RS2SSxLS2

I have good brake pressure at first then half way it just collapses. Bleeding the brakes old school the driver front is getting fluid but not any pressure in it. The rest are fine.

dreww

iTrader: (1)

sounds like brake booster and/or master cylinder issue.
being its only one caliber affected, maybe its that caliper. but I haven't seen that personally vs. many bad boosters and master cylinders.

libertyforall1776

iTrader: (2)

How did you determine that only one of four is not getting adequate pressure?

I recently put on pads on all fours, and the next day bled the brakes with a Motive Power Bleeder and the peddle does not feel as firm as it did prior to the pad change & bleed. I checked for bubbles on all four and same result, so I have a somewhat similar condition. I did wonder if this could be due to ABS and the ~2 oz of fluid that may be trapped in there -- and I need to command open its solenoid with HP Tuners and then bleed?

RS2SSxLS2

Bleeding in the brakes manually the other three shoot fluid out, meanwhile the drivers front just trickles with about a 1/16 of an inch gap between the rotor and pad. I did a LQ4 swap and haven't gotten it running yet due to wiring issues so I don't have vacuum on it. Could this be my booster problem? The rest our moves a little too when I press the brake pedal. All the bolts are tight though.

RS2SSxLS2

This car is becoming my wife love her but yet hate her at the same time

ThoR294

iTrader: (6)

maybe a clogged flexible line?

RS2SSxLS2

But the bleeder valves all have fluid coming out

ThoR294

iTrader: (6)

its either a master cylinder or that flexible line. you ever replace the lines?

RS2SSxLS2

No all stock lines and calipers. The suspension, engine, transmission and dash are what all have been upgraded.

ThoR294

iTrader: (6)

Well, since they haven't been upgraded/replaced... maybe you should replace the front flexible lines and see if that fixes it. if not, possible master cylinder issue

RS2SSxLS2

Well why does the brake reservoir flex when the pedal is pressed

ThoR294

iTrader: (6)

if it was a booster issue you'd have problems all around. drivers front is essentially the one that requires the least amount of fluid... regardless, maybe its a bad master. but what I am saying is a flex line is cheaper and easier to do than a master, and it is worth it to do it because of the age of your car

libertyforall1776

iTrader: (2)

Have you thought to have the ABS system scanned for codes? This usually requires a dedicated system which can do this, since it is a separate set of codes from most engine code readers. Some parts shops scan ABS codes free now, like Advance Auto by me, be sure to ask year coverage...

Doing this could give you some good clues about problems -- it told me I had a bad ABS Motor Pack (which is easily replaced) on my now sold '95 Camaro 3.4L...

RS2SSxLS2

What about not having applied vacuum to the booster since the swap was done, will that cause my issue?

gak68

I had a similar issue with my Chevy truck. The abs solenoid was closed not allowing air to bleed from the brake line. My professional mechanic friend said to drive down a dirt road or on wet pavement and slam on the brakes enough to lock up the tires activating the abs. This caused the valve to open and it let me purge out the air that was locked up in there.

libertyforall1776

iTrader: (2)

Yea, I think this could be the issue I experienced as well. You could also use a tool like a Tech 2 to command the solenoid open... I am trying to find out if HP Tuners can do this...