Rusty rotors

[Donald]

A mechanic told me if the vanes on a rotor are rusty they they will not cool the rotor properly and if will get too hot and warp. I understand the theory but not sure rotors ever get that rusty to cause overheating.

The rotors might get very hot from braking down a mountain road but not sure if pristine vanes on a rotor would prevent it.

 

[robertcope]

This sounds like one of those "theoretically true but not really useful" facts. I'm guessing most people never get their brakes hot enough for it to matter, for one thing.

 

[SteveSRT8]

Since almost any complaint about brake pulsations is virtually never a warped rotor, only runout and/or pad deposits, this seems like an answer in search of the question...

 

[MasterSolenoid]

When my Father was teaching me about car maintenance,
I remember using a welders chipping hammer and removing 'heavy' rust from the Drums & Rotors.
The cooling fins on the Rotors were so heavily rusted, it couldn't hurt chipping some off.
But how much did it help ? I didn't have a lot of money and cheap replacements weren't available.
Same with the rear Drums.
I never again want to spend my Saturday afternoon chipping rust from Rotors/Drums.
With Cast Iron, I don't think you could chip off enough 'heavy' rust to make a difference.


Surface rust - of coarse no problem, leave as is
-------------------------------------
3/32" of cast iron rust - if they warp, get new ones

 

[slacktide_bitog]

coated rotors are awesome. The Centric Premium and Wagner E-coated rotors do coat the vanes, too, so they won't rust for a long time

 

[Kestas]

It costs money to make a vented rotor. The vents are cast in there for a reason, otherwise they'd be solid rotors. Most people don't notice any difference because they don't push the rotors to their limit. As mentioned, driving down from a mountain pass may be the extreme rotors can be put through.

Regardless, I'll clean out the vents with a screwdriver when I'm in there.

 

[Snagglefoot]

Originally Posted By: Kestas
It costs money to make a vented rotor. The vents are cast in there for a reason, otherwise they'd be solid rotors. Most people don't notice any difference because they don't push the rotors to their limit. As mentioned, driving down from a mountain pass may be the extreme rotors can be put through.

Regardless, I'll clean out the vents with a screwdriver when I'm in there.


Here’s that mountain pass, at the bottom of the pass at Radium, BC, CANADA, LOL. I was standing at the bottom of the pass and the air smelled like fried brakes. Notice the fault in the rock formation, for the geology fans out there.

 

[Hall]

Originally Posted By: Donald
A mechanic told me if the vanes on a rotor are rusty they they will not cool the rotor properly and if will get too hot and warp. I understand the theory but not sure rotors ever get that rusty to cause overheating.


I bet he wouldn't use that argument 4 months after he replaced them for you and they're rusted again. He'll tell you "they're fine".

 

[benjy]

bad or inadequate brakes are not noticed until its TOOO LATE. example older pickup with a big travel trailer, be was going to fast + the smoke flew as they overheated, luckily i was behind him + lucky again he got around the car in front of him!!!!! bigger better brakes are ???? so OE brakes are "just enough" in normal conditions HOPEFULLY!!!!!!!!

 

[123Saab]

Originally Posted By: slacktide_bitog
coated rotors are awesome. The Centric Premium and Wagner E-coated rotors do coat the vanes, too, so they won't rust for a long time

Agreed.

Rusty rotors suck.

 

[JLawrence08648]

I would guess that rust does not dissipate heat as well as bare steel however as others have said, this is under extreme conditions. The worse can happen, the rotors start to warp and you have pedal pulsation, then replace them. If you are going that fast down a mountain, maybe you should slow down, or pull over allowing the brakes to cool. Also, the thicker the brake pads, the more heat will be absorbed and released. The thinner the brake pads, the more heat will be passed through to the rotors.

 

[camrydriver111]

Originally Posted By: hallstevenson
Originally Posted By: Donald
A mechanic told me if the vanes on a rotor are rusty they they will not cool the rotor properly and if will get too hot and warp. I understand the theory but not sure rotors ever get that rusty to cause overheating.


I bet he wouldn't use that argument 4 months after he replaced them for you and they're rusted again. He'll tell you "they're fine".


lol yes

 

[cronk]

i think it depends on the extent of the rust. Minor flaking or rusting will not have any major effect on brake cooling.
I have seen rotors where the cooling fins are almost totally swelled shut with rust. That would definitely increase rotor temps.