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More Brakes Questions....Again

needabronco

Bronco Guru
Joined
Jul 2, 2004
Messages
6,411
Loc.
Prescott/Farmington
OK, I did the GM disk conversion and was having problems with the rear locking up early, so I added an adjustable proportioning valve and deleted the 'H' block. I also installed new wheel cylinders and shoes out back.

Now I can't get the brakes to lock up at all (the adjustable valve is open all the way). They do work really good, just no skiddy skid. Is this a problem? I bled the system really well and used a quart of synthetic fluid, could there still be air in there somewhere??? Thanks again. Casey
 

ken75ranger

Bronco Guru
Joined
Jan 27, 2002
Messages
5,069
Loc.
Troy, NY
What size or year wheel cylinder did you use? I had stock '75 cyilinders and they didn't work well with the chevy disc brakes. They wouldn't grab too good. I switched to 76-77 wheel cylinders. They are a little larger bore and they work fine.
 
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needabronco

needabronco

Bronco Guru
Joined
Jul 2, 2004
Messages
6,411
Loc.
Prescott/Farmington
Thats interesting because the rearend in question is a 74/75 'medium' bearing, with the 10" breaks. I believe I had to use the later 76/77 wheel cylinders because we couldn't find a part number/right part for the big bearing 10" backing plates, but the 11" wheel cylinders worked. The wheel cylinders for the 74/75 didn't fit the backing plates and we ordered both sizes...
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,821
A few common things.

First, did you clearance the knuckles enough? Not just enough to fit but enough room for the caliper to move in toward the knuckle. The outer brake pad will only work when the caliper moves toward the knuckle. If it hits the knuckle the outer pad will do nothing and only the inner pad will work.

Second, when you did the master cylinder, did you mix the front and rear ports? The front port does the rear brakes and the rear port does the front brakes (backwards of what would make sence when laying it out).

Is everything bled out? Front calipers need to have the bleeders on top. If you put left on right they will bolt up just fine but the bleeder will be on the bottom. That makes getting the air out nearly impossible. Imagine a soda (beer) bottle. You want to fill it. Stick the bottle in a lake. If the opening is on top the air will rise to the top and go out the hole. Turn the bottle over and and there is an air bubble that will never come out.
 

Apogee

Contributor
Bronco Guru
Joined
Nov 26, 2005
Messages
6,030
What MC are you using? That will determine which port goes where, although the reversed front port/back brakes and rear port/front brakes is the "norm" with the Ford units.
 
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needabronco

needabronco

Bronco Guru
Joined
Jul 2, 2004
Messages
6,411
Loc.
Prescott/Farmington
I'm using the stock drum/drum master, it worked before only the rears locked up early. All the lines are hooked up correctly and I used a quart to bleed everything out really well. The only thing I changed besides new shoes was addin new wheel cylinders, removing the 'H' block, and adding an adjustable proportioning valve which is open all the way.

The bakes work really well, the only concern I have is that I can't seem to get the brakes to lock up (IE in a panic stop).
 
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