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Hot Rods Strange brake booster problem

Discussion in 'The Hokey Ass Message Board' started by tommyd, Aug 6, 2014.

  1. tommyd
    Joined: Dec 10, 2010
    Posts: 11,999

    tommyd
    Member
    from South Indy

    Working on a Ford car with a Midland booster. It has a decent pedal for about 3 inches then goes rock hard. When I got it the front part of the booster was pulled away from the back part [ a band holds them together]. I took it off and cleaned it all up reassembled it , put it back on and when the pedal got hard I stomped it and the booster came apart again. I have never seen or heard of this. Could something be warped ? It had a new master cylinder on it when I got it , could the bore in it be wrong ? Not deep enough? Anyone know or want to speculate? Thanks in advance. tommyd.
     
  2. VoodooTwin
    Joined: Jul 13, 2011
    Posts: 3,453

    VoodooTwin
    Member
    from Noo Yawk

    Scrap it and get a new one. Why take a chance on something as important as brakes?
     
  3. Sounds like it has the wrong master cylinder.
     
  4. tommyd
    Joined: Dec 10, 2010
    Posts: 11,999

    tommyd
    Member
    from South Indy

    Thanks for the reply's. I will most likely get another one. I'm thinking that because it came to me with this problem and the owner had replaced the m/c that it is most likely the problem. This car had set for years and the new owner put all new brakes and did an engine bay detail but never drove it. I just went out and it looks like the outer rod is bottomed out in the bore as soon as I bolt it on. Thanks.
     
  5. Dragger52
    Joined: Jul 31, 2014
    Posts: 110

    Dragger52
    Member

    How much vacuum are you making at idle? What bore size is the master cylinder? What size is the booster? This may not be a booster problem...
     
  6. Something is the wrong length, master cylinder, one of the pushrods, etc. Does the car have the correct pedal set for the rest of the parts?
     
  7. tommyd
    Joined: Dec 10, 2010
    Posts: 11,999

    tommyd
    Member
    from South Indy

    The car is a factory power brake car so I think the pedal is good. Drager52, this entire set - up is a factory deal. I managed to get a hold of the owner and he thinks he still has the m/c that came with the car. I hope that there is a big difference the in bore for the rod length. That's what she said.:D Sorry had to beat tfeverfred to it.
     
  8. Dragger52
    Joined: Jul 31, 2014
    Posts: 110

    Dragger52
    Member

    Measure your vacuum at idle. If you are getting anything less than say 17", no booster will work properly. Vacuum boosters cant work without vacuum.
     
  9. tommyd
    Joined: Dec 10, 2010
    Posts: 11,999

    tommyd
    Member
    from South Indy

    Its not that it doesn't work. The problem is it keeps splitting apart when you lean hard on the peddle.
     
  10. tommyd
    Joined: Dec 10, 2010
    Posts: 11,999

    tommyd
    Member
    from South Indy

    Well, the m/c has the same depth bore as the new one. I checked the stroke to make sure the new one isn't binding or sticking. HAS to be something going on inside that booster. Hunting for a new one now. Thanks for the ideas.
     
  11. Just to clarify:
    (1) What year/model is the car?
    (2) Is the booster between the firewall and master cylinder, or remotely mounted?
    (3) If remote mount, where? Inside passenger compartment connected to brake pedal arm, or on driver's side inner front fender? I'm wagering you're working on a '55-'56 full-size Ford/'55-'57 T-bird?
     
  12. tommyd
    Joined: Dec 10, 2010
    Posts: 11,999

    tommyd
    Member
    from South Indy

    Dang! gonna get me in trouble! Its an off topic Ford Fastback. All factory stuff. I pulled the booster back off today put it back together bolted the original m/c on and tested the stroke on the bench. Also bolted the replacement m/c on and both work perfect , no sticking or binding. In the morning its going up on jack stands and I'm going to check all of the brake system. 'm beginning to think that I have some kind of hydraulic lock in the distribution block or somewhere else. The owner did all of the brake work on the car THEN brought it to me to figure out. I have the advantage of more experience and tons of good advice from you guys. The HAMB can make us look a lot smarter than we are. Uh.....squirrel is excluded from the previous comment. He IS smarter than I are!
     
  13. greybeard360
    Joined: Feb 28, 2008
    Posts: 2,096

    greybeard360
    Member

    Have someone put their foot on the pedal with light pressure and crack each bleeder one at a time and see if you get a squirt of fluid. If none, crack the lines loose on the m/c side of each of the brake hoses... keep working your way back towards the m/c until you find tje blockage.

    Posted using the Full Custom H.A.M.B. App!
     
  14. tommyd
    Joined: Dec 10, 2010
    Posts: 11,999

    tommyd
    Member
    from South Indy

    greybeard360. Have you ever had a blockage like this? I'm going to do what you recommend tomorrow but in 40 years of hammering on cars I've never had a line blocked. Just curious. I do think that is the problem though. tommyd.
     
  15. saltflats
    Joined: Aug 14, 2007
    Posts: 13,236

    saltflats
    Member
    from Missouri

    Is there a chance that the push rod is in the wrong hole in the peddle say like in a hole for manual brakes not power?
     
  16. tommyd
    Joined: Dec 10, 2010
    Posts: 11,999

    tommyd
    Member
    from South Indy

    I had that same thought at first because I had seen a pedal or two that had that. This one only has the one hole.
     
  17. No matter whatever other problem there may be; there is no way a booster should
    come apart when pedal pressure is applied, think about it. There has to be something
    structurally wrong with either the flanges or the clamp.
     
  18. tommyd
    Joined: Dec 10, 2010
    Posts: 11,999

    tommyd
    Member
    from South Indy

    That's for sure. I'll get er' figured out and make sure I post it here. I t could be worse...could be my car!
     
  19. tommyd
    Joined: Dec 10, 2010
    Posts: 11,999

    tommyd
    Member
    from South Indy

    Well its fixed but I'm not sure how or why. Pulled the booster back apart and checked everything. Put it all back together and reinstalled it. Started cracking brake lines closest to the m/c at the distribution block and worked my way out. Bleed the crap out of the calipers and wheel cylinders and it works just fine now. I also cranked the band clamp on the booster real tight. At least I know the brake system works. Maybe there was dirt or rust in the proportioning valve and I moved it around by bleeding everything. I'm still going to recommend that he get another booster as this deal has me spooked a little. Thanks for all the good suggestions guys.
     

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