Brakes are acting funny...

[MikeBergy]

Well, the brakes on my integra have been acting odd. Symptoms are that of a leaky master cylinder: Pedal will drop to the floor. But it isn't consistent, and so this kind of freaks me out a bit; and I wonder if there may be other problems. I used Valvoline synthetic Dot 3/Dot 4 brake fluid, and was wondering if the fact that it is a synthetic may have any effect on the performance, or if you think it is just an intermitently failing master cylinder seal. I am just confused because it is so inconsistent. The sinking pedal happens most often when it's hot outside, or when I am on an incline facing downhill, but like I said, it doesn't happen all the time.

Here is a picture of the bottle of fluid I am running.

Anybody had these intermittent problems? I'm hoping to do the legend brakes upgrade next month if I can source in expensive parts.

 

[posol]

try re-bleeding them. you may have an air pocket in there somewhere.

 

[phunky.buddha]

That's what I think too.

 

[MikeBergy]

I was thinking the same thing, as I completely drained the master cylinder when I painted the engine bay and dropped the motor in. I'll try that today, as I have to go get my rotors turned anyway. thanks.

 

[MikeBergy]

Quick note. After pulling the rotors, I noticed that the pads are wearing unevenly, not per corner, as you would see with stuck calipers, but from side to side, variance is noticeable in the thickness of the pads. The right front pads are worn probably 30-40% more than the left front. Would this variation in pad thickness from side to side also be a symptom of an air pocket in the lines? thanks for the suggestions thus far.

 

[GSRCRXsi]

had the same problem in the crx. replaced the MC and that fixed it.

also currently dealing with the same problem on the integra. happens most often when its hot out, very inconsistent doesnt happen all the time, etc. same symptoms. im 99% sure its the MC. havent gotten around to replacing the MC on the integra since i havent had any time to really work on it. it will brake good enough to get me to a stop, and i just pull the ebrake to keep me stopped.

 

[MikeBergy]

Yeah, the master cylinder is next if this doesn't fix it. I ran the MC completely dry when I pulled it out, so I haven't ruled out the rogue air pocket theory, but if rebleeding doesn't solve my problem, I think I am going to pick up a wilwood mc, and adapt it to fit the booster.

 

[phunky.buddha]

Hmm. If you just pulled it out and didn't use it while it was dry, you can probably get away with just pulling it and bench bleeding it, then reinstalling it. You always need to bench bleed the master every time you empty it out.

 

[MikeBergy]

how do you bench bleed?

 

[phunky.buddha]

Remove master cylinder
Install some kind of fitting in the output ports so that you can attach clear hoses
Run hoses from outputs back into reservoir
Clamp the whole mess in a vise
SLOWLY work the plunger in and out, full stroke, pausing about 10 seconds between each stroke (in, wait, out, wait, repeat)
Go until there are no more bubbles in the hoses

 

[GSRCRXsi]

emphasis on the SLOWLY. i was doidng it fast one time and couldnt figure out for the life of me why it wasnt getting the bubbles out.

 

[MikeBergy]

So, it's the MC that's bad. Bled the lines thoroughly, no air, and sure enough, as the fluid warmed up, the pedal began to sink. Napa has an OEM replacement for $78 w/ a warantee, I'm gonna pick one up Sunday after the motogp race is over. On a better note, I've found that a $5 can of 1200 deg krylon bbq paint is sufficiently holding up on the calipers and rotor hats. no more rusty rotor hats for me.

 

[phunky.buddha]

Cool. Hope it all works out!

Spray your calipers lime green.

 

[MikeBergy]

if they had copper or lime green bbq paint, it would be on there, lol!

 

[phunky.buddha]

Sweeeeet