After installing a fresh set of brake pads and rotors, is it normal for the pads to rub up against the rotors until they are driven on?

I just installed a set of EBC Green Stuff brake pads with AEM oversized rotors, and have NOT put the wheel back on the car and driven it yet. However, whenever I turn the rotor assembly with my hands, I am noticing some amount of resistance from friction. After compressing the caliper piston and installing the new pads, I did notice that the caliper BARELY fit back over the rotor surface.

Whenever I take the car for its first test drive, will this even itself out?

 

Perfectly normal. Disc brakes operate at what's called zero tolerance. Meaning that there's almost no space between the pad and rotor

 

So after I drive on them for a little bit the pads will back off of the rotor?

 

u should be fine

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rawNAprelude &raquo;</TD></TR><TR><TD CLASS="quote">u should be fine</TD></TR></TABLE>

I thought so... however, I am having trouble understanding how the piston in the caliper backs away from the brake rotor after being compressed? I understand fully how a hydraulic system works, and how the master cylinder and brake fluid all work to compress the piston in the caliper to move the pads onto the rotor. What I don't get is how the piston in the caliper returns away from the rotor after being compressed.

 

The system is compressed by the cylinders pushing the fluid through the lines. So the pressure created by pushing the pedal pushes it back away from the rotors when the pressure is relieved off the pedal. But just enough to where there is probably a nanometer or less in between.

 

The square cut piston seal answers your first and second question.

It has a little bit of flex, but if it's pushed too far it'll let the piston slide out and contact the rotor. That's why they'll automatically adjust themselves to the clearance that they need to be when you press on the brakes the first time after a brake job.

Because it flexes, after you release the pedal it pulls the piston back by a few ten thousands of an inch.

 

Okay, thanks guys... on emore stupid question then I swear I'm done.

If the pads are inserted slightly crooked into the calipers, will they straighten-out upon being pressed against the brake rotor for the first time?