Brake Drama - Caliper Adjustment Needed?

[MazdaSpeeder]

So, I did rear rotors and pads a month or so ago, and all has been well. However, I drove my car the other day after leaving it to sit for 10 days, and of course the surface of all my rotors had a light coat of rust. I ran the car for a day or so and noticed that one of the rear rotors has all the rust scrubbed off by the pads, while the other has quite a bit still on. I'm thinking that I may need to adjust the allen screw and bring that pad a little closer to the rotor.

I suppose it could also be seized, but I lubed the crap out of the slider pins when I took it apart, and the piston retracted and extended with no issues then. I have noticed nothing to indicate that the caliper is frozen...the ebrake holds well, the car doesn't pull under hard braking, and the rotor is not abnormally hot or cold after hard driving.

I just figured I would post this to get opinions. I'm a little gunshy on the allen adjustment since I stripped it on on another caliper and had to buy a whole new caliper. Feel free to chime in.

 

[thecrash91]

i would also like to know this, because my back pads have not made full contact in quite some time and the rear rotors look like s***. hoping i dont need to calipers. also one of my fronts is a little seized down is there a way to get rid of that?

 

[MazdaSpeeder]

You might be able to disassemble, lube the pins and get it going again. If the piston is seized, you need a new one, though fronts are not hard to change.

 

[thecrash91]

what shall i lube with, wd40, 2 cycle oil, or what

 

[flash75]

You can buy caliper/brake grease at most good parts stores. You need something that
will not run off when the brakes get hot. WD 40 is not a good lubricant for anything. Wheel bearing grease should also work. I used Versachem Synthetic caliper grease for my recent brake service.

Use grease on the slider pins/bolts and perhaps a little on the pad shims. Do not use
grease to free caliper pistions. Either rebuild or replace the caliper if the piston is binding.

Clifton

 

[GTRay7]

You can buy caliper/brake grease at most good parts stores. You need something that
will not run off when the brakes get hot. WD 40 is not a good lubricant for anything. Wheel bearing grease should also work. I used Versachem Synthetic caliper grease for my recent brake service.

Use grease on the slider pins/bolts and perhaps a little on the pad shims. Do not use
grease to free caliper pistions. Either rebuild or replace the caliper if the piston is binding.

Clifton

Do NOT, under any circumstance, use any petrochemical product to lube your brake parts that make contact with rubber (primarily the slide pins) petroleum products will cause the rubber boots and dampers on some slide pins to swell thereby causing those parts to sieze. Silicone caliper lube is all that you need for all of the sliding parts. The pads can be lubed with brake specific moly lube. Only lube the contact points and NOT the friction surface.

Ray

 

[MazdaSpeeder]

Okay, back on topic and some new information. Here's the deal...one of my rotors looks buffed to a mirror shine (the one I suspect is fine) and the other doesn't look bad, but it's not near as shiny and doesn't have the regular surface pattern of the other. I have been feeling the rotors when I finish driving, and it seems like the one that I think has an issue is cooler.

Here's the thing...it's not like one is hot and the other is cold...one is just a little bit hotter than the other. Rolling each of them yields no definitive results.

So the question is this: would a slightly misadjusted pad account for the differing wear patterns on the rotor? Or would it be close enough that it shouldn't matter. And if it's not a matter of an 1/8th of a turn of the allen gear, then what is causing this? I wouldn't replace the caliper over this, but if this issue is as a result of the caliper wearing out, then I suppose I should be looking for a caliper eventually. Thoughts?

 

[CheeseHelmet]

Okay, back on topic and some new information. Here's the deal...one of my rotors looks buffed to a mirror shine (the one I suspect is fine) and the other doesn't look bad, but it's not near as shiny and doesn't have the regular surface pattern of the other. I have been feeling the rotors when I finish driving, and it seems like the one that I think has an issue is cooler.

Here's the thing...it's not like one is hot and the other is cold...one is just a little bit hotter than the other. Rolling each of them yields no definitive results.

So the question is this: would a slightly misadjusted pad account for the differing wear patterns on the rotor? Or would it be close enough that it shouldn't matter. And if it's not a matter of an 1/8th of a turn of the allen gear, then what is causing this? I wouldn't replace the caliper over this, but if this issue is as a result of the caliper wearing out, then I suppose I should be looking for a caliper eventually. Thoughts?

If the caliper were seized, it would probably be hotter than the properly working one (because the pad is always touching the rotor). I think you're right about turning in the allen gear.

 

[wildo]

To my knowledge, the allen bolt simply positions the caliper side pad towards or away from the rotor. This is important because the cable-driven hand brake only has a short movement. However, the hydraulic pressure from the brake system should have no problem pushing the piston a large distance (relatively speaking). As soon as pressure is applied, the caliper piston should move the required distance to make contact with the rotor. The point being that the allen bolt should really only affect the hand brake usage, not the foot brake usage. Even so- it's certainly not hard to check that it's set right...

I could also see the thought that since one piston (of the back two) has more distance to travel than the other- then less overall pressure will be exerted on the one side with more distance. However, we can be sure that:

1) There is more than sufficent pressure to move the piston all the way to the rotor, and continue to exert pressure on the rotor
2) Fluid distributes pressure evenly throughout it's container. So you should, in theory, be getting the same pressure applied at both sides.

The question may be if the caliper is properly doing it's job as that fluid pressure is applied. Sounds like the one may be slightly weak. Or maybe you just have a bad set of pads on that side, where they aren't as effective as the other side. Those are my thoughts...

 

[CheeseHelmet]

Perhaps there's air in the line of weaker caliper.

 

[MazdaSpeeder]

To my knowledge, the allen bolt simply positions the caliper side pad towards or away from the rotor. This is important because the cable-driven hand brake only has a short movement. However, the hydraulic pressure from the brake system should have no problem pushing the piston a large distance (relatively speaking). As soon as pressure is applied, the caliper piston should move the required distance to make contact with the rotor. The point being that the allen bolt should really only affect the hand brake usage, not the foot brake usage.

This is what I thought.

Perhaps there's air in the line of weaker caliper.

Could be, although that would be odd since I bled the line on the side with the caliper that has not been having a problem. All this to say that I am not sure I want to mess with the allen gear either...I stripped one once (hence the new caliper) and I don't want to make another $80 mistake.