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Technical Struggling to bench bleed a new recalled replacement Wilwood master!!!

Discussion in 'The Hokey Ass Message Board' started by 55Thunderboy, Aug 1, 2017.

  1. 55Thunderboy
    Joined: Mar 27, 2009
    Posts: 356

    from NYC

    well some of you guys might know that Wilwood issued a national recall on their master cylinders a few weeks back, their 7/8 which most of us running manual brakes are using.

    one of my cars had a unit that needed to be recalled so I mailed it back and got the new one today.

    I typically do the bench bleed in my vise using the tubes and i push and push forever. it seems no matter how long i push the piston i can not get all the air out of the rear chamber. I called tech which was a waste of time on hold and the tech told me i should tilt the master forward 40 degrees in my vise, i never tried this or ever heard of anyone doing this.
    When i mount it in my vise the master is 100% level, in the car is about 90% level, slight tilt toward the rear.

    I also tried forcing fluid with a syringe at each port, still not luck once mounted on the car.
    If i plug both ports the master does hydralock but on the car the pedal travels to damn far it i don't feel safe as it is.

    im just beat up and exhausted, hot was hell doing this today after work.

    any of you guys suggest i try tilting it forward or rearward in my vise to see if i can get this to finally work? which makes most sense?
  2. pwschuh
    Joined: Oct 27, 2008
    Posts: 2,273


    Don't have any suggestions but anxious to hear inputs since my M/C is still off at Wilwood getting rebuilt...
  3. saltflats
    Joined: Aug 14, 2007
    Posts: 10,106

    from Missouri

    If it will hydro lock with the ports plugged it has to be a problem down the line somewhere.
  4. 325w
    Joined: Feb 18, 2008
    Posts: 5,299

    from texas

    Plug the ports. Then pump slowly. Do full strokes. When,it,quits bubbling stop. Let,it,set,for,20 min. Try and see if it still has bubbles.
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  5. southcross2631
    Joined: Jan 20, 2013
    Posts: 3,764


    I'm with 325w , I just plug the ports and pump the master cylinder piston slowly. Most rebuilt master cylinders these days come with plugs instead of the little hose kit they used to come with.
  6. Never heard of the tilting thing. I'd do as a couple have suggested and try the plugging method.

    Sent from my iPhone using The H.A.M.B. mobile app
  7. My friend just went crazy trying to bleed the brakes on his impala willwood techs were no help .They told us we could not rebuild the master, had to send it back to them. we finally got it by cracking the fitting open at the master and bleeding it big mess . I sure would like to know why I can't rebuild it .
  8. seb fontana
    Joined: Sep 1, 2005
    Posts: 6,476

    seb fontana
    from ct

    You could try gravity bleeding on the car..Open bleeder farthest from MC [front or back or both] and give pedal a little pump to get things going; takes a while as is slow...
  9. 55Thunderboy
    Joined: Mar 27, 2009
    Posts: 356

    from NYC

    guys i did a few more things tonight, so frustrated so i had to try some more. I took the lid off each reservoir and i noticed the rear chamber the rubber baffle seal was totally sucked in and distorted but the front was not. im running dual remote reservoirs. this to me indicates something weird.

    I pulled it off the car and plugged both ports and to be honest i pushed well over 60 times off the car and i keep getting bubbles on the return stroke of the pushrod, when i push in i don't get bubbles.

    i kept the ports plugged then got my mityvac pump. I made an adaptor using a spare reservoir cap and tried to hold vacuum on each reservoir. well for the front it held 20 inches no problem, when i went to the rear chamber reservoir i cant get any more than 8 inches of vacuum, the lid is sealed tight no leaks whatsoever.

    so this def seems to be an issue with a serious air pocket on the rear chamber closest to the push rod. I am going to try tilting it both ways tomorrow after work to see what happens. this is not supposed to be such a struggle but damn these aftermarket parts suck at times.
  10. That's what SHE said....
  11. 37gas
    Joined: May 25, 2013
    Posts: 51


    don't use the plastic fittings and rubber hoses, make up hard lines from the fluid outlet and bend them so they go to almost the bottom of the reservoir. pump master cyl and see if the bubbles stop, if they do bend hard lines so you can get cap on and put rubber hose from one tube to the other so fluid does not leak out. Put master back on car and hook up lines one at a time so not to lose any brake fluid. when that is done loosen up both fitting at master and have someone push pedal to floor slowly and hold it there until you tighten fittings. I think your problem is with the plastic fittings and rubber hose , this will eliminate that part
  12. 55Thunderboy
    Joined: Mar 27, 2009
    Posts: 356

    from NYC

    thanks i came home for lunch and bench bled it with the fittings and hose, i didn't use the hose that comes in the kit i actually did at first and the bubbles would not stop. I then found some R/C nitro fuel line which is much more flexible and has a tighter seal. i finally got it to where no bubbles in either chamber. just mounted back on the car but wont finish until tomorrow or weekend. im damn tired and sore from pushing this damn thing so much.

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