Brake Piston Question

[AJII]

If the caliper is off the rotor and just hanging there, and you press the brake pedal, how far should the piston come out of the caliper?

I ask because on my truck, the brakes have never been right. When I bought it, only the insides of the rotors were worn, outsides looked brand new. So I replaced the calipers, rotors, pads, master cylinder, and powerbooster (truck had been sitting for ~8 years)

When I got it all together, I wanted to see if it all worked as it should, and when I pressed the brakes, the piston doesn't push out a whole lot. Should it pretty much come all the way out as if the pads were worn completely? Or would it take a lot of pedal pumps to get it to that point?

Sorry for the long post, but brakes are important

 

[davbell22602]

The piston should come out and touch the inside of the rotor with inside pad while the caliper itself pulls in toward the vehicle pressing the outside of the rotor with outside pad. Thats if you have a floating caliper.

 

[Irishman999]

Dont press the brakes when the calipers are off, its going to shoot the piston out. They wont move out alot, they are all about applied psi in short strokes, as the pads slowly wear and you push the pedal thousands of times more fluid moves in and the pistons move out slowly over time and wear.

Did you replaces the brake hoses?

 

[AJII]

Dont press the brakes when the calipers are off, its going to shoot the piston out. They wont move out alot, they are all about applied psi in short strokes, as the pads slowly wear and you push the pedal thousands of times more fluid moves in and the pistons move out slowly over time and wear.

Did you replaces the brake hoses?

So should the piston shoot out? Or no? Your answer is kinda both ways haha.

Because I was expecting the piston to just shoot out, but it just kind "pumps" a couple millimeters and seems to retract back into the caliper. I just want to make sure all is good before I screw up my new calipers

And no, didn't replace the hoses. Probably will now that I think about it though.

 

[Irishman999]

So should the piston shoot out? Or no? Your answer is kinda both ways haha.

Because I was expecting the piston to just shoot out, but it just kind "pumps" a couple millimeters and seems to retract back into the caliper. I just want to make sure all is good before I screw up my new calipers

And no, didn't replace the hoses. Probably will now that I think about it though.

I mean dont pump it with the brake off, There is nothing to keep the piston from coming out after a certain point.

Usually if a rotor is only wearing on one side its caused by the guides that the caliper rides on being screwed up and not letting the caliper float, if all that **** is new I am not sure what would be causing it.

 

[davbell22602]

The spindles might need filed/cleaned where the caliper sit in between when mounted on rotor.

 

[oneluckypops]

The spindles might need filed/cleaned where the caliper sit in between when mounted on rotor.

Dave "Spindles" would not have anything to do with it, Perhaps you are refering to the Knuckle.

It is NOT uncommon for the inside pads to wear more then the Outer pad, EXCESSIVE wear on the other hand is different.
Anytime you do a break job you should clean the caliber slides, then coat them with anti seize, also clean the Knuckles. You want the caliber to be able to slide NOT just the Piston.

 

[davbell22602]

Dave "Spindles" would not have anything to do with it, Perhaps you are refering to the Knuckle.

It is NOT uncommon for the inside pads to wear more then the Outer pad, EXCESSIVE wear on the other hand is different.
Anytime you do a break job you should clean the caliber slides, then coat them with anti seize, also clean the Knuckles. You want the caliber to be able to slide NOT just the Piston.

Thats what I meant. Knuckle

 

[AJII]

Think everyone is missing the question.

Everything is now new. How much should the piston come out if it is off the truck and I pump the brakes? A millimeter or so with each pump? Or should it come out pretty far?

Trying to make sure everything is now working A OK.