Bleeding Brake System

[broncosam]

Been trying for a few days to get the brake system bled on my 74 Bronco. I have Chevy discs on the front and drums on the rear. Everything is new on the rear, shoes, brake drums, wheel cylinders, and all the small hardware pieces. On the front I changed the pads and the center brake hose that goes from the axle up to the prop valve. Master cylinder looks new and seems to be in good condition. Before I started all this I had a good firm pedal. Now after re-doing the brakes I'm getting a soft pedal. I've tried gravity bleeding them a couple of times, and the way I've always done it with one person inside working the brake pedal, tried this method several times. Never had this much trouble getting the air out of the system. I drove it a bit around the neighborhood, it stops, but like I said the pedal feels soft and spongy. Looking for some help. Would it be better to take it somewhere and have them pressure bleed the system? It's sure got me stumped.

 

[SteveL]

Are the calipers on the correct side with the bleeder screws up?

 

[gr8scott]

Power brakes or manual? Are the rear shoes adjusted properly? What type of prop valve? This type? If so, there's a certain procedure to bleed the front brakes.
@DirtDonk will chime in with the specifics.

And speed bleeders are your friends

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[broncosam]

Are the calipers on the correct side with the bleeder screws up?

Yes they are, thanks.

 

[broncosam]

Power brakes or manual? Are the rear shoes adjusted properly? What type of prop valve? This type? If so, there's a certain procedure to bleed the front brakes.
@DirtDonk will chime in with the specifics.

View attachment 885782

And speed bleeders are your friends

http://[URL]https://www.summitracing.com/search/part-type/brake-bleeders/thread-size/3-8-in-24

[/URL]

Power brakes. I'll have to look at the prop valve to be sure what type it is. Rear shoes are adjusted the way I was taught in auto mechanics class in high school, a long time ago, LOL.
To me it seems most of the air in the system is coming from the rear brakes. That's where I still am getting air bubbles.

 

[EPB72]

Did the master cylinder go empty during your parts replacment??? If so you may have to bench bleed master..

 

[ngsd]

I can't over stress the need to use the bench bleeding procedure. It needs to be done especially if you are having issues. Also I use a power bleeder as I do these solo and it works great.

 

[broncosam]

Did the master cylinder go empty during your parts replacment??? If so you may have to bench bleed master..

No , I kept a good eye on that.

 

[Shimmy]

I can't over stress the need to use the bench bleeding procedure. It needs to be done especially if you are having issues. Also I use a power bleeder as I do these solo and it works great.

do you use the motive bleeder that pushes from the MC or a suction at the caliper style?

 

[ngsd]

do you use the motive bleeder that pushes from the MC or a suction at the caliper style?

Motive. They make different size plates so if you have a Wilwood larger res you can get one that covers it. Some say they are messy but I use a large C clamp and never spilled a drop using them.

 

[Rustytruck]

try the pressure pump and motive bleeder and use the plastic ford tool to keep the brake shuttle valve centered.

Combination Prop Proportioning Valve Bleed Bleeder Tool Disc Drum PV2 PV4 | eBay

Specially designed for CPP proportional valve to prevent the combined valve from tripping. Used to lock the low pressure exhaust valve, so that the braking system on PV2/PV4 can exhaust quickly and easily.

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https://www.amazon.com/dp/B00CJ5DY16/?tag=cbama-20

 

[airman]

Did you find a smoking gun, I'm in the same boat right now. My pedal just seems spongy.

 

[DirtDonk]

Curious too. So joining the party finally to hear what the OP was able to do.
In the meantime, anything different between theirs and yours airman?