Now, before someone just writes SEARCH, I have been searching and working on this problem for 6 weeks and I’m at my wits end.
I did an ABS removal on my 90GS and have not had a stiff brake pedal since. I have flared and re-flared lines over and over. Used new ones wherever possible and bled the brakes over and over after each change.
I don’t seem to have any leaks at any of my connections but no matter what I do I cannot get the spongy nonsense to go away. I am at a loss and am about to take it to a shop to see if they can do anything for me.
Any brake experts in here have any suggestions as to what might be wrong? Really need some help here. Thanks!
were the lines ever disconnected at the MC?
No, they are stock and never disconnected. It’s odd, they basically feel like there is air in the lines. When the car is off, the pedal is perfectly stiff. Hard as a rock. As soon as the car starts they act like there is a ton of air in the lines which is strange because when i bleed them there is not so much as a tiny bubble. Can air still be stuck in there?
does the pedal hit pressure, then sink? or is it just spongy all the way?
it’s possible that the seal(s) in the master cylinder may have been damaged when bleeding.
the piston in the master cylinder travels a small distance it’s whole life. this develops a ridge inside the cylinder. if the piston and seals travel past that ridge during bleeding, the seals can become damaged.
when bleeding the system in which the old master cylinder is still being used, you have to pump very short strokes
Thanks for looking guys. i think welfare’s option is more likely at this point. The pedal starts out spongy, then holds up about 2/3’s of the way, then pretty much slowly seeps to the floor. A little bit of everything i guess. Im basically going to bite the bullet at this point and install a new MC.
If the brake booster is bad im just ripping it out and going with manual brakes…Or burning the car. 
i agree with welfare that definitely sounds like a bad master cylinder. and welfare i wasn’t trying to be a dick on the other post i just felt like everybody was knockin me. I don’t mean to (Thread Jack).
[QUOTE=welfare;2220590] if the piston and seals travel past that ridge during bleeding, the seals can become damaged.
when bleeding the system in which the old master cylinder is still being used, you have to pump very short strokes[/QUOTE]
This I did not know, and is very likely the cause of my problems. Thanks for the info Welfare. Really appreciate all the help guys. Brake hell is a sucky place to be.
ahaha. no worries, bud. it’s just the internet. long as we try and help eachother up in here
A little update. Tried an old MC I had but it was bypassing. Decided to take apart all four corners and have a closer look. The first corner I found a badly leaking and seized caliper. Now rebuilding that one, then gonna tackle the others, then I will try the MC again to see if it solves the sponge. If it does great. If it doesn’t I will try the pushrod adjustment. I’ll update the thread when I know more.
if the caliper’s leaking, that’s gonna cause sponge
Yup, and both fronts were apparently leaking. One REALLY badly. Rebuilding them now, had to order an OEM piston for one, got new seals for both so should be putting them back together soon. (After I replace a torn lower ball joint dust cover and what looks to be a bent upper control arm) You know what it’s like, take one thing apart and before you know it the whole front end is disassembled lol
Will update this as soon as everything is back together to see if it solved my issue. Honestly, after seeing what that caliper looked like on the inside, I can’t imagine how it could NOT be spongy…What a rusted out leaky mess.
if you run rubber/stock brake lines it’s always a good idea to check that too. have someone step on the ped while you carefully inspect the lines for leaks or bubbles.
My wife’s car had a bit of sponge to the brakes, one day the front passenger side line burst.
easy fix for sure, but I imagine it could have been caught much earlier if I checked the lines once when she mentioned it.
Good call Malformed. Definitely good to check these before tearing things apart. I suspected my lines at first but they are in surprisingly good shape. Very stiff with no softness to them at all. I kinda wanted them to be bad to be honest so I could replace them with SS lines but I can’t justify it.
Oh and in case anyone does need to replace stock lines, OEM honda is actually cheaper than any aftermarket lines I found. Which is odd.
jobber or raybestos oem replacement may be cheaper than oem.
sometimes the line will collapse from the inside. you won’t be able to tell by looking or feeling.
if you go to bleed the brakes and fluid doesn’t flow like it should, that’s when you’d look at it as a possibility
Alright so a little update: I have replaced all four rotors and pads and rebuilt all 4 calipers by hand, painted them and reinstalled. The result? Pretty much the same thing except the pedal doesn’t “fade” right to the floor anymore. Its sponges, then stops about a half inch from the floor. I also tried to adjust the booster push pin to no avail. I made the tools needed as listed in the Tegger article but did a lousy job of it apparently because I pretty much stripped the “star” nut and could not get it to let go so…
Now that I no longer have any leaks, next I am going to replace the Brake Master Cylinder and hope it works. If it doesn’t? I’ll replace the soft lines…if that doesn’t work I will have no choice but to remove the brake booster and try and adjust the push pin with the booster off the car.
Stay tuned for another update from spongy brake hell…
The symptom of spongy brakes that still hold pressure is more synonymous with air being trapped. If it were a leaking seal in the master cylinder, the pedal would hit a point and then sink to the floor slowly.
If you can get ahold of one, try using a power bleeder. This will ensure all air is evacuated
I hear ya welfare, but that being said a person really should be able to remove all air from a working system by using the standard pump and bleed method no? I mean, if everyone else can do it, shouldn’t i be able to as well?
I don’t have a power bleeder unfortunately and the damned things are prohibitively expensive.
Definitely wouldnt go out and buy one just for this. Just figured if you knew somebody who worked at a shop maybe…
Usually what I like to do when bleeding after replacing calipers is, while the screw is closed and you’re purging your air, is give the caliper a few light taps with the hammer in the piston housing area, then back the screw off. Sometimes bubbles can get trapped in there and that can dislodge them
I have read that before, I think I will do the same to the prop valve and MC (gently of course). It so seems like air. Car is off? Pedal is rock solid. Car is on? pedal sinks half way and stops.