Brakes Newbie / Prop Valve Replacement

[CopperBronco]

I need to replace my prop valve as it’s leaking decently. I’ve been reading a bunch of threads and watching Duffs videos on brakes. Still some things I don’t fully understand. Also need reco’s for brake flushing and bleeding. I’m running disc front, drum rear, power boost brake, MC, & combo prop valve from Toms Bronco parts.

1. What’s the best way to extract fluid to then remove old prop valve and install new one?

2. What’s the best way to bleed brakes if you’re alone? Speed bleeders? Power bleed?

3. Duff recommends pressure ball bleeder as most effective. Is this a MityVac or Motive manual pressure bleeder? Or a pneumatic system? Bench bleed MC?

4. When installing new prop valve, it’s between master cylinder and the brake lines… how do you ensure all the air gets out? Does order of disassembly or assembly reduce air getting into the system in the first place. Also seems like the air will be at the top of the system with a prop valve swap. Does it make more sense to inject pressure from bleeders and push air up out of system vs down and all the way out of the lines? But speed bleeders would prevent this with the check valve, right?

5. My fluid looks dirty, I want to flush it all anyways. No idea if PO ever did it, or when. Needs a full flush. Tool reco’s for this or just gravity flush? I’d like to ensure any water or other build up gets removed from bottoms of cylinders.

6. Lastly, I’m anal retentive about brakes and a little tentative as a newbie, okay with spending money to get the right pro tools that are most efficient / least messy and help a one man team. I’ve done a ton of other stuff on my Bronco now and managed to do it successfully, hoping I can figure this out.

Thanks!

 

[Speedrdr]

Best way to bleed brakes if you’re ALONE??? My experience says find someone who understands basic instructions and use them to help. I’m not saying you cannot bleed by yourself, I’ve done it, BUT it’s a pain. My 2 cents worth.

Randy

 

[DirtDonk]

Is this a factory valve, or aftermarket?
Usually the factory ones don’t leak, but the aftermarket ones are well known for that problem.

If an aftermarket version, then before replacing it, is it leaking out of the little rubber boot on the end? If so you might be able to remove the boot, unscrew the fitting, and clean the sealing surface. Maybe even replace any gaskets are O-rings.

 

[CopperBronco]

Best way to bleed brakes if you’re ALONE??? My experience says find someone who understands basic instructions and use them to help. I’m not saying you cannot bleed by yourself, I’ve done it, BUT it’s a pain. My 2 cents worth.

Randy

Got a motive pressure bleeder kit. Hoping that should do the trick, apparently better than gravity bleeding or vacuum bleeding I’m told… curious if you all find this to be true?

 

[CopperBronco]

Is this a factory valve, or aftermarket?
Usually the factory ones don’t leak, but the aftermarket ones are well known for that problem.

If an aftermarket version, then before replacing it, is it leaking out of the little rubber boot on the end? If so you might be able to remove the boot, unscrew the fitting, and clean the sealing surface. Maybe even replace any gaskets are O-rings.

Yea, this aftermarket combination valve. Good to know… i can’t actually full tell the exact leak spot… need to clean up fluid and check it again. Is there a good way to identify my disc brakes as well? No idea which kind PO put on. I’m running a Dana 30, early kingpin style axle. PO put on spacers then for wheels to clear disc brakes (not ideal I’m told).

 

[CopperBronco]

It’s this style of prop valve: https://tomsoffroad.com/parts/66-77...MIrf7txuWm9gIVBRDnCh1RZQX7EAQYASABEgK19_D_BwE

 

[CopperBronco]

Can anyone also confirm brake light warning switch basic wiring? I’m guessing here, The light has a purple wire(to prop valve) and a red wire(to ignition?), and prop valve has two wires which I’m reading you crimp together and connect to purple wire of light. Does this sound right? Does the light ground through the dash then? Or secondarily through ignition?

 

[DirtDonk]

Is there a good way to identify my disc brakes as well? No idea which kind PO put on. I’m running a Dana 30, early kingpin style axle.

They only disc conversion that you would normally find on a bronco with a Dana 30 is the one using a combination of the GM and Ford components.
You can confirm this by looking at the brake calipers. The GM version uses two pins that the caliper slides on.

When replacing calipers or pads, use 73 to 75 GM K5, 10 and 20 series trucks for your donor source. They changed the calipers slightly after 76, so I use 75 as a cut off.
I think the pads remained the same all the way through the 80s and maybe even into the early 90s, but don’t quote me on that.

 

[DirtDonk]

If there’s any doubt at all, just post up a couple of pictures and the members here will tell you for sure what you have.

That same conversion uses a Ford hub and rotor. So if you ever have to replace a rotor used 76 to 79 Bronco and F150 4wd.

 

[DirtDonk]

Can anyone also confirm brake light warning switch basic wiring?

The factory wiring as it comes out of the firewall will be two wires. The switch has one wire.
You do crimp the three together to make it work.

Does the light ground through the dash then? Or secondarily through ignition?

Yes and yes. Sort of…
I still don’t have my head fully wrapped around that circuit. Even after all these years I haven’t put it to memory.

The wire to the side of the ignition switch is actually a ground. When you turn the key to the start position that terminal grounds to the dashboard and turns the light on temporarily as a bulb test to let you know the system is working.
Traditionally that circuit was called a “proof out” or “prove out” and may have been used for many different purposes. But in this case Ford used it as a way to make sure that brake warning system was functioning every time you turn the key to start.

 

[.94 OR]

Adding to this thread. I'm adding the GM conversion discs to the front of my D44. How does GM mount the axle housing end of the caliper hose? Ford would use a bracket and a small horseshoe clip, but the GM version is threaded. Same bracket type assembly and a fine thread 5/8" nut/washer to get it snug?

 

[jamesroney]

Adding to this thread. I'm adding the GM conversion discs to the front of my D44. How does GM mount the axle housing end of the caliper hose? Ford would use a bracket and a small horseshoe clip, but the GM version is threaded. Same bracket type assembly and a fine thread 5/8" nut/washer to get it snug?

Yes, that how GM does it.

The nut is special, and is thin...like a jam nut. You can use a regular nut, but it looks funny.



I think I had to drill out the hole in my bracket when I did my GM brake hoses. But the jam but works great.

 

[bronkenn]

I used a nut that I cut in half and made a bracket to fix it to. If you zoom in pic you can see it on the right side.

 

[.94 OR]

I used a nut that I cut in half and made a bracket to fix it to. If you zoom in pic you can see it on the right side.

Thanks. Your bump stops tall enough?

 

[bronkenn]

They are for what I do. I have never checked them for travel. I believe they are the same height as the stock ones were.

 

[fluffybunny]

I just replaced my entire brake system and to the point of bleeding. I picked up the $30 pneumatic brake bleeder from Harbor Freight and will be trying to bleed my by myself. I'm thinking that I'll trigger the air a few cycles, run around and refill the master cylinder, and repeat probably a million times until I'm done. Then finish with the help of the wife by having her pump and hold the brakes while I crack the bleeders just to make sure. I hope it works because that's my plan.

 

[hsach]

It’s this style of prop valve: https://tomsoffroad.com/parts/66-77...MIrf7txuWm9gIVBRDnCh1RZQX7EAQYASABEgK19_D_BwE

That looks like the one I just bought for my 78 Bronco. I hope it works well for you, I am trying to fix an issue where my rears lock up too soon, and this is the only thing I haven't replaced. I want to fix it before I install my Hydroboost. Let us know how it turned out.

 

[CopperBronco]

That looks like the one I just bought for my 78 Bronco. I hope it works well for you, I am trying to fix an issue where my rears lock up too soon, and this is the only thing I haven't replaced. I want to fix it before I install my Hydroboost. Let us know how it turned out.

Mine is working fine so far, I also used a bit brake/hydraulic thread lock for brake systems as I’m told they tend to leak… but so far so good, all fixed and no signs of brake fluid leak after 3 weeks

 

[bayoubronco]

Buy the bleeding tool and be careful not to over tighten the connections. I toasted a PV, a rookie doing a rookie move..."steel is stronger than brass". Make sure all the lines are loose fit while laying them all out. Then when going to bleeding, snug fit and be ok with leaks in the connections; while you find and snug them more.
I also was chasing my tail with low pressure to the rear. finally figured out it was a MC (6 months old) because it wasn't pumping the small reservoir to the rear.
With all that only used 1 Lg can of Brake fluid. Surprising how little it takes in the small diameter lines. Brakes are solid for now; still waiting for any residual bubbles.