[FATnLOW]

What a day...Took my 40 ford out on the street for the first time today,,,went about 5 miles turned around and was headed back to the house.  The 40 felt really sluggish coming back  home...thought I was having tranny trouble,,pulled off to the side of the road, checked tranny fluid it was at the full level.then got to thinking about the rear  brakes,,,sure enough hotter than Hades...
   Brakes system is 4 wheel discs  ..Mustang  II in the front.and  Nova rear end with Cadillac Seville Disc brake conversion
Booster and  master cylinder are under the floor  with the following attached....see attached photo




Have the 2lb residual valve  for the front  and 2 lb residual valve in the rear
  was able to get it back home by removing tires and opening bleeders and pushing on pads  releasing  the brake fluid and re-tighting the  bleeders. I suspect that the 2lb residual valve  for  the rear is the culprit. I ran discs brakes before without any residual valves..  Might go out and remove the rear residual valve  but before I do I was curious  to  what are your thoughts on this problem..Thanks  FATnLOW

[sammons]

I had the same problem with my '59 Elcamino, only it was the front disc brakes. A brand new SSBC conversion kit. No residual valve in system(mine was up stock local)but it had an adjustable proportioning valve. About two weeks of driving it started on mine, the only thing I could do was get out and crack the line open to move again. My buddie traced it down to the new master cyl. Apperently the pistion had a burr or something onthat resivore. Replaced master cyl, done deal.

[EDNY]

Not my field of experience...but remember the master cylinder is low below the floor...

[FATnLOW]

Sammons... Had poor brakes with the first master cylinder 15/16 bore...went to the 1 1/8 inch bore,,made a world of difference
hope it is not the master cylinder as it is a new unit...thanks

[sammons]

I would try the residual inline valve first. Like I said, mine was new, that's what tweeked me.  Mine acted like the brake pedal wasn't returning all the way. Unhooked the rod and it still wouldn't release the pressure. I guess the piston was either off a little or burr not letting it return fully

[ghost28]

I had that problem with the 27 and 28 chevy. What I found out was the weight of the pedal without a return spring was pushing on the master cylinder just enough to add pressure to the system and causing the brake fluid to swell from dragging the brakes. Before I fixed it with a good return spring I went out and lifted the pedal up occasionally while driving. and didn't have the problem so I put the spring on it.

[FATnLOW]

Sammons....Do you think rod adjustment from pedal to master cylinder could be adjusted too far in??Thought about this when you said  disconnected rod,and also ghost comment  just thinking about  the comments.  I do have a return spring installed

[sammons]

It very well could be. Get them locked up and unhook the rod. See if the pressure is released.  I like about 3/4" free play on the brake pedal myself.

[Dugeman]

I have a similar brake setup on my coupe .. This pdf. my or may not be of some help . I found it helpful when install my rear brake system.
http://www.mpbrakes.com/docs/orig-guides/DB1791BR-INSTALLATION%20INSTRUCTIONS.pdf

[FATnLOW]

Dugeman ..good article on clocking the calipers...I saved it ,,Thanks