How long should brakes last

[Philster]

For the record, the most offensive anecdotal and non-scientific information in this thread is the implications that GM cars (and/or American cars) are poor quality.

Get over your bad-ass 70’s and 80’s self. Live in the now.

[Gary_T]

@commasense

Uneven deposition of pad material on the rotor, which can happen if pads are not bedded in properly, is the leading cause of brake vibration and shudder, and is frequently mistaken for a “warped disc.” In fact, brake discs are rarely if ever actually warped. Famous racing expert Caroll Smith says that in 40 years of racing, “I have never seen a warped brake disc. Every case of ‘warped brake disc’ that I have investigated, whether on a racing car or a street car, has turned out to be friction pad material transferred unevenly to the surface of the disc.”

All I can say is that he hasn’t seen the warped discs that those of us working in the field have seen. He might be a racing expert, but his knowledge does not apply to ordinary cars driven by ordinary people.

One of the links mentions that uneven pad deposits of a few ten thousandths of an inch can cause judder and vibration. Hmmm. Maybe on race cars. On street cars, the manufacturers’ specs for disc runout (warpage) typically call for a maximum of 2 to 6 thousandths of an inch. That’s ten times the amount referred to in the article. And warpage within those specs is not a problem - it’s asymptomatic. On cars that do have symptoms (pedal pulsation, steering wheel wobble if it’s the front pads), the runout is generally about twice the spec amount. This is something I have measured many times with a dial indicator, and I can assure you of two things: the rotor is indeed warped, and the variation is not caused by pad material buildup.

Up until 10-15 years ago, brake pad burnishing was recommended. It was taught in training seminars and done by conscientious mechanics. But with modern pad materials, it is not necessary. The brake experts who teach normal repair for passenger cars do not recommend it now.

[groman]

How are you determining that you need brakes? Does the indicator go off or do you check the brake yourself?

I have a Chrysler, my ex drove Fords all her life. I changed my brakes at around 100K miles about 5K miles after the indicator started going off (the whine). About 10K miles later she drove my car and declared I need new brakes. When asked for her reasoning she insisted that “they got spongy” “That can be adjusted, and I like it that way!” but she claimed they weren’t spongy when they were new and spongy now means they’re gone. All the non-Ford cars I have owned had very spongy brakes from about 1K after replacement. The brakes are fine, I checked.