How often to change rotors?

maintenance
brakes

#1

I have a 2006 Dodge Grand Caravan, but I suspect this question applies to other recent-model vehicles. When my front brake pads wore out at 23,000 miles, the dealer informed me that the rotors had to be replaced also, and showed me the wear on them. I had them replaced. Now, at 32,000 miles, my trusted local mechanic tells me the rear brake pads need replacing - AND the rotors! I have owned 5 cars before this one, and kept all into “old age,” but I have never needed to change rotors before. The local mechanic said that “modern cars need to have their rotors replaced when the brake pads are replaced.” Could this possibly be true?


#2

Some cars recommend replacing the rotors with every set of pads (and many do not recommend turning them). Personally, I replace my rotors with every second set of pads based on observing the wear.


#3

Often it is. Rotors are being manufactured thinner now (weight savings) and when performing a brake job the rotors should either be replaced or machined.
There is a minimum thickness required on the rotors and there are 2 reasons why the rotors are often replaced.

  1. Machining the rotors may place them underneath the min. thickness and this is a safety/liability issue.
  2. Many shop labor rates are in the 70 to 100 dollar an hour flat rate range, depending on location.
    Flat rate time on surfacing a rotor is often around an hour per rotor so this means that one could have 140-200 dollars
    tied up in machining a pair of rotors. This does not factor in the cost of R and R (remove and replace) the rotors or
    machining could be pointless after a few cuts on the rotors. It could be determined after a few cuts that they’re not
    going to clean up so total replacement will be necessary anyway.

Rotors can often be salvageable if any brake pulsation or shudder is not too bad. This means that it is at least possible the rotors could be machined and will clean up within the specifications.

Hope that helps to explain it. :slight_smile:


#4

What has changed is today’s metallic brake pads are as hard as the rotors and both pretty much wear at the same or similar rates. This wasn’t the case several years ago when pads were considerably softer than the rotors. I noticed this situation on my wife’s 03 Expedition. When I noticed the brakes getting close to needing changed, I also noted that it appeared the pads had worn deep slots in all 4 rotors. Not the rivet part, but the path of the entire pad. I knew then that there was no saving those rotors and figured the pads had another 5,0oo to 8,000 miles left in them, so I just let her wear the 2 on down. No, I wasn’t happy about having to buy 4 rotors for that truck, but from what I understand from my longtime mechanic, that’s the way it is these days. Additionally, since the newer vehicles are 4 wheel disc, all 4 wear out around the same time frame where it used to be the rear drums would outlast 2 or 3 sets of front brakes.

That said, she did manage to get around 65,000 on the brakes before having them replaced. If you are replacing at 23,000 you are doing one of 3 things, delivering mail, delivering news papers, or you are overdriving your vehicle and using too much brake. Try letting off the gas 400’ before you get to the stoplight and let the vehicle slow itself down. Don’t tailgate. Don’t overdrive curvy roads. Treat the gas pedal like there’s an egg between your foot and it and you’ll loose a lot less brake. Brakes should last between 50,000 and 70,000 miles. Under 50,000 miles, and something is wrong.

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#5

It depends on the car, I get about 40K miles on my front pads because I drive 90% highway miles. For some cars 20 or 30K would be considered normal.


#6

It is possible that you need new rotors but 'taint necessarily so. It may be true that some new cars come with paper-thin rotors that are only good for one set of brake pads but this doesn’t apply to everyone.

A trustworthy mechanic will measure the thickness of the rotor. The minimum thickness is always stamped on the rotor’s edge itself. The mechanic will mention when the old rotor can no longer be resurfaced because of it has worn too thin. If he does not mention thickness then he never measured and he may be trying for a little extra profit.

Since you have the original rotors at 32,000 miles, then it is quite likely they are still good. BTW, why are you having your brakes done at the dealership? There is no reason to go to a dealership for non-warranty work. Any independent shop can perform the same service, often for much le$$.


#7

Manyy shops now do only rotor changes and no rotor machining on late model cars for a variety of reasons:

  1. Modern rotors just aren’t made with excess metal. One machining and they’re at the minimum.
  2. they’ve had to do too many reworks due to warpage on turned rotors.
  3. it just isn’t worth it. In many cases it’s cheaper to just replace them than to turn them.

#8

Brake wear is very much more dependent on the driver than it is the car. In my teens and early 20’s I could burn a set of brakes off a truck in no time because I thought I had to go into every turn at 60 miles an hour, stand on the brakes to make it through and repeat on the next turn. I remember taking a new F150 across a mountain once and by the time I got home I’d had the brakes so hot that they were killed and you couldn’t touch the pedal without putting the truck in the ditch. At 6000 miles I put a set of brakes on it. We all should learn from mistakes like that and paying for rotors, calipers, and pads has a way of doing that. Over the next 288,000 miles on that truck I went through a set of front pads every 60 to 70,000 miles or so.

People drive these days like complete idiots. They tailgate, run right up to a light and jam the brakes on, run right into a turn and jam brakes, and I’m not talking about kids, I’m talking about adults. Trust me, you’ll get there every bit as fast if you’ll follow at a safe distance, let off and let the engine brake the vehicle coming up to a light or turn, slow down a few miles an hour on crooked roads, get the cell phone out of their ear and drive the vehicle. If you are burning through brakes at 20,000 miles, it’s your driving not the car. Now some are legitimate. A rural mail vehicle will wear out breaks fast or a paper delivery vehicle because they stop at every mail box on the road. However, a normal person shouldn’t use their brakes that hard to cause that much wear. Drive around in Eastern Kentucky with a load behind your truck and you’ll figure out how to save your brakes or wreck one. Going to pick up the kids at school isn’t a Nascar race and shouldn’t be treated as such.

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#9

I agree that driving style has a lot to do with it, but not every car will make 50K miles on a set of pads under the best conditions. I drive about 45K miles per year, almost all highway, and do not drive aggressively in traffic. About the best I get is 40K on the fronts and 80K on the rears, according to my mechanic that is better than average for my car. I replace the rotors with every second set of pads, my rotors only cost about $40 each so it’s not worth turning them.


#10

I agree it all depends on vehicle weight and driving habits/area. 50k-70k is a mainly highway or country driver. It is not a city or in town driver.


#11

On my older F150’s, I quit turning the rotors when changing the front pads for the simple reason that turning them almost always made them too thin and would cause them to get too hot in these mountains. I found out that I could get pretty close to normal pad life even without surfacing the rotors and my rotors would last longer. On the last one that I put nearly 300,000 on, I did change rotors at 6000 miles. Actually, Ford had a recall out on the rotors, they’d made them too thin and they did put new rotors and calipers on it in that short of mileage. Those rotors went through about 4 sets of pads and I ended up changing them at around 270,000 because they pitted out in places. But they did hold up fine without surfacing and I didn’t have brake issues. I didn’t allow the pads to get down to the rivets. Still later on they had some ridges, but in a couple hundred miles, the new pads would conform to the ridges and didn’t have any problems with it. I know that’s not the preferred way, but it worked.

I found with my wife’s Expedition, it wasn’t possible. The pads are evidently too hard for the factory rotors and by the time the pads were ready to change, there was an 1/8" lip on the rotors. I didn’t figure they would turn out and didn’t attempt it.

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