I've recently replaced my brake master cylinder. I had purchased one an OEM from honda. I had bench bleed the brake master cylinder, gravity bleed from the 14mm bolt brake line, and bleed from the nozzle many times. However, I still have a spongy feel to my brake pedal.

The reason why i replaced my brake master cylinder was due to a my pedal sinking while braking. I figured i had a leak in my brake master cylinder.

Currently, it brakes fine, but i have a spongy feel.

Found this thread - http://www.ht-archive.net/showthread.php?p=40714837

and noticed this reply- "When changing a master cylinder. Always make sure the seal either comes off withthe brake master cylinder(which it will not) or that you remove it from the brake booster where it will be stuck or otherwise you will have a spongy pedal headache."

Would this be my issue? I dont remember seeing any seals nor did i remove any on the master cylinder plunger. I did not remove anything from the brake booster as well. What do these seals look like?





any info would be greatly appreciated.

 

It has been a while, but I believe the part labelled dust seal can stick in the booster. There should have been a dust seal on the removed MC that remained with it, and a new one on the new MC. Sometimes you pull out the old MC and the seal is not on it. Account for an old one and a new one. I learned the hard way, soft pedal.

 

is this the seal?

 

or could it be possible my miss matched master cylinder. I have a 15/16 MC in a 95 del sol si.

I found this thread with this response - "Until you upgrade the front rotors/calipers to Integra-sized parts you will have a rock hard bake pedal, and you can actually increase (which is bad) stopping distances if you go ahead and install the oversized Integra booster and master cylinder."

https://honda-tech.com/forums/showth...aster+Cylinder

 

Maybe it has the old seal plus the new one u installed. Also when u bleed the brakes, do it with the top on, creates more presure.

 

That looks like the seal. You can easily pick it loose and slide it on the rod. Is that the old or new? I do not think the cylinder size will make it feel spongy. It changes the amount of flow per foot/piston movement and may move farther, but will still feel a firm stop. You are still moving hydraulic fluid to a stop.

 

hmm i will try this. I've bleed the system many times. I dont think it would hurt to bleed it again.

the picture i posted is me asking if this is how the seal looks like. Ill have to unbolt the MC to check to see if it has two seals. I hope this is my issue.

Ill take pictures tonight of my old one. But yes it feels spongy, or maybe im describing it wrong. There is a bit more "foot/piston movement/spongy feeling" before my car actually stops. The stop is pretty firm.

Im wondering if i should of stuck with the stock 13/16 MC instead of the 15/16 MC. This is on stock 9.4" delsol si brakes. I also have stainless steel lines by the way.

my next thing i want to try is probably purchasing a new 13/16 MC or purchase integra knuckles.

Thanks guys for your response. I really appreciate it.

 

I have a few MC i can hook you up with LMK.

 

it looks like i left the seal on the booster.

old master cylinder.


old master cylinder with seal


Brakes feel alot better. Ill be waiting to upgrade th em soon.

Thanks crazyheadrush for the offer. I think im okay with my current setup.