A question about ABS brakes....

My wife has proven to me that rear rotors really do wear out faster than front ones on her Taurus wagon. And it's perfectly normal. Third set going on this weekend, only 60k miles. Must be something wrong with the car I guess.

A collapsed brake line or a problem with the parking brake mechanism, or maybe the proportioning valve. Rear brake pads usually last at least twice as long as the front, since maybe 80% of the braking effort is on the front.

Sharon Cooke wrote in news:TAQ8h.306$ snipped-for-privacy@newsfe18.lga:

unless she is a two footed driver which will cause problems no mater how they claim it doesn`t. KB

"two footed driver"? You mean a left-foot braker (LFB)? That's a myth; I've been a LFB for over 50 years (only on automatics, of course) and I need a brake job on one of my vehicles maybe every 60K miles, with the fronts being done every time and the rears maybe 1/2 the time. I think the whole LFB thing relating to premature brake wear is something that was started by someone that tried it and wasn?t coordinated enough to do it properly. I?ve also owned two Tauri over the years and the wear pattern on the brake pads/rotors/drums was the same as any other passenger vehicle, so I stil say there?s something mechanically wrong with the thread starter?s vehicle, and not due to any ?odd? driving habits.

Hi.... thanks for the replies....

But going back to my question.... has anyone ever heard of these type of brakes locking up on thier own?? She claims her foot is off the brake pedal when it happens.... I can't get it to do it.... and I've never heard of this problem from anyone else....

Is it possible for brakes to activate on thier own?? Doesn't the brake master cylinder get its "pressure" from the pedal being pushed?? I know thier power brakes but for the life of me I can't see a way for them to activate without pedal pressure.... Mikal

Sharon Cooke wrote in news:h729h.100$ snipped-for-privacy@newsfe17.lga:

IT is NOT a myth, very seldom do 2 footed drivers not have problems. In the shop we see it all the time. Some do manage to get by but sooner or later it manages to bite em. KB

Well it hasn't bitten me in over 50 years of driving, so I still think it's BS, but please enlighten us. HOW do you think that riding the brake with the left foot can cause an abnormally high rate of wear on just the rears, which is the stated initial problem?

As I wrote before, get the system checked out. Brake hoses that have collapsed internally can cause the wheel cylinders to not completely retract, building frictional heat, and at some point, that heat will cause the brakes to grab, just as if someone slammed them on. If you still believe it's your wife's driving habits causing this, have her drive a different vehicle for a while, and see if the problem follows the driver. I'll bet not.

It is ABSOLUTELY IMPOSSIBLE for the ABS to apply the brakes on its own. The ABS unit does NOT apply the brakes. All it does is reduce pressure to whichever wheel is reaching lockup, and then reapply the SAME pressure slowly after the lockup is released. All it does is enlarge the volume of the particular circuit momentarily to reduce the pressure.

Neither of these situations will APPLY the brake. They may cause a brake to lock up after it is applied (which is not, from what I understood, what his wife is complaining of). As for proportioning valves, IIRC there is no such animal on a vehicle with 4 channel ABS (or even 3 channel, 4 wheel)

If the car is chewing up the rear brake pads and rotors that fast check the parking brake mechanism. AFAIK if you have rear discs they have a mechanical gidge on the rear calipers that applies the rear pads for the parking brake function, and they can hang up and cause brake drag and rapid wear.

If you are in the Rust Belt the parking brake actuating cables can get salt water inside the flex cable sheath and rust or freeze up - you release them at the front but they don't let go at the rear. Problems from locking up because of water inside the cables is a bastard to trace down, because it will only do it when the weather is really cold - but don't worry, once they rust it'll do it all the time..

Check that the dashboard brake warning light comes on when the parking brakes are applied and only goes out on the very last click of the handle/pedal - she could be releasing the parking brake partially (only till the light goes out) and it still drags.

And check that she knows what that light means - some people actually get the wrong impression that a certain warning light is /supposed/ to be on, or not a big problem...

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It's simple; your brain can't guesstimate quite as well the pressure force you are exerting on the brake with the 'wrong' foot.

That's *why* people don't generally do it, ti's not just some random system we've all developed!

They (bad hoses) may cause them to DRAG, but there will be PLENTY of warning before they grab. They will be hot and stinky, and make the car very "lazy". GENERALLY the brakes will get so hot they FADE , rather than grab, unless you are running ceramic pads.

I thought the problem was the brakes were grabbing????

Your answer is a non sequitur, since both feet are controlled by the same mechanism and one foot can?t be smarter than the other, so it's just a matter of practice & training. Even if that weren?t so, ABS brakes supposedly have the ?expertise? built-in, so the amount of pressure on the brakes is modulated by the braking system and not the foot on the pedal. Your answer also doesn?t even address the actual question, "HOW do you think that riding the brake with the LEFT foot can cause an abnormally high rate of wear ON JUST THE REARS, which is the stated initial problem??

Yeah thats kind of what I was wondering if anyone had ever heard of.... the brakes activating on thier own without anyone touching the brake pedal.... I am getting some good advice from these folks and appreciate it.... BTW.... Happy Thanksgiving everyone.... and thanks for the replies.... Mikal

Sharon Cooke wrote in news:3T59h.2016$% snipped-for-privacy@newsfe19.lga:

I am guessing it is a driver problem, but specific car related as it sounds like the brake and gas are too close together on this car. When I have my work boots on this is a problem on several different ones. It is quite easy to catch the edge of the brake when going for the gas, and many times not noticable by the unaware driver hense the swearing she is not doing it. Some cars are just bad about it. KB

As a mechanic, I could pretty well pick out the left foot brakers by the combination of brake lining lfe and the wear on the brake pedal. The ONLY time left foot braking is acceptable is as a short term remedy for stalling at idle-transition until the car can be fixed properly. EVERY left foot braker I have ever known has had at least a few close calls related to the habit. And the vast majority are one of two types of drivers - nervous nellies or aggressive hamfisted idiots. Both are dangerous in their own way.

I'm sure you can detect a LFB by WHERE the wear is on the brake pedal, but as far as brake life goes, that's pure bullshit, since I go 60K~70K miles between brake jobs, and have even bought several new cars and sold/traded them with maybe 80K miles on the odometer without EVER HAVING HAD A BRAKE JOB (and yes, the brakes still worked fine). I am neither a Nervous Nelly nor an aggressive ham-fisted idiot. I haven't had a point on my license in over 40 years, and I'm quite in control of my vehicle at all times. I?m a LFB for several reasons, one being the reduced time required to get on that brake pedal about 1/10 of a second faster than a one-legged driver, which gives me a 9-foot stopping advantage at 60 mph; if some RFB rear-ends my vehicle in a panic situation at that moment, it?s on them. Another reason that I drive that way is because that?s the way it was taught at my High School in the mid 1950s, and automobile makers back then were promoting the concept actively as a selling point for automatic transmissions. I also have no difficulty transitioning to my one manual shift vehicle, which I drive heel & toe on the fuel/brake and use the LF for the clutch (new clutch at 162K miles). It hasn?t had a brake job in the last 120,000 miles or so (first brake job at 120K miles), and it may be due for a brake job.

....oil light, anyone?