30 BRAKES OVERHAULING OFTANDEM MASTER CYLINDER Master cylinder should be overhauled as per recommended service schedule during overhaul, all internal parts including plungers and springs should be replaced with genuine parts provided in the kit. Subsequently, if the condition of the bore is sat isfactory fur ther overhaul ing should be undertaken, or else, the whole cylinder should be discarded and fitted with new assembly. REMOVAL OF TANDEM MASTER CYLINDER Connect a transparent (Vinyl) bleed tube to one of the rear wheel cylinder’s bleed screw and drain the fluid into a container by pumping the pedal, from the primary circuit. Repeat the same by connecting the bleed tube to one of the front wheel cylinder’s bleed screws and collect the fluid from the secondary circuit. Disconnect all outlet pipes from the master cylinder. Fig. 31. Loosen master cylinder mounting nuts and remove the same. DISMANTLING OF TANDEM MASTER CYLINDER Fig. 32 Clean the tandem master cyl inder assembly externally with alcohol or fresh brake fluid before dismantling it. Hold the fluid reservoir and by rocking it on either side, lift the same out of the grommets in the tandem master cylinder. Remove both the grommets from the master cylinder body using a connector screw driver with blunt edge. Remove the ‘O’ ring fitted in the groove on the mounting flange with a blunt edge pin. Remove the residual pressure valve from the primary outlet port. Slightly push the primary plunger with a round rod, hold it in depressed position and remove the stop pin with gasket. Without removing the stop pin, if any attempt is made to dismantle the tandem master cylinder, the secondary plunger, cannot be removed. Remove the adaptor from the secondary outlet. Then, clamp the cylinder (housing) in a vice with soft jaws. With the help of circlip plier, remove the circlip. Remove the complete primary plunger assembly out of the bore. Remove the stop washers intermediate ring and the primary back seals out from the shaft of the primary plunger. Remove the cylinder from the vice. Tap the cylinder, bore facing downwards, on a wooden block to al low the secondary plunger and the return spring to slide out of the bore. Clean the cylinder bore in fresh brake fluid or alcohol and blow with compressed air. Be sure that the four holes (two cut off holes and two feed holes visible through the primary and secondary inlet ports) in the cylinder body are clean, by blowing dry compressed air. Do not poke the holes with sharp instrument. Blow breather hole at the flange and make sure it is clear. INSPECTION OF TANDEM MASTER CYLINDER : Examine the bore of the tandem master cylinder. If it is not scored, ridged or corroded and is smooth to the touch, the master cylinder can be reassembled using the appropriate parts from the repair kit. If there is slightest doubt about the condition of the bore like having deep grooves or pitting marks, there is no other way than to fit a new master cylinder assembly. If contamination is observed in the removed seals (normally they would have swollen and can be compared with new seals from the kit which will tell clearly that the size is enlarged), the entire system, i.e. wheels cylinder rubber parts including both front and rear hoses must be discarded and the entire system should be flushed. CAUTION : Do not use kerosene (or) petrol (or) any other mineral oils to clean the cylinder and its internal parts. As it will lead to contamination and damage of rubber parts. Clean al l dismant led par ts wi th alcohol or recommended fresh brake fluid only. Fig. 31
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