Problem with Big Brake Swap

[ETS Michael]

So I have Galant VR4 big brakes on my 94 elantra. The problem i'm having is on the driver side. The brakes seem to be opening 1 of the 2 pistons and not retracting enough to let the pad off the rotor. This makes for a rather warm rotor =)

Anyone have ideas? I replaced the caliper and the same thing happens. I did find a leak on the passenger side piston seal, which I will need to rebuild I guess.

Do you think it will come down to a porpotion valve?

Thanks,

Michael

 

[ETS Michael]

On dual piston calipers does the brake have an internal proportion valve? meaning, if no pressure is applied to piston 1, the piston will keep trying to open and piston 2 will stay down. If we apply pressure to piston 1 would piston 2 then start to move? To keep the pad equal?

Thank,

michael

 

[HIGHPSI4]

Sounds like one of the pistons is dragging. You may have to get that one rebuilt or replace. Fluid pressure is applied to both pistons. What keeps them squared to the rotor is if one piston pushes more it will press the pad to the rotor first. This provides more fluid resistance to that piston and allows the other piston to 'catch' up. Of course both pistons should be free and operate equal for best performance. But if one is binding it will stick and keep the pad in contact with the rotor.