1969_Mach1 333 Report post Posted August 17, 2018 If it's a master cylinder for drum brakes it should have residual check valve in it. I wouldn't focus too much energy on finding the residual check valve. Unless the rear wheel cylinders are worn badly, rusty, pitted, and are relatively new, the seals should work well enough on their own. On a side note, rebuilding a wheel cylinder usually doesn't last very long simply because the honed finish from cleaning the bore causes rapid wear on the rubber seals. Brake fluid is hydroscopic so it will absorb moisture. If you are having a moisture issue in the brake system make certain you always use fresh new sealed containers of brake fluid. If you use brake fluid from a container that was opened a long time ago, even though stored, it can have moisture in it. Not much more I can offer. I think you are fighting mismatched parts. Not saying there isn't a solution. But it can be more difficult to find. Quote Share this post Link to post Share on other sites
