brake system questions

[georgeramos]

I just put new calipers on the rear but did not have a chance to bleed the system before driving.

When the system is properly bled and you depress the brakes does the piston (Rears) rotate out then back in? If not bled will it just go out and stay out? That seems to be what has happened here...there is a lot of wheel drag.

So when Im ready to bleed the brakes I am assuming i will have to re insert the pistons by rotating them in...

Does this all sound correct?

Thx and sorry for the dumb questions

[So Cal Mark]

they shouldn't be dragging, with or without air in the system

[azruss]

yes, on the rear calibers, the piston needs to be screwed back in. The piston has a slot for doing this. It is important to retain the orientation of the slot.

[georgeramos]

Are there any typical reasons why they would be dragging? When i pull up on the e brake handle so far it has no effect so i had assumed it was too loose to be causing the drag but might that be incorrect?

When i say drag i mean when i turn the rotor by hand it does not spin freely. It spins but there is some effort needed. When i removed the calipers i had to use a wood block and a mallet as i could not get them off by hand. It might be time for me to let a pro step in despite the relative "ease' of the brake system

[TStark]

Maybe your sliders are dry and not letting the caliper slide

[So Cal Mark]

if the hand brake doesn't work the rear calipers may not be assembled correctly. We've found a high percentage of production rebuilds that are assembled incorrectly. It's easier to put them together incorrectly than it is to get it right, so I imagine production rebuilders that aren't familiar with them get them wrong

[AndyVAS]

When the system has fluid and is properly bled then the pistons will extend when you depress the pedal. When the rears extend, they automatically slide down the internal parking brake screw. Releasing the pedal simply stops applying pressure. The pistons don't really retract. Dragging after pedal release tends to be from the system holding pressure after release or from the caliper not moving properly.

Remove the wedges and check them, the calipers, and the brackets for signs of damage. If you didn't change the hoses, look them over for any signs of cracking. If the outsides look bad then the insides do as well and you may have the rear hoses acting as check valves and holding pressure.

[So Cal Mark]

actually, the pistons do retract. The resiliency of the o-ring on the piston causes the pistons to retract slightly otherwise you would have dragging brakes

[georgeramos]

Got the calipers spun and the system bled and have a good firm pedal but there seems to be a slight scrape of the brakes i can hear when i let off the gas (and its quiet) and am coasting for example. The odd thing is if i feather the brake the sound stops.

I originally thought brake shield got bent and was rubbing on the newly installed wheela but that would not stop.

Any thoughts?

Thx

[Nitrate]

A bad brake hose can cause the caliper not to release. The internal passage can be so small it can flow one way but not the other. The exterior can look brand new. It has no bearing on what the internal condition is. RB

[klweimer]

Is your e-brake working correctly now? Can you pull it up 2-3 clicks before it starts to tighten up? If all that's OK, take the car for a ride and see if the rear brakes are heating up (are they hotter than the front brakes?). If not, I'd call it good and see if the noise goes away after a while.
Kirk