Newer master cylinder

[87GMQ]

So, after reading kodachromewolfs post on his brake valve mishap. I would like to eliminate that valve completely and upgrade to the newer style master cylinder.

Can someone give me a list of everything I need to complete this. Ideally everything brand new. I know I need the electrical connector to utilize the warning light on the dash. (junkyard it is) but where can I buy these fittings circled in the photo??

If someone has time can I get a list of everything needed? I’d like to use unions like Kodachromewolf so is that a metric to imperial fitting?

Like I said a complete list would help greatly

[Kodachrome Wolf]

So for parts that I came up with was a:
Master cylinder: Wagner MC122580
Residual pressure valve: F2AZ-2B091-A; Best reasonable shot is getting one at a junkyard, as they don't really seem to appear that often as an individual retail item. I got mine off a 1994 Crown Victoria. You can also get the electrical connector off the same car since the connector is a match.
Lines: 2x M10 bubble flare lines at the choice of your length and 1x BLA-B312 (an M12 bubble flare to 3/8" flare, this comes off the residual pressure valve). You may want to get a third bubble flare line as I'll mention below. I used 20" units in this case.
Line Nuts: 3x 3/8"-24
Unions: 3x 3/16" unions

The stock front disc lines coming off the proportioning valve are both 3/8"-24 nuts on a 3/16" line, and the rear drum line is a 7/16"-24 nut on a 3/16" line IIRC. Adapters do exist to go from the 3/8" to 7/16" config, but it's also pretty easy to just cut and flare a new fitting on using a 3/8" nut to avoid fooling with the adapters.

I removed the frame mounted valve, lines between it and the master cylinder, and the old master cylinder. I fitted the new master, and mocked up the lines from the master down towards the hard lines. Once I had the bends and lengths set, I cut one end of the metric bubble flare lines off so I could fit the SAE 3/8" nut on and make an inverted flare so it would match up to the existing lines with a union. The rear feed line was the funny one that needs the M12 fitting on a 3/16" line at the master cylinder. I found the adapter piece arguably too short to get where it needed to be without adding another section, and I had a third 3/16" bubble flare line handy, so I just cut that adapter line in half, stole the fittings off it, and swapped them onto the longer piece after cutting it to length.

[gadget73]

Those valves are going to be different disc vs drum. No residual pressure valve on a disc, need it on drums to keep the wheel cylinder seals pushed out in contact with the bore. Residual pressure with discs just makes for pad drag. I expect the pressure split and slope will not be the same either.

[kishy]

I'm not even sure the valve does that on the drum setup, because it sure feels like I get the full travel of the drums in the pedal on my wagon, which is the setup that KW is replicating as I was the one who sorta figured it out and did it first (or first recently who mentioned it, anyway).

I bought a new master for a 91 Grand Marquis, which as we know was built with front disc and rear drum. I junkyard sourced the valve for the rear line, don't recall exactly what from but I'm sure it was probably a 90-91 Ford or Mercury Panther.

I modeled all of this/based my purchasing decisions originally off my own, as-factory-built 91 MGM.

[Kodachrome Wolf]

I'm not even sure the valve does that on the drum setup, because it sure feels like I get the full travel of the drums in the pedal on my wagon, which is the setup that KW is replicating as I was the one who sorta figured it out and did it first (or first recently who mentioned it, anyway).

I bought a new master for a 91 Grand Marquis, which as we know was built with front disc and rear drum. I junkyard sourced the valve for the rear line, don't recall exactly what from but I'm sure it was probably a 90-91 Ford or Mercury Panther.

I modeled all of this/based my purchasing decisions originally off my own, as-factory-built 91 MGM.

The whole setup I ran was based off your initial suggestion in my RR thread and what I saw you do in your own RR thread. Seemed straight forward enough after reading what you did I had no issue recreating it to a certain level.

I did find one more, perhaps more appropriate part number for that valve: E9SZ-2B091-A. It's internally labeled as a brake pressure reducing valve, so I can only imagine it's job is restricting some level of flow to the rear brakes to prevent them from premature locking. Not sure how much different it is from the later disc one, but pedal travel doesn't seem abnormal.

I will mention that pinning on the brakes hard did not result in premature rear wheel lock, except in one brief instance at probably sub-10 MPH. Otherwise, the fronts come on strong and the rears are definitely grabbing well without being excessive from what I could tell during the test drive.

[kishy]

Yes, that premature wheel lock (which randomly decides which wheel to hit!) was one of the things about stock "earlier" box brakes that annoyed me a lot prior to doing other things.

My wagon does have 95-97 front stuff, but I had reasoned that people do big brake swaps all the time and keep their car's original-design master and plumbing so there should be no problem mix-and-matching to an extent. My wagon is an extremely even and confident-braking car and I aim to replicate its setup on the others that still have original bits.

[gadget73]

Its the disc vs drum thing that screws it up significantly, but the relative sizes of the front and rear calipers or caliper / wheel cylinders also affect the proportioning.

I'm not a hydraulic systems engineer, but consider that Ford employs a bunch of them and they did not use the same valving from 1979-2011. Every time the brake system component sizes changed, there were different valves. Drum brake valving is inappropriate for rear discs, and rear disc valving is inappropriate for rear drums. Change the size of the fronts without doing anything in the back and you need different pressures to keep the stopping power correct.

As for big brakes without updating the rest of it. I did that on my car. I later changed the valving, master cylinder, and booster to the 98-02 non-ABS stuff which is a proper match for the bits and bobs on my car and the improvement in brake feel and performance was not insignificant. Just because people do it doesn't mean its a great idea. Plenty of people smoke meth too, but I don't exactly consider that to be a ringing endorsement.

[gadget73]

I knew I'd done a dive into this stuff years ago but its been long enough that I've forgotten most of the particulars. Pretty sure I was smarter back in 2010.

https://www.grandmarq.net/vb/forum/technical/box-tech/-5-0-5-8-engine-stock/30614-no-conventional-brake-prop-valves-in-any-88-91

and some brake system specs over the years to show what changed

https://www.grandmarq.net/vb/forum/technical/box-tech/drivetrain-chassis/30863-brake-system-specifications

Looks like its also got details on fitting sizes which may be relevant.