Any recommendations on what to do with my brake rotors?

most people just replace them. how many miles on the rotors? are they warped?

 

you need a dial caliper tool. if they look decent, there's no need to replace them. 80k is nothing for prius brakes. some people just wire brush them to remove rust or break the glaze.

 

My experience with really cheap, aftermarket rotors is the entire rotor (not just the braking surface) rust a LOT more than OEM and look awful; quality of materials and all that.

 

I was really hoping there'd be a picture with your post. Do they look ok? You're not noticing a pulsing when using the brakes?

Chances are they're just fine, and nothing needs doing, neither resurfacing or replacement.

I can post 2nd gen rotor inspection info in a bit. If you want to check them you need a dial gauge on a magnetic base and and a micrometeter.

The first instrument checks for side-to-side "pulsation", the second checks thickness (and uniformity of thickness).

Each of those instruments is $30~50, and readily available.

 

1. Are they warped?: If the car shakes as you come to a stop, they are warped. If you're not sure, you'd need a special dial gauge kind of like this one:
   One way or another, you should resurface or replace warped rotors.
2. Are they rough? Rub your fingernail across the surface from the hub to the rotor edge. The more grooved they are the more you really should resurface or replace them. You could take some fine emery cloth and sand in a circular motion if you don't want to pay for new ones or for resurfacing.
3. Are they too thin to resurface? For this you need a dial caliper or micrometer like this one:
   I don't know the recommended limit though since I haven't gotten my Haynes manual yet nor got a subscription to TIS to download the factor repair files. But any rotor I take to my machinist he checks them for free for me and has all the numbers on hand to tell me if the rotor is too far gone or not. Edit: I see you only have 81,000 miles on them. Chances of the rotors being too thin are slim.

Just a thought. As far as buying new vs. resurfacing, there have been times on certain vehicles that the factory rotors and drums, resurfaced or not, seemed to hold up better than new aftermarket ones.

 

A micrometer would be better than a caliper. You want something that can kinda pinch on the inside of the rotor, and not being riding up on the outer rusty edge:



Again, with 81K miles, and no apparent problems, your rotors are likely fine, within specs for runout and thickness. But doesn't hurt to check.

Excerpt from 2nd gen Repair Manual attached, has details on rotor inspection, runout and thickness limits/variation.

A couple of tips:

1. Disconnect the negative 12 volt cable before starting any caliper removal. (The car may try to pressurize the brakes, say if you open driver's door, and this can be disastrous with the caliper off.)

2. After reassembly, pump the brake pedal multiple times before reconnecting the negative 12 volt cable. (This avoids the car's computers possibly detecting excessive brake pedal travel at next start up, throwing a code.)

 

Too thin! Wow! Do you live in the mountains? Or have they been resurfaced before? Do you drive with both feet?

When I was a school bus driver the mechanic told me he never had to replace even the shoes on a bus, much less the drums. He said it was because all of the school bus drivers had been trained so well to use every other means to slow down the bus before using the brakes. So we had +30,000lb GVWR buses with as much as 200,000 miles and aparently the original brakes on them. Mind you this is in the Colorado Rockies.

But on the otherhand, the same mechanic told me that the company cars and Suburbans would come back with warped rotors after every trip. The teachers who would take them down to city had to cross several mountain passes to get there, but aparently had no idea of how to engine brake. The mechanic ended up installing oversized slotted and drilled rotors with high performance ceramic pads on all the cars and Suburbans, and that seemed to have "solved" the problem.

I personally never have had to replace a brake pad/shoe or rotor/drum on my personal vehicles except when I first get them. (I buy used) Mind you I can put as much as 30,000 miles a year on a car and have kept cars for up to 9 years. (And yes, that 1985 VW Golf is still running and still has the factory brakes!) I guess as a trained bus driver, I use every means necessary to slow down my cars before resorting to the brakes. I still inspect my brakes every year though.

One neighbor lady once asked me to take a look at her "squeally" brakes on her car. And low and behold, the pads were gone and the rotors were deeply grooved! So I recommended she stop driving it and get those replaced ASAP. After all new parts and 6 months later her brakes were once again gone and deeply grooved! I wonder if she drover around with one foot on the gas pedal and one on the brake.

Now I'm not saying all this to make anyone feel bad. Replacing rotors and drums after 13 years is normal. Just inspect your brakes regularly, don't hesitate to replace them if they need it, don't drive if your parking brake doesn't work, don't rest your left foot on the brake pedal as you drive, and use B mode when going down hills and you'll be fine.

 

My neighbor has a Gen. 2 Prius with 205k miles and still has the original brake pads and rotors.

 

Your vehicle hardly uses those rotors because of regenerative breaking system is doing most of the work... Unless you're delivering mail and are constantly driving under 6 mph you're rarely going to be using your pads and rotors. In fact most mechanics not trained on regenerative braking will see those rusty unused rotors and think they need to be replaced. Truth is they're only rusty because they aren't being used.

But next time you're getting off the freeway, put your car in neutral and that shuts down regenerative braking and is mechanical brakes only. By the time your car stops those rotors will be clean and shiny again.

In other words, unless you can physically feel warping vibrations in the pedal or the car pulls to one side when braking below 6mph there's no reason to replace or resurface. Your car only uses those rotors for emergency braking and braking below 6 mph... For example, I have 1/4 million miles on my Prius and they still have original pads and rotors. That's because regenerative braking does all the work and most of my miles are freeway miles.

 

That's not true with hybrid and electric cars... Mine is 13 years old with 1/4 million miles, original pads and rotors and after all that time no issues.

 

I've owned one electric car and two hybrids, so I know the regenerative braking advantage these cars can have. And like I've said, I've also gotten several hundred miles on a single set of brake components that still are in great shape even in a non-hybrid. But I also am certain that brake wear has more to do with the way the car is driven than the type of car. There can also be other factors. Consider:

• Someone who always slams on the brakes. (I know a few who do.)
• Someone who shifts into neutral when braking. (Yes, I know someone who does that!)
• Someone who drives over mountain passes with several thousand foot decents and doesn't use B mode. (Yep, lots do.)
• Someone who lives in extremely cold climates, especially if he or she parks outside. (It gets to -40°F here and was below freezing in the mornings just a couple weeks ago.)
• Someone with a mechanical problem that causes the brakes to stay "on". (I've seen this happen due to a couple different reasons.)

The OP thinks the rotors are too thin for some reason. For all we know that could be based off an actual measurement, in which case they would need to be replaced, regardless of why they wore out in the amount of time they did. Or that could be just an "opinion" from a shop that's eager to sell him some new rotors.

In case he's sure they are worn too thin, it would be a good question to ask why they wore out in the time they did. The OP did mention that he needs to be a bit more careful. Careful of what? The way he drives perhaps? Or maybe who he lets borrow his car?

In any case this is all speculation until we get an actual number from a micrometer that has been squeezed onto his rotors. For all we know he could have got a bad batch of soft metal rotors that accidentally made it past quality control.

 

ALL rotors rust, especially on the surfaces where the pads do NOT contact.
Who is this "they" ?
Ask them what your's measure and what the minimum spec. IS.
Modern rotors on small cars look too thin when new........to an "old" mechanic.

 

Standard thickness: 22.0 mm (0.866 in.) Minimum thickness: 20.0 mm (0.787 in.)

So not much between new and minimum.

 

And runout: .05 mm (measured with the dial indicator).

Even just visual inspection through the spokes would provide clues.

 

hard to be careful with rotors, it is what it is

 

Unless you're a mail carrier, I'll always be suspicious of anyone who thinks they need to replace brake parts on vehicles that predominantly use the electric motor(s) for most braking. It just doesn't make any sense. Just because something doesn't get used very often and looks as such doesn't mean it's worn out or damaged in any way.