Soft pedal with a lot of stroke.......I'd ask the guy the size of the bore of the MC he installed.
I will check the pedal rod. It was a factory 4 wheel drum car. I think there is a good 1/4-1/2 inch before rod engages the pocket. It's a deep pocket master like the one that came out of it.The bigger the bore the harder the push and the shorter the travel. 1 1/8 is probably the next step but you could run the risk of it requiring way too much pedal pressure. Literally, a fraction of an inch can make a big and not so desirable difference.
The fact that it "feels like power brakes" tells me the bore is too small.
First however, I'd make sure the rod is the right length for the MC and that is adjusted correctly. Push the pedal with your hand and feel for how much travel there is before it meets any resistance. The rod may be too short or more likely out of adjustment.
Well from what I understand yes. Disc/drum master's have a residual pressure valve in the rear circuit. I have a master cylinder from a 68 Corvette that was disc/disc and manual brakes.This is only a guess...
Is it possible that the amount of brake fluid required to fully engage the rear disc brakes (fill the calipers with fluid) is a higher volume of fluid than would normally be needed in rear brake cylinders to move the brake shoes for drum brakes?
Could that be why your brake pedal has more travel when attempting to stop your car?
Is there a differnt master cylinder that is needed for a disc/disc set-up vs a disc/drum set-up?
Its a Right Stuff Kit. I do not believe the rotors are reflecting. I believe the are fixed.I'm assuming you have floating rear calipers as opposed to fixed. I'd make sure they do float and are not stuck on the pins thus deflecting the rotor under pressure. I'd remove the wheel and have someone mash the brake pedal. The caliper should be moving on the pins in order to self-center over the rotor. Any deflection of the rotor is adding to brake pedal travel before the pads "clamp".
I gravity bled them yesterday with a piece of wood tapping. I was able to get some very small bubbles(2-3) out but the pedal did not improve.Could you / or have you . . . try tapping on the brake calipers before any bleeding . Air could be trapped in the lines, still . I DID 'Tap on my front calipers' between bleeding each wheel. ( I even lightly ' tapped on my new lines ' . . . just too help move those ' Air Bubbles ' towards the highest spot = the calipers .
I'm just saying ?
Doesn't take too much . . . . . use a small piece of 'wood' . . . go easy .
Yea if it wasn't a manual trans I would probably just go get some non-e Brake calipers and be done with it but I need an e-brake. I have only tried to bleed furthest to closest at this point. I will see if the shop can figure it out. I also got some replacement calipers from advanced auto (they will warranty them) and see if maybe we can get lucky. I am definitely pulling my hair out at this point. It does stop straight and fast but the pedal sinking so low really is concerning.I would be pulling my hair out, especially since you not only are getting the advice from the experts on the site, you've also broken down and brought it to a shop to have it figured out. Not sure if this is something to consider but I know that I once changed the pads on my nephews vehicle. I made the mistake of loosening up the bleeders on the calipers to move the piston instead of using a c-clamp and for the life of me I couldn't get it to bleed where the peddle felt right. He eventually took it to a shop and they told him that I was bleeding it wrong, instead of bleeding from the furthest to closest they said you had to bleed it in an X pattern. I haven't run into the issue since because I learned my lesson and have used a c-clamp to open the piston on any disc brakes I've done since then. Has anyone else heard of this? Is it a possibility that the brakes are being bled wrong? I was able to find some articles on-line that seem to back this way of bleeding up. Just my two cents, not sure if it's gonna make a difference on your ride or not but definitely won't hurt to try. No matter what the fix is, please post it on here to maybe save a future site member from going through the same troubles.
Thanks again for the help Alf. I will try that this weekend along with making sure there is as little slack as possible in the e-brake lever. I moved the levers in the direction of clamping on both sides while the springs were off and it seemed to help the pedal. They probably move about 1/2 inch before they engage the rotor.All Right Stuff calipers float on pins. They are essentially copies of OEM parts.
Remove the wheel and look thru the opening in the top of the caliper. Those calipers only have pucks on the inside and when the pedal is pushed they put force of the inboard pad contacting the inside surface of the rotor causing the caliper to slide or float on the pins. When they work, calipers float on the pins forcing the outboard pad to contact the outer side of the rotor.
It is quite possible your caliper is not moving enough on the pins and the inside pad is pushing hard on the rotor before outside pad contacts the rotor. This will give you excessive and soft pedal.
Remove the pins and lube 'em up with Permatex ceramic brake parts lube.