Calling all MeFi Greasemonkeys!

September 1, 2009 8:14 AM

Could brake pads wear down from 50% worn to metal against metal after one 12 hour round trip to Yosemite? (See details)

I have a 2004 Honda Accord. Had it checked by a mechanic friend before we went on a trip to Yosemite and he said the brakes were fine. At least 50% of the pads were still there. We came back and noticed the A/C wasnt working, so since it's still under warranty we took it to the local dealer. Brakes were working fine to this point. they replaced some parts and the AC works fine, driving back we noticed the brakes were suddenly squealing quite loudly and grinding on the rotor!! Before I accuse of them of foul play, could the brakes pads wear down that quickly?

posted by stevyb to travel & transportation (17 comments total)

How much stuff was in the Accord? If it was filled with gear, on that road, it seems quite possible (I am not a mechanic).
posted by infinitefloatingbrains at 8:17 AM on September 1

30 to 50 thousand miles isn't an unreasonable expectation for a set of brake pads. So unless you were travelling at 1,000 mph, something's wrong there.
posted by le morte de bea arthur at 8:21 AM on September 1

Highly unlikely, but possible I suppose if you had a heavily loaded car and went down a lot of very steep hills.
posted by lohmannn at 8:22 AM on September 1

How long ago did you put the brake pads on initially? What were the driving conditions/mileage from the time of install of brake pads up until you left for Yosemite?

Are all four brake pads down to metal?
posted by jerseygirl at 8:26 AM on September 1

How much brake dust is on the wheels? If you did indeed wear thru the pads, all of the lost material is probably on your wheels or wheel wells and they should be quite black with copious material that will wipe off on your finger. If they are mostly clean, I suggest something's amiss. (Bonus tip, even if the dealership cleaned the wheels, it will be very unlikely that they cleaned the caliper, so check it also.)
posted by 1f2frfbf at 8:30 AM on September 1

Are you one of those people who rides the brakes all the way down the mountain?
posted by majick at 8:31 AM on September 1 [1 favorite]

If you were breaking to slow yourself down on steep grades, you could have significantly contributed to the wear of your brakes. When some mechanics say 50% of the pad is left, that's a best guess. But mechanics taking your wheels off and putting bad brakes on your wheels? That's work, people don't like to work for free.
posted by bigmusic at 8:31 AM on September 1

You could have a rock caught in there. Have you checked the pads?
posted by weapons-grade pandemonium at 8:41 AM on September 1 [1 favorite]

I'm not completely familiar with the Accord, but the AC mechanic might have taken off the wheel and/or brakes caliper to get at the AC, and either knocked a pad out of place or repositioned it improperly; I had a Firestone place do that to me - the pad was put back on cock-eyed, so it was against the edge of the rotor funny and a narrow band wore through faster than the rest and started scraping. You should have a brakes guy look at it: scraping and squealing isn't a good thing - even if it is just a rock, you're likely causing damage the longer you drive it that way.
posted by AzraelBrown at 8:46 AM on September 1

Two quick points:

1) As mentioned above, that "50% left" was just a guess. Your friend likely took a look at the pads, observed some wear, but though they looked like they still had some life in them. Hence -- 50% left.

2) Just because you hear metal on metal doesn't necessarily mean your brakes are completely worn down (although it does mean they need to be replaced). Brake pads have what is called an "indicator pin". Once the pads are worn down to a certain point, the pin is exposed causing the driver to hear the grinding noise you are talking about. The purpose of the pin is to alert the driver that the brakes are nearly finished, while still providing them with enough pads to stop the car.
posted by Mr. X at 8:46 AM on September 1

Yes.
posted by torquemaniac at 8:55 AM on September 1

If you're riding the brakes downhilll, you can absolutely wipe them out if they're "50%" or less, especially if your car is full of gear and people.

But what's most likely is that you overheated your brakes and now they're noisy. I mean, has someone pulled a wheel off and told you that you've got 0% remaining? If there's still life on the pads, then you've probably have an (several) overheated and damaged rotor(s) or a caliper that's sticking from being overheated. If you have alloy wheels, you can look through the spokes and inspect the brake rotor. It should be shiny and smooth. If it's dark and blueish, grooved and pitted, then they're visibly overheated and possibly warped. Do you feel the pedal pulse when you brake? If so, then they are absolutely warped and need to be replaced. Some places will resurface rotors, but if they're already warped from overheating, removing more of that heat-dissapating metal isn't the best solution for your aplication, in my professional opinion.

Brake squeel is almost 100% caused by vibration. When the pad vibrates minutely against the rotor and caliper, the frequency of that vibration becomes the audible squeel that you hear. A certain amount of that is pretty normal, even though manufacturers go to great lenghts to subdue those vibrations. A warpage of the rotor that changes the pad-to-rotor clearance as the rotor spins can make that squeel worse.
Brake noises that should be concerned about are a loud grinding and a grinding feeling through the pedal during normal non-emergency braking.

but the AC mechanic might have taken off the wheel and/or brakes caliper to get at the AC
I would not worry about that. You don't have to remove any brakes or suspension components to service the A/C on an Accord.
posted by Jon-o at 9:19 AM on September 1 [3 favorites]

Nthing "50%" is just an estimate, unless you or your friend happened to have a pair of fresh pads lying around to compare to.

bigmusic is also right - I can't imagine a mechanic (even a dealership) taking the time to replace pads on your wheels just to get you back in for the same work.

And either way, I think the hassle you'll have trying to pursue this outweighs the ease with which pads can be replaced. Get your mechanic friend to do one of the wheels while you watch, and you can do the others in an hour or two.

On preview, Jon-o's overheating suggestion sounds plausible too.
posted by ish__ at 9:26 AM on September 1

Any good wrench will change left/right pads @ the same time when they do a pad slap. Meaning front of the car, left side needs done, you do right side too. In fact, if you buy pads yourself, there are generally two full sets in the box.

If one side is worn and the other isn't that close, you've got some issue. Could be a seized caliper, could be a hydraulic issue pushing the offending pad too tight, could be a faulty install or a rock or a faulty slider pin.

I'd have the alternate side pulled and go from there.

Silly Question (and I don't know your accord, is it a stick? automatic? hybrid?), is it possible that AC place engaged your parking brake and you're driving with it on?
posted by TomMelee at 9:36 AM on September 1 [1 favorite]

Yes.

Very doubtful it is foul play. More likely the brakes were dragging, or that there indeed IS plenty of material left, and the wear indicators are contacting the rotor surface early.

What I would do is go back to the person who said there was 50% left and have them figure out what's going on.
posted by gjc at 4:44 PM on September 1

You didn't happen to take the Old Priest Grade downhill, did you? That drive alone will annihilate your brake pads.
posted by corey flood at 10:36 PM on September 1

You know you can take the front wheels off and inspect the pads yourself, right?
posted by weapons-grade pandemonium at 5:21 AM on September 2