brake master cylinder options for two-circuit?

I had a really frightening experience earlier today wherein I suddenly lost all brake pressure without warning. Thankfully it was before I drove down a very steep and winding hill (which I was going to do in a moment) and I was able to roll backward into a hedge and then have AAA tow me back.

I think my master cylinder is fine (at least it doesn't seem to be leaking) but one of the rubber lines failed and/or a wheel cylinder failed. I'm going to fix it when I have time however now I don't feel safe driving again until I have two-circuit brakes. Maybe something like this?
http://www.summitracing.com/parts/wil-2 ... /overview/
or
http://www.summitracing.com/parts/aar-a ... /overview/

It looks like the master cylinder on my B110 has a 1" bore size, is that what I need in a two-circuit replacement? I figure any generic one will work as long as the bore is about the same and I can adapt it up but I am not sure. Does anyone have suggestions?

Also this looks interesting:
https://travelallparts.com/products/?vi ... t_id=18295
...has anyone tried it? Is there a good place to tap the intake manifold on the V8 for vacuum?

ayb,
I installed a dual master cylinder frame mount on the S series, I don't recall if the B series is on the firewall or frame, you could get a MC cheaper than the links you posted. Also use the same piston bore. I can post some pics later if you have a frame mount. Firewall mount would be easy. A few other members have don't it, so they will chime in. Here is a link
viewtopic.php?f=8&t=328&p=1462#p1462

I asked several times on here about that; got no responses. I have installed a dual circuit master cylinder from a 1979 Chevrolet 3/4 ton 4x4 on my 57 A120 pickup. Yes, it did require fabrication of an adapter (1/4" flat plate) and I did have to shorten the pushrod a little bit. Both pretty simple tasks. I'll put some pics up in my thread tomorrow showing how easy it was. I'm ready to run brake lines now. My thread is the 57 A120 4x4 build thread. I'm due for some more pics anyway. You can email me anytime. I've owned more than 50 jeeps, 20 IH's, and many old power wagons and I've worked on them all. I have experience with almost any issue. Not an "expert", but I've probably tackled it at some point.

Thanks guys. Mine is a firewall mount and should be easy to adapt though if I use a booster I have to space it out a bit due to the clutch linkage just to the side of the master cylinder.

That 1979 Chevrolet unit is likely set up for disc brakes up front, are you concerned about that? Are you using a proportioning valve or something like that to ensure the right pressure or did you convert to disc brakes?

If you're going to use a boosted system do some research. I don't recall what sites it was on but I do distinctly remember that the MC should not have the same bore as the original non boosted MC. IIRC the bore should be smaller.

I put some pics over on my thread. 57 IH A120 build thread. I used the non-boosted version, and yes, I also put disc brake chevy axles under it. I, so far, have retained the original axles as there is no interest in them. If your clutch linkage is the same as mine, you can see there is plenty of room.

I used a 90-ies chevy hydraboost unit, complete with the master and all, on both my trycks. Works like a charm, one has discs and the other one has drums. No problems what so ever with proportioning valves or anything else.

I finally got a chance to see what happened and the failure was actually the hard line that connects the front and rear axles! It somehow burst near the gearbox, like toward the back on the cab, any fluid I put in the master cylinder leaks right out at that point and does so quite fast. Wow!

So it looks like I'll replace the entire hard line first and then I'll look in to upgrading the system in terms of safety (I'd really like to have lost only the rear brakes if possible, though I admit this is a really strange failure).

Now you understand why back in the day you had an Emergency Brake, and now we just have parking brakes! Very important to make sure the Emergency Brake was adjusted properly at all times! MM

Yeah, no kidding! I feel stupid driving around having never tested the emergency brake. I was told that it supposedly works but may not release all the way and then keep holding the driveshaft, I need to clean and lubricate it. I'll do that when I'm in there replacing the brake lines.