It has been along time i post anything on this forum. So here my setup and i have been driving it like that for awhile and never thought i need 2 do anything until i almost had an accident on the highway couple days ago. i have an eg6 1992 vx, dc2 f/r brakes setup, stock brake lines, f/r slotted rotors, aftermarkert pads, 40/40 proportional valve, and dc2 master cylinder. when my car is rolling i have pressure to the brake pedal, but when it at a complete stop, it started to sink all the way to the floor. I redo my air line to vac booster and it has pressure going in it. I try bleeding the brake and check all my hard lines if there any leaks, but found none. I check the brake calibu... if there any leaks or my rotors where thin which could cause my piston to sink. then came my master cylinder and brake booster and to no result i couldnt find nothing. All the casket is there in between the master cylinder and brake booster to the firewall. i think i do need to change up my master cylinder because i have an dc2 abs which i don't have abs in my car and probable my brake lines which it could expand from the heat. I want 2 know if anybody has the similar setup and having no problems with their setup or a way to correct this problem. yes, i do sometime have to add some brake fluid, but never alot.

 

Sounds like your master cylinder is taking a dump... Can you "pump" up the brakes, then will it hold for a moment?

 

I agree master cyl.

 

srry guys, i just got back from houston. to this questions, yes. it will hold for a moment but when idling it will stay for a short period of time. i'll try to check my vacuum line just to make sure its correct, because i forgot to mention that i also running a oil canister and probable running the lines incorrect, but like i said i try searching thru forums and applied the methods to no result. i'll post some pics when i have a digital camera that i can use, if this will help with my vac lines which causing my sinking, will save $... thx guys

 

I have/had the exact same problem in my dc Integra. I just replaced the MC and I have yet to bleed the system. I suspect this will take care of the issue. I will post after the system is bled.

Just bled the system and it was in fact the MC. Brakes are the best they have ever been on the car since I have had it!

 

If you don't have any external leaks, it is your master cylinder. It sounds like you do have leaks, though, by you saying you have to keep adding brake fluid to the reservoir, even if it's only a little bit. Go over everything. Unbolt the calipers and check your piston boots. Check all your fittings and hoses, especially at your prop valve. Sometimes they can be leaking ever so slightly and it'll run down the back of it where you can't see unless you're really looking for it. Unbolt the master and check its seal. A little bit of seepage is normal, but if there's a bunch of fluid between it and the booster, replace or rebuild it.