Rusted out brake rotors

Most rotors are made from unprotected cast iron, so they are going to rust. The pads will clean the rust off the swept area, but the rest of the rotor can rust. Normally this isn’t a problem, but there are rotors available that have a treatment for the unswept areas of the rotors. I believe Centrix is one of those brands. EBC brand rotors are also treated and are available in slotted and slotted and cross drilled. I chose the slotted for my Saturn.

The first time was a well-respected independent garage who was doing my state inspection, and wouldn’t pass it in this condition. They showed me the pulled rotors – the outboard sides were fine, but the inboards had about one inch of clean metal and the rest was deeply rusted and pitted. This wasn’t light surface rust – it was obvious that the pads were only working on a small portion of the disc.

The second time was the Saturn dealer. The condition of the rotors was almost exactly the same as the year before. So, did I get screwed twice, or do I have hung-up calipers, or is my light braking style failing to wipe off rust before it gets too deeply embedded, or what? After the pads and rotors were replaced, the braking seemed perhaps a little better (smoother and firmer) than before. There were no real symptoms to report “before” – the car braked fine, although the first braking or two after a rain would squeal a little. Would “exercising” the brakes by braking harder do any good? Replacing stuff this often is getting expensive!

I would check your calipers. I had a frozen caliper on my '01 Mazda and the outboard side of my rotor was all rusted and pitted, inboard looked normal. I put new rotors and calipers on the back and everything is fine now.

I think you are getting screwed.  Either they did not need anything or you may have a caliper problem as clemrick suggested.

I talked to the dealer’s service manager, and he said that the technician would have checked for sticky/hung-up calipers during the service. We discussed why rotors would develop such severe rust, and he thought I just wasn’t driving it enough (typically one day a week). It’s practically a rain forest around here (the Catskills), so there’s plenty of rain, snow, and moisture.

I guess what I’ll do is de-consolidate my trips and get the car out one or two additional days a week, and keep an eye on the rotors. Yeah, this will burn more gas, but it’s cheaper than another brake job.

Thanks for the comments, everyone, and if you have any further suggestions, please post them here.

i would find another inspection station to go to next time. this is over kill, as far as i am concerned; because the problem has not been remedied, but just keeps recurring, and costing.

if this has happened twice, i would be really suspect of having caliper pistons that are corroded or gunked up, and they may be adding to your problem.

i would guess (a WAG at that) that it is NOT the calipers that are the problem. i think the slides that the pads slide on to “self adjust” are getting rusty, and jamming the pads so only one side pad can grab the rotor, thus the recurring “rusted rotors”, and accompanying excuses for replacement.

if this IS the slide and pads that are rusting and jamming there IS a solution. I have a similar problem on one of my cars (same issue with low use).

the real problem is finding a mechanic who can diagnose the problem, without just saying: new parts, calipers, rotors, and pads! i have interpreted my problem as too little clearance between caliper slides, and brake pads, so rust (from lack of use) binds them up. my solution is to “make” a little room between so they can “rattle” off the rust.

on my car the rear pads ALWAYS jam in the slides, cocking and then work on one side only. i found if i grind a small amount off the inside of the steel pad mounting U it gives a little “wobble room” for the pads to move along the slides, so the pads dont jam anymore. mind you, i DONT remove any metal from the caliper slide frame, but from the new brake pad mounting plate (the steel, not the ceramic!). AND im only talking about a small amount!

Topical rust is not a problem, except that your brakes might squeal until you wear it off and the dust goes away. If the rotors are pitted badly, you should be concerned. You would avoid much of the rust by parking in the garage. The car would not be subject to morning condensation which accelerates rusting. I’d park in the garage anyway. It’s sooo nice to get in and drive without having to clean dew or ice off the windows. BTW, your gentle braking is fine. It will wear the rust off as well as any hard braking would.

Like the others, I’m wondering exactly what reason was given to you as the cause for needing new rotors. If the brakes are functioning normally you do not need rotors. Rust is normal, and can even be observed after paring the car at the mall in the rain for a few hours while shopping.

Unlike the others, I have seen rust destroy rotors on a vehicle that was parked in a leafy, woodsy, wet area under trees for a six month period. The cooling vanes that were on the upside of the parked rotors, which wre apparently keeping moisture, rotted to the point where the rotor surfaces were actually splayed outward. The first drive when we took the car out, just touching the brakes at slow speeds (ALWAYS test a stored car at slow speeds first) caused the car to shake so badly that I honestly thought the rear drums were cracked. But this was an extreme case. Under normal circumstances this will not happen.

Like the others, I’m wondering exactly what reason was given to you as the cause for needing new rotors.

OK, where is the dividing line between light cosmetic rust and serious stuff? Both times, the rotors had (inboard side only) very deep solid rust and pitting except for about one inch of swept-clean metal (noticeably deeper than the rust). The pads were of course misshapen from this.

I think I’m going to bite the bullet and clean out the garage and keep the car in there.

You should expect rust on the rotors where the pads do not touch the rotor. This will occur whether you park in a garage or not. It will certainly occur when you drive on wet roads. I would not be concerned about it. I’d still park in the garage (see previous post). Let us know what lost treasures you find when you clean the garage!

You said, “…it was obvious that the pads were only working on a small portion of the disc.” That sounds like the real issue and the reason that the discs were rusty. I would be looking at the calipers as well as the rotors, actually I would probably just replace both calipers and rotors and see what happens.

There is more to this story…Rotors are machined flat. Brake pads are machined flat. Over a week the rotors may rust a LITTLE, but they will still be FLAT. The point contact you observed can only be caused by damaged or defective rotors or incorrectly installed pads. If the piston moves freely in the caliper and it’s not leaking, it’s FINE and does NOT need to be replaced.

For a groove to form in a rotor because of corrosion would take a year or more, and even then they would rust more or less evenly and the pads would quickly clean it off when the brakes were applied.

How about THIS explanation. Someone replaced the pads and ignored the damaged rotors during a backyard brake job. That’s the only thing, really, that explains this…Two times?? That’s because the first shop never replaced the rotors either…

That’s possible, it’s also possible that the caliper was not moving freely and was not putting even force on both sides of the rotor. I don’t know what kind of caliper design this car uses, but if it has those silly sliding calipers with the piston on one side only it could be hanging up on the slides and allowing rust to form on one surface only.

Brake components, including calipers, are pretty cheap so I would be inclined to replace them first and ask questions later. I just replaced the front calipers, rotors, and pads on my car for about $500 (parts only). For that price, it’s not worth messing around.

I have NEVER replaced the calipers on any car I have ever owned…

I have owned MANY 10 -14 year old cars with well over 100,000 miles on them. In my experience, caliper failure is a very rare event.

those “silly” sliding calipers and self adjusting pads are on every car out there. they all move to adjust for the wear as the pads get used up. if the pads didnt move they would stop rubbing on the rotors.

its not the silly slides, its the lack of a proper brake job (cleaning and regreasing the pins) or having the brake pads jam on the rails due to close clearances (so the pads CAN’T self adjust)

Good for you, but your experience may not be typical. My original calipers did last over 400K miles before one of them began to seep. I have also replaced calipers on other cars. I have no idea of the quality or longevity of Saturn’s OEM calipers, but I don’t take chances with brake components. If I don’t trust them (i.e., they are not perfect), they get replaced.

Auto parts stores seem to stock plenty of brake calipers, so I must not be the only one who has to replace them occasionally.

In any event, none of use can really knw whats going on without looking at it ourselves.

I was referring to the “silly” calipers with pistons on only one side where the entire caliper has to slide for the other pad to make contact (a pretty cheesy design, IMHO). If the caliper does not slide freely the pads will not have equal pressure. I understand they are cheaper, but its just not a very good design. Others have pistons on both sides and the calipers are fixed in place. Each brake pad moves independently on the guide pins, but there are no slides for the caliper itself. As an example, mine look like this:

http://catalog.worldpac.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1CQ0J3JZ428A1EEFTU&baseurl=http://catalog.mercedesshop.com/&partner=mercedesshop&year=1982&product=N1040-76182&application=000477646

These tend to wear very evenly because the inner and outer pads always have equal pressure.

The dividing line is when the operation of the brakes becomes affected. If the car is stopping straiht and smooth the rotors are fine. A swept clean area the surface of which is depressed from (into?) the rust are is normal, as is a “misshapen” brake pad surface.

Selling anything good at your garage sale?

I’ve only had to replace a caliper on a pickup that I used regularly on construction roads to haul wood and stone. Dusty, sandy, dirty driving may have been a factor. Driving environments vary, and I’d be reluctant to suggest that none affect calipers. Calipers sticking on vehicles that drive dusty roads often may be common, I really don’t know.

How about THIS explanation. Someone replaced the pads and ignored the damaged rotors during a backyard brake job. That’s the only thing, really, that explains this…Two times?? That’s because the first shop never replaced the rotors either…

No backyard brake jobs here. Dealer only for that kind of service (if routine). The independent shop removed the rotors (I requested that I be shown them), and I saw the replacement new rotors being delivered, so it would be incredible if they put the bad rotors back on (and the brakes passed inspection 12 months later at the dealer, only to be red-tagged 4 months/6K miles later during 120K routine service). Go figure…

The Saturn service manager says that the calipers would be fully inspected for rusty/damaged/sticking slides during the rotor and pad replacement. I asked him specifically about that when we talked. So, the rotors went from acceptable to the dealer at 114K to bad at 120K 4 months later. Note that most of those miles were put on in the first month, with very light use the last 3 months (and a very wet summer).