![](mc/2899s.jpg) Master Cylinder 7/8" bore with locked up pistons. Getting ready to get rebuilt. |
![](mc/2900s.jpg) Front view |
![](mc/2901s.jpg) Side view |
![](mc/2902s.jpg) Noticed immediately that cap had crack in it. |
![](mc/2904s.jpg) I would suggest getting a thick piece of cardboard with smooth surface so any fluids can be wiped up and not soaked in. |
![](mc/2905s.jpg) Unscrew two screws on front plate. If there was rubber caps, take off and discard. |
![](mc/2911s.jpg) TRICK OF THE TRADE for seized pistons - place banjo bolt, banjo and adapter in one of the holes. |
![](mc/2912s.jpg) Ensure banjo bolt and adapter is tight, take grease fitting off and screw in rod from grease gun into the banjo. |
![](mc/2913s.jpg) Fill master cylinder reservoir with fluid. |
![](mc/2914s.jpg) Pump grease gun and watch the locked up piston come out. |
![](mc/2915s.jpg) Continue to pump until piston is sticking out enough to grab hold of. Be careful because it is being moved out with pressure and could cause injury. |
![](mc/2917s.jpg) If piston shoots out, keep clear. |
![](mc/2919s.jpg) Once piston is far enough out to grab, Unscrew banjo bolt and adapter. |
![](mc/2920s.jpg) Place it in the other side. |
![](mc/2921s.jpg) This piston is really stuck on this side. Typically brake side is worse than clutch side. |
![](mc/2923s.jpg) Start pumping the grease gun and watch it come out. |
![](mc/2925s.jpg) Once it is out enough, unscrew the banjo bolt and adapter. Use 101 of a grease gun is complete. |
![](mc/2926s.jpg) Easy as pie. Get ready for the mess. Fluid, grease and what ever was in there will be coming out. |
![](mc/2928s.jpg) This one kind of shot out. Remember, be cautious when pumping pressure into this. Also Safety Glasses would be a good idea. |
![](mc/2929s.jpg) Now for the messy part. Grease everywhere. |
![](mc/2930s.jpg) Now that you have springs, pistons and old rubber out. |
![](mc/2931s.jpg) Wipe out bores and check the damage. |
![](mc/2932s.jpg) This particular one is in very good shape. There is only some surface rust and hardly any pitting at all. |
![](mc/2906s.jpg) Now go to top and take off lid. |
![](mc/2907s.jpg) Use putty knife or screw driver carefully as typically lids are aluminum and can be easily damaged. |
![](mc/2933s.jpg) Empty reservoir of any remaining fluids and note condition of surface where lid fits. |
![](mc/2934s.jpg) Place everything in pan. |
![](mc/2935s.jpg) Pour a grease / dirt eating solvent. I use paint thinner which isn't good on rubber, but all rubber will be replaced. |
![](mc/2936s.jpg) The grease will be pretty thick on everything, use detail brush or small wire brush to clean items. Soak core for 15 / 30 minutes to loosen grime. |
![](mc/2937s.jpg) If rust is thick on exterior, take putty knife and scrape as much as you can. It will make sand blasting easier. |
![](mc/2938s.jpg) Spray core with carburetor cleaner all over, this will eat paint thinner and prep surface for sand blasting. |
![](mc/2939s.jpg) Make sure it is completely dry before sandblasting. Carb cleaner is perfect for that. Do a good job blasting as it will show at end. |
![](mc/2940s.jpg) Get it all, this is longest process. |
![](mc/2941s.jpg) You are over the hump now. It is now rebuildable core. |
![](mc/2942s.jpg) Inspect and make sure you got it all. |
![](mc/2943s.jpg) Get your hone ready with 220 medium grit hone stone. IF there is severe pitting, at this step it should be sleeved. |
![](mc/2944s.jpg) You can buy stone refills at auto part stores for approx. $3.50. these are the 1" stones. |
![](mc/2945s.jpg) Hone for 7/8" bore. you can pick this up at most auto parts stores for approx. $15 -takes 1" stone cartridges. |
![](mc/2946s.jpg) Set core in clamp and put your safety glasses on. |
![](mc/2948s.jpg) Measure your bore diameter and it should be .875 or close to it. |
![](mc/2949s.jpg) Put hone in high speed drill, insert hone before starting drill. Be cautious, parts may fly. |
![](mc/2950s.jpg) Slowly move hone in and out evenly first using the 220 medium grit stones. |
![](mc/2952s.jpg) Make sure you keep the stones lubricated. |
![](mc/2953s.jpg) Continue to check the diameter. It will not change much using these grits of stones. Do both cylinders then use the 400 Grit stone same way. |
![](mc/2954s.jpg) When honing is complete, you should have a nice smooth cylinder walls. Maximum safe diameter size is .885 which is about .010 larger than starting. |
![](mc/2955s.jpg) It is important to have honed it evenly throughout entire cylinder. |
![](mc/2957s.jpg) After cylinders are completed. Put wire brush in drill. |
![](mc/2958s.jpg) This process brings the core back to origional finish. It will look like it came right from the cast. USE SAFETY GLASSES. FLYING METAL HAIRS. |
![](mc/2959s.jpg) Shows difference, bottom brushed top still sand blated finish. |
![](mc/2960s.jpg) Use a very stiff wire brush to clean inside of reservoir. |
![](mc/2961s.jpg) Very important to get reservoir clean and clear of any debris. If anyting gets into the cylinder from here, it could cause master cylinder to fail. |
![](mc/2964s.jpg) Exterior is finished. |
![](mc/2965s.jpg) Bores finished. |
![](mc/2966s.jpg) Double check cylinders after working on inside reservior. |
![](mc/2967s.jpg) Reservoir finished. |
![](mc/2968s.jpg) Looks beautiful. |
![](mc/2969s.jpg) Make sure there is nothing stuck in these holes as it could make its way into cylinders and again could make master cylinder fail. |
![](mc/2970s.jpg) Now to work on lid. Check over it make sure no cracks. |
![](mc/2971s.jpg) Make sure butting surface is clear of any debris where it meets with core. |
![](mc/2972s.jpg) I use super fine grit steel wool to polish the aluminum lid. It brings a nice shine to it. |
![](mc/2973s.jpg) Core and lid complete. |
![](mc/2975s.jpg) I like to take some polyurethane and spray the exterior. |
![](mc/2976s.jpg) It puts a clear coat on it and keeps master cylinder from rusting. |
![](mc/2977s.jpg) Hard to even tell it was sprayed. |
![](mc/2980s.jpg) Ok, now the rebuild kit and guts. |
![](mc/2981s.jpg) Check pistons for pitting, buggered edges, rust. make sure springs aren't cracked or expended. |
![](mc/2982s.jpg) Rubber rebuild kits can be purchased for approx. $13 from Moss or other retailers. Pistons and springs can be also. Double check rubber for defects. |
![](mc/2983s.jpg) Lube the cylinder walls and rubber pieces. Do NOT use WD40. Use only brake fluid or red rubebr grease. |
![](mc/2984s.jpg) Put rubber seals on pistons. This can be a frustrating task as you have to get rubber over large end of piston. Lube it up. |
![](mc/2985s.jpg) Hardware is different for each cylinder. Brake side has extra rubber ring and back flow valve. |
![](mc/2986s.jpg) After you get guts in, put gasket on and front cap. Make sure pistons are in straight and not in a bind. |
![](mc/2987s.jpg) Place rubber boots on front plate. |
![](mc/2988s.jpg) Place lid on and cap. I would recommend always replacing cap during restore. These plastic caps can be cracked and not know it. |
![](mc/2989s.jpg) Critical: when putting lid on, make sure surfaces are flat and free of any debris. Don't over tighten screws. It doesn't take much to get good seal |
![](mc/2990s.jpg) with cork gasket. |
![](mc/2991s.jpg) Your master cylinder is as good as new. |
![](mc/2992s.jpg) Check over everything, make sure you don't have any left over pieces. Throw all old rubber in trash as it should never be used again. |
![](mc/2993s.jpg) Double check to make sure new lid fits securely and has no cracks. |
![](mc/2994s.jpg) Double check all screws are tight. Hand tightened not torqued. |
![](mc/2995s.jpg) Last but not least, until it is ready to go back into your car, cap up the open holes. Thank you. Chad Pagel |
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