Wilwood brakes

[novaracer]

I have a 68 Nova that has 4 wheel wilwood brakes and a hydro boost on it. A little history 2 years ago we got the car done brake worked great the last 2 years up until the end of last year the rear brakes stopped working (no pressure), I sent the master cyl in to wilwood they said it was bad...ok replaced it...installed a new one (same 1in bore as before) bleed the brakes drove the car worked good....then drove it again last weekend the brakes started dragging after about 10 miles (in town) then came out of it?? drive it again yesterday and after driving again for 10 miles they were really dragging (would stop the car from 25 mph) again started heading for shop and they freed up again?? inspected the brakes they all look the same (not like 1 is discolored from heat)...I am thinking I got a faulty master cyl? Thoughts?

[chpr1972]

I would check all your brake rod lengths. possible one is not right length? That causes problems with power/regular brakes sometime. Is there a return spring on brake pedal under the dash? Did you replace the rubber brake lines? Wilwood requires 3/16 brake lines all the way around. Is the line to the rear 1/4?