Brakes Cobra 13" Setup Not Grabbin'

Discussion in '1994 - 1995 Specific Tech' started by dubbsix, Apr 9, 2014.

  1. dubbsix

    dubbsix Member

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    I performed the brake upgrade using my GT master cylinder and I feel like the brakes arent grabbing the way I expected them to. The pedal is firm and doesnt goto the floor, but the setup just doesnt feel like its grabbing. How long does it take to bed the big ole brakes.. and is there a chance I have the wrong pad material in the calipers? Is there a chance I need to bleed the brakes more?

    I got the complete setup from LRS that has the load calipers -- so I dunno what brand or temp rating the pads are.

    Thanks guys.
     
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  2. Noobz347

    Noobz347 Stangnet Facilities Maint Tech... Er... Janitor
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    Lemme see if I can get one of the resident brake experts in here to lend you a hand.

    @Mustang5L5
     
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  3. madspeed

    madspeed Colonel Mustard
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    did ou heat cycle the brakes?
     
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  4. madspeed

    madspeed Colonel Mustard
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    http://www.wilwood.com/m/techtip/TechRotorTip.aspx


    Not all relevent but this is from Wilwood....

    Rotor Bedding
    All new iron rotors should be bedded-in before being used under racing conditions. Proper bedding-in will prepare the rotor surface, prolong the rotor's life and make it more resistant to thermal checking or cracking under severe braking conditions. Once the brake system has been tested and determined safe to operate the vehicle, follow these steps for the bedding of all new rotors. These procedures should only be performed on a race track, or other safe location where you can safely and legally obtains speeds up to 65 MPH, while also being able to rapidly decelerate.

    Thoroughly inspect all brake system components before proceeding to track. Check all bolt connections, make sure mounting bolts and rotor bolts are properly lockwired, that brake pads are properly secured by retaining clips or cotter pins, that master cylinders and brake pedals are working properly, that brakes are properly bled with plenty of fluid, and that proper engagement of brakes occur when pedal is depressed.

    Because the bedding process is different for rotors and pads, it is best to bed-in a new rotor (disc) using a used set of pads, preferably ones which will not create heat rapidly. Generating heat too quickly will thermal shock the rotors. Likewise, when bedding-in a new set of brake pads, use a used rotor. This new-used bedding process permits controlled bedding of each individual component.

    Make sure that the rotor surfaces are free from oils, grease and brake fluid.

    Close air ducts approximately 75% to expedite the bedding-in process.

    Begin with a series of light decelerations to gradually build some heat in the brakes. Use an on-and-off the pedal technique by applying the brakes for 3-5 seconds, and then allow them to fully release for a period roughly twice as long as the deceleration cycle. If you use a 5 count during the deceleration interval, use a 10 count during the release to allow the heat to sink into the pads & rotors.

    After several cycles of light stops to begin warming the brakes, proceed with a series of medium to firm deceleration stops to continue raising the temperature level in the brakes.

    Finish the bedding cycle with a series of 8-10 hard decelerations from 55-65 MPH down to 25 MPH while allowing a proportionate release and heat-sinking interval between each stop. The pads should now be providing positive and consistent response.

    If any amount of brake fade is observed during the bed-in cycle, immediately begin the cool down cycle.

    Drive at a moderate cruising speed, with the least amount of brake contact possible, until most of the heat has dissipated from the brakes. Avoid sitting stopped with the brake pedal depressed to hold the car in place during this time. Park the vehicle and allow the brakes to cool to ambient air temperature.
     
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  5. madspeed

    madspeed Colonel Mustard
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  6. dubbsix

    dubbsix Member

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    Yes I did. I went through two cycles, but they only seem to really grab once they are nice and hot. I'm wondering if it's the pad. Bought the set used so no idea what was loaded in the calipers.
     
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  7. Mustang5L5

    Mustang5L5 Car used in adult film "Highway Gangbang-InDaButt"
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    Simple answer here...you're missing the MC

    Ford markets the 13" Cobra kit for the 94-95 Mustangs with a master cylinder included in the kit. The GT MC is 1 1/16" bore, while the 94-95 Cobra MC is 15/16"

    It was sold as the M-2300-Q kit

    http://www.fordracingparts.com/download/instructionsheets/FordInstShtM-2300-Q.pdf

    Now, keep in mind this kit was designed with the 38mm cobra calipers found on 94-98 Mustangs. These are mostly replaced by the 99+ 40mm cobra calipers these days. More than likely this is what you have.

    Rather than use the 94-95 Cobra MC with the 15/16" bore, a more popular swap (and easier to install) MC used is the 1993 Cobra 1" bore MC.

    This is actually the combo I run on my '88. For a short while, i ran a 94-95 Gt 1 1/16" MC and the pedal effort was very hard with a lack of brake response. I swapped to the 1" MC and pedal effort was MUCH better and i could actually stop!


    If you do have a set of 94-98 Cobra calipers, you'll need the 94-95 Cobra MC, although you could run the 1" MC. I did speak with a Ford engineer who said the 1994 Cobra originally came with a 1" MC, but Ford changed it last second to make the pedal effort more agreeable for street driving.

    1993 Cobra MC will direct swap
    94-95 Cobra MC requires brake line adapter kit from max motorsports.

    In terms of identifying your calipers....

    38mm piston on the left...notice ribbing around the piston bores
    40mm piston on the right. Notice no ribbing

    [​IMG]


    Hopefully that helps
     
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  8. Noobz347

    Noobz347 Stangnet Facilities Maint Tech... Er... Janitor
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    As always... You da man! :nice:
     
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  9. dubbsix

    dubbsix Member

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    Okay you were right. We talked about this before my swap. I was smart enough to go ahead and order the 93 cobra MC!! I have the smooth bores on mine so Im guessing the 93 cobra MC will work and give me a bit more pedal response.
     
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