Pedal to the floor

[73duster47]

I just did some major brake work on my Duster, installed a rear disc conversion kit, all new lines, front calipers and rotors and new master cylinder all from Right Stuff Detailing.
After stopping leaks and bleeding the brakes I can sit and pump the pedal with engine off and have a good firm pedal, but start the engine and it goes straight to the floor. The car still seems to stop ok (never got it above 5mph), but there is no pedal feel at all.
These are power brakes, and I did not replace the booster. It seemed to be working OK after I did my engine swap from a slant to a 408 small block. I know that a larger cam will hurt the performance of the booster, and I did unhook the vacuum line from the booster and drove the car a tiny bit and had good pedal feel there.
Do I need to replace the booster? Or is there something else I can do to give me a firm pedal with the vacuum hooked up? Everything is new and installed/adjusted properly. I'll be giving Right Stuff a call in the morning to see what they cam suggest.
Thanks!

 

[67Dart273]

You may have multiple problems, but a bad booster won't cause "no pedal."

 

[yarcraft91]

Right Stuff lists a 24/7 telephone support number. Call them now.

Did you have the engine running or otherwise provide vacuum to the brake booster when you adjusted the pedal pushrod?

 

[73duster47]

I did not touch the pedal pushrod at all as the factory service manual says nothing about doing that.
I'm giving right Stuff a call once I get to work

 

[SirDan]

I had the same problem and it ended up being the push rod length. I ended up jacking the front up so both tires were off the ground, then I adjusted the rod until the brakes dragged slightly and backed off a bit until they did not drag.

Mine work great now. my rod was wayyyy off.

 

[73duster47]

Called and spoke with Right Stuff, it's an ebrake cable related issue.
The cables that come in their rear disc conversion kit are universal and are the right cable length, but the sleeve length is about 3 inches too long, so they don't really fit the bracket. Because they use the ebrake to adjust the rear calipers, and the ebrake cables arn't working properly the rear calipers never got adjusted and arn't moving the pads, leading to the soft pedal condition.
I'll give them a call back with measurements and they'll send me the right cables if they have them or a Lokar make-your-own kit if they don't have anything that'll work.
They don't have an a-body rear disc ebrake cable yet, but from the measurements I give them they should be able to get some made and in production by the end of the year, so if anyone is looking for a good rear disc conversion kit, Right Stuff is a good way to go, just wait for the new ebrake cables coming soon!
Thanks.