Rear disc brakes freezing up

make sure that the calliper body is free to move on the support pins
the pins are there to allow the calliper to centralize on the rotor
if the pins are seed up then when pressure is applied to the piston the calliper is pulled sideways but then keeps that pad in hard contact with the rotor
as there is no check valve in the master cylinder for disk brakes, there may be a problem in the compensating port for the disc section that is keeping the disc brake section on

the brake calliper body that the pads are contained in slides on 2 pins to allow the equalization of pressure to either side of the disc
these pins rust up and prevent the equalization process
on most vehicles it results on the non moving pad wearing faster than the piston pad as the piston pad pulls the calliper body across but it is not free to move back
I suspect that in your case one pin is sticking and allowing the calliper body to twist slightly resulting in that wear pattern
as to the discoloration of the disc, that indicates a pad in constant contact with the disc and over heating the disc
when fitting new pads it is a requirement to do both wheels and to machine the discs to ensure true running of the disc
check that the callipers move freely on the mounting pins before reassembly

Rear Disc Brakes Pads Removal & Installation L4-2.2L (Vin F) & V6-3.0L (Vin R) To Remove:
WARNING
Ensure that vehicle is securely supported before lifting. To help avoid personal injury when a vehicle is not on a hoist provide additional support for the vehicle on the opposite end from where components are being removed. Ensure that the lift does not contact fuel or brake lines.

1. Before servicing the vehicle refer to the precautions at the beginning of this section
2. Loosen the lug nuts on the rear wheel and tire assemblies but do not remove the lug nuts
3. Raise and support the vehicle
4. Remove the rear wheel and tire assemblies
5. Drive out the brake pad retaining pins from outside-to-inside then remove the pins and retaining spring
   
   
   
   
6. Remove the brake pads
7. Inspect the following:
   • Brake pad retaining pins for deterioration or damage; replace as needed
   • Brake pad retaining spring for deterioration or damage; replace as needed
   • Brake caliper piston seal for leakage or damage; overhaul the caliper as needed

To Install:
NOTE: Never replace brake pads on one side of axle only. Left and right side brake pads must be replaced only as axle sets.

1. Install the new brake pads onto the caliper
2. Apply a small amount of silicone grease to the retaining pins NOTE: Check to ensure that the brake pads move freely in the guide.
   
3. Install the brake pad retaining spring then drive the brake pad retaining pins in from inside outward
   
   NOTE:Before installing the wheel and tire assemblies remove rust or corrosion from wheel mounting surfaces and brake rotors. Failure to do so can cause wheel bolts to loosen in service.
   
4. Install the wheel and tire assemblies
5. Lower the vehicle to the ground
6. Torque the lug nuts as follows:
   • First Pass: Torque to 46 lb-ft. (63 Nm)
   • Second Pass: Torque to 92 lb-ft. (125 Nm)
   CAUTION
   If this operation is not carried out brakes will not operate properly during initial brake applications.
   
7. Prior to operating the vehicle depress the brake a few times until the brake pads are seated against the rotor

Brake Pads
Removal & Installation
Front





3.4L front disc brake assembly









4.0L and 4.7L front disc brake assembly




To Remove:

1. Before servicing the vehicle, refer to the precautions in the beginning of
   this section.
   
2. Remove or disconnect the following:
   
   
   
   • Front wheel
     
   • Clip, 2 caliper pins, the anti-rattle spring then remove the 2 brake pads
     and the 4 anti-squeal shims

To Install:

CAUTION
Only replace brake pads on 1 side of the
vehicle at a time. Failure to use this procedure could cause the caliper pistons
on the opposite side of the vehicle to pop out requiring the reconditioning or
replacement of the brake caliper.

1. Remove a small amount of brake fluid from the master cylinder.
   
2. Install a used brake pad into the caliper and compress the caliper pistons.
   
3. Apply disc brake grease to both sides of the inner anti-squeal shims.
   
4. Install or connect the following:
   
   
   
   • Anti-squeal shims to the new brake pads
     NOTE: When replacing worn pads, the anti-squeal shims must be replaced
     together with the pads.
     
     
   • 2 brake pads
     
   • Anti-rattle spring and the 2 caliper pins
     
   • Clip
     
   • Front wheel
   
   
5. Depress the brake pedal several times to seat the brake pads.
   
6. Check the brake fluid level and top off as needed.

Rear
To Remove:

1. Before servicing the vehicle, refer to the precautions in the beginning of
   this section.
   
2. Remove or disconnect the following:
   
   
   
   • Rear wheel
     
     
     
     
     
     
     
     
     
     
     
   • 2 cylinder slide pins from rear caliper assembly
     
   • Caliper assembly from rear caliper mounting
     
   • 2 brake pads with anti-squeal shims from rear caliper mounting
     
   • 2 anti-squeal shims from each disc brake pads
     
   • Pad wear indicator plate from the inner side disc brake pad
     
   • 4 pad support plates from the rear caliper mounting

To Install:

1. Install or connect the following:
   
   
   
   • 4 pad support plates on the rear caliper mounting
     
   • Pad wear indicator plate on the inside brake pad
     Note: Install the pad wear indicator facing downward.
     
     
   • Anti-squeal shims on each brake pad
     
   • 2 disc brake pads with anti-squeal shims to the caliper assembly
   
   
2. Apply lithium soap base glycol grease to the sliding part of 2 caliper slide
   pins.
   
3. Install or connect the following:
   
   
   
   • Disc brake caliper assembly with 2 caliper slide pins
     
   • Torque to 65 ft-lbs (88 Nm)
     
   • Rear wheel
   
   
4. Depress the brake pedal several times to seat the brake pads.
   
5. Check the brake fluid level and top off as needed.

--- Removal & Installation
Front
To Remove:

1. Before servicing the vehicle, refer to the precautions in the beginning of
   this section.
   
2. Remove or disconnect the following:
   
   
   
   • Front wheel
     
   • Front brake caliper assembly
   
   
3. Make matchmarks on the disc and the axle hub.
   
4. Remove the front disc.

To Install:

1. Align matchmarks and disc onto axle hub.
   
2. Install or connect the following:
   
   
   
   • Front brake caliper assembly with the 2 bolts
     
     
     
     1. Torque to 90 ft-lbs (123 Nm)
     
     
   • Front wheel

yes, you can rent one from Auto Zone, Advanced Auto Parts, etc.

Rear disc brake pads offer better performance and are not as affected by moisture like conventional brake shoe style brakes are. Rear disc brakes are similar to front disc brakes. The main difference is that rear disc brake systems must incorporate the emergency brake system. There are two methods widely used for the emergency brake with rear disc systems. The first system is a brake shoe inside the brake disc that is actuated by the emergency brake lever. The second is a screw style actuator inside the brake caliper. When activated the brake pads are forced into the brake disc and held tightly by the emergency brake lever.
READ COMPLETELY BEFORE STARTING
Step 1 - Identify Rear Disc Brake Components
Rear disc brake assembly includes; rear brake disc, rear brake pads, brake caliper mount and a caliper mounting screw. (Note: Some vehicles do not have the rotor mounting screw.)
Step 2 - Removing the Rear Brake Caliper Mount Bolts
To replace rear brake pads and rotors the rear brake caliper needs to be removed. First loosen the rear brake caliper mount bolts and remove them. Turn counter clockwise.
Step 3 - Lift Rear Brake Caliper from The Caliper Mount
After the caliper mount bolts have been removed, gently lift the brake caliper from the caliper mount. Inspect the caliper slides; they should move freely in the caliper mount. Remove rear brake pads and hardware.

Step 4 - Removing Caliper Mount Bolts
With a socket wrench or other appropriate removal tool, loosen the rear brake caliper mounting bolts. Remove bolts and lift the caliper mount and remove it from the vehicle. Remove the retaining screw from the disc mounting hole. Tap the rotor gently to release any rust that has accumulated between the rotor and bearing hub. Lift brake rotor from wheel hub holding on tightly, using both hands. You do not want to drop the rotor.

Step 5 - Removing Rear Brake Rotor
Remove the retaining screw from the disc mounting hole, tap the rotor gently to release any rust that has accumulated between the rotor and bearing hub. Lift brake rotor from wheel hub, hold on using both hands and do not drop.

Step 6 - Install New Brake Rotor
Check the new rotor against the old brake rotor to make sure they are the same size. Clean the mating surface on the wheel hub before the new brake rotor is installed. Reinstall rotor retainer screw.
Step 7 - Reset Rear Brake Caliper
Before new brake pads can be installed, the rear brake caliper must be reset. The reset tool winds the piston back into position so the new brake pads will fit. This style of brake caliper will not compress with a clamp tool; it can only be reset with the proper reset tool.
Step 8 - Reinstall Rear Caliper Mount and Install New Rear Brake Pads
After the caliper has been reset, reinstall caliper mounting bolts and make sure the bolts are tight. Then match up the old brake pads to the new brake pads. They should be exactly the same except, of course; the old ones will be worn out. Check the new brake pads for proper fit and install any brake hardware that is required.
Step 9 - Remount Rear Brake Caliper
Reinstall the brake caliper, align brake pad hardware and reinstall caliper mounting bolts. (Note: align the rear peg of the brake pad to the groove in the caliper piston.) Recheck and retighten all caliper and caliper mount bolts. Bleed brake system to relieve any air in the system. Before driving the vehicle, push the brake pedal down and let it up slowly. This operation forces the brake pads to travel to the brake rotors. DO NOT DRIVE VEHICLE until proper brake pedal operation resumes. When test driving vehicle listen for any unusual noises during the operation of the brakes.
WARNING! Always have the vehicle under inspection on level ground, in park with the emergency brake on. Always wear protective eyewear, gloves and necessary clothing before inspection or work begins. Never crank an engine over when anyone is near the battery or engine. Always have an operational fire extinguisher close by, obey all first aid instructions in the event of an injury. Never stand in front or behind a vehicle when cranked over or running. When engine is cranked over keep hands and clothing away from rotating components. Never move a car without proper brake pedal operation.

Remove brake fluid from the master cylinder brake fluid reservoir until the reservoir is approximately 1/2 full. Discard the removed fluid.

1. Raise and safely support the front of the vehicle. Remove the front wheels.
   

1. Remove or disconnect the following:
2. Front brake caliper guide pin bolts
   

• Brake caliper by slowly sliding it up and off the adapter and brake rotor. Support the caliper out of the way with a strong piece of wire. Do not let the caliper hang by the brake hose or damage to the brake hose will result.
  

1. If necessary, compress the caliper piston into the bore using a C-clamp. Insert a suitable piece of wood between the C-clamp and caliper piston to protect the piston.
2. Outboard disc brake pad from the caliper by prying the brake pad retaining clip over the raised area on the caliper. Slide the brake pad down and off the caliper.
   

• Inboard disc brake pad from the caliper by pulling the brake pad away from the caliper piston until the retaining clip on the pad is free from the caliper piston cavity
  

To install:

1. Be sure the caliper piston has been completely retracted into the piston bore of the caliper assembly. This is required when installing the brake caliper equipped with new brake pads.
   
2. If equipped, remove the protective paper from the noise suppression gaskets on the new disc brake pads.
   
3. Install or connect the following:
   
   • New inboard disc brake pad into the caliper piston by pressing the pad firmly into the cavity of the caliper piston. Be sure the new inboard brake pad is seated squarely against the face of the brake caliper piston.
     
   • Outboard disc brake pad by sliding it onto the caliper assembly
     
   • Brake caliper assembly over the brake rotor and onto the steering knuckle adapter
     
   • Caliper guide pin bolts and torque to: 35 ft. lbs. (47 Nm) on 2002–04 models or 26 ft. lbs. (35 Nm) on 2005 models
     
   • Front. Apply the brake pedal several times until a firm pedal is obtained.
     
4. Check the fluid level in the master cylinder and add fluid as necessary. Road-test the vehicle.
   

For the rotors:

1. Remove brake fluid from the master cylinder brake fluid reservoir until the reservoir is approximately 1/2 full. Discard the removed fluid.
   
2. Raise and safely support the front of the vehicle. Remove the front wheels.
   

1. Remove or disconnect the following:
2. Front brake caliper guide pin bolts
   

• Brake caliper by slowly sliding it up and off the adapter and brake rotor. Support the caliper out of the way with a strong piece of wire. Do not let the caliper hang by the brake hose or damage to the brake hose will result.
  

1. If necessary, compress the caliper piston into the bore using a C-clamp. Insert a suitable piece of wood between the C-clamp and caliper piston to protect the piston.
2. Outboard disc brake pad from the caliper by prying the brake pad retaining clip over the raised area on the caliper. Slide the brake pad down and off the caliper.
   

• Inboard disc brake pad from the caliper by pulling the brake pad away from the caliper piston until the retaining clip on the pad is free from the caliper piston cavity
  

To install:

1. Be sure the caliper piston has been completely retracted into the piston bore of the caliper assembly. This is required when installing the brake caliper equipped with new brake pads.
   
2. If equipped, remove the protective paper from the noise suppression gaskets on the new disc brake pads.
   
3. Install or connect the following:
   
   • New inboard disc brake pad into the caliper piston by pressing the pad firmly into the cavity of the caliper piston. Be sure the new inboard brake pad is seated squarely against the face of the brake caliper piston.
     
   • Outboard disc brake pad by sliding it onto the caliper assembly
     
   • Brake caliper assembly over the brake rotor and onto the steering knuckle adapter
     
   • Caliper guide pin bolts and torque to: 35 ft. lbs. (47 Nm) on 2002–04 models or 26 ft. lbs. (35 Nm) on 2005 models
     
   • Front. Apply the brake pedal several times until a firm pedal is obtained.
     
4. Check the fluid level in the master cylinder and add fluid as necessary. Road-test the vehicle.
   

Removal & Installation

1. Raise and safely support the vehicle.
   
2. Remove the rear wheel and tire assembly.
   
3. Remove the brake fitting retaining bolt from the caliper and disconnect the flexible brake hose from the caliper. Plug the hose and the caliper fitting.
   
4. Remove the caliper locating pins. Lift the caliper off the rotor and anchor plate using a rotating motion.
   

WARNING Do NOT pry directly against the plastic piston or damage to the piston will occur.




Rear disc brake caliper removal



Rear disc brake caliper installation

To install:

1. Position the caliper assembly above the rotor with the anti-rattle spring located on the lower adapter support arm. Install the caliper over the rotor with a rotating motion. Make sure the inner pad is properly positioned.
   
2. Install the caliper locating pins and start them in the threads by hand. Tighten them to 19-26 ft. lbs. (26-35 Nm).
   
3. Install the brake hose on the caliper with a new gasket on each side of the fitting outlet. Insert the retaining bolt and tighten to 30-40 ft. lbs. (40-54 Nm).
   
4. Bleed the brake system, install the wheel and tire assembly and lower the vehicle.
   
5. Pump the brake pedal prior to moving the vehicle to position the linings.
   
6. Road test the vehicle.
   

The hard part is pressing the caliper piston abck into the caliper so you can get the new, thicker pads over the rotor. A large C Clamp works best.

SECTION 206-03: Front Disc Brake 2001 Villager Workshop Manual
REMOVAL AND INSTALLATION Pads —Front Disc Brake Removal

1. Remove the wheel and tire assembly. For additional information, refer to Section 204-04 .

1. Remove the front disc brake caliper bolts. torx bit. T20?

1. Support the front disc brake caliper from the front strut and spring assembly using mechanics wire.

1. Remove the front disc brake pads.
   1. Remove the outboard front disc brake pad.
   1. Remove the inboard front disc brake pad.

Installation

1. CAUTION: Make sure the master cylinder reservoir does not overfill and spill brake fluid while retracting the front disc brake caliper piston.
   NOTE: It is necessary to fully retract the front disc brake caliper piston in the bore before installing the front disc brake pads.
   Install the front disc brake pads.
   1. Install the inboard front disc brake pad.
   1. Install the outboard front disc brake pad.

Caution. The outer pads are left and right. put left on driver side.

1. Position the front disc brake caliper on the front-wheel knuckle and install the brake caliper pin bolts.

1. WARNING: It is necessary to depress the brake pedal several times to position the front disc brake caliper piston before driving the vehicle.
   

Interesting, disc brakes don't normally stick. Since there is no tension pressure against the pads like drum brakes.

You indicated you replaced the right caliper and the master cylinder, but no mention of the disc or the piston (Some caliper assemblies are all in one, some are not.)

Here are some thoughts:

Disc is contaminated with oil, grease, brake fluid etc, when you brake, it is absorbed by the pad, gets hot and sticks.

You didn't replace left caliper, piston isn't working well, sending all pressure to right side.

You didn't indicate, new, used or rebuilt caliper. If used, get anew/remanufactured SET of calipers and either semi-mettalic or ceramic pads, and new rotors (I used to get rotors turned, but new replacements are now generally cheaper that turning old ones. When working with brakes I always recommend you work them as a set, regardless of how good the other side looks.

Make sure you clean the rotors with a solvent to ensure any grease or anti-rust agent is removed and dry will with several paper towels.

When installing pads, ensure you do not touch the braking surface of the pad or the rotor, body oil can contaminate too.
Make sure that the siding surface of the caliper is lubricatred with silicone grease designed for calipers (little packets are available at your parts store) On my GM Cars, it is the bolts that mount the caliper, but this varies by caliper design

Hope that is