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EXTENSIVE ARTICLE BY 40X MARKOV GURUPim25

BUY FULL FRONT BRAKE KIT FOR TOYOTA MARK II

NEW FRONT BRAKE DISK

WHERE DO BRAKES BEGIN?

"WITH THE PEDAL" - some will say. Indeed, for the driver, it's the pedal that serves as a point of contact with this life-critical system.

"WITH THE TREAD" - others will argue, and they would also be correct. Without grip in the contact patch between tire and road, there is no braking.

BUT THESE ARE EXTREME ENDPOINTS OF THE SYSTEM. In reality, of course, brake reliability depends on the proper functioning of each component within the braking system.

SIMPLY LISTING THEM FOR OUR CARS WITH HYDRAULIC BRAKES YIELDS THE FOLLOWING:

- BRAKE PEDAL

- MASTER CYLINDER

- VACUUM BRAKE BOOSTER

- RESERVOIR TANK

- HOSES AND PIPES

- DISTRIBUTORS

- CALIPERS WITH SLIDING CYLINDERS AND LININGS

- LININGS

- BRAKE DISCS

- BRAKE FLUID

- PARKING BRAKE: LEVER, ADJUSTABLE CABLE, BRACKETS, DIVIDER LINING MECHANISM, DRUM.

BESIDES THE LISTED COMPONENTS, I WOULD ALSO INCLUDE SOME ELECTRONIC PARTS AS PART OF THE BRAKING SYSTEM: SWITCH ABOVE PEDAL, BRAKE LIGHT LAMPS, FLUID LEVEL SENSOR, SYSTEM PRESSURE SENSOR, HAND BRAKE SWITCH, INSTRUMENT PANEL INDICATOR, LINING THICKNESS SENSORS, AND ALL WIRING THAT CONNECTS THEM.

IF WE LOOK AT THE SYSTEM FROM A DIFFERENT PERSPECTIVE AND ANALYZE WHICH COMPONENT IS MOST VULNERABLE TO ENVIRONMENTAL DEGRADATION, THE LEADER WILL CLEARLY BE BRAKE CALIPERS. CONSISTING OF MANY INTERDEPENDENT PARTS THAT MUST MOVE SMOOTHLY WITHOUT STICKAGE, THIS UNIT ALSO HEATS UP TO HIGH TEMPERATURES DURING OPERATION, GETS WET WHEN PASSING THROUGH POOLS, EXPERIENCES HIGH LOADS ON SHEAR AND TENSION, NEEDS TO OPERATE RELIABLY FOR A LONG TIME, AND IS MADE OF COUNTLESS PARTS MOST OF WHICH ARE PRONE TO CORROSION!

IN MY CASE, THE BRAKE CALIPERS WERE SIGNIFICANTLY RUSTED SUMITOMO UNITS THAT STILL PARTIALLY PERFORMED THEIR FUNCTION (THE CAR WAS DRIVEN UNTIL REPAIRS BEGAN AND COULD TORMOT, ALTHOUGH BOTH ACTIONS WERE DONE VERY CAREFULLY AND ONLY WHEN NECESSARY :).

DISASSEMBLY AND DECONSTRUCTION SHOWED EXTENSIVE CORROSION SPREADING THROUGHOUT THE UNIT, BROKEN RUBBER DUST BOOTS, CRACKED HOME-MADE LININGS HERE AND THERE, AS WELL AS (THANKS BE TO ANONYMOUS JAPANESE ENGINEER!) AWFULLY GOOD PRESERVATION OF FEW STEEL PARTS!

IN MY OPINION, BOTH FRONT AND REAR BRAKES ON OUR CARS HAVE QUITE INTERESTING AND COMPLEX CONSTRUCTION.

REAR (IN CASE OF INDEPENDENT SUSPENSION) DISC BRAKES ARE SINGLE-PISTON WITH A FLOATING CALIPER MOUNTED TO A MOVABLE BRACKET THAT CAN FREELY MOVE, WITH A PISTON DIAMETER OF 43 MM. THE BRACKET HAS TWO CYLINDRICAL STICKS; ONE MOVES IN A LUBRICATED CYLINDER PROTECTED BY A SEAL, WHILE THE OTHER MOVES THROUGH AN AMORTIZING RUBBER INSERT-CYLINDER. THE ENTIRE CALIPER'S MOVEMENT ALONG THE BRACKET SHROUD, SECURELY FASTENED TO THE STEERING KNUCKLE, MAKES IT FLOATABLE. THIS MOVEMENT EQUALIZES PRESSURE ON BOTH SIDES OF THE DISK (EXCEPT FOR FRICTION IN TWO DIFFERENT STICK-CYLINDER PAIRS), HELPS LININGS RELEASE THE DISK AFTER BRAKING AND COMPENSATES POSSIBLE INEQUALITIES BETWEEN THEIR WEAR, ALSO HELPING ADAPT THE CALIPER UNIT TO THE DISK DURING MOUNTING.

FRONT DISC BRAKES ARE DESIGNED ON AN ENTIRELY DIFFERENT PRINCIPLE.

NO FLOATING BRACKETS, SEALS, AND RUBBER CYLINDERS - ONLY TWO OPPOSITELY-PLACED PISTONS WITH A DIAMETER OF 54 MM THAT COMPRESSION THE DISK FROM BOTH SIDES. THIS LEADS TO FULLY EQUAL PRESSURE ON BOTH SIDES OF THE DISK IN FUNCTIONING BRAKES, NO STICKAGE POSSIBLE IN GUIDES AND SIGNIFICANT (COMPARABLE TO REARS) BRAKING EFFORT.

EVEN THOUGH THEY SEEM SIMPLY DESIGNED, BOTH FRONT AND REAR CALIPERS CONTAIN A LARGE NUMBER OF PARTS - ABOUT 20 FOR THE REAR, APPROXIMATELY 30 FOR THE FRONT. IN BOTH TYPES, CYLINDRICAL GUIDES (STUDS) ARE USED FOR LININGS, WHICH MANUFACTURER LATER GAVE UP ON IN FAVOR OF SLOT MOUNTING. THOUGH STUDS CREATE MINIMAL FRICTION FOR LININGS MOVEMENT COMPARED TO SLOTS, THEY'RE POORLY PROTECTED FROM CORROSION AND REQUIRE REGULAR LUBRICATION AND CARE DURING AUTOMOBILE USE.

AFTER A 100% DISASSEMBLING AND INSPECTION OF EACH CALIPER'S PARTS WERE PLACED IN SEPARATE BOXES WITH THE APPROPRIATE LABELING:

THEN I BEGAN LOOKING FOR REPLACEMENT PARTS FOR ALL PARTIALLY OR FULLY DAMAGED COMPONENTS. IT'S SAFE TO SAY THAT THIS WAS A CHALLENGING TASK, MADE HARDER BY THE FACT THAT AUTOMOBILE CATALOGS MAKING IT DIFFICULT TO FIND INDEPENDENT REAR SUSPENSION FOR OUR BODY STYLE AND THEREFORE SCHEMATIC OF REAR DISC BRAKES. EVEN IF I MANAGED TO FIND AND KNOW A PART NUMBER, SUPPLIERS USUALLY REFUSED THE ORDER BECAUSE OF THE VEHICLE'S AGE. OUT OF TEN REQUESTS, NINE WERE DENIED, WITH SUCCESS IN ONE CASE ON AVERAGE. CARS IN THIS BODY STYLE WERE SOLD TO THE USA MARKET IN VERY SMALL QUANTITIES, SO EVEN AUTO PART INDUSTRIES THERE COULD NOT HELP MOST TIMES.

I SHOULD MENTION THAT SEARCHING FOR PARTS WAS RATHER ADDICTIVE AND EXCITING; SOME PARTS TOOK WEEKS TO FIND BY CROSS-REFERENCING NUMBERS TO OTHER MODELS. EXAMPLE: REAR DISK BRAKE OF MY MARK II 1978 IS ALMOST A COMPLETE COPY OF FRONT BRAKE FROM COROLLA 1982, AND SEARCHES ON EBAY FOR THE LATTER GAVE POSITIVE RESULTS.

AT THE SAME TIME I HAD A MORE ROUGH OPTION - BUYING USED REBUILT CALIPERS ASSEMBLIES FROM EBAY OR OTHER SUPPLIERS. BUT THIS WAS MY LAST RESORT IF NO SOLUTION WAS FOUND. THE FACT THAT ALL CALIPER CASINGS WERE ALREADY IN STOCK MADE ME RELUCTANT TO PURCHASE THEM. I DID NOT END UP USING THIS OPTION - EVERYTHING NEEDED PARTS WERE FOUND SEPARATELY.

NOW, I THINK I'D HAVE SERIOUSLY CONSIDERED IT THEN.

ANYWAY, THE RESULT OF MY MONTHS OF SEARCHES AND SHOPPING WAS A BOX FULL OF BRAKE PARTS.

AFTER SOME TIME PASSED, I FINALLY BEGAN WORK ON REPAIRING MY CAR'S BRAKING SYSTEM.

I STARTED WITH ELECTRO-CLEANING, PRIMING AND PAINTING THE CALIPER CASINGS.

THEN I BEGAN ASSEMBLING THE MECHANISM. IT WAS DONE USING STANDARD TOOLS - SOCKET SETS, FLAT SCREWDRIVER, Pliers, LIGHT HAMMER, CLAMP, METAL SHEARS. Permatex SLIDING CYLINDER LUBRICANT AND Thread Sealer were used during assembly:

NEXT I WILL DESCRIBE THE ASSEMBLY OF THE REAR CALIPER.

Important! The support bracket must be installed before tightening the bolts!

Assembly in a different order may lead to errors and the need for rework.

So, first we lay out everything that needs to be replaced – old parts on the right of the photo, new ones on the left as replacements.

Then we will lay out all the support parts intended for assembly, as a full set:

First, insert the lubricated rubber ring into the cylinder groove:

Put the boot over the piston:

...and carefully insert the piston into the cylinder 5-7mm deep until it touches the inner rubber ring of the cylinder. Then, using pliers, gently and without tilting push the piston into the cylinder to its full depth:

Then calmly put the boot on the outer rim of the cylinder and secure it with a steel clip:

After lightly moistening the rubber insert, insert it into the brake caliper housing:

And now it is in place, slightly recessed into the housing depression:

With gentle taps from a hammer, we press the seal and cap of the second cylinder into place:

After lubricating the cylinder parts and pistons of the support bracket, carefully and without tilting insert it into position:

Clean the threads on the bolts:

Apply thread locker to the bolts:

And tighten both halves of the caliper together:

Assemble and install the brake pad assembly – pins/spring/pads/shield:

Screw in the bleed nipple...

and 'Voila!' The assembled support bracket is now in our hands!