Quick question, my 280zx 15/16 master cylinder just went out on me and I have a spare 7/8 280z master cylinder that I can use. The question is, does the 7/8 have check valve in them, on both front and back? how do I take it out, because I already use a 17mm wrench and unbolt the bolt from underneath, and for some reason it isn't falling out. Btw, I have a rear 240sx rear disc brake conversion and toyota 4x4 front brakes.