Poor brakes after all new parts installed Help please

Discussion in 'Suspension, Steering, Brake & Wheel Topics' started by Stox58, Oct 22, 2017.

  1. Stox58

    Stox58 New Member

    Jan 16, 2016
    United Kingdom

    I live in the UK and I own a 1977 Camaro, in the UK our cars have to pass an MOT test each year and on my last test there said my brakes / lines are corroded. My brakes where never very good anyway, so I thought it was a good time for some upgrades !.
    I spent a lot of money shipping the parts over and paying a so called American car specialist garage to fit them, the brakes are now worse than before and the vehicle is too dangerous to drive and the garage didn't seem capable of identifying the issue. The brakes on all four wheels do operate and cant be turned by hand when applied, but during driving conditions it takes along long time to slow down / stop.
    I will list the parts below a long with some other information, please can someone inform me what the issue might be and what I should try next.
    new brake lines front and back
    7 inch dual diaphragm booster ( seems to make a hissing sound when braking at speed )
    Willwood D52 2 pot front disc brakes
    11inch rear drums
    Willwood master cylinder / garage have replaced with another one now but same issue
    Vaccum booster filter replaced
    Engine is a 1989 small block 305 with a Edelbrock 2102 cam

    Any information / thoughts would be really appreciated

    Many thanks from Luke
  2. Camaro75LT

    Camaro75LT Masshole Staff Member Lifetime Gold Member

    May 17, 2001
    I would start by putting a pressure gauge at each corner of the car. There is a rubber hose at the rear axle center that sometimes gets overlooked. If that is swells when the brakes are pressed, you would have crap stopping power.
  3. czizza

    czizza Veteran Member

    Jan 8, 2004
    N. Massapequa, NY, USA
    If you cannot do the pressure gauge, then have them re-bleed all brakes. Have them check the Vacuum line at the brake booster to make sure you have at least 15lbs of vacuum.

    Remember this is simple hydraulics; and you need fluid and pressure to make it work anything else like air in the lines or faulty pressure will make the system fail.
  4. phat80

    phat80 Veteran Member

    Jan 4, 2013
    Victoria BC
    Okay, just off the top of my head...swollen/rotten flexible lines, primary/secondary shoe reversed, dirt in master cylinder, were the wheel cylinders changed or cleaned, vent hole plugged. I'm sure others will chime in. Does pumping the pedal change the response?
  5. 8pack

    8pack Veteran Member Lifetime Gold Member

    Aug 29, 2007
    Pittsburgh, PA
    The brake set up on these cars is pretty straightforward.

    Which model Wilwood MC do you have?

    Are you sure they properly bench bled the master cylinder before mounting? This is critical to proper functioning. You really have to work at it to ensure all the air bubbles are out prior to install. My bet is this is the issue....

    If you have all new lines that variable should be eliminated although you could still have a bad line...did you also replace the distribution line over the rear end?

    What proportioning valve are you using? Is it a factory one or part of the Wilwood set up? Is it proper for a disc/drum configuration?

    Do you have the right length pushrod?

    Why are you running a 7” booster and not a stock 11”?

    Are you confident they bled the brakes correctly?
  6. badazz81z28

    badazz81z28 Veteran Member

    May 4, 2001
    Las Vegas, NV
    If all the parts are new, the most probable cause is air in the system. A hissing sound while pumping the brakes is normal. However with the car off, hissing should go away and the pedal get pretty hard after a few pumps. If you're mechanically inclined, make sure you don't see any leaks or a disconnected vacuum line. Then proceed to bleed the system
  7. ol' grouch

    ol' grouch Veteran Member

    Jul 4, 2013
    Evansville, In.

    First off, did you just replace the steel lines or did you replace all three rubber lines? Failing rubber lines can restrict the pressure flow and you can really honk down but barely stop. Do the front rotors have the proper non-directional finish? This will look like swirl marks in the metal. Are the rear show properly installed? There is a front and back shoe and it does make a difference. The rear shoe does most of the work so it goes on back. This is the secondary shoe. It MUST go towards the rear of the car. I'm assuming you replaced the wheel cylinders. I use a small brass machinists hammer when bleeding brakes. This can often dislodge small bubbles. Did the shop do a pressure bleed or vacuum bleed. The old style of bleeding is still the best for these vintage cars. A bottle and hose is the best way to bleed these.

    When your car was built, it would easily lock the wheels up. I'm assuming you have the proportioning valve set right. Lastly, I'm not being silly here. Are the front calipers on the correct side? The bleeder valve MUST be on the top of you'll never get the air out.
  8. badazz81z28

    badazz81z28 Veteran Member

    May 4, 2001
    Las Vegas, NV
    ^^^ There is a lot of silliness that can go on, have you thought about taking it back to them and saying WTF?
  9. 8pack

    8pack Veteran Member Lifetime Gold Member

    Aug 29, 2007
    Pittsburgh, PA
    In further support of the above comments I am going to repeat myself a bit....

    I will bet it is air in the system somewhere. Save yourself some effort and bench bleed the master cylinder again and be sure every tiny air bubble is out and you are leaning on the piston with everything you have to be sure it is fully depressed under pressure. If it were me I would take it out and do it myself at this point.....

    Then reinstall and bleed the brakes old school with a buddy and a bottle and hose starting at the right rear, then left rear, then right front and left front.

    You can definitely do this yourself if you read up, watch you tube videos and ask questions here. Will take you an afternoon.....
  10. badazz81z28

    badazz81z28 Veteran Member

    May 4, 2001
    Las Vegas, NV
    I wouldn't bother removing the MC, its more pain then it's worth. Just bleed the brakes. All the air in the MC will work its way out through the normal bleeding process.

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