#1
Old 03-30-2012, 09:54 AM
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Brake Rotors

200 Pontiac vibe with 225,000 miles.

The brakes are making a grinding sound. I am assuming they need to be replaced. When I take them in they will probably say I need to have the rotors replaced (they never seem to be able to turn them these days). If I tell them to just replace the pads (in deference to the miles on this car) does anything bad happen. Is this a safety issue, or an aesthetic one?
#2
Old 03-30-2012, 09:57 AM
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Well, if your rotors are bad then they need replaced. If they simply replace the pads, and your brakes fail as a result of bad rotors, they could be held liable.
#3
Old 03-30-2012, 10:14 AM
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Quote:
Originally Posted by dauerbach View Post
(they never seem to be able to turn them these days).
What is up with that? Whenever the dealership tells me I need new brakes, I ALWAYS need new rotors. ALWAYS. They can never been turned. If you go to Autozone and buy a brand new rotor and hand it to the Ford dealer and ask them to turn it, they will look at it, frown, and say that it is too worn down to cut. You need a new one. Until 15 years ago, I had never even HEARD of replacing rotors. You turned them (or "cut" them as the old guys called it).

Last time, my truck had 36k miles on it and it was the first brake pad change. Need new brakes and rotors. Bullshit. I pulled the tires myself and they didn't even need cut. Two and half years later still doing fine.

Local mechanics always turn them, though. I think I see a pattern..
#4
Old 03-30-2012, 10:14 AM
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Well, that was my initial thought, but is it correct? Generally the rotors become scored and noisy. The question is whether this makes them less effective? If not, I am not going to spend the money on them.
#5
Old 03-30-2012, 10:20 AM
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Quote:
Originally Posted by dauerbach View Post
Well, that was my initial thought, but is it correct? Generally the rotors become scored and noisy. The question is whether this makes them less effective? If not, I am not going to spend the money on them.
Since my rant is over, it probably will depend on how bad the rotors really are. If they are truly shot, they will just chew up your new pads. This is why you need a trusted mechanic.
#6
Old 03-30-2012, 10:47 AM
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Fortunately, I have a mechanic that I trust. Let's say he thinks the brakes will continue to grind because the rotors are slightly scored, and that the brake pads will then wear out more quickly. He will honestly recommend turning or replacing. My thought is that I can live with the noise, and the pads will still probably outlive the car (I drive a lot but most is limited access roads and I don't brake that often).
#7
Old 03-30-2012, 10:52 AM
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Quote:
Originally Posted by dauerbach View Post
Fortunately, I have a mechanic that I trust. Let's say he thinks the brakes will continue to grind because the rotors are slightly scored, and that the brake pads will then wear out more quickly. He will honestly recommend turning or replacing. My thought is that I can live with the noise, and the pads will still probably outlive the car (I drive a lot but most is limited access roads and I don't brake that often).
Then have him turn them.

If that's not an option for some reason, then I would still be wary. A grinding sound is never good, especially for an item like brakes. I wouldn't want that at all.

Now, will you have a catastrophic failure causing a crash? Probably not, but you could have a lock up that destroys the calipers and what not, making rotors cheap by comparison.

I would beg and plead to get the rotors turned, but if he won't then bite the bullet and get new ones.
#8
Old 03-30-2012, 10:56 AM
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The pads will wear faster, and the brakes might not have the same braking power. Rotors are so cheap these days that it costs more to turn them than to replace them.

I do my own brakes and constantly put pads on shitty rotors when the car has high mileage and I don't care about pristine conditions. Maybe Gary or Rick will find this and provide a professional opinion, but it's your car and if you tell the mechanic you don't care about the rotor condition, it's your call.
#9
Old 03-30-2012, 11:16 AM
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Quote:
Originally Posted by dauerbach View Post
If I tell them to just replace the pads (in deference to the miles on this car) does anything bad happen.
The stopping won't be as even, and the bad rotors will chew through the new brake pads very quickly. I did it on an old truck once, when I was short for cash. I could afford the 15 bucks for brake pads but not the 100 bucks for a new rotor. So I just slapped on new pads and six months later replaced both the pads and the rotor. Because of the bad rotor, the pads were already shot after only six months.

Note that I replaced the pads myself. A shop typically guarantees their work and they might refuse to just change the pads, and might even refuse to turn the rotors if they don't think they can get guaranteed results from them.

Quote:
Originally Posted by jtgain View Post
What is up with that? Whenever the dealership tells me I need new brakes, I ALWAYS need new rotors. ALWAYS. They can never been turned.
Some of it is probably lawyer-type CYA. If they turn the rotors and the rotors warp, and the brakes do something funky like grab as a result of it and cause an accident, they could be held liable.

I suspect that some of it is just them gouging you for profit.

To be fair, though, a lot of it is just that they make rotors much smaller and thinner these days, just as they make everything else smaller and thinner to cut down on weight. Rotors a couple of decades ago were significantly thicker and heavier and could usually be turned a few times before they completely wore out. The newer, smaller, and tighter fitting parts don't allow as much of that these days.
#10
Old 03-30-2012, 11:38 AM
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Quote:
Originally Posted by dauerbach View Post
Well, that was my initial thought, but is it correct? Generally the rotors become scored and noisy. The question is whether this makes them less effective? If not, I am not going to spend the money on them.
once they start to "grind" during use, you've worn away all of the friction material on one or more pads and the rotors are now trashed. Gone. Kaput. You will replace them.

ETA: why did you let it get that bad in the first place?

Last edited by jz78817; 03-30-2012 at 11:40 AM.
#11
Old 03-30-2012, 12:15 PM
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It happened quite suddenly. I was away for a week and when I got back and drove the car for the first time it initially felt like the breaks were on, then I heard a quiet "pop" and then when I used the brakes I heard the grinding sound. I got new tires about 6 weeks ago and they said nothing about the brakes. I figured they must still be good. I can't tell by looking myself, and would never consider taking the car in just to have an opinion on brakes that are behaving.
#12
Old 03-30-2012, 12:31 PM
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Quote:
Originally Posted by dauerbach View Post
200 Pontiac vibe
Man that is one freakishly old car.
#13
Old 03-30-2012, 12:31 PM
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how many miles since they were last done?
#14
Old 03-30-2012, 12:47 PM
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Brakes convert motion to heat. The rotor heats up and then cools when finished braking. The more beef in the rotor, the more heat it can absorb without over heating your brake linings. I think they have cheapened them coming from the factory only thick to last about one set of pads. Run them anyhow? 2 problems. Reduced braking capacity. Of course if you don't drive like an idiot, you may get away with less. Also, the caliper piston must extend out further to push the pads further.

I do all my own work and skimp on replacing rotors. It has worked for me.
#15
Old 03-30-2012, 01:03 PM
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Really really old car. Ummm, maybe 2003 would be closer to the truth. I have no recollection as to when this was last done. However, I drive around 35,000 per year and don't have to brake very often, so they should last a freakishly long time.
#16
Old 03-30-2012, 01:12 PM
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and you never once thought to have them checked? Even as part of an oil change or other service?
#17
Old 03-30-2012, 01:50 PM
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Not at all. I always assume that they check the brakes when they change the tires. That is usually when I hear I need new brakes.
#18
Old 03-30-2012, 01:50 PM
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Quote:
Originally Posted by jtgain View Post
What is up with that? Whenever the dealership tells me I need new brakes, I ALWAYS need new rotors. ALWAYS. They can never been turned. If you go to Autozone and buy a brand new rotor and hand it to the Ford dealer and ask them to turn it, they will look at it, frown, and say that it is too worn down to cut. You need a new one. Until 15 years ago, I had never even HEARD of replacing rotors. You turned them (or "cut" them as the old guys called it).

Last time, my truck had 36k miles on it and it was the first brake pad change. Need new brakes and rotors. Bullshit. I pulled the tires myself and they didn't even need cut. Two and half years later still doing fine.
Blame cheap Chinese labor. Car parts are as big a market for them as electronics. Consequently they've gotten so inexpensive as to be cheaper than the labor that shops can charge to cut them.

Also, I know it's hard to accept but rotors should always be cut when you replace the pads. They're not cut merely to remove any grooves from pad rivets, they're cut to 'roughen' up their surface after being polished perfectly smooth for thousands of miles. The brakes will work much better this way.

If a dealer rejected brand new AutoZone rotors then they're ripping you off. Not only are new rotors obviously going to be thick enough their surfaces come already machined with the proper roughness to be used right away. More likely it's because repair shops simply don't like customers bringing their own parts. I don't blame them for that. You don't bring your own eggs to restaurant and say "over-easy please"...
#19
Old 03-30-2012, 01:51 PM
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The grinding this is what disturbs me. That's metal on metal. You are eating into those rotors and may have damaged them already.

I know that Pontiac's are a pain in the ass (not sure about brakes, but other things), but I posted in another thread about brake replacement. It is pitifully easy. If you can operate a jack and a ratchet, you can replace pads and rotors (at least on my Ford F-150). My brother-in-law showed me how to do it and I am still kicking myself in the nuts for letting garages charge me hundreds of dollars for it. Never again.
#20
Old 03-30-2012, 01:52 PM
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Originally Posted by Hail Ants View Post
If a dealer rejected brand new AutoZone rotors then they're ripping you off. Not only are new rotors obviously going to be thick enough their surfaces come already machined with the proper roughness to be used right away. More likely it's because repair shops simply don't like customers bringing their own parts. I don't blame them for that. You don't bring your own eggs to restaurant and say "over-easy please"...
No, that didn't happen. That was smart ass hyperbole on my part.
#21
Old 03-30-2012, 01:54 PM
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Originally Posted by jtgain View Post
..It is pitifully easy. ..
I know, eh? You might need a clamp to compress the brake piston, but easy-peasy.
#22
Old 03-30-2012, 02:12 PM
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Brake rotor rip-offs occur because 99.99% of car owners are not in a position (skill and/or tools) to determine whether there is enough material remaining on the rotor to make re-surfacing feasible.

Couple of years ago an employee came to me asking me about an $800.00 quote from her dealer to replace pads and rotors. Advised it was a bit high. I then aked her about symptoms to which she replied "steering wheel shake when braking from freeway speed." Being suspicious of the diagnosis, to say nothing of the price quote, I recommended a friend's shop for a second opinion. $60.00 later the shake was gone. As noted earlier, and unless you are equipped to make your own evaluation, you just need a good mechanic you can trust. Lots of good ones out there, not so many you can trust.
#23
Old 03-30-2012, 02:23 PM
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I replaced the pads on my last van two weeks before trading it in. The rotors needed replacing. My mechanic warned me it would shorten the life of the new pads. But they'd still be fine for a few thousand miles. More than enough for a van getting traded in. The brakes worked great with new pads.

Last edited by aceplace57; 03-30-2012 at 02:24 PM.
#24
Old 03-30-2012, 02:35 PM
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FYI, brake rotor warpage increased dramatically when the federal government prohibited asbestos from being used in brake pads. Asbestos was relatively efficient w/regard to the dissipation of heat. Heat not dissipated ends up in the rotor. Another source of warpage is indiscriminate use pneumatic impact wrenches which frequently over-torque lug nuts. A good shop will only use a torque wrench to tighten lugs.
#25
Old 03-30-2012, 02:37 PM
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Try going to an indipendent mechanic for your brakes. I have never met one yet that didn't measure the rotor and if it was in spec, to turn them. My local NAPA will still turn rotors for you if you are doing the job yourself. The reason the dealers don't want to turn rotors are: it is easier to replace than turn, bigger profit in new parts than rehabing old ones and sadly, most OEM rotors are paper thin, making turning impossible more than once if even that.
#26
Old 03-30-2012, 03:45 PM
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Quote:
Originally Posted by Hail Ants View Post
Also, I know it's hard to accept but rotors should always be cut when you replace the pads. They're not cut merely to remove any grooves from pad rivets, they're cut to 'roughen' up their surface after being polished perfectly smooth for thousands of miles. The brakes will work much better this way.
One reason it's hard to accept is because CAR MANUFACTURERS specifically instruct to NOT resurface rotors unless they're warped or have significant scoring, e.g. greater than 0.060". Another is that an uncut used rotor surface works better than a new or resurfaced one, until the fresh surface has been embedded with some pad material.

Decades ago we routinely resurfaced or replaced rotors to get the desired surface finish for the purpose of minimizing noise. With modern noise-reduction pads, this is usually no longer an issue.
#27
Old 03-30-2012, 03:59 PM
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Quote:
Originally Posted by dauerbach View Post
200 Pontiac vibe with 225,000 miles.

The brakes are making a grinding sound. I am assuming they need to be replaced. When I take them in they will probably say I need to have the rotors replaced (they never seem to be able to turn them these days). If I tell them to just replace the pads (in deference to the miles on this car) does anything bad happen. Is this a safety issue, or an aesthetic one?
Grinding sound usually means a pad has worn totally and its metal backing is digging into the rotor. A certain amount of resultant rotor wear is acceptable for reuse as-is; beyond that amount typically means there's not enough metal to resurface and reuse and thus new rotors are called for. Where to draw the line between safe and unsafe can come down to a matter of professional opinion, and will vary with one's personal experience, regard for manufacturer's specs, and "worry factor" about safety-related issues.

Quote:
Originally Posted by dauerbach View Post
Fortunately, I have a mechanic that I trust. Let's say he thinks the brakes will continue to grind because the rotors are slightly scored, and that the brake pads will then wear out more quickly. He will honestly recommend turning or replacing. My thought is that I can live with the noise, and the pads will still probably outlive the car (I drive a lot but most is limited access roads and I don't brake that often).
If you trust him, then just tell him what your goal is. With new pads, noise isn't likely, it's braking power and longevity that are the concerns. But this fellow will have a HUGE advantage over us here in actually seeing the rotors.

Quote:
Originally Posted by dauerbach View Post
It happened quite suddenly. I was away for a week and when I got back and drove the car for the first time it initially felt like the breaks were on, then I heard a quiet "pop" and then when I used the brakes I heard the grinding sound.
This I find worrisome. It may be part of normal wear patterns, or it may be something more sinister -- and serious -- like a pad falling out place. Best bet: have it checked yesterday.
#28
Old 03-30-2012, 04:06 PM
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To clarify post #26, factory instructions are to reuse rotors as-is, without resurfacing, unless they have certain specified problems.
#29
Old 03-30-2012, 10:07 PM
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Often the outer edge of a rotor has a ridge outside where the pads rubbed. It needs to go. I simply grind it off.
#30
Old 03-30-2012, 11:19 PM
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Quote:
Originally Posted by dauerbach View Post
It happened quite suddenly. I was away for a week and when I got back and drove the car for the first time it initially felt like the breaks were on, then I heard a quiet "pop" and then when I used the brakes I heard the grinding sound.
While you should definitely have things inspected by someone who knows what they're doing (shop or amateur), this can occasionally be innocuous. Rust can build up on the surfaces of the rotors. Most often, this is from something like washing the car and spraying water on the rotors, then letting the car sit where it is, provding no chance to disperse the water. It can also happen from road salt being splashed onto a parked car.

In some cases, this can be so extreme that the car will act like it is "stuck to the floor" and will refuse to move until the brakes are freed up.
#31
Old 03-31-2012, 12:38 AM
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I hadn't thought of what what Terry Kennedy mentioned -- surface rust (usually invisible) can cause pads to stick to the rotor, and can cause (harmless) noise that sounds for all the world like metal grinding away vigorously. Usually it will get cleaned off of the rotors in a few stops. How much has the car been driven since the noise came on?
#32
Old 03-31-2012, 08:47 AM
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I would say the brakes have been used moderately in the time since this has occured. All four rotors have rust on their surface. Hopefully this is all it is. It is going in on Monday, mainly to get the check engine light turned off (I have a mandatory emissions inspection coming up).

It love this car, it has been very good to me. I just hate to spend much money on it when it has so very many miles.
#33
Old 03-31-2012, 10:39 AM
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Take off the wheel and simply measure the rotor, look up the acceptable wear limit.

If it squeals as well as grinds then its the pad wear indicator...do not ignore that.

Videos of how to change the pads is easy to find on youtube, as a car fix job its pretty simple for most cars, and cheap to boot, a simple cheapo c clamp is enough to push the piston back in so yu can reinstall the thing. i did mine after watching a few youtube videos and reading the chiltons/haynes manual. but first things first, take the wheel off and look at the rotor.

rotor wear depends on the type of pad, the harder ceramics and such will go through your rotor faster. factory pads and cheaper pads won't.

there shouldn't be rust on the rotor surface, any should be worn away just from brake use.

Last edited by Woodenspoon; 03-31-2012 at 10:43 AM.
#34
Old 03-31-2012, 11:00 AM
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Quote:
Originally Posted by Woodenspoon View Post
Take off the wheel and simply measure the rotor, look up the acceptable wear limit.
Step one is "acquire a micrometer."

Quote:
there shouldn't be rust on the rotor surface, any should be worn away just from brake use.
yeah, that's true; if there's rust on the braking surfaces even after driving, then the caliper is likely stuck on its slide.
#35
Old 03-31-2012, 07:47 PM
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micrometers on ebay are next to nothing in cost
#36
Old 03-31-2012, 10:49 PM
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If discard is 1.0 inches, a good scale will tell what you need. Whether it is 1.002'' or 0.998 makes little difference.
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