For the love of the Subaru!

September 16, 2009 6:50 PM

Are there any preventative measures, leaving aside driving the car every day, that will prevent my brakes from rusting like mad?

So the dear Subaru wagon has gone into the shop to get what, originally, I thought, was at least one rear brake caliper replaced... Actually, it's the whole rear brake shooting match (rotors, brakes, calipers) that needs to be replaced. The shop-guy barely contained his astonishment.
The formula, as I see it, that led to this fairly pricey repair is the following:
A 1993 Subaru, driven ~100 miles a month, sits idle on Chicago streets otherwise... pining... + most of its driving, and certainly all of its sitting time is during the winter, when all the road surfaces are extremely salted down and thus when she's not sitting, pining, she's careening through a corrosive bath, however joyously. All this sitting, plus corrosive moisture = completely rusted brakes.
Aside from driving the damn thing more regularly –which I'll try to do, but that's essentially a lifestyle issue– is there any other tip or best practice that you can recommend for to prevent this infernal corrosion? for this or for any other car?
–there is another car in the household but it is but a honda, and I care not for it like I do the Subaru. The honda also has the sitting issue, and has started to get the brake wubbies.

posted by Cold Lurkey to Travel & Transportation (11 answers total)

To be honest, I think the only solution is to drive more. Heck, I live in a relatively dry and salt-free (though humid) environment, and my car's brakes scrub a bit if i leave it sitting for one weekend.
posted by sonic meat machine at 7:28 PM on September 16, 2009

You may---may---be able to spray the rotors with zinc. I think Rust Oleum makes a pure zinc spray for use on chain-link fences. At the end of the storage period, you could probably take a wire brush and clean it off, and since zinc is metal, it would be less likely to ruin your pads, if any happened to remain.

But I've never done this, nor do I know anyone else who has. In theory, though, it would work.
posted by luckypozzo at 7:43 PM on September 16, 2009

I've noticed that aftermarket/replacement rotors seem to rust more than the ones that came from the factory. But I drive often enough that it rarely causes a problem.

The only thing I can suggest besides trial and error is to take the cars to a carwash every now and then and spray the snot out of the wheel areas and the undercarriage in general. This will remove built up snow, salt and dirt that not only corrode, but retain moisture. Kinda like how dirty deck furniture seems to not dry as quickly as clean.

I wouldn't spray anything on them. Although I would see if the shop can spray the non-working surfaces of the calipers with some high-heat spray paint. Might knock down some of the damage or slow the process.
posted by gjc at 7:54 PM on September 16, 2009

I forgot the other thing. One thing that works for me when the brakes start not feeling right is to do a couple of really hard stops, from like 70 to 30, and then drive long enough to let them cool back down. I'm sure it increases wear, but it seems to make them "feel" better for a while.

Another thing to consider is whether the emergency/parking brake is causing some of the issue. If it keeps the main brake shoes closed, that part of the rotor won't rust as much as the rest. Over time, the various random un-rusted sections could cause the brakes to feel lumpy.
posted by gjc at 7:58 PM on September 16, 2009

If the mode of failure is rust due to salty water on the moving parts of the brake calipers, which I'm guessing it is, what you'll need to do is inspect the calipers frequently, replace any damaged boots or other bits of rubber that serve to keep water out, keep everything greased up nicely and replace parts that can be replaced (slider bolts, etc.) as needed. You will also want to make sure your parking brake cable is moving freely (water can get into the cable housing and freeze it in place or rust it into place). If you can keep the calipers from seizing, then your pads won't wear out quickly and your rotors should be OK (they get rusty pretty quickly, but the rust comes off quite quickly when you brake).

If you are only driving 100mi per month, you might find that joining a car sharing organisation would be cheaper and far less hassle.
posted by ssg at 8:25 PM on September 16, 2009 [1 favorite]

If this is the first time in 16 years that the calipers have been replaced, I'd say they've lived a full life. Pads and rotors are a wear item, no matter what climate you live in.

The rust that appears on the rotors is harmless surface rust. It goes away as soon as you touch the pedal once when driving.
posted by hwyengr at 9:48 PM on September 16, 2009

Best answer: Just accept that there is no easy way to prevent rust in that climate other than a garage. You are regularly blasting a bunch of metal parts with a mixture of salt, sand, and water, then letting it sit through repeated freeze and thaw cycles. It's about the worst possible environment for a mechanical device.

I say you just keep on doing things like you have been, knowing that the new brakes should last many years even without constant care. As hwyengr points out, 16 years is a pretty good run for those calipers.

Disclaimer: Subaru driver and survivor of many Wisconsin winters.
posted by Max Camber at 10:24 PM on September 16, 2009

The amount and speed which the brake parts rust would depend on what they are made of, more specifically the amount of iron in the brakes. I would hazard a guess and say that different makers of brakes have different iron "makeups" in their products. Another brand may rust faster or slower than what you had previously. But that said, driving 100 miles a month isn't enough to keep the rust off.

FWIW I too, would not be spraying anything on my rotors.
posted by Taurid at 11:06 PM on September 16, 2009

Don't spray anything on your rotors. It'll create a layer of material between the pad and the rotor that will, depending on what you're spraying on there, prevent the brake from, you know, braking, gunk up your pads as it comes off the rotor, or both.

I think your best option is more thorough cleaning of the undercarriage, or just to drive it more.

Your situation reminds me of a coworker's 2004 Subaru WRX. He almost never drives it, as he and his wife work with me at the same site and so commute in her RAV-4. In four years of ownership he put less than 20,000km on the car, and one day last year it just wouldn't start - the WRX had been sitting so long in his garage that the battery had died. Due to the car's fancy alarm system, it wasn't just case of getting a new battery, though. He had to pay $$$ to get a Subaru technician to come out and reset the alarm and immobilizer. When my mate asked what the best way was to prevent this from happening again, the tech looked at the odometer, and the logs that indicated that he'd owned the car since new, and suggested that as my mate had made a rather serious financial outlay for a rather fast car, that maybe he might think about actually driving it from time to time.

I've mentioned that, if he can't find the time, this is a service that I'm more than willing to provide; I'll quite happily keep the battery charged in his car via 200km runs through the Adelaide Hills every couple of weekends (it's what mates are for), and I won't ask for anything more than the cost of fuel (and maybe lunch) to do so. I am sorry to report that at the time of writing he has yet to take up my very generous offer...
posted by MarchHare at 11:18 PM on September 16, 2009

Hose off your wheels every night.
posted by Civil_Disobedient at 5:50 AM on September 17, 2009

Response by poster: Thank you all for your responses... I get the overall impression that in fact there isn't anything aside from regular driving and washing there is very little to be done that will prevent rust formation. Rather I can only prevent it from accreting. Sigh.

I'm not sure if these are the original calipers or not. I've had the car since 2000, so they are at least 10 years old. Indeed, a good run, and these replacements will likely outlive the transmission. ( I just don't want to have to repeat this on the front if possible)
Garaging really isn't an option. Nor is washing it down every night. While car-sharing is nice in theory, in practice, no. I don't use the Subaru to just drive around from point A to point B... It is used for hauling bikes or furniture around or treacherous winter driving. Car sharing cars do not offer this utility.

In Subaru we Rust.
posted by Cold Lurkey at 6:55 AM on September 17, 2009