Disc Brake Maintenance

Redoing your brakes is one on the simpler auto maintenance tasks, especially if your car has disc brakes all the way around.

That being said, keeping your brakes working is pretty important, so it's well worth the extra time spent to do the job right, rather than stopping at simply throwing new pads on and calling it a day.

I've probably redone the brakes on 4 or 5 vehicles at this point, and I've learned something new each time.

1. Brake Pads. This is the most basic step of brake maintenance. Brake pads are usually equipped with a metal clip the creates a high pitched sound when the pads are worn too thin. This signals that they should be replaced before they damage the rotors, or even the calipers. I inspect my break pads twice a year when I swap summer and winter tires, so I usually replace them before they get that worn.

When installing new brake pads, make sure they slide freely in the caliper bracket. The new pads should come with new metal shims and packets of lubrication for the metal to metal contact. It is critical that the pads slide freely in the rotor. If they do not slide freely, the brakes will not release properly after braking. The calipers in a Subaru I used to have always fit very tight. The first time I did the brakes, I filed the "ears" on the pads down to get the right fit. The second time around I used a file on the caliper bracket itself. I suspect that after 17 Minnesota winters, the calipers had enough rust built up that a wire wheel just wasn't good enough. Taking a file to caliper until bare, shiny, metal showed did the trick.

2. Rotors. This may not be necessary. If your braking is smooth and the rotor surface shows no signs of rust, pitting, etc., then your rotors are fine. Usually rotors are simply squeezed between the wheel and the hub by the lug nuts. If they've been on there a while, they can take quite a bit of convincing with a hammer. Avoid this on the new ones by coating the mating surface with axel grease or anti-seize. On my wife's Ford Flex, the rotor was held to the hub with a flat-head Torx screw. Quite annoying since I didn't have the right size bit and had to borrow one from a neighbor. According to 'the internet' this is just used during assembly and isn't necessary. I left it off with no ill effects.

3. Grease the caliper pins. These are the two pins that attach the caliper to the caliper bracket. Clean these and replace the grease and rubber bushings every time you replace brake pads to avoid a seized caliper. Make sure to use a non-petroleum based lubricant, as the petroleum will degrade the rubber (yes, I know this from experience). Don't reuse rusty pins. They are cheap and it isn't worth the cost of ruining a new set of pads and rotors if one freezes in the near future. I've tried cleaning and reusing rusty ones before, and they were already getting sticky just six months later.

4. Brake Lines, Bleed & Flush. In my Subaru, I replaced all my brake lines with braided stainless steel. I was amazed at the difference it made in "brake feel." My brakes felt very spongy and this was the only fix (new pads and rotors did not help).

Bleeding.
1. Do not ever let the reservoir run dry, as you will suck air into your master cylinder. This is one mistake I've not made, but I'm told it is not good.
2. Keep caustic brake fluid away from metal on your car or tools. It will rust steel almost instantly. I purchased a brake bleed kit just for the plastic tubes that let the brake fluid drain safely away.
Use the right brake fluid. Check your manual to see if it takes DOT 3 or DOT 4.
3. Bleed brakes in the correct order. Start with the wheel furthest from the master cylinder. Once that line has been bled there will be no fluid flowing past or down it when you bleed the other lines. If you were to bleed a "middle" branch first, you could theoretically pull more air into while bleeding a "later" line.