okeley dokely, lets see if i can figure how to say this intelligibibibibly. .. (beyond here be dragons
)
some notes on dual feed hydraulic brake systems i've experienced;
losing one circuit, especially at the entrance to a corner, just might turn your shorts brown but it's worse with a single pot system
dynamic weight transfer is an issue and can be effectively controlled thru pressure bias front to rear
tire width has a definite and verifiable effect on weight transfer
"dual diagonal" ie. l/f connected to r/r and r/f connected to l/r
very safe, short of catastrophic system failure you'll be able to come to a controllable stop.
requires a dual path proportioning method to maintain brake bias(oem valving could work but without a LOT of testing
its hard to figure out the right bias (balancing) spring, free range calculators exist that get pretty darn close)
(if you drive roundyround being able to offset the brake response might be useful but thats beyond my experience)
system requires that the master cylinder(s) have matched bore sizes (ok that ones pretty obvious i admit)
requires additional hard lines (2 separate rear feeds)
pedal doesn't "sink" quite as scarily as a f/r split system if one circuit is lost but it still goes soft
front/rear split system
easy to plumb and easy to make sure there's no side to side variance due to friction loss.(not really an issue in my experience)
only requires one bias control
front and rear master cylinder bores do not have to match, size changes can be used to effect bias
with dual single pot master cylinders the bias can be done mechanically which is more robust i'm told
hydraulic biasing can be done a variety of ways including valving and pipe diameter as a flow/pressure control
proportioning valves;
used to control the application of brake pressure to allow adjustment for brake dynamics
a lot of methods exist from mechanical to hydraulic or electronic/hydraulic and "set and forget" to active control (eg modern abs)
a must in my experience even for a road car
as an example, several years ago i did up a 66 mustang coupe with full shelby suspension mods using granada brakes (disc/drum)
stopped great but the granada proportioning valve left a little to be desired, it liked to wag the dog on hard stops
ran the data thru a calculator and figured out that the much shorter rear overhang of the mustang in comparison to the granada was
enough to imbalance the brakes so i went to an adjustable valve, that change shaved 15 feet of of my 60-0 stops
(yeah i'm one of those anal kinda guys sometimes, i actually measured it to make sure i wasn't daydreaming plus i was single back then)
(side note, chris machado at mustangs, muscles and classics in santa rosa ca. is a durn good guy and wonderful to do business with)
i haven't used the biasing rod method but if i understand correctly how they function, they use mechanical leverage to vary how the
total load force is distributed, someone please correct me if thats wrong.