Losing brake pressure

[500"Dart]

I Did the 73 up swap on a 65 dart,turn the steering wheel all the way to the lock position either left or right and the pedal goes to the floor....the brakes work fine with the wheel straight.Any Ideas?

Thanks

[jeffmrfixit]

sounds like mabe a bad master cylander?

[65DartGT]

Are they power or manual brakes? If they are power brakes, do you have a check valve in the vacuum line going to the booster? If not or the valve is bad the change in idle when you load the PS pump up could be affecting the vacuum to the booster and causing it to actully pull the pedal down. Hope this helps.

[sunsetdart]

If you are losing the pedal when you turn the wheel, you may be crimping one of the lines.

[Midnight Special]

I recently was losing pressure with the line loc engaged.  Check the upper brass fitting on top of the prop valve mine was loose and seeping.  Tightened 'er up---solved the problem...for me at least.