Brakes "grinding"

Alfas have a brake regulating valve which, under light application, will allow a greater percentage of the brake pressure to be applied the rear brakes. Under heavier applications, the valve will reduce the rear brake pressure by up to ~80%. That is why you notice the noise in the rear brakes under light application. Most dirty issues with brake pads can be cured by a light sanding of the pad. One thing to keep in mind is brake pads were originally made of asbestos. Any asbestos dust created by sanding must be controlled and not inhaled. Modern lining material no longer contains asbestos but I would treat it as if it did. You only need to knock the glaze off the braking surface of the pad when sanding. I would consider a brake lining,shoe or pad, worn the a thickness of 1/8 inch to need to be replaced.

redspiderveloce said:

Ok, finally got to work on it today Tooks lots of effort, prying, and hammering (maybe not a good sign)? There was rust on the backs of the pads, as well as kind of deep circle impressions (made sliding out kinda hard). Next, I try slipping in the new pads, but I noticed that the pistons are pushed out too far for me to slip the new pads in. Is any of this out of the ordinary, and what should I do about it? Sorry for the newbie questions, I've been working on this car piece, so its time for a little learning.

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Pistons extended is normal. That's just from using the brakes. To get new pads in you'll have to push them back in.
To do that, you need:
a. The correct size end wrench for the bleeders
2. A plastic bottle with some rubber fuel line hose and some brake fluid poured in it(about 1-2 inches)
III. a C-clamp

1st. Put the hose on the bleeder and slip the hose in the bottle with fluid
2nd. Crack the bleeders
3rd. With the bleeders still cracked use the C-Clamp to push the piston back in.
4th. When you've got the piston pushed in as far as you want it, close the bleeder and remove the hose and bottle.

-Or-

a. Purchase rebuilt calipers.

Disc brakes compensate for wear of the pads by the piston extending from its' bore. The piston will need to be pressed back into the bore. Usually, I use 2 screwdrivers applying equal pressure to opposite sides of the piston. A caliper in good shape will allow the piston to slide in smoothly. When doing this, fluid will be pushed back to the master cylinder. Check the reservoir regularly. Brake fluid will damage a painted surface. You can suction the excess fluid out of the reservoir. The point of contact between the pads and caliper should be clean and lightly lubed with preferably, white lube. Usually I use a little sandpaper to clean the area prior to lubing. Use a little lube on the caliper/pad pins, too. When all is said and done i would recommend flushing the system by bleeding until fresh fluid runs out every bleeder. One purpose of the fluid is to absorb moisture. Fresh fluid protects the whole system.

AN easier solution is to grab the missus turkey baster from the kitchen drawer (when she's not looking) and suck some fluid out of the master reservior and then compress the piston back in all the way. Top off the rez when you're done with FRESH fluid. If you fool with the bleeders and don't have a good idea of what your doing, you can let air into the system or at the worst break off a bleeder screw.

The min thikcness for your brake pads is when the friction material is the same thickness as the backing plate of the pad. Make sure to check BOTH sides of each disk for thickness when inspecting.

To make it easier to remove the caliper and old pads from the rotor, try to slip a thin screw driver in between the backing place and the piston. Push the piston back a bit. This will allow the pads to slip over the ridge that has formed at the edge.

Do one side at a time so that you have a reference as to how it all goes back together AND so that you don't POP the PISTON out of the caliper on the other side.

After your done and if you feel confident that you can loosen the bleeder screws, you can then flush out the old brake fluid which should be done every 2 years or so.

Be CAREFUL with brake fluid around paint!!! It will eat the paint up pretty fast. I keep a spray bottle filled with water arounf to spritz and wipe up and spills or drips.

Go have an adult beverage to celbrate.

Good luck!

getting better

Just finished! Wasn't so bad. After replacing the master cylinder, I got pretty good a bleeding the brakes, so no air in the system. Fluid hasn't been in the car long, but once I am done with all 4 brakes, I will flush it.

Took the car for a test drive and noticed that the grinding was not gone. The car no longer pulls to the left when braking, but when turning left it makes the grinding noise. While driving straight it does not. When the brakes are applied the grinding comes back no matter what direction the wheel is turned. I'm going back in tomorrow to see if the pad is touching that center circle of the disk again, but I'm wondering what could be wrong.

Very glad to see the grinding lessen, and to drive the car again. I'm sure the neighbors aren't so happy about the loud revving engine and me locking up the tires, but maybe they will sleep through it? Anyway, thanks so much for all the help. If anyone has any idea as to what could be causing this, please, let me know.

Thanks,
Andy