Brake Drag on rear question

[wisel1]

Hello All. I have what may seem to be a basic question but this is my 1st build so bare with me. I have a rebuilt 8 inch rear axle with the std new 11.5 inch mustang calibers and new pads. I don't have wheels yet but I notice some drag when spinning the rear roter. with my hands The brakes do engage when pressing the pedal and they do release but the caliber is still slightly touching the roter when released thus producing the drag. I am not sure if this is normal or not. Someone told me that they will loosen up once I start driving and they"bed". balance bar is released (no issue there) and e brake is disengaged. I wanted to check before I go pulling the calibers off and replacing them. Again, holding the lugs, I can turn them but its definately got some drag on the pad. Does this sound normal? Should I change pads? Drive and see what happens? Any opinions welcome. Thanks

[Fixit]

Let it go. The new parts need to get to know each other for a few miles. If the brakes clamp hard, then when released you can spin the rotor/wheel assy by hand with nothing but a little "scuff" worth of drag you're good. Run it and let things bed-in.

[CraigS]

Let it go. The new parts need to get to know each other for a few miles. If the brakes clamp hard, then when released you can spin the rotor/wheel assy by hand with nothing but a little "scuff" worth of drag you're good. Run it and let things bed-in.

I agree. If you can spin it by hand just using the lugs or edge of the rotor you are fine. Don't forget, w/ the lim slip unit you are actually spinning both wheels when you turn one, so the drag feels worse than it actually is.

[wisel1]

- yes they clamp hard when pedal pressed and when released I can turn them by hand (with some effort). I will give it a shot and see if they loosen up. thanks for the help.

[initiator]

I was concerned about the drag and audible scraping noise, too, until I remembered that I'm also working the (dry) differential gears. In my case, the drag is mostly the diff with the sound coming from a light touch on the calipers.

Initially I had more grab, but then found that I could rotate the brake piston so the pin aligned with the relief in the back of the brake pad - that gave a little extra clearance and reduced the effort considerably.

All this assumes you've got your shims/washers installed to center up your caliper properly.

[Fixit]

Good point by Initiator... Just did a brake job on the rear of #2 kids Taurus. We won't go into how much of a Mutha it was to crank the pistons back in... but there is a "Gotcha" with them.

Most rear disc brake setups use a mechanical "screw jack" mechanism on a lever to crank the piston out (thus clamping the pads to the rotor). When you release the mechanical mechanism, the "screw jack" allows the piston to pull back slightly.
(This sometimes part of the wear adjustment procedure for rear discs! I'm using Caddy Eldo calipers on the rear of my El Camino, and I have to pump & release the E-brake a dozen times every few months to get the rear brakes adjusted).

Most rear caliper setups have slots/recesses cut into the pistons that register into pins on the backs of the pads. If the pistons and pads aren't "clocked"/aligned together you'll be fighting nearly an 1/8" of freeplay that should be there, or the "self-adjuster" mechanism won't work right. Get the pads & pistons "clocked", and lever the E-brake a zillion times to set the initial clearance.