Hey guys, I am in the process of putting stock brake back on the front of my fourth gen, but in the process I am painting all of my calipers black. So I had the rear calipers off last night and the rear left side had odd brake pad wear. One side of the pad (right to left, not front to back) was worn about twice as much as the other side and there was a hairline crack in the pad material going east to west. Both of my rear calipers are new rebuilt units from Advanced auto. Is this a sign that I have a stuck slide pin? How tight are the slide pin bolts supposed to be tightened? I don't use a tq wrench on them and I usually tighten them down pretty tight. Both pins pulled out easily when I had the calipers off. Any ideas on this?

I have a spongy brake pedal and from searching around it looks like a stuck slide pin could be the culprit, that's why I am checking into this.

 

Spongy breaks as in you didnt bleed them correctly or its spongy and you dont know why? I would say your answer is in your post, you should always use a torque wrench on bolts that have a specific spec, esp breaks and manifolds and the like.

 

Like spongy all of the sudden. The car was braking awesome, then one day it was spongy. I replaced the master cylinder, and there was no change.

 

Sounds like you already know the answer. Unbolt your calipers and check for smooth movement of the slide pins. Clean and regrease them if you have any doubts. Torque on the caliper bolts have any effect on pedal feel or sticking pins, but you definitly don't want them coming loose or snapping.

Sticking pins can cause spongy feel due to runout in the caliper forcing the piston into the caliper, rather that the calliper moving lateraly with the rotor runout.

 

The bolts only need about 20 ft lbs, its not much.

The slide pins should move freely. If in doubt remove them and see if there is enough grease or any rust build up. If they are rusty you need new boots. Also the pins with rubber inserts should be in good shape. If they are torn they can stick.

 

what? good n' tight isnt a torque spec?

 

The rear pad has a "pin" on it this needs to. E indexed to the caliper piston or you will get a "spongy pedal" and uneven wear
The kinda like plus looking thing that's used to turn in the piston has an opening big enough for the pin to fit inside make sure there both indexed properly and report back

 

The uneven brake wear can be from a cupple of things. The sliding guide pins can be rusty or dry, The guide pins need to be grease up at all times.The guide pins need to have good rubber boots that are not letting any dirt or any water on surface of the pins, when your tapping the brake pedal to stop the caliper piston pushes out on the brake pads and the other half of the caliper slides on the pin to close in on the rotor making a stop. If the pin has rust sanded it down and clean it up and grease it up. It's good to go. If the caliper is seized you can see if the piston comes out fully or if it comes out half way. The both rear calipers can be compared to see which one sticks out further or you can check which side ate up the brake pad more. The side that ate up more brake pad is the normal side. There is a special tool that you use to seat the piston back into it's housing turning the piston counter clockwise to bring it back in or clockwise to bring it back out of the housing use pb and sand it all around and remove the rubber boot that's on the piston get better access. This should help with the seizing piston. If you want you can take apart the whole caliper and do a good rebuilt.

 

IIRC... If the outer pad is wearing faster it's the pins!!! If the inner pad is wearing it's a sticking caliper piston..... You can buy a rebuilt caliper from NAPA or order a hardware kit and rebuild kit and do it yourself!

 

The rebuilt calipers are so cheap...why bother doing it yourself? (I know, I know...self gratification )

 

It's not the inner or outer pad....both the front and back (on either side of the rotor) are wearing the same. One side (the same side on front and back pad) is wearing faster than the other. As if only one side of the pads is being pushed down when you hit the brakes.

 

I'm having a hard time understanding what you're trying to say. Picture?

 

So the inner and outer pad are both tapered? Leading edge thinner than trailing edge or visa versa?

 

I think he is saying, looking at a pad with the split in the middle, 1 half, right or left half, is wearing faster as if the pad is being compressed unevenly. Correct me if Im wrong.

 

I'll take on when I take my wheels back off.

yes, this sound right....I am bad at explaining things

See above

 

Make sure it's not a sticking E-brake cable on that side that's wearing faster!