hydraulic brake dilema, I just can't get them to work on a streetrod. NEED HELP!

Reply

  #1  
Old 12-15-13, 04:56 PM
Member
Thread Starter
Join Date: Dec 2002
Location: Pittsburgh, PA
Posts: 551
hydraulic brake dilema, I just can't get them to work on a streetrod. NEED HELP!

I've been beating my head off of this for almost 3 years now, for those of you who haven't already made suggestions over the years, here is an update and description of how it is today.

Brakes worked fine for 10 years, replaced the master (rear seal leaked but I had brakes on the original) and they worked but the lid leaked, replaced master again, lid leaked again (thanks Advance Auto), 3rd master... I sucked the drivers front reservoir dry using a mighty vac and never had brakes again.

Since that time I have replaced ... 4 masters, 2 front calipers, 2 rear wheel cylinders, pitched the combo valve and installed a manual valve, replaced the booster, replaced and adjusted the rear shoes, installed a residual pressure valve in the rear circuit. I have run probably 2 gallons of DOT3-4 synthetic brake fluid thru it, and I'm not kidding! And, yes, I have bench bled every master and I adjusted the brake rod with precision.

Currently I can push the pedal to the floor easily, but I have enough brake to lock up the wheels, it is very touchy. It acts like I still have air in the lines and won't build any pressure to stop the pedal. I purchased a Motive Products pressure bleeder and have been using that to bleed the system and used the RR, LR, RF, LF sequence. I even removed the calipers and held them high while bleeding.

ANY SUGGESTIONS are welcome! Does the manual valve create any change in procedure? I assume that the DOT3-4 synthetic is OK.

BTW, its a 1978 Ford Fairmont booster/with a 7/8" master, connected to 1977 Monte Carlo read drums with 7/8" wheel cylinders, and 1977 Monte Carlo front calipers off of the same donor car, all hanging under a 1953 Ford F100 pickup. And BTW, the master is up on the firewall, not under the floor.
 
Sponsored Links
  #2  
Old 12-16-13, 09:39 PM
Member
Join Date: Aug 2006
Location: santa fe /texas
Posts: 998
I went back & forth a little with you,on this problem, a couple years ago(I think)
I am a retired( 30 years) Ford Dealership mechanic.
My specialty is brakes, & suspension.
I have solved many a problem over the years, & working at a Dealer, there is no such thing as "I don't know how to fix it" !
So I may have lost a-lot of time/money on a problem, But I always determined the
root cause of the problem.
I have No doubt that I can Fix this thing for You !
But I'm a little south of Houston, & it looks like you are in the north east ?
so How can you get the truck to me ?
 
  #3  
Old 12-20-13, 07:54 PM
Member
Join Date: Aug 2006
Location: santa fe /texas
Posts: 998
the brake proportioning/isolation- valve "May' have 'tripped'.
it will trip, when there is a hydraulic failure in one of the fluid circuits ( ft, or rear)
& it turns the red brake lite On.
(is the red brake lite On?)

it will need to be reset.

I do it with the engine 'off', but you 'may' need it running 'if 'you cannot get it to move without the engine running.

Loosen the brake line fitting at the master cylinder for the rear brakes ( the small chamber) about 1/2 turn.
slowly press the brake pedal, considerable force may be needed, once it goes almost to the floor, keep pushing, & listen for an audible 'click/pop' this is when the shuttle valve (inside the isolation valve) goes to the other side.

stop pushing immediately when you hear the click, tighten the loosened fitting.

see if this works for you?

if NOT, try the other end of the M/Cyl?

Read more: http://www.doityourself.com/forum/pi...#ixzz2o4tz3lGE
 
  #4  
Old 12-21-13, 08:04 AM
Member
Thread Starter
Join Date: Dec 2002
Location: Pittsburgh, PA
Posts: 551
Newtofta.... I would like nothing more than to have you assist me with this, unfortunately I'm in Pittsburgh, PA!

The proportioning/isolation valve that you are talking about, isn't that in the combo valve external to the master cylinder? I no longer have a proportioning valve, I removed it, plumbed the fronts right to the master, and put a manual valve in series with the rear, I also added a residual valve in series with the rear since I have drums in the rear. This being a hotrod, I don't have a light either.

If using a manual valve in the rear, what position should I be bleeding in, full pressure to the back, minimum pressure, or does it matter? I removed the combo valve at the recommendation of a friend, I'm not sure if that was the right thing to do or not. I guess if all that prop valve does is shift the piston back and forth in order to light a BRAKE light, it wouldn't matter if it's gone. The braking system had a 1977 Chevy Monte Carlo prop valve which I discarded some time ago. I have tried so many things on this project, an outside opinion would surely help.
 
  #5  
Old 12-21-13, 08:14 AM
Member
Join Date: Aug 2006
Location: santa fe /texas
Posts: 998
well, that pretty much eliminates the isolation/combo valve !

Have you considered bypassing the other valves, just to "see"
 
Reply

Posting Rules
You may not post new threads
You may not 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 Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'