EJ1 wilcox

Background and vehicle info: 1990 Civic STD hatch. I recently added rear brakes from a DA integra. When I did the rear disk swap, I swapped out the stock prop valve to a 4040 prop valve from the integra as well. So it's a 1990 STD with integra rear disks, 4040 prop valve, and everything else is stock STD. Pads etc. are in good shape.

I noticed this before I did the rear disk swap but didn't think much about it until recently. When I depress the brake pedal at stop lights the car stops fine, but if I hold my foot there and put gentle steady pressure on the pedal, the pedal sinks bit by bit and will go all the way down to the floor. If I then release the pedal and press it again, it is firm at the top and then slowly fades to the floor again.

Other than that the brakes work great. I don't ever even notice it unless I keep steady pressure on the brakes.

Today I was thinking about it and since I have worked out the other kinks I figure this is a good time to take care of this one as well. I checked the brake fluid level and it is still completely full. I also checked the prop valve and other brake lines and nothing is leaking at all.

When I did the rear disks and the prop valve I bled the brakes a TON and got all the air out of the lines. I mean, I spent a while making sure all the air was out of the lines. But, I suppose that could be the issue. I was also wondering if maybe it's a problem with the master cylinder.

I also read that many people replace the stock MC with a larger one when they install rear disk brakes because the rear brakes require more fluid movement and that typically translates to more pedal travel unless you install the larger MC.

Anyways, what do you think? Time for a new MC? Is there just air in the system? Or, is it a different problem that I haven't considered?

If it's the MC, which one should I get? I heard that the MC from the 88-91 EX is larger and bolts right up, is this correct?

Thanks for the help!!

** Cliffs Notes **

- Brake pedal fades to the floor with steady pressure
- Replace the MC or is there just air in the system?
- Which MC should I use if that's the problem? 88-91 EX? Or something else??

Crx Jimmy

yes its probably the master, and use the accord/prelude master, I dont think the sedan one will work

mahatma

Yeah I vote MC as well....

Unless the standard civics are different somehow, then the 90-91 EX sedan MC will bolt right up, don't have to bend lines or anything. And it's 15/16"

EJ1 wilcox

Thanks for the replies.

I noticed this morning on the way to work that the pedal was soft, but wouldn't sink all the way to the floor like it would last night. Maybe it has to do with how hot the brakes were?

Either way, I think I'm going to look into getting a new MC. I think that's the cause of the soft pedal.

ludesrv

If your brakes get steaming, they will get mushy and just go right to the floor. Not a good thing. Means the brakes you have are too soft to take the punishment you give it, time to upgrade. Direct bolt on rotors from KVR are nice, I run them, with hawk brake pads. It's a good setup for a daily.

Black4thgenEF

My vote is master cylinder. Mine went out last year. If I just kept my foot on the brake it would slowly sink to the floor. Sometimes it would almost get to the floor without slowing the car and then the tires would lock up. Definately get a new one in there. Make sure you bench bleed it properly and you wont have a problem.

EJ1 wilcox

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Black4thgenEF &raquo;</TD></TR><TR><TD CLASS="quote">My vote is master cylinder. Mine went out last year. If I just kept my foot on the brake it would slowly sink to the floor. Sometimes it would almost get to the floor without slowing the car and then the tires would lock up. Definately get a new one in there. Make sure you bench bleed it properly and you wont have a problem. </TD></TR></TABLE>

Yeah, I'm looking into getting an 89 Accord MC. I guess they are 15/16 and bolt right up to the stock brake booster. That should help the pedal pressure as well.

The install is as easy as it looks right? Drain fluid, unbolt lines, unbolt MC, replace MC with new one, install lines, add fluid, and bleed...

Seems like a simple job. I'm going to try to knock this out tomorrow so I can have it done before the autocross event on Sunday.

sanimalp

you can also rebuild your stock master cylinder for like $30 in parts from napa or another higher end parts store. just throwing that out there, because i had pedal travel issues with 2 master cylinders i bought from autozone which required me to bleed my brakes 3 times in the course of 2 days. and there is nothing i hate more than bleeding brakes. i havent tried the prelude idea but a lot of people do that upgrade..