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S12 Technical Areas => Handling Tech => Topic started by: MoB pineapple on 04:11:34 PM / 28-Nov-15

Title: Did J30 brake upgrade, now my brakes don't work
Post by: MoB pineapple on 04:11:34 PM / 28-Nov-15
Alrighty, so as the title says.
I upgraded my front brakes.
I bled the brakes, and the pedal goes straight to the floor.
There is no air in the line at all.
Replaced the master cylinder as well. (yes a bench bled it)

The rear brakes grab when the pedal is too the floor only to the floor not at all before that.
The fronts do nothing.

If you pump the brakes fast the pressure builds and holds but when you release and press back down it goes straight to the floor.
If you build the pressure and turn the engine on the pressure goes away and the pedal goes straight to the floor.

I would really love a solution, this is the only thing keeping me from having the car on the road.
Please help me(http://images.tapatalk-cdn.com/15/11/28/f8a2d88014b87501ee11e149da341428.jpg)
Title: Re: Did J30 brake upgrade, now my brakes don't work
Post by: sideways_s12 on 05:23:54 PM / 28-Nov-15
Brake booster? I don't know much about the J30 upgrade but I had a similar problem and it turned out to be the booster... It's worth a look if you haven't
Title: Re: Did J30 brake upgrade, now my brakes don't work
Post by: MoB pineapple on 09:20:47 PM / 28-Nov-15
Brake booster? I don't know much about the J30 upgrade but I had a similar problem and it turned out to be the booster... It's worth a look if you haven't
The pedal isn't hard to push. The booster just makes the pedal easier to push down.
There is hardly any resistance.
Alex is dead set on the master cylinder being bad.
Title: Re: Did J30 brake upgrade, now my brakes don't work
Post by: mc on 08:39:02 AM / 29-Nov-15
i've had a lot of issues with "rebuilt" master cylinders....wasted so much time ...and brake fluid trying to get them to bleed....buy new.
Title: Re: Did J30 brake upgrade, now my brakes don't work
Post by: MoB pineapple on 10:24:59 PM / 02-Dec-15
It's not a rebuilt.
It's brand new and doesn't work.
I'm thinking it's the master cylinder not being big enough
Title: Re: Did J30 brake upgrade, now my brakes don\'t work
Post by: onephatser on 09:01:00 PM / 03-Dec-15
Are you getting fluid to the front calipers when you bleed the system?  Next I would take the caliper off if you're getting fluid there and make sure the pistons are coming out.  Not too far though or the piston will pop right out of the caliper.

Post Merge
I would start at the front brakes and work your way back to the master cyl taking all lines off and seeing where there is no fluid being delivered.
Title: Re: Did J30 brake upgrade, now my brakes don't work
Post by: mc on 06:46:42 AM / 04-Dec-15
...make sure you have mounted the calipers so the bleeders are pointing upward.
Title: Re: Did J30 brake upgrade, now my brakes don't work
Post by: MoB pineapple on 12:39:29 AM / 08-Jan-16
Replaced the master cylinder with a Z32 master and rebuilt the calipers.
Works fine now.
Title: Re: Did J30 brake upgrade, now my brakes don't work
Post by: Cajun1guy on 10:54:45 AM / 08-Jan-16
Alright! Time to get that biotch on the road.
Title: Re: Did J30 brake upgrade, now my brakes don't work
Post by: sideways_s12 on 12:58:58 PM / 13-Feb-16
Nice! I need to do a brake upgrade myself I assumed you used the rotors as well whats he size difference? Wait those are 5 lug right?
Title: Re: Did J30 brake upgrade, now my brakes don't work
Post by: 8SixS12 on 07:47:23 PM / 18-Feb-16

I thought they bolted right up to s13 calipers.