Residual check valves

[Blue Oval Man]

I am building an all new brake system on my 68 Mustang and custom bending all new lines and routing them out of site. I am using Wilwood brakes on all four corners along with a hydroboost unit.
I have recently read that I should put 2lb residual check valves in the front and rear brake lines. Is this true?
If so, can the front check valve be placed before it splits to go to each side or should one be placed in each line?
On the rear axle, can the hardline be ran from side to side on the car body then use stainless flex lines to each brake caliper instead of the more common method of routing brake line, using a flex line and splitting the lines then going around the axle housing and using short flex lines from that to the brake calipers? Hope that is clear enough.



David.

[Schwartz Performance]

If you have 4 wheel discs you shouldn't need a residual check valve- typically these are used if you have drums in the back or all around.
As for the flex line question, you can do what you said no problem. Just be sure that your flex lines are long enough and routed in such a way that they won't kink or bind with the suspension travel.
-Dale

[Blue Oval Man]

Thanks Dale. That's what I thought as I had never heard anyone doing that with four wheel discs but was just reading an article in the February issue of Classic Trucks and the author says to use them to keep a little bit of pressure on the brake pads to help decrease the pedal travel needed to apply the brakes.
Good point about the rear flex lines, I will be moving the suspension through it's cycles to ensure everything clears.
David.

[79-TA]

Old trucks that have master cylinders that mount on the chassis rather than the firewall sometimes need a residual check valve as there might not be enough of a natural pressure differential from the difference in height between the master cylinder and the brake caliper. This shouldn't be an issue on your Mustang.

[Apogee]

In general, 2 psi residual pressure valves are to keep fluid from draining from the calipers back into the MC in applications where the master cylinder(s) are mounted at or below the level of calipers. This is commonly an issue anywhere the MC's are mounted below the floor. As for keeping the caliper pistons and pads from retracting as far, 2 psi won't make much of a difference if any in that regard IMO, and people that use 10 psi units in disc applications are usually doing so as a band-aid for some other issue.

Drum brakes that use wheel cylinders with a certain style of cup seal generally benefit from the use of a 10 psi residual pressure valve, since that helps keep the seals "inflated" against the sealing surface during release, where the large return spring rapidly collapses the wheel cylinders.

Tobin
KORE3

[Blue Oval Man]

Do I feel stupid or what! It never even occurred to me that the build in question had the master mounted on the frame, so yes, of course it would need the check valves.
Thanks for the replies guys, now I can get back to work.