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Discussion Starter #1
So, I first finished the install of my newly acquired/built up 429 at the end of November, and was thrilled at how it turned out. But, I've had a steady stream of problems since then, to the point that I've only been able to put 150 miles on the beast in that time. The motor runs great, that's not the problem, but it seems like everything else is deciding this is a good time to go out too.

So, here's my current problem: While messing with the transmission for most of January, and finally having it rebuilt (again), one of my rear wheel cylinders started to leak. Not a big deal. I bought new ones, but waited until I had the tranny back in and working correctly before I started that project. This morning I swapped in the new wheel cylinders and bled the rear brakes. My braking is now worse than it was. Previously, 2-3 pumps of the brake pedal were required for any real braking. Now it doesn't matter how many times I pump it, it just goes to the floor and gives me piss-poor braking. I re-bled everything, in the correct sequence (RR, LR, RF, LF), taking my time and making sure I had no air bubbles, and still no difference. I even propped open that stupid button on the proportioning valve. At this point I'm throwing tools across the shop and using colorful language. My guess is that the master cylinder decided this was a good time to join the long list of failed parts. Is there anything else I should be looking at???

My intent is to do the braking upgrade with the F-350/Thunderbird parts, but right now the Bronco is the only running vehicle I have. I am apparently going to have to drive it minimally and cautiously while I get my Mustang back on the road, and then park the Bronco (again) while I re-do the whole braking system.... :banghead

At this point I welcome any thoughts/theories/commiserations.
 

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SteelSteeds said:
So, I first finished the install of my newly acquired/built up 429 at the end of November, and was thrilled at how it turned out. But, I've had a steady stream of problems since then, to the point that I've only been able to put 150 miles on the beast in that time. The motor runs great, that's not the problem, but it seems like everything else is deciding this is a good time to go out too.

So, here's my current problem: While messing with the transmission for most of January, and finally having it rebuilt (again), one of my rear wheel cylinders started to leak. Not a big deal. I bought new ones, but waited until I had the tranny back in and working correctly before I started that project. This morning I swapped in the new wheel cylinders and bled the rear brakes. My braking is now worse than it was. Previously, 2-3 pumps of the brake pedal were required for any real braking. Now it doesn't matter how many times I pump it, it just goes to the floor and gives me piss-poor braking. I re-bled everything, in the correct sequence (RR, LR, RF, LF), taking my time and making sure I had no air bubbles, and still no difference. I even propped open that stupid button on the proportioning valve. At this point I'm throwing tools across the shop and using colorful language. My guess is that the master cylinder decided this was a good time to join the long list of failed parts. Is there anything else I should be looking at???

My intent is to do the braking upgrade with the F-350/Thunderbird parts, but right now the Bronco is the only running vehicle I have. I am apparently going to have to drive it minimally and cautiously while I get my Mustang back on the road, and then park the Bronco (again) while I re-do the whole braking system.... :banghead

At this point I welcome any thoughts/theories/commiserations.
I feel your pain. I am going through the same thing right now. (See my post f-350 brake upgrade problems) I am down to my last option of replacing the proportioning valve. I should have that done today. I'll let you know.
 

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I know it is easy for me to say but it sounds like you should not be driving that vehicle as it is now! Since you are in a hurry, I'd go ahead and try the new master cylinder. I sounds like the most likely problem to me and its prettty cheap/quick. (Assuming you don't have a leak somewhere) If you had a little more time I'd say go ahead with the F350 booster/cylinder but that takes brake line mods and more time. I'm not a brake expert but its my .02 worth. Good Luck!!
 

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You did'nt let the M/C run dry in between bleeding did ya? If you are sure all the lines are properly bled there is not much left other than a M/C. You do have good vaccum going to the booster right?

F that pin in the P/V, I have never pulled that to bleed brakes.
 

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Discussion Starter #5
I'd never messed with that button on the P/V either, but that was the only thing I could think of that I didn't do. The M/C never ran dry, and there aren't any leaks, fluid level is staying constant. I've got 18" of vacuum at the manifold, but I didn't verify that at the booster.

If the P/V goes bad, what exactly goes wrong? Too much braking in the rear? My P/V is so crusted with crud that it's barely recognizable, but those things are spendy, so I've just left it alone...
 

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SteelSteeds said:
I'd never messed with that button on the P/V either, but that was the only thing I could think of that I didn't do. The M/C never ran dry, and there aren't any leaks, fluid level is staying constant. I've got 18" of vacuum at the manifold, but I didn't verify that at the booster.

If the P/V goes bad, what exactly goes wrong? Too much braking in the rear? My P/V is so crusted with crud that it's barely recognizable, but those things are spendy, so I've just left it alone...
I just did my PV and it didn't help at all.:banghead
 

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Discussion Starter #7
So, more thoughts - my Bronco has one of those trailer brake doo-dads mounted to the bottom of the dash, and a whole mess of brake lines hooking things up that I've never really bothered to look at that closely. When I hit the brakes, that unit on the dash has always made a clicking noise and the little lever that is mounted on the front of it moves to one side.

It's still doing that, but now I also get a click when my brake pedal hits bottom. Does this signify anything? This unit I believe is either a factory optional one or a dealer add-on circa 79, as I've seen the exact same Kelsey Hayes unit in pictures from factory brochures. I've never pulled a trailer that I hooked up anything other than lights, so I know nothing about the thing. Does that sound mean anything? Could the trailer brake system have something to do with my lack of brakes?

After reading the postings on bmboll's similar headache, the only other thing that stood out was that I had just replaced my rear wheel cylinders, and I know that when I put everything back together the starwheel adjusters were all the way in, and they were in poor shape, so it is possible that my rear brakes aren't adjusting outward like they should. Could this really be causing the front brakes to not grab? That just doesn't seem to make sense to me...
 

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The best theing that I found is to use disk brakes on the back and put in a in line PV. And ditch the factory one. It is well worth the work.
 

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Discussion Starter #9
SUCCESS!!!! :chili: :chili: :chili:

I have brakes!

It turns out that skumandeth was right: it was my rear brakes being completely out of adjustment. I bought a new pair of the starwheel adjusters, set the shoes to where they were just barely starting to drag on the drums, and put it all back together again. Shazam, the brakes are working fine.

So, here's to you skumandeth :beer you got my brain thinking in the right direction. I really didn't think that the rears being out of whack would degrade brake performance THAT much, but they do.
 
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