Brake Bleeding Woes After MC/Caliper upgrade

90rexzc90rexzc New Wagonist
in Suspension, Braking & Wheels
I recently upgraded to Legend/Prelude/ITR front calipers, 15/16" Prelude MC, front and rear SS lines and AEM pads w/ '91 EX rotors on my '89 DX wagon. I bench bled the MC twice because I wasn't sure I did a good job the first time around (I was right, lots of bubbles left inside). I also replaced the wheel cylinders outback. At first when I started to bleed the system I was getting no pedal and uneven pressure at all of the bleeders. A few more laps in the correct sequence and I have SOME pedal and I'm getting fresh clean air-less Motul fluid out of the RR and LF with healthy pressure at the bleeders. However, the LR and RF are barely spitting out any fluid and more importantly the pedal does not sink completely when the bleeders at these corners are cracked. Does anyone know if those 2 corners share a line that may be obstructed? It would have to be uncommon to the other 2 which is what throws me off. I think his set up has the potential to put some teeth marks in my steering wheel but certainly not with air/crap in the lines. If anyone can shed some light on my situation It would be greatly appreciated.

Comments

  • 90rexzc90rexzc New Wagonist
    well I'm pretty sure I've got it narrowed down to my new MC. I traced all the lines under the hood and drew up a diagram because I couldn't find one that depicted what I needed to see. The front piston in the MC pushes fluid out of the corresponding line on the front of the MC and over to the prop. valve. That is where the common circuit for those 2 corners ends. I disconnected the shared line at the prop. valve and had a buddy press the pedal and it still never bottomed out the whole way. Next I removed that line and ran a wire through it to be sure it wasn't blocked and sure enough it was clear. The only common part left is the MC itself so the new one will be at AutoZone at 9am and I can do it all over again.
  • GriftyGrifty Wagonist
    yeah it sounds like one half of the master cylinder has failed, ive heard of it happening a few times after people go to the track. Im sure you can buy a brand new aftermarket 15/16 master cylinder cheap?
  • 90rexzc90rexzc New Wagonist
    56 bucks. I picked it up today. Hopefully I'll have time to bench bleed and install tomorrow before work. I might go to pull-a-part instead though because there's a blue 2wd wagon and I'd like to get some more stuff before it's completely gutted.
  • 90rexzc90rexzc New Wagonist
    All moved in to my new house and finally got my internet up and running. The master cylinder was indeed the culprit. I had to bleed all of my Motul fluid back out (20 smacks down the drain) and re-flush with regular dot 4 but the performance difference is awesome. Couldn't be happier with the current set up with the exception of the drums out back but, oh well. I have to be careful on wet roads because the fronts lock up rather easily. I can actually lock them up from a 40 mph roll without too much pedal effort!
  • 949949 Senior Wagonist
    this is a good motivation for me to finish my mc and booster upgrade.
  • 90rexzc90rexzc New Wagonist
    What mc/booster comboare you going to use?
Sign In or Register to comment.

© Vanilla Keystone Theme 2025