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Does anyone really understand how these aftermarket "balance" front to back valves work ? Without say a floating piston of say two diameters it cannot "change pressure front to back " ..and then keep a ratio as pressure changes. The stepped piston to do that ( could be done) would have to displace as much fluid on each side as a master and be as big as a master . And would not be adjustable in machined in diameter / pressure ratio . I got into the 4 pipe ones mopar put in dodge trucks in late 70's . Although called balance valve , disc brake valve , proportional valve etc what it REALLY does ( surprise coming ) is it has a very small piston that sits in the middle--- if pressures are the same on each side , it never moves hardly at all (ends of piston chambers connect to F and rear ) . If unbalanced F to Rear it moves about 1/4 " and turns on the light , by grounding a feeler that then touches necked down center of piston and at same time I think it closes or restricts the outlet port in line with piston , with the high flow ( gas meters have this , excess flow valve shuts of gas if over normal flow and locks off, held there by gas pressure = broken pipe in both cases ) .makes these Dodges a total bear to bleed . Open one part to bleed , piston moves , light goes on . And to end up with light off is a long game of one then the other .. After air is out . But it might save your tail if a line bursts . So they mean it checks F-R pressure balance , NOT impacting brake balance at all . I think this function was misunderstood by many right from the get go , due to words used around that valve . And passed on down . "Experts" told me stuff that was 100% wrong on what does (" it is needed for discs "etc ) . It has no function except safety . For sure . I took it apart . You can see what it does. Nothing else in it . If a simple needle valve is used in rear ( ? What is sold by hot rod guys) it cannot change ( the eventual) pressure , but would slow initial application of rear brakes .. But pressure would soon rise to whatever it is . I have talked to a lot of people about this , no one really knows a coherent explanation of what it does , or is intended to do , and how it does it . ( last part is essential knowledge) Yes it works, to ?delay ? Rears , might be all it does . Anyone really know ?? It may be that braking ratio is set forever by wheel cylinder bores ( common sense , equal front and rear MC bores) ---and unadjustable brake parts on say a high performance Vette say that is true ) and if you go too far from stock on that ---it cannot ever work right by adjusting a needle valve in the rear line. In fact can be a disaster where big back brake just locks up a bit later .. Yet people increase rear brakes or mix up parts and think this valve will fix it ... ??? Yes ---agree, if you shut off back brakes with a needle valve restriction , they for sure will not lock up as soon (!) I once saw a wilwood setup with a bar across two single masters , you effectively move pedal push point horizontally along the bar , between the two masters ---used in circle track cars . That will really adjust front to rear ratio . It would seem one should stick with matched parts . I used full setup off late 60 's Dodge cop car on fifties torsion bar dodge . Because of this thinking . Ratio is built into the cop car disc / drum brakes day one . . And correct ? Understanding all this is critical ? 57 61 12" total contact brakes are almost ok when they work right , but seldom do . So doing front discs correctly re : balance is something we need to understand better. Cannot pick a master or disc cuz it fits booster easy . Well , you can , I guess . And maybe we get lucky . First guess says rear wheel cylinders set MC bore, same size as car they came from . Plus the prior long story of pedal ratio and bore sizes ...... .......and residual pressure valves . Comments welcome . Still learning .. Sent from my iPhone On Jul 23, 2015, at 12:05 PM, Anna F Noia sa-noia@xxxxxxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:
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