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Guest Message by DevFuse
 

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need help, no brake pressure after rotor change


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11 replies to this topic

#1 danbennett2u

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Posted 05 March 2012 - 02:48 PM

I know it is normal for the first couple of pumps to not have pressure but I have zero pressure and the pedal goes straight to the floor after about 20 pumps.

Rotors are brand new and fit perfect. pads are not brand new but 1 month old and plenty thick. i dont know what i did wrong here, is there any troubleshooting I can perform?

#2 Durania

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Posted 05 March 2012 - 02:59 PM

Did you open a bleeder screw?

#3 danbennett2u

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Posted 05 March 2012 - 03:14 PM

nope but its fixed now.

My resivoir does not have the rubber seal, screwed that down really tight, swung each caliper out one at a time and hit the brakes enough to let the pistons extend out, undid the lid compressed them back in, closed the lid and brakes are rock solid now. would the lid of the resivoir have antything to do with this?

#4 nipper

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Posted 05 March 2012 - 04:20 PM

You need that rubber seal. It serves two purposes (and on seom cars three). It keeps the fluid from jostling around and getting airated. It keeps the fluid from coming back quickly into the resivoir and areating (like a fountain). It takes up volume to keep air out.

#5 danbennett2u

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Posted 05 March 2012 - 07:05 PM

ugh going to have to get one of those now :(

#6 LeolaPA

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Posted 06 March 2012 - 08:37 PM

It's not normal to have to pump the brakes a couple times to get pedal. Sounds like you have air in the lines.

#7 MilesFox

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Posted 06 March 2012 - 10:45 PM

If the master cylinder pumped dry, you will have to bleed it by hand to get pressure.

Also, if you have an MT with hill holder, depress the clutch while bleeding to ensure the rears bleed out properly.

#8 danbennett2u

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Posted 07 March 2012 - 12:16 AM

It is normal to have to pump a few times after brake work because the pistons are compressed and not making contact with anything. Miles it was an auto and I compressed. The pistons so that should have made the fluid level go up not down. Still stumped by what happened exactly. I change brakes all the time bxut have never had this happen

#9 Fairtax4me

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Posted 07 March 2012 - 12:36 AM

Methinks you got a master cylinder goin bad. I've had similar happen before. Tried to bleed the system out after it wouldn't pump up and it wouldn't bleed. Got a small amount of fluid into the bleed hose but it would just draw back when the brake pedal was released. Had a friend assist by locking the bleeder down while I was pumping the pedal and still could not get the pedal to feel right.
Put a vacuum bleeder on it and finally got it bled out. Not long after the pedal started "sinking". Replaced master and all was well. The new master bled perfectly fine just by pressing the pedal.

#10 danbennett2u

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Posted 07 March 2012 - 01:04 PM

dont know, guess we will find out. feels 100% after a couple of days of driving, no sinking or sponginess but I guess if I rearend someone I will know :( Any signs of this happening again that sucker is getting swapped immediately.

#11 nipper

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Posted 07 March 2012 - 03:05 PM

Sometimes if it is an old Master cylinder a brake job can damage the internals if bled by foot (really old). What happens is that the cups are pushed past their usual travel, the same travel that they have been doing for millions of strokes. A ridge and gunk can build up and damage the cups.

( I said sometimes :P )

#12 danbennett2u

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Posted 07 March 2012 - 03:49 PM

I could see that. I just dont see why it works perfectly now. I didnt even change the pads, some doofus did a brake job and put new pads on but left severely warped rotors because they "looked" good. The rotors didnt appear to be worn much either, so not a lot of movement happened.




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