Normal wear and tear on wheel cylinders may cause the piston seals to leak Also, corrosion and pitting can occur inside wheel cylinders as moisture builds up in the brake fluid. A leaky wheel cylinder can be dangerous to the driver, causing gradual softening of the brake pedal and creating brake pull to one side. Replace your worn out or faulty cylinders with new ones from Obsolete & Classic Auto Parts. Made with quality EPDM rubber cups and boots for performance that lasts and lasts. Generally, whenever you replace or machine your drums, you should replace your wheel cylinders.