posted 12-19-2000 11:56 AM                  

I knew that.

posted 12-21-2000 09:11 PM                  

You fund all of the "A's" and as many of the "B's" as you have investment, piece cost and personnel to properly develop and the "C's" often don't make the cut. Especially on low volume specialty cars like Prowler and Viper. Viper just got ABS in 2001 and it's been around since 1992.

I'm sure that you noted the comments regarding the desirability of ABS from knowledgable owners.

Ask yourself how the vehicle is going to be driven? Where is ABS most effective? It is most effective during limit braking on very slippery (snow & ice) surfaces where it allows you to better maintain steering control while braking.

posted 12-22-2000 03:41 PM                  

BENEFITS OF ANTI-LOCK BREAKING SYSTEM
In a hard breaking situation without ABS the wheels may skid losing traction between the tires and the road. Wheel lock up is kept to a minimum.

4 wheel anti-lock brakes also improve steering control throughout the breaking situation. Since the front wheels don't lock up, traction with the road is maintained helping the driver steer around any obstacles.

Anti-lock will activate on rain slick pavement, on roads that are snow covered or on ice. Braking on gravel roads, sand covered roads and other loose surfaces may activate the anti-lock brakes, as could breaking going over bumps or elevations such as railway tracks. And even if road surfaces are dry smooth concrete such as a highway the ABS will activate the break applications hard enough. So no matter what the road surface of driving conditions you can be assured that your 4 wheel ABS can help you get safer more controlled stops.

HOW DO YOU USE ABS?
Do not pump the brakes. Apply constant firm pressure to the brake pedal and let the anti-lock system do the rest.

Also like a conventional brake system ABS is most effective when the tires are in good operating condition with good tread and correct tire pressure is maintained.

Like any vehicle whether equipped with anti-lock or not proper seat adjustment is important. Position yourself confortably for maximum effectiveness with your ABS.

For commercial applications the load should be evenly distributed over the rear axle for maximum effectiveness of the anti-lock brakes.

WHAT WILL I EXPERIENCE WHEN ABS IS WORKING NORMALLY?

When the brake pedal is applied and the anti-lock brakes activated the brake pedal may feel hard, it may also seem to ratchet or pulsate or there can be a combination of these sensations. Maintain firm and constant pressure on the pedal and be able to push it further if it travels to the floor. You may even here a sound like grinding this is normal.

posted 12-22-2000 03:43 PM                  

A lot of newer cars, both Mercedes and others, come with "ABS" or Antilock Braking Systems. I thought you might like to know what this is and how to adjust your driving if your car is equipped with this feature.

ABS helps prevent the loss of braking and steering control that occurs when your car wheels "lock up," or stop turning, while the car is still moving. A locked wheel loses effective contact with the road and cannot help you brake or steer. If the rear wheels both lock, the car can spin around, totally out of control.

If your dad taught you how to drive, like mine did, he probably showed you how to "pump" the brake pedal on bad surfaces, so none of the wheels get a chance to lock for more than a second or so. ABS is just a sophisticated way of doing this. A computer "reads" the speed of each wheel, and if one of them tries to go slower than the others (a sure sign that it is locking) the computer operates a valve to interrupt braking to just that wheel, and a pump to put the diverted fluid back into the master cylinder. It does this so quickly (many times per second) that maximum braking power can be used, while the ABS system prevents wheel locking.

Here's the shocker, in spite of the obvious potential benefit, insurance statistics so far have failed to show a decrease in accidents or fatalities in ABS-equipped cars. Researchers say this is because drivers are failing to take advantage of the ABS system, and even in an emergency situation fail to brake aggressively enough to stop in time. In controlled tests, ABS always decreases stopping distances on poor traction surfaces, and on good surfaces it's at least as good as conventional brakes.

Here's how to use your ABS-equipped car to best advantage:

If the risk of collision exists, brake hard!!!! Don't worry about skidding.
The brake pedal may "knock" or "chatter" under panic braking or on poor surfaces. Don't worry about this-it's just the ABS system doing it's job. It is not a sign to lift your foot!
Whenever you turn the key on in an ABS-equipped car, a yellow lamp marked "ABS" or "ANTILOCK" should illuminate. When you start the car, it should go out after a few seconds. If it does not illuminate with the key on, or does not go out after starting the car, the ABS system has a defect that must be investigated. The brakes will still work normally, the same as in a car not equipped with ABS.

If you have a car with the ABS braking system, you may want to practice using the braking system (of course, not in traffic).

Any questions, as always give me a call or drop me an email.

posted 12-22-2000 03:46 PM                  

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Some basic terminology to get started:

ABS - Stands for Anti-Lock Braking System.
ABS Actuator - The work horse of the ABS system, it's the piece that actually releases pressure in the ABS channel to modulate the brakes.
ABS Channel - The channel is the hydraulic line(s) from the ABS actuator to the wheel(s). ABS channel can consist of 1 or 2 wheels that will pulse/modulate when the ABS actuator performs its work.
ABS Sensor - Measures the speed of a wheel. Consists of gear-shaped sensor rotor and a sensor element. The element contains a bar magnet around which a coil is wound. The sensor is installed on the back side of the brake rotor. Sine-wave current is generated by the sensor as the wheel rotates. The frequency and voltage increase(s) as the rotating speed increases.
ABS Pulse or modulation - When the ABS Actuator engages and pulses/modulates the brake pressure being applied to the ABS channel. This is the method by which the system actually works. When the brakes pulse, they are prevented from locking because they rotate for a split second.
ABS comes in about 4 different flavors:

1 or 2 Channel 2-wheel (Rear ABS) - This ABS is usually prevalent on trucks. It consists of 2 ABS sensors on the rear wheels and one or two ABS channels to pulse the rear wheel together (1 channel) or separately (2 channels).
2 Channel 4-wheel Criss-cross - This is the ABS system present on the 91-94 Sentra. It consists of 4 ABS sensors (one on each wheel) and 2 ABS channels arranged in a Criss-cross (Left Front & Right Rear, Right Front & Left Rear). When the right rear wheel locks up, the left front wheel & right rear wheel are pulsed together.
3 Channel 4-wheel - This is the more common ABS system in cars. It consists of 4 wheel sensors and 2 channels in the front (LF, RF) and one channel for the rear wheels. When one of the front wheels locks up, it pulses independently of the other wheels. When one of the rear wheels locks up, it is pulsed together with the other rear wheel, similar to a very fast pulling and releasing of the emergency brake.
4 Channel 4-wheel - This is the ABS system present on the 95+ 200SX/Sentra. It consists of 4 ABS sensors and 4 ABS channels. All wheels pulse independently of each other, like it should be.
So, the long and short of it is that a 4 channel system will work better because only the wheel that is locked pulses (loses braking power), while the other 3 wheels continue to do braking for the car. This results in more stability while braking and possibly shorter braking distances.

Some myths about ABS:

With ABS I came stop faster. - Not necessarily. On a wet road, you MAY be able to stop quicker because your wheels are not locked up. However, in several conditions you can stop faster by locking up the wheels. One example is in deep snow. If you lock the brakes you create a wedge effect and stop quicker. Usually ABS distances are a tad shorter (10 feet) than non-ABS brakes, however, ABS gives you more steering ability then non-ABS brakes, the real advantage.
Pumping the brakes will help ABS - NO. You will probably confuse the ABS system more than anything else. If you need to stop in a hurry then press firmly on the brakes and DON'T pump them. The ABS system will pump the brakes for you.
With ABS I can steer around obstacles while braking - Most of the time. This is the theory, but in practice, if you don't have traction, you can't steer. Take for example ice. You could press on the brakes all you want but the car may not turn, because there is very little traction.

posted 12-22-2000 03:48 PM                  

One of the best ways to survive an accident is not to have one at all. But since no one has come up with a way to avoid accidents all together, more consumers are requesting air bags, anti-lock braking systems and other safety features to help save their lives in an accident. By the turn of the century, virtually every new vehicle will use some form of anti-lock brake system (ABS). Verifying proper operation of this safety equipment is an important check in both the estimating and collision repair process. This feature covers the basics in ABS diagnosis.

The Origins of ABS

Anti-lock braking was originally designed for trains in the early 1900s, and developed for jet aircraft after World War II. In the late 1960s, car manufacturers began to adapt ABS for use in luxury automobiles. However, early prototype systems were severely limited by mechanical and analog technologies of the time.

Advances in electronics technology allowed car manufacturers to develop highly reliable anti-lock braking systems that can be economically installed in a wide variety of vehicles.

How They Work

Applying excessive pressure on the brake pedal, or panic slamming the brake pedal, can cause wheels to lockup and possibly send the vehicle careening into a terrifying skid. Excessive brake pedal pressure often occurs in an emergency or adverse situations, such as on wet or icy roads. With an anti-lock braking system, computerized sensors located at each wheel will monitor deceleration when the brake is applied. The sensor will detect any wheel lockup and trigger the hydraulic system to automatically pump the brakes up to 15 times per second. Threshold braking is the term used to describe how ABS works.

A driver will press down on the brake pedal until he or she senses that wheel lockup is imminent. At that point, the driver will ease up on the pedal pressure just enough to avoid the feel of lockup, and repeat the process. ABS eliminates the need for the driver to manually pump the brake pedal.

Threshold braking should not be confused with pumping the brakes. In threshold braking, the driver is applying pressure to the brakes all of the time. While pumping the brakes is an alternative that most people think of first, each pedal pressure and release can eventually cause wheel lockup. Unfortunately, threshold braking requires practice, and is a technique with which most drivers are unfamiliar.

The dynamic technology in ABS allows the driver to be master of threshold braking. All the driver has to do is apply pressure on the brake pedal, and the ABS system will mechanically threshold brake evenly and smoothly. The well-developed and complex ABS feature allows the driver to maintain control of the vehicle and shorten the stopping distance.

Automakers would like us to believe that anti-lock brakes are the mechanical wonder of the century, and possibly they are. For example, General Motors has manufactured more than 12 million systems since 1991.

However, with all of this positive technical support from the carmakers there are also negative statistics including one from a recent study performed by the Insurance Institute for Highway Safety (IIHS).

The IIHS study states, "Cars with anti-lock brakes are more likely to be involved in fatal crashes than cars without them." However, the systems themselves do not seem to be the problem.

There are many factors to be considered when reading facts and figures about anti-lock braking systems. Injuries and deaths reveal alarming statistics; however, according to several industry studies, ABS systems have also saved more lives in emergency situations than standard braking systems. Notwithstanding, there are some concerns about the complexity of ABS systems:

* First, there are more cars equipped with anti-lock brakes on the road today. This is a new feature for drivers who have never driven with anti-lock brakes before. Possibly, drivers panic while mashing down on the brake pedal to avoid an accident in emergency situations, and thus propel their vehicle into a potentially dangerous skid, especially under adverse road conditions.

* Drivers are still pumping the brakes during sudden stops, or not steering away from obstacles even when the ABS system gives them the ability to do so.

* Also, more importantly, people are driving at higher speeds and placing themselves at greater risk of having an accident. More often, drivers are used to applying their brake pedal with a certain foot pressure in order for the vehicle to come to a stop. Drivers should be aware of how anti-lock braking systems work, so as not to apply as much pressure or use the new system as a safety crutch.

* Finally, some drivers actually believe that they can travel at almost any speed and have the assurance that their anti-lock brakes will securely stop the vehicle on a dime, and without an accident.

Technical Information From NHTSA

Anti-lock brakes eliminate the screeching sound that most drivers are accustomed to hearing when they apply excessive pressure on their brakes, according to a recently published technical report from the National Highway Traffic Safety Administration (NHTSA). Since anti-lock brakes prevent wheel lockup, there is no screeching sound. The absence of a screech means the ABS system is working. Also, according to NHTSA, the typical anti-lock system includes the following major components:

* Wheel speed sensors. These measure wheel speed and then transmit this information to an electronic control unit.

* The electronic control unit. This receives information from the sensors, determines when a wheel is about to lockup and activates the brake pressure modulator. Also, it detects any malfunction of the ABS.

* The brake pressure modulator. This reduces, holds and restores pressure to one or more brakes, independent of the driver's brake pedal effort.

* Some anti-lock systems control only the two rear wheels; others control all four wheels of the vehicle. In general, the four-wheel systems provide better stability and control during braking, but are more expensive.

* In the event of a malfunction in the anti-lock system, a warning lamp on the instrument panel alerts the driver that the ABS system is in need of repair. However, the vehicle's normal brakes will still function.

NHTSA is working with motor vehicle dealers to improve the understanding among consumers of anti-lock braking systems.

Activating ABS Systems

According to NHTSA, manufacturers currently offer two types of ABS systems: four-wheel anti-lock systems available on cars and trucks, and rear-wheel anti-lock (RWAL) systems offered on some trucks. Under normal driving conditions, ABS brakes do not operate any differently than conventional brakes. Motorists should operate the brake pedal as they normally would, gently pushing it down while applying steady pressure.

To correctly activate four-wheel ABS, step or push down hard on the brake pedal and hold it. Do not pump the brakes. Just keep your foot pressed firmly on the brake pedal, and let the anti-lock brake system work for you. The motorist may feel the brake pedal vibrate, or notice some noise, but this is normal.

RWAL systems are activated the same way as four-wheel ABS, by holding the brake pedal down. RWAL systems differ from four-wheel ABS in that the front wheels have conventional disc brake systems. Upon brake application, the motorist may feel the front wheels begin to lockup. If this happens, the motorist should momentarily release and reapply the brakes as necessary in order to avoid wheel lockup.

The driver may want to practice an ABS-activated stop just to get a feel for the brake pedal and how the system works. However, always be sure this is done in a safe area, such as a vacant parking lot clear of any obstacles.

The motorist should remember that in vehicles equipped with ABS, the system is always available, but if the driver does not maintain substantial pressure on the brake pedal, the system will not work properly, if at all.

An ABS Advantage

According to NHTSA, the important capability of ABS systems is control. Under most driving conditions, ABS provides the driver with improved vehicle steerability in order to get around an object while braking, and provides improved vehicle stability while performing these functions so that the vehicle is less likely to spin out of control.

Also, according to NHTSA, in all braking situations, stopping distance is critical. Under good driving conditions, the motorist should follow at least 2­3 seconds behind the vehicle in front of them. This time should be doubled if weather and/or road conditions are hazardous. These requirements are no different for vehicles equipped with ABS systems.

Under normal operating conditions, a vehicle equipped with an ABS system stops by using the conventional braking system. In severe braking conditions, however, the ABS system is automatically activated when any one of the vehicle's wheels approaches a lock condition. The system determines when ABS activation is required through wheel speed sensors and an electronic brake module (EBCM).

The sensors continuously relay information concerning the rotational speed and acceleration of each wheel to the EBCM, which compares these inputs with calibrated values of allowable wheel slip and other pertinent vehicle dynamics information. If and when conditions warrant, the EBCM then signals the ABS system's hydraulic modulator to begin ABS action.

The system modulates pressure to the affected wheel(s) by first isolating the wheel brake from further pressure build-up. This is performed by closing the solenoid bypass valve and energizing an electric motor that closes the displacement cylinder check valve assembly as pressure is released.

Stopping Distance

According to General Motors Delco Chassis Division, braking performance is one of the most important contributors to driving safety. There are several hazardous situations in which an ABS system is advantageous. These conditions include: a vehicle in front of the motorist suddenly stops in heavy traffic; a child or animal runs into the motorist's path or a road obstruction suddenly comes into view, especially at night. All of these situations require a high level of braking performance, especially under adverse road conditions.

Also, according to Delco Chassis Division, ABS systems will greatly enhance the performance of conventional hydraulic brake systems in several critical operations.

First, ABS systems can provide shorter controlled stopping distances in hazardous conditions, such as on wet and slippery roads, than most drivers can achieve without an ABS system, by providing optimum braking pressure at each wheel.

Second, it enhances steerability, allowing the driver to steer the vehicle in the desired direction during braking.

Finally, and perhaps most importantly, the ABS system enhances vehicle stability by preventing individual wheel lock.

The amount of improvement in stopping distance depends on many factors, including the road surface, severity of braking, initial vehicle speed, etc. On some surfaces, such as roads covered with deep snow or gravel, braking distances can be longer with an ABS system, because the wheels keep rolling along the surface of the snow or gravel, rather than locking and plowing the snow or gravel as the vehicle slides to a stop. The driver would, however, still have the control benefits of the ABS system.

NHTSA notes that even a vehicle with a failed ABS system meets the federal safety standard for stopping distance.

Important Facts

A motorist should never operate an ABS-equipped vehicle more aggressively than a vehicle not equipped with an ABS system. A motorist should always leave enough room in order to stop safely.

There are no effective anti-lock brake systems available, in either OEM or aftermarket, for installation on older vehicles. ABS is designed to work together with the base hydraulic brake system, and is tailored to each specific vehicle in order to achieve optimum performance. For these reasons, the American Coalition for Traffic Safety does not recommend advertised aftermarket ABS products.

Additionally, ABS performance may be affected by a change in tire size. Always consult and follow the recommendations contained in the vehicle owner's manual regarding a replacement tire size.

Anti-lock braking systems may add to automotive safety; however, driveability is also a part of safety. If motorists continue to drive at a high rate of speed or carelessly in adverse weather conditions, it is unlikely that they will be able to safely stop the vehicle in emergency situations. A possible solution could be for the manufacturers to make sure consumers understand how to use their products safely, rather than adjusting the product.

posted 12-22-2000 10:22 PM                  

It is abundantly clear that my sincere attempt to answer your question, after you ask my wife to have me respond, was a total waste of my time. I'm truly sorry that you didn't respect my answer to your original question.