Rotor is rusted ?!?

Sounds like nothings wrong with them. Anytime I wash our car, and then the car sits for a day or two: the rotors will get surface rust. And like you say: drive a bit and it clears up.

One thing that is serious: if you see rust on only a portion of the disc, and it persists. This likely indicates uneven pad pressure. Happened to me with the rears.

 

FYI, rust on any part that DOES NOT make contact with the brake pads is normal. There's nothing scraping the rust off.

I don't have this issue where I live, but I'd suggest having someone wire brush the rotor parts that are rusting (like the hub) and apply a coat of something that will retard rusting. It isn't really needed, but rust can complicate trying to pull parts off, and sooner or later, work will need to be done.

 

Don't coat them, lol.

 

When my rear rotors were rusted due to uneven pad contact, I took them off and just went over them with steel wool, did the best I could.

Reinstalled with new pads and shims, they sounded horrible at first, due to the pads properly contacting the full surface.

Just a few blocks later they got a little quieter. A week later I could still hear them, just a bit.

A month later you'd never have known there was a problem: quiet, and they looked great. Moral of the story: minor rust can heal.

 

I am in California and I have rust on "wet" days until I use my brakes.

... Normal...


iPhone ?

 

The mechanic needed to repaint his boat.

If the rust bothers you, you can clean it off (stay away from the pad contact areas) and paint it by hand - a brush, not a spray can. You need to properly prep the surface (remove all oils) or the paint won't stick. You don't need to use high temp. paint but it doesn't harm anything if you do.

What I do is worry about the wheels corroding on the hubs - the brake disks are part of it.
If you rotate your own tyres you can do what I do. Get some "waterproof grease" - I use Lubriplate. Remove the wheel, and apply the grease with your finger wherever the wheel contacts the hub - then use your finger and wipe it off. It will leave a very thin coat, and that will prevent the wheel from sticking to the hub, but there won't be enough grease to bother the brakes.

If the pad contact areas become pitted with rust the rotors probably should be replaced. They should appear smooth and shiny once the pads have scraped the rust off.

Pearl S will give an alarming sound backing out of the garage the next day after I wash her and park her in there. It lasts about 10 feet. That's the surface rust being scraped off by the pads. And yes, it is "normal" as stated above.

 

Left rear of a Mercury that I see now and then in the parking garage at work:

I've left notes on or in the car on several occasions, asked the local parking patrol or the police whether they can try to contact the driver, etc. You can sort of tell I live in an area without an inspection regime.

At this point I'm just hoping I can be watching from a safe distance when that last veneer of cast iron punches through and the pad goes into the vent vanes.

-Chap

 

Here's a thing you want to avoid on your Prius:

Usable friction area on the inner surface down to about half....

Here's how I think it happens:

1. Bit of rust starts around the edges where not wiped by the pad. Grows thicker and rougher until:
2. Chews away some of the pad at the top and bottom edges.
3. Now there's a slightly wider area at the edges not wiped by the pad. See rule 1.

When I first found my rotors like this (and the pads, ahem, matching), I bought new pads, and had the rotors lathed.

Since then, I try to look a little more often. If I catch it when it is just starting and the pads are only slightly chewed at the edges (a year or so), it responds very well to some 150 grit wet sandpaper (pad makes a good sanding block to do the rotor, rotor makes a good sanding table to do the pad).

I've also learned that re-zinc-electroplating a rotor is a possible thing (and I found the electroplate shop around here, and have not tried a rotor yet, but was happy with what I did try). The plating will be removed quickly where the pads contact, but remain to protect the rest of the metal. Shop will probably plate as many rotors as you can carry in an armload for the minimum batch charge, less than you'd pay Toyota to buy one.

Obviously not worth doing on a badly worn rotor (or one on a normal car you expect to wear quickly), but on a Prius the wear effect is so low the rust effect predominates, and it might turn out reasonable to plate once or so in the car's lifetime and get very long service out of original parts.... If anyone else tries it before I do I'd be interested in the results.

-Chap

 

how many miles on her?

 

yup, i think everyone above is correct. these rotors rust from condensation, everywhere but where the pads rub. mine look exactly like yours, you don't need any work.

 

Chapman, just like to say: I looked at that first picture you posted, for maybe 5 minutes, before my brain finally unseized and I could understand what it was, lol. I'd converted all the "innies" into "outies" or something: could not figure out what I was looking at.

 

It's fine. The only place you need to make sure is rust free is your hub and wheel mounting surfaces. That means taking the wheel off and taking a wire brush and lightly scrubbing off any surface rust. All other places on the rotor are aesthetics only.

 

Looks perfectly normal for the average car.

 

Looks like something going on, the metal spalling, in the zone I marked with a red line:



For comparison, a couple of pics of ours.

Front:



Rear: