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Rusted out brake rotors

For the second time in 16 months/10K miles I just had to replace my front disc rotors (as well as the pads) because they were too rusty ('98 Saturn SL2, 120K miles). The car is now typically driven 1 day a week and sits outside. How can I keep this from happening again? For best mileage and least wear and tear, I was taught to brake gently – have I babied my brakes too much? Do I need to make sure I brake really hard (just short of lockup) once a day, to wear off the light rust before it gets too deep? Is there a better way? Is my only hope to clean out the garage and park inside?

Exactly what are the brake symptoms and where are these rotors “rusting out”?

Light rust will be scrubbed off after several applications. We get rust almost overnight with some brands of vehicles. Who said that you needed new rotors and why? Ask to see the parts that must be replaced or ask for the old parts next time. There is an abundance of charlatans and less than reasonably intelligent mechanics in the auto repair business. Light or heavy braking should not matter; just brake to remove rust.

Rust, can progress, however, so that the swept braking area on a rotor is diminished. Even so, brakes can work quite well according to my experience with some reduction in swept area but don’t let this go too long.

You can leave brake rotors out in the rain for years and they will never “rust out”. Your brakes are getting rusty from ambient moisture and maybe some road moisture, but as the other posters alluded to, it’s hard to swallow that your rotors need replacement if they haven’t been sitting at the bottom of a lake.

For a car driven only one day a week here is no good way to prevent disc rotor rusting (unless you can move to Phoenix). Rotors rust quickly – that’s what they do.

Generally this is normal and harmless. A few applications of the brakes will remove this light surface rust. Of course, the rust will only come back. Did someone tell you that you needed new rotors because of a little rust? Next time, don’t be so hasty to replace them. Take a short drive and come back with shiny surfaces.

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)