On most models, Ford used four abutment clips. Some aftermarket shims have two.

3. Inspect the brake pads and shims for wear or contamination. There should be at least 3 mm of material and the pads should not differ from side-to-side by more than 2 mm. The pads should not taper more than 2 mm.

4. Remove the brake pad slides.

1. Protect the caliper piston and boots when pushing the caliper piston into the bores. Make sure that the caliper guide pin boots are fully seated to the caliper bracket. Using a suitable tool and a worn brake pad, compress the disc brake caliper pistons into the caliper.

2. Install new brake pad slides/abutment clips.

3. Apply a thin coating of the supplied grease to the shims and the shim contact area of the brake pads.

4. Install the shims to the pads.

5. The guide pin bolts are different sizes. The longer/bigger bolt is the upper guide pin bolt. Position the brake caliper and install the guide pin bolts. Tighten to 88 Nm (65 ft. lbs).

Rotor Installation
1. Clean and dry the brake disc-to-wheel hub mounting surface and apply a thin coat of anti-seize to the mating surfaces hub’s face. Do not put on the studs.

2. Install the rotor.

3. Position the brake caliper and anchor plate assembly and install the brake caliper anchor plate bolts. Tighten to 133 Nm (98 ft/lbs).

Rear Brake Pads:
1. Remove the two brake caliper guide pin bolts and position the caliper aside.

2. Install new brake pads if they are worn past the specified thickness above the metal backing plates. Install new brake pads in complete axle sets. Remove the two brake pads, shims and slide clips. Inspect the brake pads and shims for wear, damage or contamination. Discard the slide/abutment clips.

3. Push back the piston with the appropriate tool. Protect the caliper piston and boots when pushing the caliper piston into the bores.

4. Remove the caliper bracket if you are servicing or
machining the rotor. Clean the surfaces the make contact with the slide/abutment clips. The torque specification is 55 Nm (41 ft/lbs).

5. Install the two brake pads, shims and new slide clips to the brake caliper anchor plate. Position the brake caliper on the anchor plate and install the two guide pin bolts. Tighten to 26 Nm (19 ft. lbs).

Parking Brake
Cable tension is adjusted in two locations. The first location is at the parking brake control, the second location is at the parking brake cable equalizer. The tension must be adjusted equally at both locations.

1. With the vehicle in NEUTRAL, position it on a hoist.

2. The dimension will vary depending on the amount of cable stretch. New cables require cycling the parking brake control 5-10 times to remove the cable slack. Adjust the parking brake control adjustment so the stud protrudes 8mm ±1mm from the top of the nut.

3. Adjust the parking brake cable equalizer adjustment nut so the stud protrudes 24mm ±1mm from the top of the nut.

4. Fully apply the parking brake pedal three times to verify correct operation of the parking brake system.

5. With the parking brake cable in the fully released position, brake drag should not be present.

Getting to the master cylinder requires removal of the trunking for the air intake, battery tray and other components.Brake System Bleeding
Bleeding the Hydraulic Control Unit (HCU) is required only when removing or installing the HCU, master cylinder or opening the lines to the HCU. A scan tool with the ability to interface with the HCU is required for bleeding.

Note: Carrying out the system bleed function drives trapped air from the HCU. Subsequent bleeding removes the air from the brake hydraulic system through the bleeder screws.

Note: Adequate voltage to the HCU module is required during the anti-lock portion of the system bleed.

1. Connect the diagnostic tool.

2. Access the system bleed function.

3. Manually bleed the brake hydraulic system.

4. Repeat the procedure carrying out a total of two diagnostic tool cycles and two manual bleed cycles.

Anti-Lock System Bleed
If the vehicle is equipped with ABS, connect the vehicle communication module (VCM) and scan tool into the vehicle data link connector (DLC) under the dash and carry out the chassis brake bleeding procedure.
1. Clean all dirt from the master cylinder filler cap, then remove the cap and fill the brake master cylinder reservoir with clean, specified brake fluid. The Edge has a unique reservoir that is long and thin due to the rake of the windshield. Install the master cylinder filler cap.

2. If the vehicle is equipped with ABS, connect the vehicle communication module (VCM) and scan tool into the vehicle data link connector (DLC) under the dash and carry out the chassis brake bleeding procedure.

3. Place a box-end wrench on the right rear disc brake caliper bleeder screw. Attach a rubber hose to the right rear disc brake caliper bleeder screw and submerge the free end of the hose in a container partially filled with clean, specified brake fluid.

4. Have an assistant pump the brake pedal and then hold firm pressure on the brake pedal.

5. Loosen the right rear disc brake caliper bleeder screw until a stream of brake fluid comes out. Have an assistant maintain pressure on the brake pedal while tightening the right rear disc brake caliper bleeder screw. Repeat until clear, bubble-free fluid comes out.

6. Tighten the right rear disc brake caliper bleeder screw. Tighten to 8 Nm (71 inch lbs).

7. Repeat Steps 3 through 6 for the left rear disc brake caliper.

8. Move to the right front and then left front.

• Gravity bleeding is possible using the same sequence.

Automotive News

Undercover: Steering Comebacks Away From You

Adapted from  Andrew Markel’s article in BRAKE & FRONT END

The thrust angle is an imaginary line drawn perpendicular to the rear axle’s centerline. It compares the direction that the rear axle is aimed with the centerline of the vehicle. It also confirms if the rear axle is parallel to its front axle and that the wheelbase on both sides of the vehicle is the same. It is one of the most important diagnostic angles during an alignment.

Thrust Diagnosis
To measure the thrust angle on a vehicle you have to perform a four-wheel alignment. Even if the rear axle is non-adjustable, you need to take rear axle readings to properly align the front suspension.

A thrust condition exists when the rear individual toe is not equal. The thrust angle of a vehicle can be generated by two conditions or angles.  This makes it difficult for some technicians to properly diagnosis the problem. First, the thrust angle could be generated by the angle of the axle or a misaligned rear suspension cradle that can change the toe angles.

Also, a thrust angle can be generated by rear toe settings that are independent of the axle angle or implied axle angle.

  normal thrust angleThe thrust angle can determine the straight-ahead position of the front wheels. So ignoring this angle can undermine even the most accurately aligned front suspension. It can result in a crooked steering wheel as the front wheels steer to align themselves with the front wheels. Also, a miss-aligned thrust angle can cause the vehicle to handle differently when turning one direction versus the other.

RWD Vehicles With Leaf Springs

Most rear-wheel drive cars and trucks with rear leaf spring suspensions don’t have adjustments built into the suspension. But, the thrust line is a very important angle that can help you diagnose other problems.

negative thrust angle If the rear live axle vehicle has a greater than normal, thrust angle is an indication that the axle has shifted or the mounting points on the frame have shifted.

To get a better picture of the damage, look at the setback of the front wheels. Setback is a diagnostic angle that measures the difference in distances between the centers of the front wheels. Differences in the setback angle can indicate damage in the frame or within components like control arms and bushings. Take a closer look at caster angles from side to side to see if there is a larger problem.

view of a positive thrust angle A setback and thrust angle misalignment could be an indication of frame damage. If the vehicle has suffered a recent collision that was offset, the frame may be suffering from a condition known as a “diamond frame.” This occurs when one side rail shifts in relationship to the other side rail.

On a vehicle with an independent front suspension and a rear live-axle, the shifted rails will cause the front suspension to have an increased setback and thrust angle. This is caused by the mounting points of the suspension moving.

if a frame has experienced an offset impact, it can cause setback and thrust angle problems. Another piece of diagnostic information to look at is the ride height. On rear suspensions with leaf springs, the leaves of the springs can become damaged and can change the ride height and the position of the axle.

One remedy for this problem is a plate that can go between the axle and springs, and allows some fore and aft repositioning of the axle to equalize rear toe readings on both sides.

Install the plate on the side of the vehicle which will help to equalize ride height. Installation of this kit may change ride height a 1/2 inch. If ride height is negligible, then installation should be done on the right side for leaf springs above the axle (left side for leaf springs below the axle) to account for road crown.

Axle housings can become bent from impacts. If you see an axle with a difference in toe greater than .50º look at the axle for possible damage.

This is what “dog-tracking” looks like on a large scale. It can occur on vehicles with solid axles or independent rear suspensions.Rocking the Cradle
More and more automakers are offering all-wheel-drive on an increasing number of vehicles from small SUVs to compact sedans. On these vehicles they are mounting the differential and suspension components of a cradle that may only connect to the uni-body in four to six locations.

While this may make for easy assembly, it makes the alignment technician’s job more difficult.

When aligning these types of vehicles, pay attention to rear wheel setback and the thrust angle. These diagnostic angles can help you determine if the cradle or suspension components are damaged.

Most thrust angle problems on these suspensions can be resolved with toe adjustments. But, if the cradle has shifted, you may quickly run out of adjustment on the toe links.

Automotive News

Undercover: 10 Tips To Top Alignments

By Andrew Markel, Editor, BRAKE & FRONT END

Tip No. 1: Don’t neglect the importance of the pre-alignment inspection.
The more thorough the prealignment inspection, the better your chances are of not overlooking something that might cause a comeback after the wheels have been aligned.
For starters, ride height should always be measured at all four corners of the vehicle, not just eyeballed. An inch or more of sag may not be apparent, but it can cause noticeable alignment problems.

Tip No. 2: Check the accuracy of your alignment equipment.
A simple but often overlooked cause of comebacks is alignment equipment that’s out of calibration. The cause may be something as simple as a rack that isn’t level or alignment heads that are out of adjustment — or something as serious as a mechanical or electronic glitch that produces inaccurate measurements.

Tip No. 3: Do a complete alignment.
Time is money, so the faster you get the job done the more money you make, right? Wrong. If you don’t do a good job because you’ve skipped things like checking toe-out on turns, ride height, SAI, caster (if nonadjustable), rear-wheel alignment (if nonadjustable), the condition of steering and suspension parts, etc., you may end up
having to do the job over again.

Tip No. 4: Don’t try to align worn parts.
To hold an accurate alignment, steering and suspension parts must be in good condition, which means no more play than allowed by the vehicle manufacturer. Always refer to a reference manual for the exact specs since acceptable ball-joint play can vary considerably from one application to another.
As parts wear, they get progressively looser and are less able to maintain accurate wheel alignment. If a tie-rod end or ball joint is borderline, it’s better to replace it now.

Tip No. 5: Don’t just set the toe and let it go.
If a front-wheel-drive car has no factory adjustments for camber or caster (Honda, for example), don’t just set the toe and let it go — always read all the angles. Why? Because if there’s a problem, a simple toe adjustment won’t fix it.

Many so-called “nonadjustable” suspensions can often be easily adjusted with the help of various kinds of aftermarket alignment aids. If you’re not already familiar with the use of camber/caster shims, caster wedges, offset bushings and the like, get some catalogs from the specialty alignment-product suppliers and find out  what’s available.

Tip No. 6: Set to the factory-preferred specs, not rule-of-thumb specs.
There are no such things as “rule-of-thumb” specs when it comes to wheel alignment. What works on one vehicle may or may not work on another. Front-wheel-drive cars usually require different toe settings than rear-wheel-drive cars. Vehicle weight, chassis design, chassis loading, tire size, driveline configuration and intended use all affect wheel-alignment settings that the vehicle
manufacturer develops for the vehicle.

Tip No. 7: Compensate for how the vehicle is driven and used.
Vehicle loading can have a very pronounced effect on wheel alignment. If a vehicle that’s normally loaded with passengers or cargo is aligned while empty, the tires will likely exhibit rapid wear because they won’t be running true when the vehicle is driven while carrying its normal operating load.

Tip No. 8: Align all four wheels, not just the ones up front.
Four-wheel alignment has become much more commonplace in recent years, but there are still those who won’t align all four wheels because the customer doesn’t want to pay “extra” for a four-wheel alignment. This may be more of a marketing problem than a technical one, but the
public needs to be educated that the rear wheels have just as much influence on where a vehicle goes as the ones up front.

Tip No. 9: Make sure the steering wheel is centered.
One of the leading causes of alignment comebacks is a steering wheel that’s off-center. Tire wear takes a while to catch up with a customer if the alignment isn’t on the mark, but an off-center steering wheel will be noticed immediately.

Tip No. 10:
Test drive the vehicle before it’s returned to the customer.
A simple test drive can reveal a lot of problems that might have been otherwise overlooked. Sure, test drives take time, but so do comebacks. Think of it as a final quality-control check.


Management: Where Does the Small Shop Fit?

“Is MAP (Motorist Assurance Program) relevant to independent shop owners and automotive technicians?”

That’s an increasingly common question from those who look over MAP’s member list and see the names of large chains. MAP is an inclusive organization. It seeks the involvement of all firms in the automotive parts and repair industry, regardless of size.

MAP is also representative of a trend affecting a variety of industries and professions — responding to problems through constructive collective action.

Some people in the business might be offended at the notion that anyone would think they’re not trustworthy. “Maybe that other shop down the street, or a couple of the big chains that have had problems. But not me! My customers know me. And more importantly, I know my customers and what’s best for them.”

This refrain often rings hollow. Perfection eludes even the best companies and organizations. Without uniform guidelines and some basic standards, how will anyone — consumer, shop owner, technician, retail manager, government regulator — know what criteria to use in evaluating levels of performance?

If each company makes up its own standards, the consumer gets widely different treatment and advice, not to mention confused.

When more and more consumers get more and more upset about what they see as an overall lack of uniformly reliable treatment by any variety of repair shops, what do they do? They complain. Loudly. And government agencies charged with the responsibility of consumer protection step in and impose a one-size-fits-all regulation.

MAP’s Uniform Inspection and Communication Standards do reflect the reality repair shops, both large and small, have to face because they have been developed by the car manufacturers and automotive repair companies themselves. Now, right here is where the small shop owner or technician might raise a hand and shout “Whoa! Those were developed by the ‘Big Guys’ — but what about me?”

Actually, the big guys were only part of the group. Small shops, represented by members of FAQT, state ASA chapters, independent dealers/franchisees, and technical trainers from parts and equipment suppliers (the same ones that supply both the large and the small firms), took part in the uniform inspection guidelines’ development sessions.

Regulators in many states are expanding their horizons. While publicity and corporate “deep pockets” motivate them to go after the larger firms, the regulations that result (including the trend toward licensing and minimum training standards) affect all shops operating in the area.

Add to that the notion that strict adherence to MAP’s Standards of Service would have saved many of these firms the embarrassment (and a few dollars!), one can see that participation in the Motorist Assurance Program benefits everyone — no matter how “big” or “little” they might be.

To learn more about MAP, visit


Strut Your Knowledge of Ball Joints

There are specific types of ball joints for the different types of suspensions. The ball joint is one moveable part of a control arm assembly. The control arm bushings are just as important as the ball joint. If the ball joint is worn, chances are that the bushings are just as worn as the ball joint. In the case of a strut suspension, the upper mount can receive as much wear as the ball joint. The shock absorber is also and important component in the stability of the suspension system. If the shock absorber is out of oil, there is no damping. This article is about the ball joint and its construction, types, wear and inspection.

Getting a Suspension
MacPherson Strut: The strut and coil over spring requires a follower-type ball joint lower control arm.

Short Long Arm (SLA): On this type of suspension with the spring connected to the lower control arm, they typically use a loaded lower ball joint and follower upper ball joint, or if the spring is connected to the upper control arm, they will use a follower on the lower and loaded upper ball joint.

If you use a prybar and brute strength, your inspection could be influenced by the bushings. The control arm of an SLA or strut-type suspension will have two bushings to allow the arm to move in a vertical motion and a ball joint to hold the steering knuckle. The ball joint also allows the steering linkage to turn the steering knuckle. The bushings are made of rubber or an elastomer, such as polyurethane. The purpose of the bushing is to isolate the control arm from the chassis of the vehicle to reduce vehicle noise vibration and harshness (NVH). The bushings absorb road shock by compressing and twisting. Rubber bushings are normally used as original equipment applications. Polyurethane bushings are used in performance applications and normally result in an increase of NVH.

Types of Ball Joints
A ball joint is made up of a housing, ball stud, bearings, end cover and Belleville washer or spring. A Belleville washer is a conical-shaped spring designed to be loaded in the axial direction. The joint is attached to a control arm by pressing the joint into the arm or riveting the joint to the arm. If the joint is pressed into the arm, it will require a special tool to remove the old joint and install the new one. Failed pressed joints can be difficult to remove because of corrosion between the control arm and joint. This is especially true where a steel ball joint housing is pressed into an aluminum control arm. When the joint is riveted to the control arm, the rivets are drilled out or cut with a air chisel. The new joint is replaced using bolts and locking nuts.

On the left is a follower-type ball joint. On the right is a loaded ball joint. Using the arrows, write the corresponding number next to the correct component name from the choices below.

Note: Not all of the words will be used.

end cover  spring
markel clip

Belleville washer

ball stud

Note: The correct answers are provided to your instructor via the
Instructor Letter that accompanied this issue of T2.

1) Loaded Joint : A loaded joint is designed to support the weight of the vehicle and a follower joint that positions the control arm or strut assembly.

A lower control arm that is connected to the spring uses a loaded ball joint to connect the steering knuckle to the upper control arm follower ball joint for a SLA suspension. The ball joint also allows the steering linkage to rotate the steering knuckle.

2) Follower Joint: A strut suspension uses a follower ball joint to connect the lower control arm, steering knuckle and the strut. The upper strut mount assembly usually contains a thrust-type bearing to support the weight of the vehicle and allow the steering linkage to rotate the strut and steering knuckle.

Ball Joint Wear
Some ball joints that have a grease fitting use the fitting as a wear indicator. If a grease gun will not couple to the fitting, the joint needs to be replaced. As the joint wears, the Belleville washer or spring maintains the tension on the bearings to maintain zero axial endplay as the control arms move. Lateral wear causes the ball stud to move inside the bearing. It can affect camber and tire wear. The Belleville washer or spring will not compensate for lateral wear.

Making an Inspection
Loaded Joint: To check a loaded ball joint, place a jack or jack stand under the lower control arm to support the weight of the vehicle. Attach a dial indicator to the lower control arm and locate the dial in a vertical position to measure axial runout at the steering knuckle. In the case of an all-wheel-drive front ride strut or independent RWD, it may be necessary to mount the dial at the CV joint. Moving the steering knuckle can check lateral runout. For a SLA suspension that has the coil spring over the top arm, the upper joint is loaded. To check the joint, the upper control arm is supported to unload the joint. If the ball joint has a built-in wear indicator, joint play should be checked with the vehicle on its wheels.

Follower Joint: To check a follower-type joint, the Belleville washer or spring is loaded or compressed to check for axial end play. For a strut-type suspension, place a jack stand under the cradle to allow the strut to fully extend. Attach the dial indicator clamp to the lower control arm and locate the dial in a vertical position to measure axial runout at the steering knuckle. Place a jack under the ball joint and load the joint by raising the jack. Turn the steering wheel and observe the ball joint to check lateral runout. For a SLA suspension, the upper control arm can be blocked and the joint can be compressed. Attach a dial indicator to the steering knuckle and locate in a vertical or parallel position to measure axial runout at the lower control arm. Moving the steering knuckle can check lateral runout.

Bearing the Load?
Ball joints can be broken down into the load-bearing and non-load bearing categories. A load-bearing ball joint is designed to support the weight of the vehicle while providing a hinge point for the steering system. Most load-bearing ball joints are designed to cancel the effects of normal wear by centering themselves in their own sockets.

Non-load-bearing ball joints, on the other hand, are designed to maintain precise dimensional tolerances in a steering or suspension system. Wear in a non-load-bearing ball joint will cause a noticeable change in the camber, caster or toe angle of a front suspension. Consequently, non-load-bearing joints are preloaded in order to compensate for wear. Unloaded control arm ball joints, for example, should be tested for preload when the suspension system is disassembled.

Tie rod end ball joints, on the other hand, are more tolerant of wear. Providing an assistant is available to turn the steering wheel of the vehicle in a parked position, the dry-park testing method will indicate excessive wear in most tie rod ends. When a technician is working alone, the tie rod end can be compressed with a pair of water pump pliers while the technician looks for a change in toe angle.

Final Notes
For every vehicle, there are specifications for alignment, ride height and ball joint end play. The overall condition of the chassis is important to the safety and performance of the vehicle. In the area of safety, it is a good practice to cover your assets. Try to convince the owner that is important to correct all of the conditions that could cause the vehicle not to perform safely. If this is not possible, make sure that all conditions not repaired that affect safety are made a part the repair order and a
disclaimer is attached.

Understand that technicians often have a problem locating valid specifications for ball joint testing. In many cases, a vehicle manufacturers warranty tolerances are simply too liberal for real-world alignment situations. In other cases, a manufacturer simply leaves the issue to the technicians individual judgment. This allows for the real-world effects that cumulative bushing and ball joint wear will have on the steering and suspension system as a whole.

Automotive News

I Want You – to Understand Brake Performance

How Uncle Sam Sets Braking Standards.
Everybody wants safe brakes, right? You want the assurance that any brake linings you install on a customers vehicle will provide adequate braking and meet all applicable safety standards. But guess what? There are no federal safety standards for aftermarket brake linings. Federal Motor Vehicle Safety Standards (FMVSS) 105 and 135, which are issued by the National Highway Traffic & Safety Administration/Department of Transportation (NHTSA/DOT) apply to new vehicles only. They do not apply to aftermarket replacement brake linings. So technically, aftermarket brake linings are unregulated and do not have to meet the same FMVSS standards as OEM brake linings.

How will this affect you? The FMVSS standards are designed to assure new vehicles are capable of stopping within a certain distance deemed necessary for safe driving. FMVSS 135 is the current standard and applies to 2000 and newer cars, and 2002 and newer light trucks. Compared to the earlier FMVSS 105 standard, FMVSS 135 requires roughly a 25% reduction in pedal effort for the same stopping distance.

FMVSS 135 says all vehicles under 10,000 lbs. gross vehicle weight (GVW), except motorcycles, must be capable of stopping within a distance of no more than 230 feet (70 meters) from 62 mph (100 km/h) with cold brakes (under 212 F or 100 C) and with no more pedal effort than 368 ft. lbs. (500 N).

In July 2005, these same requirements were extended to trucks and buses weighing more than 10,000 lbs. Formerly, only school buses had to meet the same stopping requirements as passenger cars and light trucks.

The FMVSS 135 standard also specifies a required stopping distance for vehicles should the power brakes fail (no power assist), or if one of the two hydraulic circuits fail. Under these conditions, the maximum stopping distance from 62 mph (100 km/h) is not to exceed 551 feet (168 meters) with a maximum pedal effort of no more than 368 ft. lbs. (500 N). FMVSS 135 also has a stopping requirement in the event of an anti-lock brake (ABS) system failure. The rules require the stopping distance not to exceed 279 feet (85 meters) with a maximum pedal effort of no more than 368 ft. lbs. (500 N).

There is also a hot performance stopping requirement for fade resistance. With the brakes hot, the maximum stopping distance for the second of two back-to-back panic stops is not to exceed 292 ft. (89 meters) with the same pedal effort as before (368 ft. lbs. or 500 N). The parking brakes are also covered by FMVSS 135. The rules specify conditions under which the parking brake must be able to hold the vehicle on both an uphill and downhill incline.

The Brake Police
With no federal regulations, aftermarket brake suppliers have to police themselves and each other to assure their products are safe. No brake supplier in their right mind would sell brake linings they know are not capable of providing adequate stopping power under normal driving conditions. Even so, whats adequate is subject to interpretation, and some suppliers take a more liberal view of the bottom line requirements than others.

If you want to maintain like new brake performance, you should be installing application engineered or premium brake linings that have been tested and certified to meet standards similar to FMVSS 105 and 135. The aftermarket currently uses two such test standards: BEEP and D3EA.

In the Shop
All of this means that as a future technician, you need to pay close attention to the brake work youre doing and the kind of replacement linings and other parts you are installing on your customers vehicles. The hydraulic brakes and friction linings on todays vehicles are closely integrated with the anti-lock brake, traction control and/or stability control system on the vehicle. Consequently, any change that significantly alters the hot and cold friction characteristics of the linings has the potential of upsetting not only braking performance, but also the operation of the ABS, traction control and stability control systems.

Given the fact that aftermarket brake linings are essentially unregulated, how can you be sure the linings you are installing on your customers vehicles meet these criteria? The best advice here is to buy name-brand products from supplies who stand behind their products.

Real World Results
For the most part, the quality and performance of most aftermarket brake linings is not in question. BEEP and D3EA testing are accomplishing what they are designed to do, and virtually any name-brand brake lining that meets these criteria will provide safe braking and deliver performance that is similar to or even better than the OEM brakes on your customers vehicles. But there are some concerns with no-name offshore suppliers who are selling products that are of questionable quality or contain asbestos.

Many third world countries are not overly concerned about brake safety, the quality of their products or what kind of ingredients are used in their brake linings. They just want to sell their products at the lowest possible price. Asbestos disappeared from U.S-made brake linings years ago out of concerns over potential health hazards and litigation. But asbestos is still used in many brake linings outside the U.S., and some of these asbestos-laden brake shoes and pads are still being imported into this country.

Some say the only way to guarantee aftermarket brake linings meet the same safety requirements as new vehicles is to have FMVSS 105 and 135 apply to the aftermarket too. The brake manufacturers do not want to see that happen because it would require a lot of expensive vehicle testing. Imagine the cost of having to test brake linings for every year, make and model of vehicle in an entire product line, and how that cost would have to be passed along the distribution chain to you and your customers. It could increase the cost of brake linings significantly. Thats why the brake manufacturers prefer to use voluntary test procedures, such as BEEP or D3EA, to evaluate their aftermarket products.

Fortunately, no federal regulations are in the works for aftermarket brake linings so the brake manufacturers will continue to regulate themselves and each other to make sure their products are safe and deliver like-new or better-than-new performance. The bottom line, after all, is to have a happy brake customer.

Federal Investigator
It is often said by technicians in the field that if an engineer was placed in the field for a day he would change the way he designs cars. But, if you reverse the statement and have the technician design and engineer a new car, it would change the way technicians fix cars. Trying to see a brake system through the eyes of the OEM engineer can make you a better technician. Just like any technician, the OEM engineer has to work under certain constraints to achieve a goal that is laid out in quantifiable performance objectives, like meeting FMVSS and internal standards. Understanding how they go about this can help to make you a better technician.

Before you pitch the pads and rotors, it would pay to take a look at the evidence and history. Think of yourself as a CSI (Crime Scene Investigator) looking for clues. What was the surface condition of the friction material? Was there any type of shim or other material on the back of the pad? If the rotors were replaced, why? In todays market, it is worth it to take some digital pictures and collect some information from the customer. Like, how many times have the pads been replaced.

An engineers version of CSI is FMEA (Failure Modes and Effects Analysis). It is the if then analysis. This means that they walk through all possible scenarios. For example, if the engine stalls, you have the brakes and steering to bring the vehicle to a safe stop, even if it is a 110 lbs. weakling behind the wheel.

How OEMs Meet Government Standards
Brakes are the opposite of an engine. Brakes take the motion energy created by the fuel and turns it into friction heat energy to stop the vehicle. If a vehicle has 200 horse power at the wheels, then it should have brakes capable of the same capacity to stop the vehicle. The bigger the engine, the bigger the brakes if you are going to stop as fast as you can go. Just as engine size and performance enhancements, such as supercharging, determine the amount of power to the wheels, the drum and rotor diameter and swept area determine the stopping power.

The vehicles ability to stop and go is greatly influenced by the wheels, tires and suspension, but that is about tire construction and chassis design. But there is one CSI/FMEA to consider and that is wheel and tire diameter. If a replacement wheel and tire assembly is significantly larger than the original factory set, it can reduce the stopping power of the brake. The distance from the ground to the center of the wheel increases the leverage on the brake. This results in an increase in the stopping distances and possible thermal damage to the pads and rotors.

This is about where the friction material meets the rotor or drum. Friction material is like fuel. It creates the heat energy and is designed to use it up just like fuel. In relative terms, friction material is inexpensive in comparison to rotors and calipers. The base material for a pad or lining should have the following qualities: thermally stable, insulates, good wear characteristics, easy to process and has a reasonable cost.

There are many recipes for friction material, just as there are recipes for baked goods. There are hundreds of ingredients to make bread, and there are more than 2,000 different materials, from the common to the exotic, to make friction material. Limitless combinations can be used to produce a pad or lining to meet specifications for noise, coefficient of friction, fade, pad wear, rotor wear, compressibility and operating temperatures. There are no set standards for the quantity and types of material to produce a given specification.

Structural fibers maintain the strength of the pad or lining. These fibers include asbestos and ceramic fibers. Binders are what hold the pad or lining material together. The most common are usually synthetic resins derived from hydro-carbons known as a polymers. The phenolic resin is the most common resin used in pads and linings. Phenolic resins are derived from the hydro-carbon, benzene.

Some binders are as exotic as the resins from cashew nut shells. Each resin has a set of characteristics that can change the performance of a given type of braking system.

The concentration of this resin can change the performance of the pad or linings material strength and coefficient of friction. The amount of heat generated during braking has the greatest affect of the binding resin. Fade occurs when the heat generated causes the resin to melt and reduce the friction between the pad and rotor. Overheating of the friction material to have a glazed surface. Extreme overheating can cause the friction material to crack.

Abrasives are the materials that help to clean the rotor surface and reduce the glazing of the pads or lining. They also increase the friction when the brakes are first applied. The most common used today are aluminum oxide, iron oxides, quartz, silica and zirconium silicate.

Friction modifiers are what make the construction of pads and linings an art. These materials can raise the friction and react with the oxygen in the air to reduce glassing of the rotor and pad. These can be as simple as metal chips or complex as ceramic microspheres. The majority of the materials are metal sulfides and oxides. Fillers are as exotic as cashew nut shells and powdered iron or as simple as common as scrap rubber.

Mixing the right components in the right quantities can greatly influence if the vehicle will meet FMVSS 105 and 135. But, the engineer has other concerns besides FMVSS standards. He also has to strike a balance between material and warranty costs. This is why some of the best compounders are treated like gods by their employers. Why? Because they can save their employers millions of dollars by eliminating trial and error with their years of experience.

Did You Know Compounding pads is sometimes referred to as a black art. But, every pad is based on three or four basic ingredients that include: binding materials, abrasive, lubricants and structural fibers.
The most important point to keep in mind with respect to the FMVSS rules is that the rules are a performance standard and are based on how well the vehicle can actually stop. The rules do not specify what kind of brake linings, rotors or calipers the vehicle must be equipped with, or any friction, fade, noise or wear characteristics for the brakes. The only requirement is that the vehicle is able to stop within the specified distance under the specified conditions. Period.

In that respect, compliance is fairly easy to verify. Either the vehicle stops within the specified distance or it doesnt. But this requires field testing each and every make and model of vehicle to make sure they meet the standards. The vehicle manufacturers do their own testing and certification, and NHTSA reviews the results to make sure the vehicle manufacturers are complying with the rules.

Quality Counts In the case of the OE manufacturer, a lot of time and money are spent to produce a brake pad or lining to meet FMVSS, plus warranty and performance specifications, per a specific vehicle. If the bumper-to-bumper warranty is 36,000 miles, those pads and linings are designed to last through the warranty period. A quality brake job should meet or exceed those warranty standards. If the vehicle has specified stopping distances, check the owners manual, the vehicle should perform as stated in a court of law.

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Geometry In Motion – Stabilizing Steering and Suspension

Stabilizing Steering and Suspension
Big rims or tires can look good and give a vehicle a unique look. But what you cant see can become real ugly the alignment and suspension angles that have become altered. Also, that extra weight in stylist alloy rims or thick off-road tires can create a gyroscopic problem.

Lifting Why do vehicle enthusiasts lift trucks? Well, the primary reason is to be able to fit larger wheel and tire combinations.

Of course, light trucks and SUVs with wheels and tires that are 35-inches in diameter, combined with a lift kit, may be great for off roading, but they can have a scary effect on the way the steering reacts on a straight stretch of pavement at 70 MPH. Then there is the corner at 25 MPH where the steering wheel will not return to center or returns to center and oscillates.

A lift kit can raise the center of gravity of the vehicle and increases the possibility of a rollover. The manufacturer is required to place the following on a pickup or SUV sun visor: This is a multipurpose passenger vehicle which will handle and maneuver differently from an ordinary passenger car in driving conditions which may occur on streets, highways and off road. As with other vehicles of this type, if you make sharp turns or abrupt maneuvers, the vehicle may rollover or may go out of control and crash. You should read driving guidelines and instructions in the owners manual, and wear your seatbelt at all times.

A lift kit makes this information even more important. Government rollover ratings for light trucks and SUVs can be found Some lift kits can also change the caster angle and change the point where it intersects with the ground. But some kits take extra care to relocate the suspension mounting point so that the extra height does not change the angles.

The offset of the new wheel is probably moved to accommodate the increase in rim width. The change in the offset moves the mounting flange of the wheel and changes the point where the flange centerline and steering axis inclination meet the ground. A change in offset can change the loading on the wheel bearings that can lead to a failure. This creates a scrub radius that will affect tire wear and can cause a change in stability.

Big rims can really look great on a passenger car, too. If there is a change in ride height front to rear, it can affect caster and steering. An increase in wheel and tire diameter can affect braking for all vehicles.

Keep Em Stabile The steering stabilizer or damper for a truck or SUV can dampen a shimmy or a return-to-center condition. A steering damper for a passenger car is usually associated with manual steering on a passenger car with rack-and-pinion steering, and on the power steering linkage of light trucks and SUVs. A steering damper is a shock absorber with a 50/50 valve that applies the same hydraulic resistance in both directions.

The steering damper has to operate in a horizontal position. This means that there has to be a way to prevent aeration and foaming of the fluid in the reservoir where it compensates for fluid displacement as the shaft moves in and out of the damper.

In the early 1960s, General Motors developed a gas-filled cushion that looked like a sandwich bag, which was inserted into the reservoir of a shock absorber. The bag would expand and collapse as the shaft moved in and out of the shock. They were first used on the 1965 Olds Toranado rear axle and steering linkage.

These units will solve the majority of steering problems, like shimmying and stability problems, but if the customer has a wheel and tire combination that is outside sane recommendations, the steering stabilizer may not be able to compensate for extreme wheel sizes.

Short Long Arm Many SUVs, most crossover vehicles and some import light trucks have both front and rear independent suspensions. An independent front or rear wheel suspension is either a strut suspension or a short long arm (SLA) suspension. How the components are mounted to the chassis configures the geometry of the suspension. In a strut suspension, the strut takes the place of the upper control arm, shock absorber and steering knuckle. The SLA suspension is made up of a steering knuckle and upper and lower control arm.

When the shock absorber is mounted to the lower control arm and chassis. Changes in wheel and tire size and chassis modifications can change a vehicles handling and braking characteristics. Here is a sample laundry list of conditions: harsh ride, wander, shimmy, steering wheel will not return to center, excessive lean, etc.

A steering stabilizer may dampen some of the conditions, but it wont correct them. Power steering is both an assist and a damper, and most vehicles have power steering. The rate at which the power steering lines meter the flow of fluid to the piston is the same as if a manual steering damper would meter fluid through its piston. Modifications to the chassis can affect the built-in dampening of the power steering. A change in caster can make a power steering system overly sensitive.

Suspension geometry is what makes vehicle steering controllable. Track, caster, camber and toe are the four factors that control the stability of a vehicle in a straight line and around corners. Track is the alignment of the wheels to the centerline of the vehicle. The wheels for each axle are the same distance from the centerline and parallel to the centerline. Caster is the angle generated by a line through the center of the upper and lower ball joints and a vertical line through the center of the upper ball joint. Caster is positive when the angle is toward the front of the vehicle and negative when it is toward the rear.

Positive caster is used to cause the steering to center when traveling in a straight line and to return to straight from turning a corner. Camber is an angle generated by a line through the center of the wheel and vertical. Camber is positive when the top of the wheel is toward the outside of the vehicle and negative when toward the inside.

Toe is the angle through the center of the wheel and a line parallel the centerline. Toe-in is when the front of the wheel is angled inward to the center of the vehicle. Toe-out is when the wheel is angled outward and away from the center.

When vehicles had straight axles, the steering knuckle was attached to the axle with a kingpin. The kingpin is set at an angle that would cause it to run through the center of tire on the ground. This is called kingpin inclination. The purpose of the angle is to prevent the wheel from sliding sideways when the wheel is turned. Scrubbing is the term given to this sliding action.

On Its Axis Steering axis inclination (SAI) is the same as kingpin inclination. It is a line generated through the center of the upper and lower ball joint to the center of the tire on the ground. It is positive when the angle is inclined inward toward the center of the vehicle and negative when the angle is inclined outward. The distance between where the SLA and the centerline to the wheel intersect the ground is called the scrub radius. The scrub radius can affect the way the steering responds in both a straight line and cornering.

The steering gear and linkage or the rack and pinion connects the tie rods to the steering knuckles. The location of the steering gear linkage or rack can have a profound affect on how the vehicle handles. The biggest affect is called bump steer. When a vehicle suspension travels over a bump the movement of the suspension and tie rod move in an arc. That movement can cause the wheel to turn in or out and disturb the direction of the vehicle especially in a straight line. A lift kit should ensure that the position of the tie rods do not change in relation to the suspension location. A change in position can cause a bump steer condition.

The best performing suspension and steering systems have a quality that is called neutral steer. Neutral steer can be defined as a system that tracks straight and returns to straight with no over- or under-steer after turning. (This can occur if there is no bump steer and minimal chassis roll. The steering will also have a controlled return to center when the wheel is released. This is where damping is used to slow the movement of the steering linkage to ensure that the wheel returns to center. Every OE system is engineered for safety and neutral steer.

So how does all of the information apply to a vehicle you may one day soon service on the alignment rack? The condition of the suspension and its alignment are key to the safe operation of the vehicle. If you live in the northeast or midwest, the suspension is exposed to more severe conditions than in other parts of the country. The weather and road conditions can contribute to the deterioration of the components of the suspension and vehicle alignment. Yes, there are car-eating potholes everywhere you drive. When you are replacing the pads is a good time to take a look at the bushings, ball joints and tie rods. They could be part of the reason you are doing the brake job.

Safe and accurate steering is one of the most important contributors to the safe operation of a vehicle. Cover your assets by installing quality parts and aligning to specifications. Finally, if you do install modifications, such as oversized wheels and tires or lift kits, make sure that the owner is aware of all of the warnings and safety precautions that come with the modifications. That label on the sun visor is twice as important when there is a lift kit involved.

Follow Instructions In the instruction for a steering stabilizer kit, the manufacturer makes light of the possibility that these extreme wheel and tire packages can cause wear on the new steering stabilizer and the steering components:

(Company name Removed) does not recommend a particular tire and wheel combination for use with its products and assumes no responsibility for customer choice of tires and wheels. Consult your owners manual for recommended tire sizes and warnings related to use of oversize tires and wheels. In general, larger tire and wheel combinations may increase stress and wear on steering components leading to increased maintenance and greater risk of component failure, including loss of steering control. Property damage or personal injury may result. Large tire and wheel combinations may also reduce braking effectiveness and alter vehicle center of gravity height (see product safety warnings). Remember, BIGGER isnt necessarily better.

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Unlock The Code
Just about every brake pad or shoe you install has a cryptic code printed on the side of the friction material. As a technician, being able to read this code is just as important as the Dewey Decimal System is to a librarian or an ancient writing is to a symbologist. The Edge Code can tell you information about the product you are about to install. These letters and numbers can help you select the right friction material for a vehicle and its driver.

Do Not Despair: Edge Code is a language written by engineers, federal entities and industry associations. Like any language, edge coding has its own grammar that has been defined by standardized vehicle and laboratory tests.

Opening Your Eyes to the Decryption
If you are to take one thing away from this article, it should be how to read the letters that correspond with the friction levels of the brake compound. These are the two letters that are midway through the code. But, to understand the letters, you must first understand the tests behind the letters.

Teachings from the Society
The coefficient of friction and resistance to fading is measured using Society of Automotive Engineers (SAE) practice J661 and marked with SAE Practice J688 (truck standard). Stay with me here, when you see a SAE JXXX code or practice dont think that it is useless to a technician. Keep in mind that when SAE publishes these standards it has been reviewed and tweaked by all concerned parties like OEMs, suppliers and governmental bodies in some cases. In the cases of J661 and J688, it has direct bearing on the aftermarket technician.

The purpose of J661 and J688 is to establish a uniform laboratory procedure for securing and reporting the friction and wear characteristics of brake linings. The performance data obtained can be used for in-plant quality control and for the quality assessment of incoming shipments by the purchasers of brake linings. But, the data is also used in determining the edge code and the right friction material for a vehicle.

The Testing Begins
J661 has its roots in a Ford test that was developed in the 1960s. This is why the test takes place in a simulated drum brake. It is a simple test that just about every friction material formulation has to endure.

SAE Practice J661 and J688 testing procedure takes place on a machine (See Figure 1) that contains an 11-inch drum with three temperature sensors. The drum can also be heated during the test. But, the drum is turned at a constant speed (Figure 1a).

A fixture to contain a 1-inch /25.4 mm square by 0.24-inch/6 mm thick sample of friction material with a radius to match the drum, and weights to apply pressure to the sample. An air jack is used to apply and release the weights on the fixture (Figure 1b). A load cell is attached to the fixture to measure the force generated by the friction material when the drum is turned (Figure 1c).

The test procedure consists of 11 tests that are run in succession. The normal force placed on the sample is 150 lbs. The rotational speed of the drum is 417 rpm. The load cell measures force in lbs / sq inch. The heating elements are capable of producing drum temperatures of 200 to 650 F.

The Table of Coefficients
The SAE Practice J668 and J661 for the edge code on friction material notes the normal coefficient of friction and hot coefficient of friction or fade resistance. Letters are used to note the coefficient of friction as shown in Table 1.

Taking the Tests to Task
Test 1 – Baseline: The load is applied to the drum for 10 seconds and released for 20 seconds for 20 applications.

Test 2 – First Fade: The load is applied continuously for 10 minutes or until 550 F. The coefficient of friction is recorded with each increase in temperature.

Test 3 – First Recovery: apply load for 10 seconds at 100 F increment as the drum cools.

Test 4 – Wear Measurement: The height of the sample holder is measured.

Test 5 – Wear Run: Apply load for 20 seconds and release for 10 seconds for 100 applications.

Test 6 – Wear Measurement: The height of the sample holder is measured.

Test 7 – Second Fade: The load is applied continuously for 10 minutes or until 650 F. The coefficient is recorded with each increase in temperature of 50 F.

Test 8 – Second Recovery: Apply the load for 10 seconds at 100 F increment as the drum cools from 600 to 200 F.

Test 9 – Baseline: The load is applied to the drum for 10 seconds and released for 20 seconds for 20 applications with a drum temperature of 180 to 220 F.

Test 10 – Wear Measurement: The height of the sample holder is measured.

Test 11 – Mass and Thickness: The weight and thickness of the sample is measured.

Reading the codes
In the edge code, the first letter notes the normal coefficient of friction and the second letter notes the hot coefficient of friction (See Figure 2). The code appears in 0.25-inch letters on the edge of the friction material.

The coefficient of friction is determined using SAE Practice J661.

Wear measurement results are not indicated in the edge coding and should be an important result for the developer of the friction material. The aftermarket rating of replacement shoes and pads may have some relation to the ware characteristics of that particular assembly.

As for the edge code, the results are directly tied to the Formula of m = Fr / Fn where Fn is 150 lbs and Fr is the pressure recorded by the load cell during a normal or hot test sequence. For example, an average load cell recording of 42 lbs / sq inch during a test would produce an m of 0.28 that would relate to an E rating on the edge code.

Obeying the Standards Set Forth From FMVSS
Imagine you are working at an automotive plant assembling cars. In rushes a federal inspector demanding the keys to a random vehicle for brake testing. OK, it is not that dramatic, but it happens on a regular basis. This testing insures that new vehicles meet the Federal Motor Vehicle Safety Standards (FMVSS) standards.

The FMVSS standards 105 and 135 set performance standards for vehicles equipped with hydraulic and electric braking systems. Unlike SAE J661 and J668, the FMVSS tests take place on the vehicle, which makes it a dynamic test.

FMVSS 105 includes system configurations and braking performance for both service and parking brakes. Parking brakes must hold a vehicle in forward and reverse directions on a 30% grade for five minutes.

FMVSS 135 basically requires light vehicles (GVWR of 10,000 pounds or less) to stop, also on a high coefficient of friction pavement and with properly working brakes, in 215 feet (the actual requirement is 230 feet from 100 KPH).

Understand that the OEMs are constantly tuning and testing friction materials so that a vehicle can meet or exceed FMVSS 105 and 135. Taking chances with a replacement friction material that does not match the OEMs performance curve can mean disaster for the person who throws away the box.

Secrets Shared with the Aftermarket
Back in 1992, the Brake Manufacturers Council began funding a Society of Automotive Engineers (SAE) task force to develop a new laboratory dyno test procedure for evaluating brake linings. In 1994, SAE published the J1652 test for evaluating friction materials on front disc brakes. Then in August 1999, SAE published the J2430 test procedure for testing linings on the front and rear brakes together.

The J2430 is a test that any manufacturer can use to evaluate their products. The test is very detailed and takes about 15 hours to complete. It does not have pass/fail standards, but is designed to reveal how a given set of linings compares to the FMVSS 135 requirements for new brakes.

Greening Testing Laboratories in Detroit also has developed lab tests for certifying the performance of brake linings for several aftermarket brake suppliers. Its Dual Dynamometer Differential Effectiveness Analysis (D3EA) test procedure measures and compares the various performance windows (stopping power, fade resistance, etc.) of aftermarket linings against the OEM linings on a given vehicle platform. As long as the aftermarket linings fall within specified limits, they are certified as being OE-equivalent in terms of braking performance.

Friction as a Force

As taught in the ancient times and still holding true today, friction is a resistive force that prevents two objects from sliding freely against each other.

The coefficient of friction: The Greek letter (pronounced mew) is a number that is the ratio of the resistive force of friction (Fr) divided by the normal or perpendicular force (Fn) pushing the objects together. It is represented by the equation: m = Fr / Fn.

CODING for J668 and J661

Code Letter Friction Coefficient
C Not over 0.15
D Over 0.15, but not over 0.25
E Over 0.35, but not over 0.45
F Over 0.45, but not over 0.55
G Over 0.45, but not over 0.55
H Over 0.55
Z Unclassified


Real World- Take Me Out! – Test Drive Pointers For Technicians

Road testing a vehicle prior to an alignment can be just as important as the alignment itself. Not performing a test drive can lead to comebacks and unhappy customers.

When going for a test drive, a technician should have a clear objective and methodical plan for verifying the problem. It is also a chance to inspect the vehicle for other unperformed repairs.

Before going on a test drive, a technician should have a clear list of symptoms and related conditions the customer is experiencing. Also, before hitting the road the technician should make sure the vehicle is road worthy.

Before You Go…

Verify that car has functioning brakes, lights and enough fuel. Remember, you are driving an unfamiliar vehicle and it may exhibit behavior that could be unexpected, like a seat reclining suddenly. And nothing can be more embarrassing to a technician than running out of gas while driving a customer’s vehicle.

Reasons for Leaving
The main goal of a test drive should be to verify the customer’s problem, not to go get coffee. Also, a good test driver will be able to observe conditions or problems with the vehicle that have developed so slowly the owner is unaware of them.

One of the keys to becoming a good test driver is to find a driving “loop” or route that has a variety of road conditions. Using a predetermined loop can help to build consistency that will help you to spot small problems.

For alignment road tests, your test loop should consist of sections: a flat and straight section; an area to test braking and acceleration; an area with a dip or bump, and an area that offers both left and right turns.

Flat and Straight
On the flat and straight section of the loop, test directional instability and observe steering wheel position. The road surface should be smooth and flat with very little crown. The objective is to drive on a surface that will not influence the direction of the vehicle.

A crooked steering wheel may indicate a thrust condition that should be aligned or corrected. Check for excessive steering wheel play. The vehicle may drift if the steering system is excessively loose. This condition should be repaired before the alignment.

Stop and Start
Use a parking lot or rarely used section of road for this section of the test. This test is used to detect brake pulls, torque steer and worn or loose suspension or steering components.

Check for a brake pull when stopping the vehicle. The owner may think they have an alignment-related problem when, in fact, the braking system is at fault. This is usually most noticeable during hard braking.

The vehicle may drift to one side or the other due to dragging brakes. A brake caliper that does not fully release may be at fault. This problem is often brought about by heat and may not be evident on the alignment rack during compensation of the sensors.

Check for excessive nose-diving during braking. This is not normal and may be caused by worn springs or shocks. Worn springs will affect vehicle ride height and may affect overall vehicle handling. Check for pulls or drifts when accelerating or decelerating. This may be due to a condition known as “torque steer.” Torque steer is generally associated with FWD vehicles.

Dips and Bumps
Drive the vehicle over the bump or through the dip and observe the steering wheel position. This is an excellent test to detect weak springs, weak shocks and worn or unlevel steering components. If the vehicle changes direction or the steering wheel moves excessively, the steering components may be worn, incorrectly adjusted or unlevel. This condition is commonly known as “bump steer.” Excessive suspension bouncing may be the result of weak shocks.

Bottoming out of the suspension may be the result of weak springs. Continue to monitor suspension and steering stability throughout the remainder of the drive.

Left and Right Turns
Check the overall handling response through both left and right turns. Front and rear alignment settings, as well as steering and suspension components, affect cornering capabilities.

Check for steering difficulties that may be the result of mechanical binding or interference. This condition is commonly referred to as “memory steer.” Check for proper returnability of the steering wheel after a turn. Excessive driver effort should not be necessary.

Any excessive body sway could indicate worn springs, shocks or stabilizer assemblies.

Look for any excessive squealing of tires during turns. This can be caused by incorrect alignment settings or turning angle out of specifications.

Developing a methodical and consistent test drive loop and procedure can improve your chances of coming back from a test drive with a better understanding of the problem the owner is experiencing. Having a plan and a loop can eliminate distractions that could lead to an accident. Most importantly, prepare for the unexpected and drive defensively.

Automotive News

Measuring Up to Alignment Services

Are you measuring ride height when performing undercar service? You better. Before any alignment is performed, it is critical to measure ride height and check the condition of the springs and their mountings. If you decide to forgo this step, you could find yourself wasting critical time on the alignment rack to make a phantom adjustment.

Why Measure?
Measuring ride height is more than stepping back and measuring visually with your thumb and one closed eye. To properly measure the ride height, the factory methods and specs must be researched. Neglecting to do this can affect all angles of alignment. A reasonable ride height is necessary to allow for suspension movement and ground clearance. Among other considerations, engineers design the chassis so that the ride height places the suspension at a particular point midway in its travel. Midway is not always center, however. Suspension design dictates how much travel is needed in both directions (jounce going up, rebound going down) from its static position.

How To Measure?
Ride height of a vehicle needs to be checked on an almost perfectly level surface while the vehicle is in a static and usually unloaded condition. But, talk to the customer to find out what types of loads they typically carry. If you feel that these loads can have an effect on the load ride height, ask them to bring the vehicle by when it is loaded to check ride height. This can help you to sell additional products like heavy-duty springs, helper springs or an air spring system. If a vehicle shows signs of bottoming, or has a trailer hitch, then heavy-duty or variable-rate springs might be suggested as a suspension upgrade.

The cost of these products is minor in comparison to irregular tire wear and additional safety and control.

Most OEMs won’t admit to the problem, but heavy-set drivers or passengers (more than 180 lbs.) can radically alter the lateral weight distribution (and side-to-side alignment) of a vehicle just by sitting in the front seat. Obviously, as weight distribution changes, so do the alignment angles of any lightweight import vehicle. When alignment angles change, a scrubbing action takes place, which accelerates tire wear.

Shimming a set of weak springs with spacers or inserts is only a temporary fix that may take care of the sagging and bottoming problems, but it won’t restore the ride quality or spring rate.

Spring into Action
Most springs are made of metal. Take, for example, a coat hanger or welding rod. If you bend it in the same area several times it will eventually break from metal fatigue. These same forces are acting on the springs. Every time the suspension is compressed, the spring is essentially bending. After a few thousand miles, this constant bending can cause the metal to change its temper and eventually fatigue.

Leaf springs date back to horse-drawn carriages. But, even with their ancient design, they have one advantage over coil spring. Leaf springs are able to dampen spring rebound though fiction in the leaves. Depending upon design, the shock absorber almost becomes a redundancy in the leaf spring’s ability to dampen spring rebound.

Coil springs have some advantages over leave springs. First, they are easier to package on today’s vehicles. Second, coil springs weigh less. Third, coil springs can be tuned to fit the vehicle better than leaf springs.

Variable-rate springs can provide many of the benefits of heavy-duty springs without increasing ride harshness. This type of spring offers a smooth ride, as well as increased load carrying capacity as the suspension is compressed. Variable-rate springs are a good choice for any vehicle that tows a trailer or hauls occasional overloads.

Heavy-duty springs are an upgrade option primarily for work vehicles such as pickup trucks. These types of springs can increase the load capacity of the vehicle, but also tend to ride somewhat rougher because of their higher spring rate.

Performance springs are typically shorter and stiffer than stock springs to lower ride height for improved aerodynamics and a center of gravity that’s closer to the ground. This improves stability and reduces body roll. But the trade-off may be a somewhat harsher ride.

Customer Concerns
If a customer wants standard replacement springs, they should have the same approximate spring rate as the original to maintain the same ride height and feel. If you haven’t noticed, some aftermarket springs have a slightly stiffer spring rate because they are somewhat shorter than the OE models. But once these springs are installed, they provide the same ride height and feel as the original springs.

If the a customer wants something other than standard springs, find out how he uses his vehicle to determine what type of spring would help him out best.

If brute handling capacity is what he needs, then heavy-duty springs should be recommended. Maybe the customer has a family vehicle application – minivan or station wagon. Variable-rate springs work in this situation because they provide a soft ride when the vehicle is lightly loaded, while extra-load carrying capacity is available when needed.

With each new set of springs you sell, try to sell new rubber insulators, too. These insulators are nothing more than a rubber seat that fits between the coil spring and the upper spring seat. If the old insulators wear out, the new springs will squeak. Most shock and strut manufacturers also supply a full line of rubber parts. Also, if you do not see an insulator when you are removing the old spring, it does not mean there was not there in the first place. Be sure to consult with your jobber or parts catalogs to see if any pieces are missing.

Sway bars are essentially springs that act against body roll. The purpose of a sway bar is to reduce body roll when cornering. It has little affect on straight line driving (unless one wheel is swallowed up by a chuckhole in which case some of the blow is transferred to the opposite wheel). Most cars today are factory equipped with front sway bars, and many have rear sway bars as well, but not all. Factory sway bars are generally tuned for everyday driving and tend to be soft unless the vehicle has a performance suspension. So there’s usually ample room for improvement here, too.

Replacing the stock front sway bar with a stiffer bar, and/or adding a rear bar if the vehicle lacks one, can make a big difference in vehicle stability and handling. Many SUVs can really benefit in this area.

Another differences worth noting between factory and aftermarket sway bars are the links that tie the bars to the lower control arms.

Making Adjustments
Most aftermarket sway bars come with heavier links and solid, or hard, plastic bushings that eliminate slop for instant response. Better still, some are adjustable.

Note: By changing the mounting position of the attachment links on either end of the sway bar, the bar’s leverage, and thus it’s relative stiffness, can also be changed. Playing around with the settings allows the bar to be fine tuned to almost any driving situation.

If you are installing an upgrade sway bar, see if the manufacturer recommends replacing both front and rear units as a set. Installing just one sway bar could create handling characteristics worse than before.

Slamming Solutions
Slamming (lowering) is entering the mainstream because it looks good with 17-inch and larger wheels and it also lowers the vehicle’s center of gravity.

The desire to get closer to the ground has created a huge market for all types of lowering products. These include sport springs, coil-over kits, lowered control arms and air springs.

The right way to lower a vehicle is to install springs that are engineered to reduce ride height, or to install a coil-over kit on the shocks or struts that allow the ride height to be adjusted as desired.

Aftermarket performance spring suppliers have a wide variety of products from which to choose, so follow their recommendations as to spring rates and ride heights. A set of “sport” replacement springs, for example, might be only 15-20% stiffer than the stock OE springs and provide a significant improvement in handling without appreciably increasing ride harshness.

The next step up might be a set of stiffer street springs (25-30% stiffer) for the serious enthusiast who wants to push the envelope and is willing to suffer a little kidney damage in the process. Racing springs, which are typically 50-100% stiffer than the stock springs, are usually recommended for the track only.

Coil-over kits are a good choice for many applications because they allow the height to be adjusted as desired. Many coil-over kits allow the suspension to be lowered as much as three to five inches – or left stock. They’re affordable, too. Most kits retail in the $250-$300 range.

A coil-over kit usually includes a threaded lower spring mount that installs around the shock or strut and new springs. Some kits even use double springs (an inner and outer for a variable spring rate). Most kits can accommodate either stock or aftermarket shocks or struts. The adjuster is usually anodized aluminum and the springs are powder-coated or painted for appearance as well as corrosion protection. Some springs have variable spacing between the coils to provide a progressive spring rate for a smoother ride under normal driving conditions.

Installation of a coil-over kit is simple. Use a spring compressor to disassemble the strut, remove the OE spring, dust cap and bump stop from the strut, install the threaded adjuster sleeve on the strut and tighten the set screws to hold it in place. Then slip on the new spring, replace the bump stop and reassemble the strut.

Ride height is set with the coil-over kit by turning the adjustable spring perch to compress the spring. The adjuster is then locked in place. If ride height needs to be changed up or down later on, it’s a simple matter of unlocking the adjuster and turning it to reset the ride height. This set-up may also require wheel realignment and other suspension, wheel and tire modifications to avoid interference problems.

For those who want the ultimate in ride height adjustability, an air ride system can be installed to replace the springs entirely. Installation is a bit more complicated, and usually requires replacing the control arms to accommodate the air cylinders or air bag springs. An air ride system also needs a compressor, an air tank, and control switches and gauges to monitor and control the suspension.

Keep From Bottoming Out!
When a shorter set of springs or a coil-over kit is installed to lower a vehicle two or more inches, the stock struts or shocks may also have to be replaced with shorter ones to prevent the dampers from bottoming out. Any time ride height is reduced, suspension travel is also reduced. An added advantage with shorter struts and shocks is that they are up to several pounds lighter than the stock units.

The best approach here is to install a set of springs and shocks or struts that are engineered to work together. The dampening characteristics of the shocks are matched to the spring rate to provide the best all-round handling performance.

Adjustable shocks are a good choice for drivers who want the best of both worlds. The range of adjustment typically provides ultra-firm handling for serious racing, and reasonable ride comfort for everyday driving.