Delete all your old messages to free space on your phone. 1  Go to Settings --> Messages. 2  Scroll down to Message History. Here, you can choose to delete all messages older than 30 days, or all messages older than a year old.  Confirm that you want to delete the old messages and attachments.
Well, the master cylinder is tasked with supplying hydraulic pressure to the braking system. So when you initially step on the brake pedal the linkage activates a piston within the system and this piston then displaces hydraulic fluid.
if you are talking about the brake master cylinder, if it goes bad you have no brakes. (or a clutch master cyl.....no clutch) the master cylinder is the part of the brake hydraulic system that the driver controls with the foot pedal.