Mopar aluminium master cylinder

[greenrt_se]

Hi all
I have a problem to get good pedal effort whit Mopar aluminium master cylinder,pedal goes almost floor(travel is over 2 inch)
4 corner disc,front 4piston bendix and rear ssbc disc kit whit adjustable propotional valve in rear brake line under car.
The brakes is bleeding 8 times and master cylinder is bench bleding 3 times.in the picture is whitch master cylinder ports in my set up
goes to the rear and to the front is this correct or can they be in that way,like original disc/drum set up

the pedal goes to the almost floor when motor is stop and when motor is running


the booster is hydraboost

[Chryco Psycho]

the bore of the master you are using May be too small & not moving enough flid to work the brakes properly ,
you have the line on correctly , front line on the master is rear brakes , did you remove the residual pressure valve in the master to prevent the rear brakes dragging with 4 wheel disc brakes ?

[Ghoste]

I had the wrong master cylinder on my car and when I got one with the proper bore, even before properly bleeding the lines the pedal had a different feel.  It would go as far because of needing to be bled, but it had a feel all the way of fluid moving.  (doesn't properly explain it)

[greenrt_se]

the bore of the master you are using May be too small & not moving enough flid to work the brakes properly ,
you have the line on correctly , front line on the master is rear brakes , did you remove the residual pressure valve in the master to prevent the rear brakes dragging with 4 wheel disc brakes ?

bore in the master is 1 1/8.no I don ´t remove anything from master...is that residual pressure valve in rear brake port in master??

[Ghoste]

If it's a disc drum master, yes.

[greenrt_se]

I buy it from Gregz from magnum hp ,so maybe I have ask from him

[John_Kunkel]

The newer aluminum MC's don't have residual pressure valves.

If the pedal is firm when it stops near the floor, air isn't the problem. Like CP stated, the brakes are consuming more fluid volume than the MC can supply.

[greenrt_se]

strange,I plug master cylinder holes whit blind plug,and still pedal go to the floor

[John_Kunkel]

strange,I plug master cylinder holes whit blind plug,and still pedal go to the floor

Either the MC is bypassing internally or the bench bleeding was done incorrectly.

[Charger_Fan]

Pushrod length could possibly be too short, not giving the master cylinder piston full travel.

If I'm not mistaken, with that type of hydroboost, you need to make sure the engine is running when you bleed...so you don't damage any hydroboost pieces.

[greenrt_se]

brakes bleeding whit hydroboost engine off.and yes maybe the master cylinder is internally leaking

[greenrt_se]

Problem gone    There was small metal chip inside the master cylinder,rear piston small hole