Hello. We just had rear brake rotors and calipers installed on our Honda. They ary are completely rusted one day after installation. I believe these might be used parts. Is this normal for them to be like this?
If the car isn’t driven much, the corrosion can build-up in a couple of hours depending on weather condition.Its probably just surface rust and it will go away after a short drive.
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Return to the place that installed them. But I don’t think you have a problem.
Rusted is not so bad, we had a little ford truck, the rust the brakes built up overnight was enough to lock them up. As long as you are happy with the operation of the brakes I would put it in the let it go category.
Both are normally made of cast iron. Ever had any cast iron cookware? Wash it with water and leave it sit for an hour and there will already be rust. Same for these parts, they rust very fast unless they are painted.
Now there should be no rust on the parts that don’t wear (where the break pad and rotor contact) but otherwise this should just be light rust after one day, not severe flaking rust as often found on the vents of the rotor after some time.
There will be rust on all the parts unless you are buying a coated rotor and painted calipers.
Most aftermarket calipers are not clearcoated or painted and they will rust. All rotors will rust, but overnight is unusual in my experience.
It’s quite common for cast iron parts to rust and rust quickly. They can rust overnight or even in a few hours all depending upon the humidity.
Some rotors are protected with a rust preventative that MUST be cleaned off before installation although sometimes this is not done due to lack of knowledge about the rust preventative being present.
In some rare cases new rotors will be covered with a substance that is similar to Cosmoline but this is somewhat rare; no doubt due to cost and the fact that it’s a bit messy.
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I notice my brakes can rust overnight while parked, especially when it rains. The brakes are clean after a drive. If you find they don’t come clean after a drive then I might stop in to have them checked out.
Yes, this is normal because they are iron and not painted or plated.
I’ve said this before, but for me, who uses the car perhaps twice a week, and drives conservatively, the rotor rust is the limiting factor on brake life. I had one case where the rotors actually had holes in them, while the pads were only half warn.
I think this comes from a rust pit developing too deep for normal wear to remove. The pit can progress faster than the rotors wear off the surrounding metal, leading to a rust hole in the rotor.
Really need a better material… or is there one I don’t know about?
edit: I do see online rotors coated with aluminum and zinc. Is this coating intended to last the life of the rotor?, with steel underneath for strength?
Some people pay a lot of money for hole-filled rotors. You just found a cheaper way to get them. 
Carbon-carbon and carbon ceramic, for a couple of examples. Carbon-carbon is great for stopping fast at high temperatures (i.e., racing) but the disadvantage is that a c-c system wears both the pads and the rotors. That’s OK in racing because you change the brakes all the time anyway, but it would suck for a street car.
Carbon ceramic is pretty wonderful for a street car. It lasts longer than iron, and it stops better at high temperatures, but you pay for the advantages. You can get cast iron rotors for as little as 50 bucks per. You’re often looking at more than a grand for a carbon ceramic rotor, and if it’s on something like an AMG Mercedes the brake job can cost more than 15 grand alone.
what about these:
“Black E-coating for long lasting corrosion protection”? whatever that means…
the reviews on Amazon are pretty good. Rated to withstand 400 hours of salt water exposure without rusting but 400 hours is only 17 days of winter, not so good.
Great for the hat, but any coating on the rotor is going to get scrubbed off when you brake.
The swept surfaces aren’t coated but usually a very thin compound just to prevent flash rust during shelf life. As OK4450 pointed out, rotors coming from Japan used to have thick cosmoline and plastic to prevent rust on trip over but that has been eliminated as far as I can tell. Last set I bought was shrink wrapped. More effective and less hassle. I bought coated rotors for my truck a few months back. Some rust is starting to appear on the coated surfaces. Rough life around here in winter…
Yes, and no. The friction surface rubs the coating off but the hat section is supposed to stay nice. In the real world of road salt, they never last the life or the rotor. Same for the E-coated rotors although they look better longer.
Metallic compounds used in European cars also wear out the rotor. Properly designed, the pads and the rotor are worn out at the same time - like my wife’s Saab at 35,000 miles. All 4 corners were worn out pads and rotors! The abrasiveness keeps the rotors clean, tho! Never had an American car that aggressive on the rotors.
Absolutely agree with ceramic compounds for the pads… not the rotors, those boys are expensive!
Why not stainless steel rotors? not strong enough?
I switched to Raybestos Advanced Technology rotors a few years ago. They are coated to prevent corrosion. 60,000 miles later, on my 2014 Mazda 6, the rotor hats are still silver and the vanes in the vented area of the rotor are just starting to rust slightly. I am impressed with the lack of rust and corrosion, since I live in the snow belt and rust is a major issue in general.
They do use them on bicycles and motorcycles, but then the brake pads on a bike aren’t going to generate the kinds of temperatures you see in cars. And since stainless steel isn’t great for dissipating heat… Not to mention it has a tendency to gall when its oxide layer is removed (by, say, a pad) and is then exposed to other types of metal (such as semi-metallic pads).
It’s also more expensive than cast iron. Realistically, cast iron rotor rust will look bad, but I’ve got rotors that are over 100,000 miles old on a Minnesota car that still haven’t worn down to replacement levels, nor do they have rust that compromises their integrity. Why would I want to triple my brake cost for no performance upgrade when rust isn’t anything more than a cosmetic issue now?