Mushy brakes ALL THE TIME

Well i posted this at preludepower.com and no really help, but i was wondering if you guys knew anything about this..

No matter how well my brakes are bled they are still mushy. I have a new master cylinder, stainless steel flex hoses all around, Brake Bias controller which acts as a residual pressure valve, my calipers were rebuilt last summer alon with new pads and all rotors machined last summer. There has been one or two times where they have felt really nice and crisp with a stiff pedal after bleeding but it goes away within a month or so, back to the normal mushy shit. Could this be my power brake booster because goddam this makes me SO MAD you have no clue. And hey don;t get me wrong, there is tons of stopping power, just the pedal feel sucks! :dunno:

to check your brake booster all you need to do is pump the barke with the car off and turn the key until the lights on your dash around the speedometer come on if the brakes are still hard then your booster is shot it it goes soft then your booster should be ok

Same problem as my Audi. I can bleed the brakes till' I go insane, but the pedal is super-mushy; sometimes it gets as it should be, but it goes bad (mushy) in a few days. There is not a single drop of brakefluid that gets lost, but the air somehow gets into the lines without the brakefluid getting out the way the air came in. I also replaced my master cylinder, but no change.

Could it be a bad bleedvalve in one of the calipers?

EDIT: You could saw your brakebooster in two if you wish, it has *nothing* to do with the pedal getting mushy, as the pistons in the master cylinder has a solid link to the brakepedal, straight trough the brake booster.

with the vacuum lines to the brake booster unplugged it is stiff once again. but hmm i have no clue...

when i pump up the pedal with the car off it is really nice and firm, once the car is runing it feels like shit again

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Originally Posted by mugenprelude86

when i pump up the pedal with the car off it is really nice and firm, once the car is runing it feels like shit again

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Same as my Audi. This happens because when you press the brakepedal the air in the system is compressed (=less mushiness).

i may try a pressure bleed and see what happens

Did you bench-bleed the new master cylinder before you put it in? I've heard of problems where air get trapped in the MC that can only be bled out with it out of the car. Usually the pedal will always be mushy in a situation like that though so it doesn't explain why everything seems fine sometimes.

This may be a long shot, but I experienced similar symptoms when the caliper pins were frozen on my front brakes. No matter how much I bled them, they were still mushy. When I tried to remove the calipers, I realized they were frozen, which was preventing them from clamping firmly and making it feel spongy.

Just a thought.

Gregg

I have been doing brake like crazy at school and if you don't properly bench bleed the MC then it won't be good at all. I don't know how you guys bleed the brakes but I do it either manually or with the "Vaccula" it gets hooked up to the shop air and it sucks the fluid through the bleeder :).

But I always tap the brake lines to get any little bits of air out.

-Mike

thats for all the responses, no i did'nt not bench bleed the master clylinder, but they see, to be sorting themselves out?? slowly they are starting to feel good again

when was the last time you adjusted your rear brakes?
i am assuming you have rear disk, right?
when you pull the emergency brake, you should hear 3-4 clicks if it is more, you need to adjust it.

I have the same problem...But I still have yet to adjust my e-brake...Do you think by not having the e-brake working my brakes can get mushy after about one hour of them working correctly?

well it seems to be a common problem without a common solution.here is my plan as soon as i can afford it. new larger master cylinder' brake booster' stainless brake lines'and the larger 89 calipers and rotors and i also want a bigger prop. valve i forgot though wich one you could upgrade to anybody know i seem to remember somebody said one from a fourth gen would work but ive never checked it out.anybody know? damn i want to find an sei upgrade i hate the drums.:sad2:

i have this problem only its kinda extreme (brakes go to floor after 20 seconds of holding, sometimes less sometimes they dont at all)
i have rear drum but my ebrake has to be pulled w/ 2 hands like 20 clicks up before it even holds the car at all.
also my rear brakes make some funny noises if im like in a drive thru and i can feal my brakes starting to give so i put it into park

ideas? its got new master cyl.

1st you must have pressure in the system. The system is a closed system which means that no fluid loss should be possible. Now since it is a pieced together system cosisting of connection we have the possibility of hydraulic pressure loss.
You should never have to add fluid to a completely closed system if the resivoir is low then you should check brake pads first as the pads wear fluid level becomes low due to the loss of pad due to friction.
If pads/shoes are good to go then you must check for leaks, check connections first if no leaks at the connections/seals then check for holes in the system. Calipers crack, wheel cylinders leak and rubber lines become brittle.
If the system is closed and shows no signs of leaks then wwe check the mechanicl working of the system. Plunger in the master system can fail reducing the amount of pressure the system develops (intial brakes then pedal goes to floor) sign that master cylinder is bad. Mushy brakes contaminated fluid or air in the system. If fluid is contaminated then the system is in need of replacement corroded parts responsible for the contamination of fluid.
Now reason the rest of it out.
Hope this helps
Phil :cheers: