Dragging Rear Calipers

I've got a dragging rear left caliper at a minimum and it looks like the rear right also has an issue. Looking for some advice on next things to do

About 9 months ago, I had a problem with what I thought was the e-brake being overtightened and dragging. Got it loosened up and the dragging went away. Then a month ago it felt like the rears weren't fully releasing when I happened to use the e-brake (I usually leave it in gear and try to avoid the e-brake altogether) but after some jostling of the car, over some rr tracks, it seemed to go away. Last straw was earlier this week when I drove home a mile from a car meetup and again the car would slow down in neutral. By the time I got home, I could feel some pulsing as if the rotor was warped and the left rear had heat and burning brake smell.

So, up on the lift. Checked the ebrake cable and it was loose enough not to be activating the brakes.
Wheels off I could rotate the right rear rotor back and forth 10 degrees or so by hand. The left rear rotor could not be moved by hand

Left rear (the one that was hot and burning) removed the e-brake cable altogether, loosened the inner 4mm hex screw a few full turns (counter clockwise). Loosened the outside 13mm nut + 4mm screw a few turns and got a little liquid dribbling out. Then I could push back the outer piston by hand and remove the pad but couldn't retract the inner piston. Wear was extremely uneven.

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So for the left side, a couple of questions:

1) Seems like next step is a caliper rebuild? Or is there something else I should check that could be causing this?
2) With the pulsing, that would mean the rotor is warped and I should replace the rotor. Or do I check something before doing that?


So then I figured I'd check the right rear even though it wasn't hot or smelling to get a comparison. Removed the pins and found also very unequal wear.

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In this case I need some help with the adjustment screws for the passenger/right rear to see if I can get the pistons pushed back.

1) For the inside 4mm adjustment screw, I'm not sure if it unscrews clockwise or counter clockwise. Turning firmly either direction results in no movement and I don't want to force it and strip out the screw
2) For the outside 13mm nut + 4mm screw, similar problem. If use a socket to turn the 13mm nut, it moves a bit but the resistance is the same both counter clockwise and clockwise and I don't want to force it. I could try putting the 4mm hex wrench in the screw and then a 13mm crescent wrench in the nut to turn them against each other but would help to know if I'm going ccw or cw with the 13mm nut.

Once I do that, is there something else I would check in the right caliper or are we also looking at rebuild there?

 

Two updates:

I didn't loosen the inner adjustment screw properly, leading it to actually not be loosened at all. That could be the reason the inner piston won't release. Need to try that again tomorrow.

For the outside adjustment screw, the Porsche 914 thread had a good suggestion and picture for creating "Special Tool VG13MM" that I'll try tomorrow.

http://www.914world.com/bbs2/index.php?showtopic=90625

 

It stopped being beastly hot in Texas so back to this project

After trying to adjust the inner adjustment screw and releasing all of the pressure on the bleed valve and having no luck getting the inner piston to retract, decided to remove the rear calipers altogether and get them rebuilt. Using this thread to record the process and notes compared to the other threads on caliper removal.

Key tools were Snap-On flare wrenches. Internet said they were the best and the only ones worth a damn. I will say they were excellent for the job. I was on the verge of damaging the hard-line nuts when using standard box wrenches.

Snap-On 9–11 mm 6-Point Metric Flank Drive® Double End Flare Nut Wrench RXFMS911B
Snap-On 15-17 mm 6-Point Metric Flank Drive® Double End Flare Nut Wrench RXFMS1517B

Important references:
https://www.birdman308.com/service/caliperrebuild/index.html

Did the rear right caliper first.
For the right caliper, I could access the caliper bolts without removing the lower-hard line. I disconnected the lower hard-line connection to the caliper with the 11mm flare nut wrench and left the upper connection to the brake line intact.

The lower bolt to the caliper was accessible and loosened with a 19mm socket, 3/8-1/2 adapter, and a 1/2" breaker bar. Once it was loose, then just a 3/8 drive ratchet to get it off

The upper bolt to the caliper could be accessed with a normal short 19mm socket, 3/8 extension with a little wobble, and then the 3/8-1/2 adapter and breaker bar. There wasn't much clearance so I had to put the socket on, then get the extension most of the way in, and give it some torque with the breaker and it moved. Then it could be removed with a 19mm box wrench. The box wrench had too much play to feel safe giving it the initial torque to break it loose.

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Note: I failed to properly follow the @Bird Man instructions on the shims. Don't be me.

For the left rear caliper, I had to both remove the hard line and brake line bracket. Compared to the birdman process, I didn't mess with the tabs on the bracket and removed the entire bracket rather than trying to disassemble the rear brake hose from the bracket.

Process:
Unscrew the bottom hardline connection with the 11mm flare nut wrench as far as it would go
Unscrew the top of the hardline connection with the 11mm flare nut wrench, using the 17mm flare nut wrench to hold the larger line.
Remove the hardline
Then the lower caliper bolt could be loosened with the same process as the right side

For the top caliper bolt, I still couldn't access it so I removed the two nuts holding the brake line bracket on and moved it out of the way. There are two lock-washers to keep track of.

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With the bracket removed, then the 19mm top bolt came off with just a 19mm socket and a ratchet + a mallet to loosen it up.

Capped both brake lines with plastic bags and rubber bands. Strangely the right side brake line drained a lot of brake fluid into a catch basin and the left side brake line did not drain a drop. Hopefully that has something to do with the right side being already disconnected and not a bigger problem.

After getting the calipers off, I could see the inner brake pads on both brakes. Left side inner pad had maybe 1mm remaining. Left side outer was almost new. Right side inner had zero pad left, it seemed to just be metal to metal on the brake disc. Right side outer was also almost new.

So now packaging up the calipers for rebuild.