When do i need a 4040 prop?

i have a 92 civic dx with 99/00 SI front brakes and stock drums in the rear. I tried bleeding it numerous of time with the same outcome, soft pedal. I currently have a 4040 prop valve hooked up instead of the stock one, could this be the reason for the soft pedal feel?

 

From the research I did when I did rear brake conversion yes you do need the 40/40 prop valve

 

He has stock rear drums, so no he doesn't...

Check the full brake system for any leaks... Is the master cylinder maybe leaking? Your MC could be bad, a leak in one of the lines, or maybe the booster. First check for leaks and perform the following tests...

Brake Booster

Functional Test

1. With the engine stopped, depress the brake pedal
several times, then depress the pedal hard and hold
that pressure for 15 seconds. If the pedal sinks, the
master cylinder, brake line or a brake caliper is
faulty.

2. Start the engine with the pedal depressed. If the
pedal sinks slightly, the vacuum booster is working.
If the pedal height does not vary, the booster or
check valve is faulty.

Leak Test

1. Depress the brake pedal with the engine running,
then stop the engine. If the pedal height does not
vary while depressed for 30 seconds, the vacuum
booster is OK. If the pedal rises, the booster is
faulty.
CAUTION: Do not try to disassemble the booster.
Replace the booster assembly with a new one.

2. With the engine stopped, depress the brake pedal
several times using normal pressure. When the
pedal is first depressed, it should be low. On consecutive
applications, pedal height should gradually
rise. If the pedal position does not vary, check
the booster check valve.

Check Valve Test

1. Disconnect the brake booster vacuum hose at the
booster.

2. Start the engine and let it idle. There should be
vacuum available. If no vacuum is available, the
check valve is not working correctly.
Replace the check valve and retest.

 

do u think i should switch back to the stock prop?

 

Yes. You only need the 40/40 when you have rear discs. Your stock prop valve is what you need to use.

 

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