First I've seen of this thread. My various responses below:
... I would go with Dual M/C, hard lines except at pivot points where stainless braided will be used, both a Residual valve even if does not seem like it was required at the time and a proporsioning valve for fine tuning brakes...
If you have a true dual m/c system with a balance bar pedal assembly you do NOT need a proportioning valve. P-valves are only needed with single or tandem m/c's like the OE parts.
Dual master cylinders - I have a CNC pedal assembly with a balance bar and two 3/4" master cylinders. After looking at the set up more closley, and asking some shops, I found out in order to bleed the front or the rear brake system you need to remove one or the other plunger in order to bleed the opposite system.
Never heard of this in all my racing and brake design experience. The balance bar can only go so far and then it's travel is limited out by a feature of the pedal itself. Might not have full stroke, but it shouldn't be all that hard to bleed. They were bench bled b4 installation, right?
I was actually talked out of going with a line lock by one of the guys at McKenzie's. He had personal experience troubleshooting a brake pressure problem on a customer's car, and after checking everything out they ended up replacing his line lock. It cured the problem, but only for three weeks and the problem came back. The customer ended up removing the line lock from the system and had no more troubles. Word from McKenzie's is they are not reliable and fail too often. Their recommendation - carry a good wheel chock in your car (if you can't put in a mechanical parking brake).
It is a not so well known fact about those Park-Loc units that they bleed down over time. This is not a bashing of their mfg, all hyd systems bleed down over time. This is why the FMVSS requires a mechanical parking brake mechanism.
Skid, why no residual valve in the plan? How noticeable it is I do not know but the higher percentage of flexiable line the softer the pedal can be if not now then as expansion and contraction happen.
I've twice plumbed a race car entirely in -3 braided stainless hose. The second was a Drag car. A little flex there isn't a big deal. The first was done at the insistance of the owner/driver. This was a IMSA Showroom Stock Mazda MX-6. It won it's class national championship that year, so it couldn't have been too flexy.
Now if you were talking about using the OE type rubber hose, that would be ugly.
....I am using -3 AN fittings on the braided lines. When I measure ove rthe top of the braid they are .25" in diameter, but I don't know what the I.D. is (-3 AN should mean something here, but in my case it doesn't!).
Short course in AN (& JIC) sizing lingo: A 'dash' number is how many 16's of an inch the size is. When in reference to a screw or bolt it's the shank's OD. When in reference to hose it's in reference to the ID of the hose. Note that this isn't an exact size when dealing with AN hose, it is an approximation.
...I had Torino Motorsports make up the lines for me, after I determined the length for each one.
It's done now, but I prefer to make my own. There are some who claim that the crimped lines are better. They've never taken one apart. The crimpers have a puny, tiny little tube that connects the swivel nut & conic seal part of the fitting to the hose. In off road applications it is exceedingly easy to break these off. Then yer skrewed.
Contrast that with the much larger layout of the screw together type hose ends. A bonus of the screw togethers is that they can be field repaired. Oft times all you need is a new 'berry'. Odds are you'll be leaking blood from your finger tips, but you'll have full hydraulics! The spares I carry for brake hoses is one section of hose equal to the longest section and one of each unique type of hose end. With those parts you can field repair any of the hoses on the vehicle.
.... You can flare the pipe with the 45 degrees flare by annealing the end of the line. The annealing will make the line conform to the 37 degrees. The pipe will bend without annealing.
This works, but it really makes me nervous. If we were talking dead soft aluminum tube then I'd have no issues with it and have done it. Repeatedly. Stainless is another critter & I won't go there.
Stainless work hardens very easily. Even if it doesn't crack right away it can down the road. It's not that much $$ to get the proper 37* flare tool. Search
McMaster for p/n 2691A14 Even though it says it's for soft metals I have used it on non-annealed 304 SS tube and it works fine.
Drill the SS lines if you use a pipe cutter. The line must not be rolled in before you flare.
I always use a Mechanics' Taper Reamer followed by a 90* Countersink on each tube cut end. It also is exceedingly helpful if the cut is truly square. Flaring a unsquare end usually results in a split or crack.
Why so many fittings. The clutch could be ran in all hard line.
Agreed, but only if there is a loop at the slave cylinder to allow movement w/o working the flares to fracture. FWIW I usually prefer to plumb clutch systems with 1/4" or -4 tube/hose. This is b/c those systems typically move a lot more fluid volume than a brake system, and the operating pressure is much lower so the system doesn't not flex like a brake system done in 1/4"/-4 would.
It is common in desert racing buggies to zip tie the front brake hoses to the tie rods. Usually the right hose starts out pointing to the left either above or below the rack and makes a large radius loop onto the tie rod.
Depending on which actual size being bent I use a Rigid or Imperial Eastman size specific tube bender. Those 3 sizes fits all tubes benders aren't worth the potmetal they're made from.
For large radii bends the "bent over a tube" method described above is the best. For standard radius bends the size specific benders I mentioned above are the only way to go. Now what if you need a bend *RIGHT* behind the tube nut?
One of my bosses in my racing prep days showed me a tool he made for this. It is a piece of bar stock drilled & tapped in the end for the tube nut threads. The trick here is to use a bottoming tap, drill the hole fairly shallow, and risk breaking the tap in getting the threads all the way to the bottom of the hole. When the tube nut is tight in the bar stock the tube itself should not be able to wobble about at will.