A Look At How GM Develops Quieter Brakes4
Brakes are an essential part of any car, but they have their peripheral issues, such as grinding, squeaking, and groaning. Thankfully, General Motors is hard at work making brake noise a thing of the past.
Earlier this year, General Motors opened a state-of-the-art 14,000-square foot braking facility. The testing chambers can simulate underbody airflow and adjust in temperature and humidity within 15 minutes, and run 24 hours a day.
“If we do our job correctly, the customer won’t notice our work,” says GM performance engineer for brake noise development, Brent Lowe. “Watch any movie and you’ll hear brake squeal every time a car stops because Hollywood loves to add the brake squeaking sound effect, and nothing bugs me more. We work to make sure our brakes lead the industry in silence.”
Besides its weather-adjusting capability, the facility includes a high-tech brake chassis dynamometer (developed with supplier Link Engineering) that can simulate braking conditions that range from snowy frontiers to sandy beaches. The dynamometer allows vehicles to make up to 1,900 full stops in 2½ days, instead of 1,000 stops in two weeks. This gives engineers a better opportunity to locate and resolve any issues related to brake noise.
“The ability to control and replicate the conditions that our customers’ vehicles are driven under is just as important as the ability to control the brake pressure, vehicle speed and direction,” Lowe adds.
The facility has a soundproof design to provide a quiet environment for testing and to spare other testers outside noises or vibrations that may disrupt testing.
“The concept of a silent brake is actually very complicated,” says Lowe. “Braking creates friction and the more friction present amounts to more noise. Though the sound of brakes squealing is something every driver can easily identify as a nuisance, it is one of the more difficult things to actually remove. We have been very successful at taking on that challenge at GM.”
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Hybrids and electrics have regenerative brakes that can slow down the vehicle with no physical pad contact and no noise, and that energy is returned to the battery. Adding regen brakes to all GM vehicle will improve braking systems, and reduce pad wearing, too. There is a jet car, which will try to break the speed record, and it uses inductive braking, based on eddy currents generated on a spinning aluminum disk.
The cost of regen brakes would still be out of the price range on smaller lower priced cars and not something most more expensive cars care about.
Also they are still working on the feel as they are much like the first electric power steering units with little feed back.
the bloodhound jet car shooting for 1,000 MPH will use them but only at a very low speed. it will still relay on air brakes and some other tricks. I was at a event where Richard Noble spoke on the car he is overseeing and I would recommend everyone take notice of the Blood Hound program. The fuel pump for the car is a Cosworth F1 engine and it has a jet and rocket engine for speed.
Brakes have really improved. Where the need for real improvement is in the hub bearings as they are now back to ball bearing vs roller to cut rolling resistance. While it improves MPG they have lower life and durability.
Much of the brake issues involving what some people think is a warped rotor is really a bad hub and the rotor gets uneven wear called Rotor Thickness Variation. The rotors are not warping but they are wearing uneven in thickness due to a hub more than .002 out.
Also the dealers and companies need to address bedding in or seating the pads on new cars or replaced pads. Few people seat of bed them in and they get a build up of material and it will give a judder. These are the two major issue on todays brakes.
It’s good GM is spending money for equipment and employees to help the economy, but I haven’t heard any brake noise from my many GM vehicles over the last 15 to 20 years. The only exception is if the pads are worn out or the rotors have slightly rusted due to rain or a car wash, but that is an extraordinary situation that is easily resolved. In the case of worn out pads they are manufactured to make a noise if replacement is warranted. One or two stops cleans the rust off the rotors. In normal use I never hear them and I’m happy with that. But, you GM engineers keep supporting our economy………..good-on-ya!
When I saw the headline that was my first thought as well. There are times and purposes for some of the noise as a warning sign. Nothing worse than when the binders turn to grinders because of worn out pads.