New Master

All aftermarket aluminum master cylinders that I'm aware of, are made with hard- anodized bores, so side-wear should not be a problem. But corrosion by the water that brake fluid absorbs could affect it. Incidently, this is no worse than waters effect on cast iron; brake fluid should be changed EVERY YEAR in both hydraulic clutches and in brake systems. It almost never is.... I don't believe any master cylinders are made off-center. Due to the way all clutch linkage povots, there may be more pressure on the bottom (or top) of the bore than elsewhere, but when measured with a precision micrometer, it turns out to be mere polishing of the bore. My aluminum clutch and brake masters have worked just fine for many years.

Thanks Jack. I have heard some bad stories about the aluminum cylinders, but your experience sounds good. I still may go with the stock unit however. I took my old one out and tried to hand pump it while holding my finger over the exit hole after letting lots of fluid through. But fluid still wants to pump through the plastic cup, and just a small amount of pressure on the exit hole. I would think the pressure should be strong enough to push my finger off the hole. Is there another way to test a master to see if it is ok? Two months after all this frustration I think I am going to buy a new unit, and hope that is what is wrong.

Many who tried to rebuild the essentially non-rebuildable stock clutch masters & slaves find that by the time they hone the pits out, the piston & seals no longer fit. Running with a leaky master is foolish economy IMHO, since even when the car was brand-new, clutch disengagement was marginal. Every shift you make wears the synchros in your ZF; tranny overhauls are several thousands of dollars. Bite the bullet, buy a NEW master and long-throw slave in stainless steel, and enjoy driving your car again without worry for many more years.

Thanks Jack...I just was not sure if the master is the problem or not, as initially I just found a broken spring inside. So, I fixed the spring and then it was worse than ever, no real pressure at all after "fixing" it. Anyway I do plan to get a new master, and am wondering if it already has a long throw slave, as the car is already pretty modified. The slave is a stainless steel unit. Is there some way to tell, as I don't want to get another one if I already have one installed.

By the way, I can change my clutch master in about 10 minutes now...I got good practice.