JP Group Dansk 1661300171 Wheel Cylinder; Front – Porsche | 69535151100 69535151400 JP22620

Wheel cylinders are hydraulic rams that push brake shoes against brake drums to slow a wheel to a stop on wheels with drum brakes. They are cylinders with pistons extruding from either side, sealed in with o-rings and a boot to keep out dirt and debris. They have a hydraulic line connection and a bleeder screw on the back to remove air from the brake hydraulic system.

Symptoms of Faulty or Worn Out Wheel Cylinders
Wheel cylinders fail when the piston seals leak, when the wheel cylinder pistons get seized, or when the bleeder rusts and breaks. Wheel cylinders with leaking piston seals and broken bleeder screws allow hydraulic brake fluid to bypass the pistons. This results in the pistons not being pushed out and hydraulic fluid to leave the system and be replaced with air which prevents the wheel from slowing and will make the brake pedal feel spongy. Wheel cylinders with seized pistons will allow the brake pedal to feel normal but will prevent the pistons from pressing out the brake shoes to contact the drums and slow the wheels.

Replacing Your Porsche Wheel Cylinders
Replacing wheel cylinders requires the removal of the brake drum and brake shoes to access the brake backing plate where the wheel cylinder is mounted. From there, you’ll need to disconnect the hydraulic line and unbolt the wheel cylinder for replacement. Replacing the brake shoes and drum is highly recommended when replacing a wheel cylinder.

Once the new wheel cylinder has been bolted in place, the hydraulic line has been reconnected, and the brake shoes and brake drum have been installed, the wheel cylinder and other wheel cylinders and brake calipers on the vehicle must be bled to remove all air from the brake hydraulic system. The wheel cylinders can be bled by pumping the brake pedal and holding it pressed, and then loosening the bleeder screw on the wheel cylinder. Once the bleeder screw is loosened, air will be forced out of the wheel cylinder being replaced by brake fluid resulting in the brake pedal dropping to the floor. Before releasing the brake pedal, the bleeder screw must be tightened to prevent air from entering back into the wheel cylinder when the pedal is released. This process must be repeated until no air comes out of the wheel cylinder and then repeated for each wheel cylinder and caliper.

Porsche Wheel Cylinders.