Brake Master cyl and wheel cylinder size questions - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Suspension - Brakes - Steering
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 10-13-2013, 02:31 PM
Registered User
 
Join Date: Feb 2006
Location: Gilbert, Arizona
Posts: 4
Wiki Edits: 0

Thanks: 1
Thanked 0 Times in 0 Posts
Brake Master cyl and wheel cylinder size questions

I am building a 1965 Falcon Ranchero. I have installed a Mustang II suspension,steering,brake system up front, manufactured by TCI. I'm running a 302 w/AOD tranny. Original 8 inch diff with drum brakes in the rear. Everything in the brake system is new, including brake lines and fittings. TCI informs me that their system has 1980 Ford Granada rotors and 1985 Camaro calipers. I opted for a 1979 Mustang vacuum assist brake booster and '79 Mustang Master Cylinder. I originally installed a combination valve from So-Cal. I was unable to get a hard pedal with this setup before starting engine and activating the booster. When the booster is "on" the pedal goes to the floor with very little if any resistance. I made some calls to TCI and to Baer Brakes in Phoenix and they informed me that they do not use a combination valve; instead they use a adjustable proportioning valve in the rear brake line with a 10 psi residual valve. So, I removed the combo valve and installed a Wilwood adjustable prop valve. Same result. So, I got another new master cylinder (same type) and had the same result. So, I got another booster (same type) and same result. I get a semi-hard brake about 2 inches from the floor without boost and pedal to the floor with the engine running and booster operating. Made some more calls and they advised that I needed a 7/8 inch master cylinder bore as minimum. Called NAPA and they advised that the '79 'Stang m. c. was a 7/8" bore. Was told I should get a larger bore.
Did some reading in my brake manuals and found that a larger bore would provide more fluid and smaller bore would provide more pressure. Now I am lost! Does anybody know what combination may resolve my problem? No brakes is No FUN! Pressing on with AC installation and exterior trim. This little car is ready to rock and I'm afraid to let it roll. Thanks Bill Winnett

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 10-13-2013, 03:28 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,564
Wiki Edits: 326

Thanks: 698
Thanked 878 Times in 746 Posts
I'm unfamiliar with the '79 Mustang master, but assume it is a dual reservoir unit. Plumb the larger reservoir to the disc brakes and the other to the drums. Use a 10 lb residual valve in the rear line, along with an adjustable proportioning valve. Adjust the rear brakes up against the drums. Then, top off the master and bleed the brakes, beginning with the passenger rear, then the driver rear, then the passenger front and finally the driver front. Have your buddy standing by with a can of brake fluid so he can continuously top off the master as you bleed the brakes.

In my opinion, you would only need a 7/8" master if you were running manual disc/disc. Disc/drum with power assist should use a 1" or 1 1/8" master, again, in my opinion.
Reply With Quote Quick reply to this message
The Following User Says Thank You to techinspector1 For This Useful Post:
brwinnett (10-15-2013)
  #3 (permalink)  
Old 10-14-2013, 09:50 AM
S10xGN's Avatar
Gotta love a turbo!
 

Last journal entry: Body on Frame today.
Last photo:
Join Date: Aug 2004
Location: Port Neches, TX
Age: 61
Posts: 1,643
Wiki Edits: 0

Thanks: 0
Thanked 58 Times in 55 Posts
Everything Tech said is correct. Did you bench-bleed the master before installing it? Have you checked both pushrod lengths?

Russ
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 10-14-2013, 12:28 PM
Registered User
 
Join Date: Mar 2013
Location: NH
Age: 59
Posts: 59
Wiki Edits: 0

Thanks: 3
Thanked 8 Times in 8 Posts
Power Brakes with Disc Front and Drum Rear

Trouble Shooting your system.

No Pedal: Defective Master Cylinder. Booster Pin in MC is too Short. Air in System, Low Drag Calipers, Caliper Bleed Screw is not facing up at 12 O'clock position.

Spongy Pedal: Defective Master. No Residual valve to rear drums (10 lb residual valve required). Air in system. Small Master Cylinder Bore Diameter (with this type of Disc/Drum set up you should have a 1" Minimum MC bore). Drums too large. Incorrectly arched shoes.

Since you changed out your Proportioning valve to a manual one, no need to tell you that the proportioning valve should be BELOW the MC, not above it.
Reply With Quote Quick reply to this message

Recent Suspension - Brakes - Steering posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Questions about master cylinder and brake booster mike69 Suspension - Brakes - Steering 1 08-15-2009 09:42 AM
Will a Brake Master Cyl. Designed for Disc/Drum be Adequate for 4-Wheel Disc Brakes? mrwumper Suspension - Brakes - Steering 3 04-16-2009 09:38 AM
brake master cyl question! 67 Deuce 4 Me Suspension - Brakes - Steering 3 08-08-2006 12:47 AM
Master cylinder brake line questions Stroker56 Suspension - Brakes - Steering 5 04-27-2006 08:40 PM
brake light on, could it be a bad master cyl Turbo Terror Suspension - Brakes - Steering 4 03-07-2006 07:04 AM


All times are GMT -6. The time now is 05:37 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.