Explorer rear discs: not working at all! Thoughts???

[chuzie]

Re: Explorer rear discs: NO PEDAL!!! Thoughts???

Broncobowsher, sure thing. I figured that pic wasn't gonna do it.

Broncaz, double pump has no difference. I know it is possible to have a bad MC out of the box but geez, what are the chances in this situation. I will swap it out just in case.

Dirkdonk, the first time around, when I initially installed the Explorer rears, nothing else in the system was changed except on the rear axle and I ended up with no pedal.

The second iteration involved a new MC and I plumbed in my adjustable valve for the rear. I tried both extremes on the valve to make sure it was not adjusted wrong. Note: I do not run a stock prop valve in my system. I wonder if my adjustable valve is toast?

I am not sure if the booster rod is the right length or not. All I did was adjust it out to be in slight contact with the MC. After I still had the pedal issue, I removed the MC and measured the travel of the rod from pedal release to full application.

Please clarify what you mean by deep recess on the MC. I am not familiar.

I think the fluid flow is very slow and weak. Usually, when bleeding, after 4 or 6 pumps I have to refill the MC. Right now, it is more like 20! That is all four calipers, not just the rear so I am inclined to say my adjustable valve is not the culprit but maybe the MC.

The pads are all up against rotors and look fine. The rear caliper sliding surfaces are clean and smooth and I checked for freedom of movement during installation. The pads are not new by any means but they look good and have plenty of meat left.

Thanks guys.

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[DirtDonk]

What I was referring to about the recess is the very back of the piston on the master cylinder. It sounds like you're already set though, since you say you have the rod just barely in contact with the master.
The difference is that some masters, when viewed from the back, have just a little dimple in the back of the piston. While others, such as the stock EB manual brake masters for instance, have a very deep recess (maybe 1" or so?) into the piston. So instead of just a dimple in shiny metal, you see basically a hole, and would have to shine some light down it to see the bottom.
In those cases, some booster rods are not long enough to reach and don't actually push the piston until they're near the end of their travel.

That's what yours was sounding like, but since you have checked and verified that your rod pushes the piston, then it's sounding less and less like the issue here.

Paul

 

[chuzie]

Re: Explorer rear discs: NO PEDAL!!! Thoughts???

Gotcha. Yes, this MC is dimple, not recess. I still wonder if the travel is enough at 1.25"

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[DirtDonk]

You're talking "piston travel", correct? If so, I can't imagine that's not long enough. A good working brake system probably needs all of a 1/4" of piston movement to make things transition from go-to-whoa pretty well.
If I'm not mistaken, the pedal moves more than the piston by quite a bit. Like 6:1 or so?
If that's the case with an EB, then 1/4" of piston is 1.5" of pedal. Which would be decently firm I would think.

That sound right?

Paul

 

[blazinchuck]

Re: Explorer rear discs: NO PEDAL!!! Thoughts???

Chuzies request for pics

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[chuzie]

Re: Explorer rear discs: NO PEDAL!!! Thoughts???

Okay, so chuck just sold me out with the pics. Bleeders on rear are below supply line. Whoops! Good call chuck.

I will swap them Tuesday but I still don't think that is the issue. Doesn't explain the crappy flow on all four corners.

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[motoman]

When doing my Hydroboost I got a bad master cylinder from Checkers..... that sucked and wasted a whole lot of time.... also anywhere you have brake lines that have an upward loop to them pull down during the bleeding process as flat as you can or inverted to let the bubbles pass. They will created a pocket of air that can't be released unless flattened or inverted....... that's what finally worked on mine. And when you get partial brakes take it for a ride... the bumpier the road the better and re-bleed!

Good luck!

 

[blazinchuck]

Re: Explorer rear discs: NO PEDAL!!! Thoughts???

Let's see...here's your favorite pic

 

[Broncobowsher]

First picture confirmed it. Rear calipers are on the wrong side. Bleeders on bottom. Swap left and right rear calipers, bleed again and all will be fine.

 

[chuzie]

Re: Explorer rear discs: NO PEDAL!!! Thoughts???

First picture confirmed it. Rear calipers are on the wrong side. Bleeders on bottom. Swap left and right rear calipers, bleed again and all will be fine.

I'm gonna hold you to that one bro!

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[chuzie]

Re: Explorer rear discs: NO PEDAL!!! Thoughts???

FAIL!

Swapped the rear calipers to the correct sides.

Re-bled making sure to articulate flex hoses to move air.

Still no pedal. I coast to a stop (barely) with pedal to floor even after double pump.

Below is the rest of my setup. Someone has to have an idea here. This stuff is pretty simple. I just don't understand how this can be happening.

FWIW- the fluid regurgitation issue is now gone so I am sure the air is gone too.

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[01Dudley]

Awesome!

Let's see...here's your favorite pic

 

[01Dudley]

have your tried switching the lines on the MC front to back? If you close your adjustable proportion valve the front should lock up. You should also be able to test all this on jack stands.

 

[chuzie]

Re: Explorer rear discs: NO PEDAL!!! Thoughts???

Swapped in Ford style angle braket, booster, and MC from Chucks rig and now I have brakes!

Now it is a disc/drum MC and my fronts lock up but not the rear but that is expected.

WOW! In 12 years my brakes have NEVER locked up and all this time it was my Duffs bracket and booster. More to come on that....

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[DirtDonk]

I was going to comment on the position of the linkage chuzie. I know I'm only going from memory here, but I don't remember the bell-crank assembly (if that's what you'd call the setup in there) inside the bracket being angled that far towards the firewall. The ones I've seen seem to have been a little more towards the booster. In other words, not quite the middle, but farther forward than where yours is in the pic.

Any thoughts on that? That would tend to be the length of the pedal rod I would think. Is yours adjustable or could it have been cut too short in the past? Did you install it new? Or was it there when you bought the truck?

I don't have any images to back me up on that, but how do you think the position of your bracket in the pic compares to the one you have on there now?

Paul

 

[chuzie]

Re: Explorer rear discs: NO PEDAL!!! Thoughts???

I already swapped the ford setup back into chucks truck but I did measure the pedal rod movement on both broncos from the firewall. They were identical so I don't think it is a pedal rod length issue. That leaves the angle bracket. All the stuff was brand new from duffs.

Either way, I am going manual 4 wheel disc now. Is there any difference in the manual brake push rod amongst various bronco years? Can I still use my stock power brake pedal assembly? Where can I get the aluminum spacer to go behind the MC? What other parts am I now thinking of for this?

Thanks for your help everyone. It is always tough chasing a gremlin in a system where you assume certain parts should not be defective.

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[DirtDonk]

...Is there any difference in the manual brake push rod amongst various bronco years?

Only difference I'm aware of was between the manual and power rods. Manual is quite a bit longer and the piston bore (backside of the piston) is much deeper to accommodate it.
Rod has a spring clips wrapped around it too, that catches in the bore and keeps the pedal from pulling back. Not much danger of the rod falling out of the back of the piston though, as it's pretty deep in there, plus the thickness of the casting, plus the firewall metal.
But there's no comparison in length to the power.

... Can I still use my stock power brake pedal assembly?

Can't think of any reason why not. I think even the pedal ratios were the same between the two. Even if they weren't though, they should still work with each other.
Just don't go overboard with the master cylinder bore size. A 1" bore is likely the sweet spot, but a 1 1/8" would still work. You just have to push harder.

...Where can I get the aluminum spacer to go behind the MC? What other parts am I now thinking of for this?

What aluminum spacer? Factory master bolted right to the firewall. And you don't want a spacer in the back of the piston to make up for a shorter rod, as that will allow the rod to fall out easier if you accidentally pull up on the pedal with your foot.
I assume you meant between the master and the firewall, but there wasn't one from the factory that I've ever seen on an EB.

No other parts needed that I'm aware of. Attaching clips should be the same. Brake light switch should be the same. The rod might even come with a Bronco master cylinder if you get a stock one.
Since you're probably not thinking of a stock EB master though, you might have to source/make your own. You can give us a call to see what we might have. Pretty sure we have some that can be modified to work, but you'd be on your own there.
Here's what we do sell. http://www.wildhorses4x4.com/product/BrakePedalPushRodfor76-77WHPowerBrakeKit
And even though it's listed for a different application completely, that picture is virtually identical to what a stock manual brake master looks like in real life.
The difference in ours may be the length. But you can call in to see what they measure out at and see if it will be compatible with whatever you end up bolting together.

Good luck.

Paul

 

[blazinchuck]

Re: Explorer rear discs: NO PEDAL!!! Thoughts???

The only manual brake set ups I've seen with alum spacers... where the later years('76+'77) everything before those year just mounted MC directly to firewall. Makes you wonder why those have a spacer

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[chuzie]

Re: Explorer rear discs: NO PEDAL!!! Thoughts???

The thing that concerns me is the alleged aluminum spacer in the later models. I am sure the MC is the same for all the years, so that leads me to wonder if there is a difference in pedal rod length to account for this spacer; if it actually exists.

Can someone please confirm whether this spacer exists? If so, does it need a different rod / MC?

I want to do the Mark V MC (disc/disc)

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[Crush]

Yes the spacer exists. I have a 76 and a 77. Both have the spacer. I have not compared the rod to any other rods though so I don't know if it is longer or shorter. I am guessing that maybe the 76/7 ones for power and manual are the same and that is why the need for the spacer

Chuzie. Glad to see you got it worked out!