Close



Results 1 to 6 of 6
  1. #1
    FEP Power Member Saturn V's Avatar
    Join Date
    Jan 2011
    Location
    Houston, TX
    Posts
    1,282

    Default 84 Mustang GT 5.0 brake questions

    We're living temporarily in another Texas city and only come home every few months. This week when we were home I drove the Mustang and the brakes didn't work. The pedal almost goes to the floor and pumping the pedal didn't help. It would barely stop. The master cylinder level is full and I cannot find any leaks (new stock brakes and hoses installed about 6 years/1000 miles ago). So I'm suspecting the master cylinder. Also, the brake booster has always made a hissing sound when pressing the brake pedal ... the hissing seems to be louder now. My plan is to replace both the master cylinder and brake booster . Questions:

    1) There seems to be so many choices for master cylinders and brake boosters. All the ones I've seen seem to be rebuilt. I'm willing to pay for good quality. Recommendations?

    2) Is a basic rear disc upgrade kit worth it just for cruiser duty? I have a 4-lug 8.8" rear end. Recommendations?
    Present: '84.5 Mustang GT T-top, '06 Mazdaspeed6
    Past: '79 5.0 Capri, '86 Buick GN, '90 Mustang GT, '92 SHO, '95 SHO
    Browse cover pages of my Fox Chassis related library

  2. #2
    FEP Power Member
    Join Date
    Nov 2007
    Location
    San Mateo, CA
    Posts
    2,003

    Default

    Sounds like your master cylinder failed. Had that happen on my svo after sitting a long time. You can find some new ones around but most are rebuilt. Rabestos is usually a good brand. Not sure what was the original Ford manufacturer. You can have yours rebuilt or buy a rebuilding kit.
    Fox Body/3rd Gen MCA Gold Card Judge
    84 SVO 24K miles, 85 Mclaren Capri Vert. 84 GT Turbo Vert.
    88 Mclaren Mustang Vert 20K miles, 89 Mustang LX Sport Vert,
    03 Mach 1 7900 miles, 74 Mustang II, 69 Mustang, 67 Mustang, 14 Mustang CS/GT,
    15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

  3. #3
    FEP Power Member qikgts's Avatar
    Join Date
    Jan 2010
    Location
    Rockledge, FL
    Posts
    1,165

    Default

    Over the last few years I've been happy with Centric brand parts. I think they offer pretty much everything to replace what you have now. Not sure if they have new or reman choice available for the master but I think their parts are just fine.

    With the amount of time you've been around here I'm sure you've come across at least one post from Mr. Cook where he expresses that rear drums are just fine with a shoe upgrade and properly working components. Finding larger aluminum drums is an option as well.

    I went the '93 Cobra route in the rear with North Racecars brackets, T-Bird calipers, aero v8 front spindles with 73 mm calipers/slotted rotors/Hawk street pads, swapped the master to a 1973 LTD/Ranchero 1" unit, gutted the stock prop valve and put an adjustable one in at the union on the passenger side of the firewall and kept the stock booster. I like the feel and the drums are gone so easier maintenance. Some say a 15/16" master may be a better match with the 73mm fronts I have but I haven't tried anything different myself to say one way or the other. BTW I think there is a rear disc upgrade kit for sale in the for sale section.
    '85 GT

  4. #4

    Default

    Hey Erik ó

    I bought a rebuild kit for my master but havenít installed yet. I wanted to keep it as itís likely the original aluminum unit and all the new/rebuilt ones are cast iron, which = rust. Can dig up the part # if youíd like.

    Iíd recommend staying with rear drums unless you want to auto cross. I have the Ď93 cobra rears on my Ď86 coupe. I canít tell a difference in regular spirited driving.

    Now would be a good time to upgrade to DOT 5 fluid. Best upgrade for stuff that sits a lot. Highly recommend.

    Good luck with it.
    '84.5 GT vert / roller 5 liter 4v / t5
    '86 LX coupe / 331 / t5
    '86 F-150 - 5 liter / efi / aod
    '56 F-100 - 272 y-block / 3 on the tree

  5. #5

    Default

    Quote Originally Posted by graphicdesigner80 View Post
    Now would be a good time to upgrade to DOT 5 fluid. Best upgrade for stuff that sits a lot. Highly recommend.
    I think you mean DOT 5.1 . Not DOT 5.
    Imho, yea, they should've called it DOT 6, and not DOT 5.1.

    DOT 5 is silicon-based - that's bad for a car not specifically designed for it .
    DOT 5 also is Very bad for cars that sit, or for cars that see track use (where the brakes aren't bleed before/after).
    Imho, DOT 5 is bad on many levels.

    https://en.wikipedia.org/wiki/Brake_fluid#DOT_5
    http://goqcrew.com/what-is-the-diffe...5-brake-fluid/


    Fwiw, Imho, the main advantage of rear disks is to reduce the chance of braking imbalance between the rear brakes.
    Drum brakes are infamous for having brake imbalance between sides, as the brakes wear. That causes brake pulling, and it also reduces the max braking ability.

    In typical braking in a stock Mustang, the rear brakes don't provide a lot of the braking ability.
    To get more braking performance from the rear, wider rear tires, stiffer front springs, and stiffer front struts are needed.

  6. #6
    FEP Power Member Saturn V's Avatar
    Join Date
    Jan 2011
    Location
    Houston, TX
    Posts
    1,282

    Default

    All, thanks for the good comments above. I think I'll stick with stock brakes for now, rebuild master cylinder, replace brake booster (it's rusty anyway) and use new 5.1 fluid, flushing the old stuff out during the bleeding.
    Present: '84.5 Mustang GT T-top, '06 Mazdaspeed6
    Past: '79 5.0 Capri, '86 Buick GN, '90 Mustang GT, '92 SHO, '95 SHO
    Browse cover pages of my Fox Chassis related library

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •