Raybestos or Doctor Diff master cylinder for 1969 Dart with 9" manual drums?

72bluNblu said

None of the braking systems are airtight. The stock master cylinder allows the brake fluid to pull moisture from the air as well. If it didn’t, you wouldn’t have rust in there.

I’ve been running the DoctorDiff MC on my Duster for over a decade now. I think I’ve changed the seals in the caps once or maybe twice in that time, and the fluid lasts just as long as it did in my Challenger which has a stock cast iron MC for most of the time I was driving it. If anything the fluid lasts longer now.

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Yeah, I'm wondering if I should have gone with DoctorDiff. I received my second "Raybestos" master cylinder today. This one does not have corrosion on it, like the first one. But the box was even more beaten up, with all kinds of packing tape holding it together, and the plastic bag that presumably is supposed to protect the master cylinder from moisture had many tears and holes in it.

It really makes no sense how Raybestos packages these. They take a very heavy cast iron part, put it in a plastic bag, then shove it loose in a box with nothing holding it in place. So in shipping the very heavy object shifts around in a box that can't take the abuse, and everything, box, plastic bag, tear apart. I'm very underwhelmed.

But, I've got one in reasonable condition. I guess I'll put it in the car. But if there's a next time, I'll probably go DoctorDiff. My one hesitation is that DoctorDiff does not do a 1" bore, which is what's specified for my year Dart.