How badly can you wear out your rotors?

[Kwhistle]

So my newly (1.5 months) acquired 98 OBW had a rattling driver side front brake pads. Bought hardware kit, took it off to replace it, and brackets just weren't there. My only guess is that whomever had it before was fixing it with junk yard parts.

 

The brakes are as quiet as quiet gets, but... the pads are worn out unevenly, the inside one has about 20% left, the outside about 40%. What I found more concerning is that rotors seemed a bit on a thin side, and there was a ring of rust around that ring on the inside with holes for bolts. That rust ring is about 1/3 inch higher than the rotor surface, and it eats into the pad. The other pad has the same problem with a rust ring around the outside diameter of the rotor.

 

I would really rather not change it just now unless I have to--don't have the $125 or so that it would take for new decent rotors and pads. So how dangerous is it? Could I go 2-3 months with these pads/rotors?

[john in KY]

I would think so. Since not making that horrible screeching noise, still have some service life.

[89Ru]

Spec is 22mm width on the rotors. Pads can go down to about nothing but metal backs and still seem fine but you're taking risk especially on the fronts. 2-3 months for me is nothing, mostly highway driving...

 

Rust ring on the outside diameter of the rotor surface is common on rotors of this age and indicates either you need to turn the rotors or replace soon (much discussion on that topic on turning $$ vs. new). Turning probably won't completely remove the rust rings either...A local machinist here won't turn a rotor past its discard spec, says you might be the one behind him

 

I'm not picturing the 1/3 inch higher ring...but it doesn't sound good.

 

Any warping? That's the main reason rotors get replaced, too little metal to dissipate the heat and they warp, cause brake fade, etc.

[574-240sx]

pad wearing unevenly could be caused by weak calipers, sticky slide pins, crappy pads, etc. Best bet is to check the pins and see if they are binding up, sticking, froze, etc. Clean regrease pins or you may and to do a new pin/boot kit or even replacing the pin/caliper brackets with a new/remaned unit. As for the rust lip on the outside sometimes that just for weathing and in some cases cause a noise. I have also seen really cheap rotor no being proper diameter too cause a small rust lip on the outer diameter of the rotor. You should be fine for a few months but I would save for new rotor and pads.

[idosubaru]

rust rings are common - you almost have to have them on the rotors. basically the entire rotor is going to rust except the part in contact with the wheel and pads. if it's contacting the pads it should not be rusty there - it's impossible actually as the pad would wear the rust off immediately as soon as it started to form - the same reason that rotors stay clean and rust free on all the other millions of cars on the road. you said the "bracket is not there" - well that's impossible if by bracket you mean the "caliper bracket". a picture might help here.

 

in general though you're fine, just keep driving it if the brakes work. you'll just eat through rotors fast. i've seen guys running rotors that were rougher than sand paper - just chewed up metal. pads just wear really fast, but they'll work fine.

[EVOthis]

If you really think of things...Even when your Metal to Metal the car will stop... needless to say its a hell of a gamble and a dangerous one at that....I would most definitely replace your pads and rotors as soon as possible.... " will my car stop?" ...Is just something I really would not like to think about when I hit my brake pedal... But the answer to your question should you be ok for 2 or 3 months?...I would think so but as said I personally wouldn't take the risk...

[Kwhistle]

Thanks for all the replies. As far as what I meant by "brakets", it's those that you get in "brake hardware kit", the metal inserts that go on top and bottom of the pads. Mine were missing on the driver side (don't know about the passenger, but those don't rattle), which I thought was really strange.

 

What really picked my attention is that the inner diameter rust ring is touching the pad, and leaving a bit of a wear mark on the pad's edge. My only guess is wrong rotor side from a junk yard--these are double calipers and from my research require rotors of larger diameter.

 

Here's a diagram of the outer pad, with red mark being where it started wearing out by the inner rust ring.

The inner pad has the same patten only on the outer part of the pad. I don't know if it could by just wrong rotors and they didn't machine them after removing from another car, or if the rotors are just too worn out and to the point where the (reinforced?) inner ring starts to eat into the pads. If I were to estimate, the normal-looking part of the rotor, where the pads are is between .7 and .8 inches.

[89Ru]

Not all aftermarket brake pads come with the noise reduction pad back shims that you are missing...oem pads come with new shims and end clips plus grease.

 

uneven wear as you are experiencing can be caused by the pads hanging up on the end clips...when you replace, wire brush the caliper bracket, plenty of rust in there, I've seen inner pads with the exact wear pattern you are seeing, below the red will eventually be bare metal.

[Qman]

My take on this is as follows...

 

Brakes are critical! If there is an issue it must be repair immediately. For your safety and the safety of those on the road with you.

 

The mechanical side sounds like the pads have been replaced a few times without turning the rotors. Fronts usually have enough material to be turned a couple of times. I think it would be a good idea to go through your brakes considering you do not know the history of them. And, considering their present condition.

 

MAke sure that you clean and regrease the slide pins and slide bolts. That is the number 1 reason for brake issues on the front of most Subarus.

 

And the machinist also has more than you behind him to worry about when turning drums and rotors. If he turns the rotors below minimun and there is an accident brake related or not. He wil become liable. No business owner is going to risk his livelyhood to save you a couple of bucks.

[Fairtax4me]

If it gets thin enough you can end up with this...

 

But that's an EXTREME case of worn out. That was caused by the rotors and pads getting too thin causing the caliper pistons to jam. Rather than retracting back into the caliper they dragged on the rotor, causing uneven wear and eventually wearing it so thin the braking surface of the rotor was severed from the hub.

 

From what you've described I think you'll be OK to let it slide a few months as long as you're not driving the car long distances.

[johnceggleston]

it sound like the clips that the brake pads ride in are missing on one side and this is letting the pad move around and causing it to wear incorrectly. i have never seen brake pads in a caliper without the clips top and bottom. i think this is VERY DANGEROUS, mostly because i just don't know what might happen.

 

buy pads and clips for that side at the least, both sides would be better. even cheap, 18$ pads with clips would be better than no clips. you can re-assess in the spring.

 

or, buy as much insurance as they will let you buy.