Rust on brake rotors, when is it a problem (picture)

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5 year old rotors up here can look like that thanks to all the salt in the winter and they are fine other than cosmetically unappealing. I would drive on them.
 
I too can't understand the aversion to these rotors. My rotors routinely look like that after 10 years or so. Sometimes I take a screwdriver and ream out the space between the fins to get rid of the scale and let the rotors breathe again.
 
Originally Posted by Kestas
I too can't understand the aversion to these rotors. My rotors routinely look like that after 10 years or so. Sometimes I take a screwdriver and ream out the space between the fins to get rid of the scale and let the rotors breathe again.
This topic is people who live in the rust belt v. people who do not. Have you see the posts in some of the threads on oil spraying? LOL.
 
No offense but I don't understand the mentality of running rotten weakened parts that are critical to safe braking given the low cost of new ones. Those rotors would never pass a decent inspection.
IMHO If people cared for the most critical systems in the vehicle, brakes, steering and suspension the way they care about oil and filters they would be a lot better off.
A little rust is one thing but rotten fins can severely weaken a rotor to the point it is really unsafe in a panic stop or high speed braking.
No point in beating a dead horse the OP has to decide.
 
Originally Posted by Kestas
I too can't understand the aversion to these rotors. My rotors routinely look like that after 10 years or so. Sometimes I take a screwdriver and ream out the space between the fins to get rid of the scale and let the rotors breathe again.


Your rotors last 10 years?
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I run mine the life of the vehicle, resurfacing them until they are no longer in allowed measurements. The only exception was my Santa Fe that got new rotors at 390,000km because two of them were warped and machining them would take them out of allowable measurements.
 
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You could try soaking those rotors in EVAPORUST. It might at least knock the crust off to see how bad your rotors really are.
 
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I think you need to clean them up and take a better top down pic.. but tentatively I'd suggest replacing.


How soon ? well without better pics those look moderately terrible.. but then again you should see what hoopties drive around here.. broken frames and all. (amazing)
 
Is there any way the rotors could be repaired to save some cash? I was thinking maybe some duct tape or something
 
Originally Posted by 7055
Is there any way the rotors could be repaired to save some cash? I was thinking maybe some duct tape or something


I do hope you are joking about the duct tape!


Originally Posted by 555
I would listen to Trav.
Replace.

X2 Not worth the risk.
 
The rotor shown looks to have a lot of meat left, a smooth shiny braking surface, and a good surface for wheel mounting. If it passes thickness and has no vibration during breaking, it should be good for continued service once the scale is chipped out from between the fins.
 
Originally Posted by Trav
I would change them, if the cooling fins are as bad as they look the rotor can collapse in on itself or crack, neither is a good thing.



If Trav says to replace... That's exactly what I would do. No doubt about it.
 
Originally Posted by Kestas
The rotor shown looks to have a lot of meat left, a smooth shiny braking surface, and a good surface for wheel mounting. If it passes thickness and has no vibration during breaking, it should be good for continued service once the scale is chipped out from between the fins.


Yes the braking surfaces look fine, the mounting surface looks good also, all true but the mounting surface is covered by the wheel and the surfaces are constantly being cleaned off due to braking action, the thickness may also be okay but that's not the problem.
These are cooled rotors meaning the two braking surfaces are separated and held together from the hub section out only by the cooling fins. as I said a small to moderate amount of rust is usually not an issue but severe rust in this internal area weakens iron in the rotor. during normal driving where line psi is around 500 psi you probably wouldn't see a failure but..

Consider during a panic stop there can be 1500-2000 psi line pressure driving the pistons and pads against the rotor, this translates to lots of energy at the rotor.
Granted stopping from 100mph in NA is unlikely but 70-80 is certainly possible on the highway.

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The amount of heat produced in context with a brake system needs to be considered with reference to time meaning rate of work done or power. Looking at only one side of a front brake assembly, the rate of work done by stopping a 3500-pound car traveling at 100 Mph in eight seconds is 30,600 calories/sec or 437,100 BTU/hr or is equivalent to 128 kW or 172 Hp.


Think about the amount of pressure/force required to generate that much energy power for each front brake. If the cooling fins fail the rotor will initially crack and the brake pedal will go to the floor because all the fluid in that stroke has been used, release the pedal and push it again and it will push the pads once again against the rotor, with luck it will stop and tear the pads to pieces if unlucky the two rotor surfaces can collapse even more, not the scenario you really want to be in in an emergency situation.
Considering new rotors for most cars are very inexpensive IMO any rotor that is suspect should be replaced, you cant go wrong erring on the side of safety.

The miserable old geezer that taught me everything after 4 years of trade school said many things that have stayed with me for 40 years, one of them is..
"A rotten (not surface or light rust) stressed part is a dangerous part". He was right.

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^^ Good points. ^^ I just don't see the logic in trying to squeeze another brake job out of those rotors. In the grand scheme of things rotors aren't that expensive. Especially when your life and the lives of others depend on the car stopping.
 
Don't think I've had rotors rust like that. Usually the braking surface has long bubbled up also--that's a lot of flaking in the cooling area. I wonder if this is lightly driven, but very often. Maybe garaged?
 
Originally Posted by demarpaint
^^ Good points. ^^ I just don't see the logic in trying to squeeze another brake job out of those rotors. In the grand scheme of things rotors aren't that expensive. Especially when your life and the lives of others depend on the car stopping.

+1 . 3 things i don't cheap out on , as they will all hurt you. Brakes, shoes and mattresses!

All kidding aside, i never skimp with brakes, If anything is even slightly suspect, it gets replaced.

A few years ago when i did my avalanche brakes. A member here Carbon12 recommended i replace the metal brake lines on the rear of my truck. I never did that and a couple of years later, the lines gave way suddenly under hard braking, and i was lucky to not have hit anyone.

A lot of good experience on this forum, take advantage of it!!
 
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