Jooleeus

I had to replace the brake master cylinder on my 89 Civic Hatchback a while back, so I purchased one and had a friend help me install it. We noticed that the brake lines looked fairly worn out, so we changed them to stainless steel braided lines also. After lots of bench bleeding, then more bleeding at the car, we found that the brake pedal was really soft.

After several more attempts at bleeding the brakes, I figured that the new cylinder was bad and picked up another one. I installed the new one and the pedal is still extremely soft!

What the heck is going on with this car's brakes? If the master cylinder is new and the lines are bled of any air, then what else could cause the pedal act like this? I appreciate any help you guys can give me, I'm so frustrated with this car that I'm seriously considering getting rid of it!


Modified by Jooleeus at 7:51 PM 2/7/2008

Jooleeus

Friday night bump. Would the brake booster have anything to do with my current situation? From what I've read, booster failure = rock hard pedal, which is the opposite of what I'm experiencing. I'm going to re-bleed the system tomorrow and double check for any leaks, but I didn't see any last time so I'm not too optimistic...

thesmogman

How are you bleeding them?? Honda's have a crossed brake design and has a slightly different pattern to bleed them correctly.

Start with the right rear then the left front.
Then to the left rear and then the right front.

I had to do mine a few times (3) before I was satisfied.

EDIT: it's not the booster!

gibsanez

Are you sure you have no leaks anywheres? Check the wheel cylinders (if the car has drums)

Jooleeus

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by thesmogman &raquo;</TD></TR><TR><TD CLASS="quote">How are you bleeding them?? Honda's have a crossed brake design and has a slightly different pattern to bleed them correctly.

Start with the right rear then the left front.
Then to the left rear and then the right front.

I had to do mine a few times (3) before I was satisfied.

EDIT: it's not the booster!</TD></TR></TABLE>
That's the pattern I've been using to bleed the brakes. I've tried the traditional two-man method, the hose in the jar of fluid method, and I even tried using a vacuum hand pump with no success. I probably have a gallon of old fluid sitting around now...


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gibsanez &raquo;</TD></TR><TR><TD CLASS="quote">Are you sure you have no leaks anywheres? Check the wheel cylinders (if the car has drums)</TD></TR></TABLE>
I've inspected around the underside of the car and haven't seen any obvious leaks. I'll make sure to check out the wheel cylinders, didn't think to inspect those (sorry, still a car newbie!)

Thanks for the help guys, looks like I have a busy weekend ahead of me!

gibsanez

That's the hard part about pin-pointing those leaks, but I had the same happen to me, I was loosing fluid and couldn't find anything, and it turned out to be a leaky wheel cylinder that I couldn't see until I took the drums off.

Oh, by the way, your rear brake lines are run underneath your carpet, inside the car, so you won't find any leaks on the ground if you have a cracked line. If you've gone through as much fluid as you've said, I'd take a feel around the carpet for wet spots. You never know. Good luck.

Jooleeus

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gibsanez &raquo;</TD></TR><TR><TD CLASS="quote">That's the hard part about pin-pointing those leaks, but I had the same happen to me, I was loosing fluid and couldn't find anything, and it turned out to be a leaky wheel cylinder that I couldn't see until I took the drums off.

Oh, by the way, your rear brake lines are run underneath your carpet, inside the car, so you won't find any leaks on the ground if you have a cracked line. If you've gone through as much fluid as you've said, I'd take a feel around the carpet for wet spots. You never know. Good luck.</TD></TR></TABLE>
I'm actually not losing any brake fluid (at least, none that I can tell) and I patted down the carpet for wet spots but found none.

Popped off the brake drums and looked inside, and it doesn't look like any leaks have occurred. Lots of brake dust, but no stray fluid or stains from what I can see. Should I change them anyway just to be safe..?

Gonna go back out and poke around the car some more...

Maxcapacity

Your problem is that when you installed the new master cylinder the piston rod that gets pushed in from the power booster has a specified length..
measure with a set of calipers the free length of the rod that sticks out of M/C and measure the depth of the push rod inside of the booster.
You can adjust the booster to push out a bit more by turning the nut from inside the car, but dont turn too much or the brakes will drag.
Read in a manual about how much gap clearance between the M/C and the booster.

G0crxG0

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by thesmogman &raquo;</TD></TR><TR><TD CLASS="quote">
Start with the right rear then the left front.
Then to the left rear and then the right front.
</TD></TR></TABLE>
According to Honda you start FL, then RR, then FR, then RL