Rear drum part, whats it called?

[TurboPage]

My rear drums leaking brake fluid, whats that part called the presses outwards on the shoes?

I can't for the life of me remember..

thanks..

[Tony2005]

Piston or wheel cylinder?

Read this Autozone link.
http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1b/d8/db/0900823d801bd8db.jsp

[TurboPage]

cylinder.. thanks Tony..

Both rears were shot.. I handeled it..