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  1. #1

    Default Master Cylinders

    As I've been researching brake upgrades for my '85 I've come across a lot of opinions about Master Cylinders but not a ton of data. I've read a lot of "...if using <specific brake package> you HAVE to use <specific MC>..." with very little information backing said claim other than citing some other anecdotal "he said / she said". I'm learning that it's all about pedal feel resulting from a balance of hydraulic and mechanical forces - in effect, effort vs. travel in relation to pedal ratio. I'm starting to compile a list for Master Cylinders in the same vein as the 4/5-lug brake stickies. Working on the list now, but am asking for input and info others already have available, and what all info I should be listing.

    Right now I'm thinking:

    1) OE Application
    2) Cylinder Bore Diameter
    3) port threads
    4) bolt-in or modification required

    Suggestions? Information?

    ------

    I may include booster info as secondary to this, but I believe boosters can be summed-up as:
    a) '79-'93 Booster
    b) '93 Cobra Booster
    c) SN95 Booster
    d) Hydroboost

    Over simplified?
    1985 GT 5.0 CFI / AOD
    All Original

  2. #2
    Moderator wraithracing's Avatar
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    Default

    Start with your brake package in regards to front and rear calipers and then consider your Master Cylinder. You need enough volume (M/C Bore) to operate the calipers properly with the pedal ratio of the Fox. You can tweak pedal "feel" to your liking by moving up and down slightly in regards to M/C Bore, but if you start off with a M/C that is completely wrong for your setup your overall braking performance will suffer.

    Again depending on what your brake plans are, I personally have not seen much benefit from booster swaps. In many cases a stock 87-93 style booster works just fine, fits well, and doesn't require bashing in the driver side strut tower for clearance. Hydroboost is an option if needed, but it it more costly and you will either need to modify your brake pedal for the proper ratio or buy the kit from Maximum Motorsports. In my experience hyraboost systems work well, but the pedal feel is a bit "numb" for my personal tastes. You get used to it and again the system works when designed properly, but I personally don't like the feel as much as normal vacuum boosted or manual brakes.

    Unless you are autocrossing/road racing or just driving at 9/10ths most of the time on the road swapping to the 87-93 V8 brakes with stock booster and M/C will make a huge improvement over the 85 stock brakes. Add braided lines, quality front pads and rear shoes (Hawk/Porterfield/etc.) and even the lowly rear drums see an improvement. Moving up to SN95 brakes front and rear would be the next option (5 lug) and then SN95 Cobra front and rear. After that you are looking at Wilwood, Baer, Stoptech, etc. for improved braking performance and a lot more $$$$ Good Luck!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  3. #3

    Default

    From 1979-93, there were two vacuum boosters, 152mm and 205mm.

    The 1993 Mustang Cobra booster has the same performance as all SN95 vacuum boosters do, but the mechanics are different.

    From 1979-2004 there were 5 different brake pedal ratios used.

    For the m/c models, you need to also look at the total available throw of the primary and secondary pistons, to make sure that there is enough travel available if one system fails.

    Brake pad coefficient of friction.

    Effective rotor diameter.

    Without doing a complete analysis of the entire brake system, the results of this will be invalid. There is a lot of stuff to look at.
    Jack Hidley
    Maximum Motorsports Tech Support

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