What are the drawbacks to ABS (Anti-lock Braking System) in cars?

Replied by Bernard Ching:-thru Quora

Retired electrical engineer also study nuclear engineeringThere are three drawbacks to ABS systems.

1. Most drivers don’t know what it does thus creating more problems. Early on when they were introduced, a lot of the police patrol officers didn’t know how it work so they modulate the brake pedal pressure manually and completely defeated the purpose of the system. Even now most driver don’t use the system effectively as per study done by NHTSA. ABS systems worked less than half of one percent of the time because the way drivers were taught. ABS worked best when you slam on the brake pedal cause pulsation/modulcation that limit the slippage of the tire to less than 5 to 10% so you have steering control and the shortest stopping distance for that type of surface/tire traction combination.
2. Overconfidence on the part of drivers by casting caution to the wind. No matter how good your tires grip on average pavement, ABS can not do miracles! Ice can cause fishtailing due to total loss of directional control. When your tires can not develop traction because the friction surfaces is too slippery, ABS or any form of braking will not slow the vehicle down. That is the time studs and snow chains come into play as they can penetrate the icy/slippery surface to grip the road mechanically.
3. Most drivers manually modulate their braking control. It is not unusual that many ABS system fail due to long periods of neglect and disuse. Clean and uncontaminated brake fluid is an important requirement for ABS systems. Flushing the brake system at proper intervals is an important maintenance procedure that most drivers don’t follow and repair shops frequently fail to recommend it. With the multiple solenoids actuators, accumulator, pump motor, wheel speed sensors, ABS computer and related wiring it is another layer of maintenance that new cars owners have to pay for when that ABS warning light illuminates in your car.
4. A bit of History and function of the ABS system. ABS meaning anti-lock brake system. It has been around since mid-80s. When they first came out as standard equipment, it was for the rear of light trucks. When rear wheel lock-up during a severe braking episode due to low or no traction of the rear tires on the road surface it cause the truck to fish-tail thus compromise directional stability. Even on excellent surfaces, those early vehicle may have drum brakes. Oil contamination from leaking axle seals or over adjustment of drum brakes can cause a rear wheel to lock up and once the tire skids the heat from that patch of molten rubber will degrade traction with the pavement causing again - directional instability. The reason for its use on trucks is a trucks’ traction depends on load. Many trucks are lightly loaded thus making handling more of a problem when coming to a stop.

Rear ABS were introduced and used on luxury vehicles by Chrysler and Lincoln since 1971 using the Bendix system. Tractor-trailers were the one to use it and it was adopted by the airlines on their rear wheels. What it does is cycle the line pressure of brakes - just like a professional driver pumping the vehicle brake rapidly so the wheel have time to recover and not totally lockup. By cycling the brake line pressure using solenoids and computers, the rate of the modulating braking force to the wheels increase and will allow traction of the lockup wheel to spin enough that a control stop can be administered. The maximum force for braking on a given surface is before a total wheel lockup. That is why ABS will not help much on a totally ice overed surface because there isn’t enough traction to begin with to stop the vehicle.

Newer ABS systems which include 4 wheel systems and ABS systems with stability control and thrust vectoring on AWDs and 4WDs.