Brakes?

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Old 05-05-10, 01:07 PM
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Brakes?

Is this possible? Two years ago I had new rotors and brakes put on the front of my car. Haven't had any brake work done since. Today when I went in for an oil change they did their little inspection. They told me I need new front brakes and rotors. He siad the pads were good but the rotors were bad. Is this possible that after 2 years the pads would be good, but the rotors bad. I thought rotors lasted longer that pads.
 
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Old 05-05-10, 01:52 PM
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Are you sure they said rotors bad and not pads? I suppose it's possible to wear the rotors out before the pads [sand or other type of dirt] but I wouldn't replace rotors and reuse the pads.

You might want to inspect it yourself or have another shop take a look.
 
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Old 05-05-10, 02:01 PM
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He did say the rotors were bad and not the pads, thats what put put out the red flag. After 2 years I may expect the pads to be bad, but not just the rotors. Even if that was the case, aren't rotors able just to be ground down, resurfaced, or whatever you call that? He also said he would recommend new wipers, which I just put on last week, so I am second guessing him. I will definitly be taking it somewhere else to check it out. When I would take it, do you think I should tell them what the other found, or just play dumb and ask them to just check out my brakes. I never know who to trust anymore, especially when they see a woman come in! Thanks so much!
 
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Old 05-05-10, 02:08 PM
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Unless I was comfortable with the mechanic, I'd just ask him to check them. Rotors can be turned as long as they don't have to remove too much metal. There is a minimum thickness they have to adhere to.

My wife is a heavy braker a which tends to warp the rotors. On her cars, I've never been able to get the rotors turned - she warps them too bad the hard braking heats them up causing them to warp..... and you would feel that when you drive. I suppose it is also possible that a rotor would crack but surely the mechanic would have pointed that out and explained the urgency to have it replaced.
 
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Old 05-05-10, 02:17 PM
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i did (untill a back unjury a year ago) brake work at the local FORD dealer.
I would see this quiet often! alot of brake pad material is so hard it wears the rotors as fast/or faster than the pads.
usually the ones that the wheels are just-'black'/ not the normal brake dust you see.
( my wifes explorer included )
I made many a customer mad by telling them the rotors were to thin to machine.
on my explorer-i replaced the rotors. & installed Bendix 100% ceramic pads(a little expensive-$105 )
they squeak a little when cold.
but no more of the brake dust, or the rotor wear.
 
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Old 05-05-10, 06:13 PM
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hey bearly, you need a second opinion! Don't say anything about being told the rotors were bad. Let the new observer make his own determination because something like that will not be overlooked. Two years is NOT a determining factor for brake wear, MILEAGE would be the important factor. Everyone has different braking habits, so you have to learn what YOU usually average for brake wear. I'll get 60K out of front brakes when my wife will only get 40K, because of different driving habits and conditions. And, usually fronts will usually wear faster than the rears, but that is not always the case either. I have a Buick Regal that wears the rears faster than the fronts, go figure!

You are correct that pads will usually wear out before the rotors. Sometimes rotors can be cut or "turned" and reused but not always. Depending on the vehicle, it is just worth it to get new rotors rather than turning the old ones.

On another note, if you aren't doing this repair work yourself, you should find a local mechanic you can trust. We ARE out there and are usually found by word of mouth, so ask around and see if you can get a recommendation and then go have a chat with the guy and see what you think. A good customer being a woman or a man is not an issue for someone that just wants to fix your vehicle correctly and get you back on the road safely.
 
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Old 05-05-10, 08:12 PM
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Went to a tire place that owns the blimp used in football games for an oil change 15 years ago. Alleged mechanic told me I needed new brake calipers even though I had replaced them with new ones the previous week. Some of these garages would probably tell you that you need injector cleaning every 500 miles.
 
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Old 05-06-10, 05:44 AM
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Thanks everyone. I will absolutly be going to have someone else check it out. I may be wrong on this, but i expected around 4 years out of them. I bought the car new 6 years ago. It took 4 years before i was told that i needed the rotors and front brakes replaced. I assumed that i would get about the same amount of time, give or take a little, on this set. Normally i would deal with it, but I really don't have the cash right now. I just lost my job, due to the company moving to China, so money is quite tight at the moment, with no jobs out there. Especially here in New York. This state is ridiculous already!! Thanks Again!!!
 
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Old 05-06-10, 12:10 PM
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Brake weardown all depends on how much you drive and your style of driving.
 
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Old 05-06-10, 12:51 PM
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I totally agree with you. I am just shocked as I only got 20,000 miles out of my pads and rotors this round. I got 50,000 on the original set. Oh well, I guess thats the way the cookie crumbles. Thanks again for all the posts!
 
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Old 05-06-10, 12:53 PM
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Well...I know the questions have been answered...but it sometimes works the other way.

Both my wifes SUV and my old Dodge truck needed brake pads and rotors at about 20K miles. The replacements lasted almost 80K more.
 
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Old 05-12-10, 12:05 PM
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Originally Posted by marksr View Post
Unless I was comfortable with the mechanic, I'd just ask him to check them. Rotors can be turned as long as they don't have to remove too much metal. There is a minimum thickness they have to adhere to.

My wife is a heavy braker a which tends to warp the rotors. On her cars, I've never been able to get the rotors turned - she warps them too bad the hard braking heats them up causing them to warp..... and you would feel that when you drive. I suppose it is also possible that a rotor would crack but surely the mechanic would have pointed that out and explained the urgency to have it replaced.
I have to wonder if she has a tendency to drive with her foot on the brake. I am an instructor with a number of sports car clubs where we teach how to drive fast on road courses. For instance at Road Atlanta speeds get well over 120 in several places on the track only to be slowed to 60 mph for curves, one of which is down a hill with a drop of 100 feet. This occurs 3 times every lap which is 2.52 miles. Lap times for beginners are a little over 2 minutes so this is severe braking you won't encounter on the highway. Brake rotors rarely warp when cooled properly after the final hot lap. Her problem is more than just hard braking.
 
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Old 05-12-10, 12:15 PM
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But Lawrence, I doubt if many of those vehicles are stock Camrys, Tauri, Dodge trucks, Suzuki Veronas...etc etc etc, are they?

I would hope that even a factory stock vehicle that would be suitable for Road Atlanta 2 min laps would have upgraded components.
 
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Old 05-12-10, 12:58 PM
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My wife's had 2 mercs, the smaller mystique needed rotors everytime you replaced the pads she now has a sable, it seemed to fair better but about 8-10k after I replaced the pads, it's showing signs of warped rotors.

She's a good driver but my wife is the only person I've ever seen that accelerates to a stop sign/light. For a little woman she has a heavy foot both on the gas and brake
 
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Old 05-12-10, 07:08 PM
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Where'd you haved your oil changed? - at 1 of those 'drive thru's' IE Mr Lube etal...??
They're not mechanics and I dont think I would trust their word on mechanicals. Oil changes, maybe....but?!?!
 
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Old 05-13-10, 12:20 PM
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Long Post

Originally Posted by Gunguy45 View Post
But Lawrence, I doubt if many of those vehicles are stock Camrys, Tauri, Dodge trucks, Suzuki Veronas...etc etc etc, are they?

I would hope that even a factory stock vehicle that would be suitable for Road Atlanta 2 min laps would have upgraded components.
How about stock Subaru, Mitsubishi, Acura, VW, and Mazda vehicles? Stock brakes, all of them. Usually I get a new student to near the 2 minute mark with an average family sedan (no SUVs, pickups, or vans) that has not been modified. A stock late model BMW will easily break the 2 minute mark. Any stock sports car can. There is something wrong with the brakes or what the driver of the vehicle is doing that began this discussion. Either the pads have not been correctly bedded to the rotors, or the rotors have not been stress relieved when manufactured because they are cheap rotors, or the driver drives with a foot on the brake pedal, or the pistons in the calipers are sticking. I suppose too much play in the wheel bearings can also contribute. That's about it. Modern automobiles are pretty good.

Letís take a look at braking and energy dissipation. Brakes slow/stop vehicles by turning kinetic energy into heat energy. Iím going to give you an example of two different braking situations for a 3000 pound vehicle to demonstrate how much energy the brakes must absorb and dissipate. Both situations apply to a vehicle that is slowed 60 mph but one is from 60 to zero while the other is from 120 to 60 mph. The calculations do not include any rotational kinetic energy due to spinning engine and drive train parts as well as wheels. So the result is actually greater than what I calculate.

The point of this exercise is to show the huge difference in energy dissipation for the two changes in speed and to convince Doubting Thomases that if the rotors don't warp on the track, they certainly should not warp with ordinary driving.

For the 60 Ė 0 speed change:

KE = Ĺ*m*V**2

So at 60 mph which is 88 ft/sec the kinetic energy is 360,745 ft-lbs which is 463.7 BTU. This means the brakes must dissipate 463.7 BTU each time the vehicle is stopped from 60 mph.

Now look at the 120-60 slow down. The kinetic energy is the difference at 120 and at 60. Since we already have the 60 figure computed above, I need only compute the one at 120 mph and subtract the two.

At 120 mph which is 176 ft/sec, the kinetic energy is 1,442,981 ft-lbs which is 1855 BTU. Subtracting the KE at 60 mph leaves you with 1391 BTU. This is almost 4 times as much heat to dissipate, and this is done repeatedly when on the track. And the rotors rarely warp.

So it seems unlikely to me that the rotors should warp with ordinary street use which is, what I consider, very light duty.....unless there is something wrong.

I will say, however, that stock pads will wear out quickly when used on the track. In the beginning I used them because they are less expensive, but an hour and one half of track time will destroy them -- but not the rotors.

I have seen Camrys at the track but no Suzuki vehicles. The Camry did not set a lap record but you might be surprised what one can do with an experienced driver.
 
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Old 05-13-10, 12:50 PM
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Awwww now you start pulling numbers and calculations....make gunguy brain hurt...lol.

I completely understand that with proper operation rotors shouldn't warp, but I also know for a fact that they do, if they are marginal for the application or are subjected to stress beyond design limits or beyond "severe" driving. I also understand that track applications....slowing from high speed..then back to high speed then slowing again....and the cool down lap you mentioned earlier, is far different from 20 miles or more in stop and go in LA (or Hampton Roads, Dallas, etc) with a relatively heavily loaded vehicle and high ambient temps.

See my earlier post....factory brakes lasted 20k or so (bout 1 year)...aftermarket brakes (basic replacement, rotors and pads) lasted 80k. Driving the same routes..with the same driver..for 2 more years at least. Granted..it was 10 yrs ago...but not that long.

I know for a fact my wife never changed her style, its been 14 yrs as of Monday...and she hasn't changed a durn thing...except me....lol.

I won't argue...a Pro or knowlegable person drives differently from most people. I was just stating what happened in response to the OPs experience.

btw...Acura, Mitsu, BMW? I'd say almost everyone would consider those brands as "sporty" manufacturers.
 
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Old 05-14-10, 12:53 PM
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Getting 20K or 50K out of a set of disc brake pads also depends on what pads were installed. If you used the cheap ones, you will not be getting as many miles as a set of premium semi-metallic pads. I'm not going to pass judgement on a shop that installs those cheap, pieces of crap pads, but I think I just did anyway..... Maybe that is why bearly got half the mileage out of her recent brake job. Another reason to use a 'trusted' mechanic if you don't do the work yourself....

By the way, LawrenceC is blowing my mind with all the calculations... it's like physics class all over again!!! But it isn't going to help my wife get her damn foot out of the gas when she brakes! Two footed drivers.... geez!
 
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Old 05-14-10, 04:09 PM
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as i had stated earlier,those semi metalic pads/even the premium ones wear the rotors.
that is why i bought the $xx! ceramic pads.
just my 2cents / to each their own i guess.
 
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Old 05-14-10, 09:41 PM
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I notice you are in NY where there is snow and salted roads a good part of the year.
I notice that rear rotors rust quite a bit. Not worked hard enough I guess.
I have literally chipped my rear rotors straight again with a claw hammer when they feel warped. Fine after that. Intrepids bad for that. Rear rotors will rust themselves to failure before normal wear does them in.
Certain cars are worse then others.
No. I do not suggest you chip your rotors.
Just saying it could be rust and not normal wear that is making your brakes need changing in someones eyes.
Maybe I missed it, but what kind of car do you have?
 
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Old 05-16-10, 02:38 PM
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I was recently in a car accident and in my inspection after the accident discovered that I needed to replace my brake pads. I replaced the pads but not the rotors and the brakes are sticking now. Is a rotor change necessary or should I have a professional take a look?
 

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Old 05-16-10, 03:59 PM
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More likely a caliper instead of a rotor in my opinion.
 
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Old 05-16-10, 04:51 PM
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kmwise
I agree with NEsportsfan.
When the pistion is pushed back in to an area where it has not traveled in a long time then they can stick.
Personally I try to replace calipers every 2 to 3 pad changes.
Seen too many "marginal" brake calipers. Dont know how bad they are till you really need them at 70mph and someone pulls in front of you.
Could also be the rubber flex lines have internal damage done to them if the calipers were left daggling supported by the flex lines. They break inside and set up sort of a one way check valve.
If the car has some mileage on it then I would start with the new calipers. Cant go wrong there in my eyes.
 
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Old 05-16-10, 04:52 PM
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Guys...kmwise is just a spammer...
 
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Old 05-17-10, 12:03 AM
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Understand that kmwise is a spammer
Thanks
 
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Old 05-17-10, 04:28 PM
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Wasn't aware, didn't notice the advert. Actually the Adverts were a cool band if you are into punk.
 
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