Brakes Wont Lockup

[jeremywatco]

Paul,

Thank you for the excellent reply. I'll touch on some of the points here.

Pedal to the floor.. yes it was touching the floor. Took some effort but it was there which is why I am thinking I need to do more bleeding. This bronco was not running at all when I got it. So when I did the front conversion I found 100 other issues. All the brake lines are now new. No soft rubber, they are all stainless braided.

I didnt call in for this Master Cylinder. I just went online and read the description for this one:

https://www.wildhorses4x4.com/product/Hydroboost_Master_Cylinder/bronco-master-cylinder

Based on what I read it said that it works fine with manual brakes as long as your remove the extra rod, which i did.

I am thinking based on the amount of work i did to the brake system (all new hard lines, new MC, new prop valve, new discs up front) that there is still some sneaky air somewhere. Yes, I bench bled the MC.

Let me get a buddy to come over in the next day or so and I'll just bleed till I fall asleep LOL.

Seriously though, thanks for all the assistance.

 

[68ford]

Get a 7/8 master, and lengthen the rod between it and your pedal stud. Then thank me later ;D

 

[ntsqd]

I'd call that way too small. Total leverage ratio will be way too high (GM - ~135:1, Ford - ~129:1), resulting very mushy feeling brakes. Ideal overall manual leverage ratio is between 93:1 & 95:1 Can tolerate out to about 100:1, but can't tolerate much less than 90:1 as the pedal gets way too stiff with high pedal effort.

 

[68ford]

I'd call that way too small. Total leverage ratio will be way too high (GM - ~135:1, Ford - ~129:1), resulting very mushy feeling brakes. Ideal overall manual leverage ratio is between 93:1 & 95:1 Can tolerate out to about 100:1, but can't tolerate much less than 90:1 as the pedal gets way too stiff with high pedal effort.

I guess it's a matter of opinion then, my friends Bronco with 77 front discs and 11 by 2 and 1/4 rear drums and wilwood 7/8 master cylinder stops extremely well with very very little effort and no power assist. The pedal feels a little more mushi than the factory one inch master and the travel is a little bit more so he lengthen the rod about half an inch or something to bring the pedal up a little bit end result is very very nice and simple. He has a 94 lightning 5.8 and a electronic controlled OD trans behind it. When in gear even warm it idles at 800 and when put in gear it slightly revs up to maintain the same 800 rpm. It takes less than the weight of your foot to keep it from rolling. A hard stop where rear tires are howling requires hardly pushing. He has 35in tires.

 

[ntsqd]

It's not entirely a matter of opinion, it's also matter of the math. What pedal ratio does your friend's EB have? If he used the wilwood pedal assembly then there's a difference in pedal ratio that needs to be included in the conversation. If he did not then his total leverage ratio is way out there in the soft & mushy territory (~129:1 vs. 93:1-95:1).

From observation people are more tolerant of a total ratio that is higher than the stated ideal range, but tend to not be very tolerant of a ratio that falls just slightly short of the ideal range. Even then, again from now decades of observation, around 100:1 is the upper limit for most people. More than that and they start complaining about the 'air' in the brakes when there isn't any. For some this complain starts at about 96:1.

 

[68ford]

Stock pedal, as I stated it does feel more mushi than stock 1in bore master and the pedal does travel farther which is why he lengthened the rod to raise the pedal. But the end result is awesome he loves it. I drove it and was very impressed as well. Almost feels like a 1999 to 2009ish power stroke pedal as far as travel and being soft. Like I said it's really nice using very very little effort to stop.

 

[jeremywatco]

UPDATE...

So I re-bled the brakes. The right rear drum brake still had some air in it. Brakes are somewhat better but still not "right".

I'm thinking its the rear drums and their adjustment. I adjusted the parking brake cable but even at full depress (which is hard to do) I dont get much braking from the rear brakes.

Also I noticed when pointing downhill and rolling forward I get very little skidding from the back. When rolling backwards down the same hill the fronts lock up and skid quite a bit.

So thats where I am at. I'll adjust the drums for more drag and report back

 

[jeremywatco]

Pulled the drums. So where is what I am finding....

#1, parking brake cable needs to be replaced or something. Pushing the pedal down is an act of god and it doesnt seem to move anything inside the drum.

#2. I have a ton of pedal travel before the shoes start to move outward. Ton meaning 1/2 - 3/4 of my pedal travel. Is there an adjustment for this? Should I ditch the P valve and just run a T?

The 1/2 - 3/4 travel is pretty soft as well, doesnt firm up until that last 1/4 or so. Its not super soft but its not consistent.

 

[ntsqd]

First thought is that you still have air in the system. The caliper and wheel cylinder pistons should start to move almost as soon as the MC piston starts to move. Air also can contribute to an inconsistent feeling pedal.

How old are the wheel cylinders?

How I built a power vacuum bleeder: https://classicbroncos.com/forums/showpost.php?p=2796790&postcount=17

 

[nvrstuk]

How did you manually adjust the rear drum brakes? This would also allow your pedal to move much farther than desired until the actual shoes move...

Manual brakes work great, drum brakes work really "good" but need maintenance and proper adjustment to work properly.

 

[jeremywatco]

How did you manually adjust the rear drum brakes? This would also allow your pedal to move much farther than desired until the actual shoes move...

Manual brakes work great, drum brakes work really "good" but need maintenance and proper adjustment to work properly.

I adjusted them with the little star wheel behind the drums. I have it up on stand right now and am going to check it all out.