BRAKES 5 4 expelled brake fluid flows in a solid stream from the 7 Repeat Steps 2 through 7 on the remaining wheel bleeder hose and no bubbles are present then close oy jooorS bleeder valve tight1Y 8 Fill the main cylinder reservoirs to within 1 4 of 6 Remove brake bleeder wrench and bleeder hose from reservoir yggy rjmS wheel cylinder bleeder valve 9 Install main cylinder diaphragm and cover SERVICE OPERATIONS MAIN CYLINDER cloth Place dry cloths below main cylinder area to absorb any fluid spillage Duut Moin Cylinder Component Replacement 2 Disconnect hydraulic lines at main cylinder Cover line ends with clean lint free material to prevent The dual main cylinder used on the 1968 Corvair is foreign matter from entering the SyStem designed and built to satisfy individual brake system 3 Disconnect the push rod from the brake pede1 displacement requirements Therefore it is necessary 4 Unbon end remove the mom cylmden that correct parts be used when replacing either complete 5 Remove the main cylinder mounting gasket and boot master cylinder assemblies or the component pistons of on Remove the mein cylinder cove and dump out the these assemblies fluid Pump the remaining fluid from the cylinder by The Cl1Spl3 C 1 I l Ilt C3 p3bl lltl S of 3 particular cyl depressing fhg push I d inder are specified by the two letters which are stamped in the metal on the top of the closed end of the main DI embIY FI9 5 eyiinder rama Main oyunders should only be re 1 Clamp main Cyiinderinebench vise placed with another cylinder bearing the Same two Remove push rod retainer t b ltf b tt f letter identification Remove secon ary pis on s op o rom 0 om o The length of the secondary pistons in these main front fluid reservoir cylinders is a critical factor in the displacement capa 4 Remove the snap ring retainer and primary piston bilities of a particular main cylinder These secondary assembly Remove the secondary piston piston pistons are coded using rings or grooves in the shank spring and retainer by blowing air through the stop or center section of the piston Refer to the chart below bolt hole If no air is avai ab e 1 a pgece of wirejmey for proper identification be used Bend approximate y inc o one en in o It is mandatory that replacement pistons be identical a right angle hook the secondary piston and pull it to the original piston This can be verified by checking out the identification marks on the secondary piston and the 5 Position main cylinder in vise with outlet holes socket contour of the push rod end of the primary piston 6 faogng upig 64 h h 1 th h b th h k 1 Identification marks are as follows Dri a inc o e roug o c ec va ve Main Cylinder Code BS seats Secondary Piston Identification 1 Ring or Groove 7 Tap out both seats using 1 4 x 20 tap when Servicing the Delco Morajne dual main Cylinder 8 Install a spare brake line tube nut in the outlet hole follow the rules below when replacing either complete Place e Het Washer On e One meh Screw threadeq te main cylinder or the component pistons of the cylinder Screw into tepped hole and thread Screw mee It is equally important to use only the correct service threeded hele m tube Seet Held the S rew t 1 wp ui oerte when Servicing e Bendix main Cylinder from turning and back out the tube nut This will re l The two letter identification stamp on the end of the mOVe the tube Seem main cylinder indicates the displacement capabilities 9 Repeet Step 8 above OU Seeebd tube Seet of that particular cylinder Main cylinders should 10 Rem0Ve the check Ve1Ve and SPYUTSS from the eeV only be replaced with another cylinder bearing the 11 gies benetegh thetube Seat h I t t 6mOV 9 primary 593 prlmgry 593 prg gc gr 2 pistons in the main cyl and secondary seals from the secondary piston Re inders are critical factors in displacement cap move the piston extension screw securing the pri abilities of a particular main cylinder These pistons mary piston spring to the primary piston Remove are coded using rings or grooves in the shank of the the spring retainer primary seal primary seal piston It is mandatory that when pistons are re protector and secondary seal from the primary placed the replacing piston must contain the same piston Cleuning und Inspection rod end as the piston which as removed 1 Remove main cylinder casting from vise and inspect 3 Delco Moraine dual main cylinders used with drum the bore for corrosion pits and foreign matter Be type bra kes contain a rubber check valve and check sure that the outlet ports are clean and free of brass valve spring in each outlet boss Use care not to re cuttings from the tube seat removal operation place this type of main cylinder with one of another 2 Inspect the fluid reservoirs for foreign matter design Main cylinders for many Chevrolet models Check the bypass and compensating ports to the cyl are ver similar in desi n inder bore to insure that they are not restricted y g Do not use wire to check ports Removul 1 Provide suitable protective cover for luggage com NOTE Before washing parts hands must be partment and exterior portion of front fender panel clean Do not wash hands in gasoline or oil be Wipe main cylinder and lines clean with a clean fore cleaning parts Use soap and water only CORVAIR SHOP MANUAL SUPPLEMENT