My 1984 Cadillac has had new brake pads and new master cylinder and new rear calipers. Now the brake pedal rises up and my left rear caliper is locking the wheel up after 3- 7 miles

Hello Patricia,

Have you checked the master brake cylinder reservoir for brake fluid loss?

I don't suspect the master cylinder as you have replaced it... but am more suspect of a leaking brake line or fitting which should have
been discovered when you had the system bled.

The only time I ever had a rear brake problem with a 2500 series Chevrolet was due to seized rear brake caliper guide pins...as your calipers are also new that is not your problem.

If your brake pedal feels spongy and travels to the floor board you have air in the system, a brake fluid leak or a failure in the power steering system, such as a broken hose, broken power steering pump drive belt, or failed pump, would result in a loss of pressure to both the hydro-boost and steering.

Find more information here:

. Hydro Boost Power Assist Systems Operation Diagnosis and Repair

This may sound dum but its been done a few times and is a simple mistake , the bleeder screw is up top, with the caliper on the bleeder screw should be up top, if not then calipers are on the wrong side, it sounds like air in the system, also you pumped the pedal up to push out the piston so pads hit rotor after bleeding,i dont see anything else, if the pedal is good with pinched lines at caliper then it got to be calipers are wrong or on the wrong side and the bleeder is not atop caliper,also you bleed the rear also? these trucks and cars use left caliper and rt rear on one system of the master and rt front and left rear on one side, let me know about the caliper, heres a picture to show you what i mean. hope this helps

Disk brakes are automatically self adjusting. If you have too much travel in the pedal, bleed the brakes. Let us know if you need the procedure.

Removal & Installation Front To Remove:

1. Inspect the fluid level in the master cylinder reservoir. Remove fluid from the reservoir until the level is lower then half way between the MAX and MIN levels.
2. Remove the tire and wheel assembly.
3. Install 2 wheel nuts to secure the rotor on the hub.
4. Remove the bottom brake caliper pin bolt.
5. Pivot the brake caliper body upward and secure out of the way. Do NOT disconnect the hydraulic brake flexible hose from the caliper.
6. Compress the piston back into the bore using a C-clamp. Figure of brake assembly with caliper raised showing brake pads in mounting bracket
   
   
7. Remove the inboard and outboard brake pads from the brake caliper bracket.

To Install:

1. Install the brake pad retainers and both brake pads into the caliper bracket.
2. Pivot the brake caliper down over the brake pads and into the brake caliper bracket. Insert the lower brake caliper pin bolt and torque bolt to 70 ft-lb. (95 Nm).
3. Reinstall the tire and wheel assembly.
4. Lower the vehicle.
5. Refill the master cylinder. Pump the brake pedal several times to seat the pads against the rotor.
6. Check the master cylinder level and add fluid as necessary.

Rear To Remove:
Rear disc pads R&I

1. Inspect the fluid level in the master cylinder reservoir. Remove fluid from the reservoir until the level is lower then half way between the MAX and MIN levels.
2. Remove the tire and wheel assembly.
3. Install 2 wheel nuts to secure the rotor on the hub.
4. Remove the upper caliper mounting bolt.
5. Pivot the caliper down to access the pads.
6. Remove the inboard and outboard pads from the caliper bracket.
7. Remove the brake pad clips from the caliper bracket.
8. Compress the piston back into the bore using a C-clamp and the old inner pad.

To Install:

1. Install new brake clips in the caliper bracket.
2. Install the inboard and outboard pads in the caliper bracket.
3. Pivot the caliper up over the pads.
4. Reinstall the upper mounting bolt and tighten to 32 ft. lbs. (44 Nm).
5. Remove the 2 wheel nuts securing the rotor.
6. Reinstall the tire and wheel assembly.
7. Refill the master cylinder. Pump the brake pedal several times to seat the pads against the rotor.
8. Check the master cylinder level and add fluid as necessary.

Disc Brake Pads for Suburban 1500 Removal & Installation Front To Remove:
Front caliper mounting bracket

1. Remove the cover on the master cylinder and siphon out 2/3 of the fluid. This step prevents spilling fluid when the piston is pushed back into the caliper bore.
2. Raise and support the vehicle safely.
3. Remove the wheel and tire assembly.
4. Compress the brake piston back into its bore using a C-clamp.
5. Remove the 2 caliper mounting bolts. Lift the caliper off the rotor.
6. Remove the inboard and outboard pad.
7. Remove and discard the anti-rattle clips.

To Install:
Caliper bracket sleeves

1. Thoroughly inspect, clean and lubricate all caliper slide points, bolts and hardware.
2. Install new anti-rattle clips.
3. Position the inboard and outboard pads into the support bracket
4. With the 2 pads in position, place the caliper over the brake rotor and align the holes in the caliper with those of the mounting bracket.
5. Install the caliper mounting bolts through the sleeves in the inboard caliper ears and into the mounting bracket.
6. Tighten the mounting bolts to: 80 lb. ft, (110 Nm).
7. Install the tire and wheel assembly. Lower the vehicle.
8. Add fluid to the master cylinder reservoirs so they are 1/4 in. (6.35mm) from the top.
9. Test the brake pedal by pumping it to obtain a hard pedal. Check the fluid level and add fluid as necessary.

Rear To Remove:

1. Remove 2/3 of the brake fluid from the master cylinder.
2. Raise and safely support the vehicle.
3. Remove the wheel and tire assembly.
4. Remove the brake caliper mounting bolts. Suspend the caliper from the frame with mechanic's wire. Do not allow the caliper to hang from the brake hose.
5. Remove the brake pads from the caliper mounting bracket.
6. Remove and discard the anti-rattle clips.

Rear brake caliper

To Install:

1. Install new anti-rattle clips.
2. Position the brake pads to the caliper mounting bracket.
3. With the 2 pads in position, place the caliper over the brake rotor and align the holes in the caliper with those of the mounting bracket.
4. Install NEW caliper mounting bolts. Tighten to: 30 lb. ft, (40 Nm).
5. Install the wheel and tire assembly.
6. Lower the vehicle.
7. Refill the master cylinder to the proper level with fresh brake fluid. Pump the brake pedal slowly and firmly to seat the brake pads. Burnish the brakes as needed.

If the rear is disc...here ya go!

Removal & Installation

1. Before servicing the vehicle, refer to the Precautions section.
   
2. Remove or disconnect the following:
   
   • 2/3 of the brake fluid from the master cylinder
     
   • Wheels
     
3. Place a C-clamp around the outer pad and caliper; tighten the C-clamp until the piston is fully compressed in the caliper.
   
   • Top caliper retainer, and rotate caliper away from rotor
     
   • Inboard pad and retaining spring from the caliper
     
   • Outboard pad from the caliper
     

To install:

1. Clean and lubricate the sleeves and bushing with silicone lubricant
   
2. Install or connect the following:
   
   • Sleeves and bushings into the caliper
     
   • Clip the retaining spring onto the inboard pad and install the pad in the caliper
     
   • Outboard pad into the caliper
     
   • Caliper in position over the rotor and install the mounting bolts
     
   • Wheel and tire assemblies
     
3. Refill the master cylinder and pump pedal to attain full brake pedal before Road-testing the vehicle.
   

Its not air leak, you must bleed air from system. You have to bench bleed the master cylinder, then bleed each caliper starting from the right rear, then left rear, then front right, then front left. If you've already done this, then do it again, you must have air in your lines or they would work. The only other thing could be your rubber lines are bad and swelling(absorbing the hydraulic pressure) but they would have to both be completely mush.

Did you notice the brake fluid level in the master cylinder before you tried to collapse the calipers? You should see a rise in level as you collapse them (however far they did collapse). If you're not seeing any change in the level (it should fill up) you might have a plugged valve between the caliper and the master cylinder. Loosen the brake fluid line to the caliper and try collapsing it again. If still no go, start dismantling the caliper and look for bent, broken, stuck or mal-adjusted pieces.

You may have a leak in the booster or master cylinder. You can put a pressure tester on the system to test for leaks. It does sound like you have an air leak.
You can try to bleed the master cylinder, then slave cylinder, then brake lines.

One, take your brake fluid reservoir cap off.
Two, use a thin piece of wood to help you compress the piston on the caliper....do it slow. This way, you don't create a lot of pressure to the reservoir and it won't overflow.
Three, these are the steps to removing and replacing the pads for the rear. It does mention a special tool....but you can use a c-clamp for the same purpose:

Rear To Remove:

1. Check the brake fluid level in the brake master cylinder reservoir.
2. If required, remove the fluid until the brake master cylinder reservoir is half full. CAUTION
   Care must be taken when servicing rear brake components without disconnecting the parking brake cable from the brake caliper lever.
   
3. Remove the disc brake caliper. Support the caliper with mechanic's wire. CAUTION
   When the brake pads are separated from the brake caliper, new brake pads must be installed. The brake pads are one-time use only.
   
4. Remove and discard the brake pads and spring clips from the brake caliper anchor plate. NOTE: Do not remove the anchor plate guide pins. The guide pins are press fit to the brake caliper anchor plate. If the guide pins are damaged a new anchor plate must be installed.
   
5. Inspect the brake caliper anchor plate assembly.
6. Check the guide pins and boots for binding or damage.
7. Install a new brake caliper anchor plate if it is worn or damaged.

To Install:
NOTE: The left caliper piston turns clockwise and the right caliper piston turns counterclockwise.

1. Using the special tool, turn and compress the brake caliper piston into the cylinder.
2. Clean the residual adhesive from the brake caliper fingers and pistons using the specified brake parts cleaner. CAUTION
   Do not allow grease, oil, brake fluid or other contaminants to contact the brake pad or caliper mating surface. Do not install contaminated pads.
   NOTE: Install all the new hardware supplied with brake pad kit.
   
3. Install the new spring clips and brake pads.
4. Position the brake caliper and install the 2 bolts. Tighten caliper bolts to 23 ft-lbs (31 Nm).
5. If necessary, fill the brake master cylinder reservoir with clean brake fluid.
6. With the engine running, apply pressure on the brake pedal to seat the brake pads.
7. Test the brakes for normal operation.