FYI FORD - MustangSteve's Ford Mustang Forum
The Internet's Most Knowledgeable Classic Mustang Information
IF YOU HAVE A QUESTION ABOUT CLASSIC FORD MUSTANGS, YOU HAVE COME TO THE RIGHT PLACE!
MustangSteve has over 30 years of Mustang experience, having owned 30 of them and restored several others. With the help of other Mustangers, this site is dedicated to helping anyone wanting to restore or modify their Mustang.... THERE ARE NO DUMB QUESTIONS!!!!!
Visit MustangSteve's web site to view some of my work and find details for:
FYIFORD Contributors' PICTURES - Power Brake Retrofit Kits for 65-66 Stangs - Classic Mustang FAQ's by MustangSteve - How to wire in a Duraspark Ignition - Mustang Ride Height Pictures and Descriptions - Steel Bushings to fit Granada Spindles to Mustang Tie Rods - Visit my EBAY store MustangSteve Performance - How to Install Granada Disc Brakes MustangSteve's Disc Brake Swap Page - FYIFORD Acronyms for guide to all the acronyms used on this page - FYIFORD Important information and upcoming events

You are not logged in. Would you like to login or register?

  • Index
  •  » FYI Ford, Classic Mustang Tech Discussion
  •  » Question for the Brake line fluid pressure geniuses out there.

    • 1 of 1

       

    8/19/2017 1:58 PM  #1

    Mochaman
    Senior 24-7 FYI Addict

    Offline

    From: Royse City, Texas
    Registered: 4/02/2013
    Posts: 1,421

    Question for the Brake line fluid pressure geniuses out there.

    I am swapping out my brake master cylinder and booster set up with the Mustang Steve system. 
    I had upgraded the brake system to disc/disc on a 65 Mustang. The brake system I was running was Master Power system that has a front port of 3/16th and a rear port that is 1/4 inch. These ran into the Combination Valve assembly which ran a 1/4 inch out to the rear brakes and 3/16th to the front. 
    ​The new master cylinder has two 3/16 inch ports. I have adapter fittings that should allow me to run a 3/16th inch line to the rear brake portion of the combination valve.

    ​Question: does fluid pressure stay the same regardless of the size of the brake line. If I run a 3/16th inch line into the combination valve then I just leave the 1/4 inch line in place does the pressure stay the same. I really don't want to run all new lines if I don't have to. 

     

    8/19/2017 2:15 PM  #2

    Greg B
    Senior 24-7 FYI Addict

    Offline

    Registered: 4/01/2013
    Posts: 1,554

    Re: Question for the Brake line fluid pressure geniuses out there.

    yes, yes it does.   No I am not a genius brake guru though.      Just asking, why 1/4" line.   3/16" brake line fittings come in several sizes.   3/8", 1/4", 7/16"  1/2" and 9/16"    that I know of offhand.  The center hole in those fittings is for the 3/16" diameter brake line.  

    I have worked on some smaller dump trucks in my day, that still only had 3/16" brake line.   I have never seen actual 1/4" line on anything Ive worked on, although I know it exists.   I would think no passenger car in the world would ever need 1/4" line.  

    If multiple things can go wrong, the one that will go wrong will be the one that causes the most damage.
     

    8/19/2017 8:18 PM  #3

    MachTJ
    I FYI 24-7

    Offline

    From: Wisconsin
    Registered: 5/18/2014
    Posts: 348

    Re: Question for the Brake line fluid pressure geniuses out there.

    Alot of mid to late 90's chebby pickup trucks used the 3/16 to front and 1/4 to rear. I'm trying to think back to my schooling days, I think brake line size can affect the rate at which the object being acted upon can move. It probably will have no affect in your case because you are forcing fluid through a restriction before the 1/4 brake lines. Most of anything will be determined by the master cylinder piston diameter.

     

    8/20/2017 7:03 PM  #4

    TKOPerformance
    Hyper FYIFORD ADDICT

    Offline

    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,068

    Re: Question for the Brake line fluid pressure geniuses out there.

    Without being a brake system engineer I think I would stick with stock 3/16" because that's how the vehicle was designed.  Other vehicles using other diameters may have other factors incorporated that allow for this.

    When you apply energy to that fluid the surface area of application in a 1/4" line is almost 50% larger than in a 3/16" line.  That concerns me.  The same energy applied to a larger area to my mind results in a reduction of force, and therefore pressure.

    Now I can't say that theory bears out in the real world, but you see where my head's at. 

     

    8/21/2017 7:02 AM  #5

    DC
    Senior 24-7 FYI Addict

    Offline

    From: Marshall, MI
    Registered: 4/01/2013
    Posts: 1,235

    Re: Question for the Brake line fluid pressure geniuses out there.

    Since we are talking about a Newtonian fluid here what ever pressure is generated by the master cylinder will be the pressure at dead head for the whole system except downstream of any pressure reducing valve. Dead head means that Pads/shoes are against rotor/drum and flow has stopped. So no flow restriction generated pressure drop. The other thing to consider is the additional volume of the system with bigger lines. Brake fluid is compressible so more volume means more springiness in the pedal. Bulk modulus of brake fluid in real world is around one percent per thousand psi. So bigger lines means more pedal travel to get to required pressure to achieve required brake force.

     

     

    1 of 1

  • Index
  •  » FYI Ford, Classic Mustang Tech Discussion
  •  »  Question for the Brake line fluid pressure geniuses out there.

    • Board footera


    REMEMBER!!! When posting a question about your Mustang or other Ford on this forum, BE SURE to tell us what it is, what year, engine, etc so we have enough information to go on.