The brake peddel on my frontera 2.3 creeps to the floor when braking hard a new master cylinder has been fitted & all new disc's & pads + rear brake shoes load sensing valve & last of all a pair of calipers not sure about brake pipe lay out can any body help please

disc brakes can only lock up because the fluid is not allowed to return to the master cylinder reservoir
That is normally because the compensating port in the master cylinder is blocked
You say that you have fitted 2 new master cylinders but did you check the brake pedal free play because if there is not enough free play then the piston cup covers the compensating hole and the problem that you have is the result

It could be a faulty brake master cylinder though your description does remind me of a car that had the disc pads wrongly fitted and the anti-rattle springs were pushing the pads away from the discs instead of providing resistance.

A similar symptom can be experienced when a wheel bearing has excess free play and pushes the pads away from the disc.

I would use a hose clamp and isolate each brake in turn until the brake pedal operation is normal. If no clamping operation makes a significant difference I would then clamp two, three and then four hoses when if there is still no difference I would suspect the master cylinder or the basic brake pedal and servo adjustments.

IF the hand brake activates through the caliper piston unit and it was necessary to screw the piston back in to fit the new pads then you will have to readjust the hand brake .. The may be a bleed nipple on the abs unit . It is not necessary to run the engine to bleed the brakes. IF you used a clamp to push the piston back in then there may be crap in the master cylinder that is affecting the operation of the non-return valve at the outlet of the master-cylinder.

when you push pedal hard & pedal goes to floor does brake light come on?
assuming brake fluid leval is ok & didnt run empty have you checked for a leak?
pulling all wheels & inspecting brakes,cylinders, calipers,& lines for leaks.
does the pedal pump up & feel ok with engine running?if so there is air in the system
if it does'nt change the way the pedal feels & no leaks are found & brake linings are ok & adjusted
properly than your master cylinder is leaking internally & needs to be replaced

by stating that your pedal sinks to the floor, you leave 3 options open 1.) the master cylinder seal is bypassing allowing the fluid to bleed by the proper correction is to rebuild the master cylinder.
2. One of your drum brakes has a wheel cylinder that has failed causing a noticable behind the tire leak (most common) correction is to replace all brake hardware and wheel cylinder.
3. One of the brake lines is cracked,broken, inspect for leaks and replace with new line.
4. notice on disc brakes if a brake caliper fails (part that squeezes brake pads to rotor) you will have the same symptoms of a broken wheel cylinder, this would of gradually occured feeling a heavy pedal or pulsation.

When you pushed the pistons back into the caliper so the new pads fit over the rotors did you look an see how full the master cylinder was ? You did push the pistons in didn't you ? Over flowed from master cylinder ? After replacing pads you didn't pump up the brakes ? The pedal will go to the floor but should pump up . Just replacing pads wouldn't make the master cylinder go out . How was the pedal before your brake job ?

Brake Pads Removal & Installation Front

To Remove:

1. Drain brake fluid to ½ full level in reservoir.
2. Remove the front wheels.
   
   
3. Remove the front brake caliper assembly.
4. Remove the 2 anti-squeal shims from each of the 2 brake pads.
5. Remove the wear indicator from each of the 2 brake pads.

To Install:
NOTE: When replacing worn pads, the anti-squeal shims must be replaced together with the pads.

1. Using a large C clamp or equivalent press piston into the caliper.
2. Apply disc brake grease to the inside of each anti-squeal shim.
3. Install the anti-squeal shims on each pad.
4. Install the pad wear indicator clip to the pads.
5. Install the pads with the pad wear indicator plate facing upward.
6. Install the brake caliper with the 2 mounting bolts. Torque the bolts 25 ft-lb (34 Nm).
7. Install the front wheels.
8. Fill the master cylinder with new clean brake fluid.
9. Pump the brake pedal several times to seat the brake pads.

Rear TMC made rear brake components

TMMK made rear brake components

To Remove:

1. Drain the brake fluid to ½ full level in reservoir.
2. Remove the rear wheels.
3. Remove the caliper slide pins.
4. Remove the caliper slide pin bushings (TMMK made) (Kentucky).
5. Remove the rear brake calipers.
6. Remove the 2 brake pads with the anti-squeal shims.
7. Remove the anti-squeal shims and pad wear indicators from brake pads.

To Install:

1. Using a large C clamp or equivalent press the piston into the caliper.
2. Coat both sides of the outer anti-squeal shim with pad grease.
3. Install anti-squeal shims to each pad.
4. Install wear indicators on the 2 brake pads.
5. Install the caliper slide pin bushings (TMMK made) (Kentucky).
6. Install the rear brake caliper with the slide pins. Torque the slide pins as follows:
   • TMC made (Japan): Torque the caliper slide pin 25 ft-lb (34.3 Nm)
   • TMMK made (Kentucky): Torque the caliper slide pin 34 ft-lb (47 Nm)
7. Fill the master cylinder with new clean brake fluid.
8. Pump the brake pedal several times to seat the brake pads.
9. Install the rear wheels.

Brake Rotor Removal & Installation Front To Remove:

1. Remove the front wheels.
2. Remove the front brake caliper assembly.
3. Remove the front brake pads.
4. Remove the 2 bolts and caliper mounting bracket.
5. Place match marks on the disc and axle hub.
6. Remove the front wheel disc.

To Install:

1. Align the match marks and install the front disc.
2. Install the brake caliper mounting bracket. Torque the bolts 79 ft-lb (107 Nm).
3. Install the brake caliper. Torque the bolts 25 ft-lb (34 Nm).
4. Install new gaskets and connect the brake hose to the caliper with the banjo fitting bolt. Torque the fitting bolt 22 ft-lb (29.4 Nm).
5. Fill the reservoir with brake fluid.
6. Bleed the brake system.
7. Install the front wheel.

Rear To Remove:

1. Remove the rear wheels.
2. Remove the brake caliper assembly.
3. Remove the brake pads.
4. Remove the 2 bolts and the caliper mounting bracket.
5. Place match marks on the disc and axle hub.
6. Remove the rear disc.

To Install:

1. Align the match marks and install the rear disc.
2. Install the rear brake caliper mounting bracket. Torque the bracket bolts as follows:
   • TMC made (Japan): Torque the bracket bolt 46 ft-lb (61.8 Nm)
   • TMMK made (Kentucky): Torque the bracket bolt 34 ft-lb (47 Nm)
3. Install the rear brake caliper with the slide pins. Torque the slide pins as follows:
   • TMC made (Japan): Torque the caliper slide pin 25 ft-lb (34.3 Nm)
   • TMMK made (Kentucky): Torque the caliper slide pin 32 ft-lb (43 Nm)
4. Install new gaskets and connect the brake hose to the caliper with the banjo fitting bolt. Torque the fitting bolt 22 ft-lb (29.4 Nm).
5. Fill the reservoir with brake fluid.
6. Bleed the brake system.
7. Install the rear wheel

1. Machine or replace rotors and/or Drums
2. New Disc Pads and /or Brake Shoes & springs for brake shoes
3. New or recond Brake Booster
4. New or recond Master Cylinder
5. New or recond Disc brake calipers and/or wheel Cylinders
6. Brake fluid
7. Check all the brake fluid lines for any damage
thats about all I can think of, hope it helps

Sounds like you have a vacuum booster issue or a brake master cylinder going out. If you know of an independent mechanic the Vacuum Booster test is simple. It is recommended to replace both the booster and the master cylinder at the same time.