It's the little things
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 83
From: NorCal
If anything, pick up some IFF couplers to bypass the block. And maybe some IFM plugs to isolate the front from the rear.
And ya did bleed the system with the parking brake disengaged, right?
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 83
From: NorCal
Houston.... we have disassembly.
Turbohunter:
A guy over in Fordification just disassembled his dist. block: • "Getting on the brake lines"
Pics!
See the piston? I think that's your culprit.
Conclusion: It's a distribution block that doesn't proportion the valving. However, it does contain a piston (pressure differential valve) to block off the respective hydraulic circuit when there is an imbalance in applied pressure.
A guy over in Fordification just disassembled his dist. block: • "Getting on the brake lines"
Pics!
See the piston? I think that's your culprit.
Conclusion: It's a distribution block that doesn't proportion the valving. However, it does contain a piston (pressure differential valve) to block off the respective hydraulic circuit when there is an imbalance in applied pressure.
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 83
From: NorCal
Wanna attempt to re-center it?
Here's the note on brake bleeding out of my vintage Clymer manual (1979 Copyright!):
"If the brake warning light remains on after the brake system has been bled, loosen the tube connector of the pressure differential valve opposite the circuit that was bled last. Slowly depress the brake pedal until the brake warning light goes off, signaling that the pressure differential valve is centered. Then tighten the tube connector and recheck and correct the fluid level in the master cylinder reservoirs".
I guess this won't help if the bulb is missing or burnt out.
Here's the note on brake bleeding out of my vintage Clymer manual (1979 Copyright!):
"If the brake warning light remains on after the brake system has been bled, loosen the tube connector of the pressure differential valve opposite the circuit that was bled last. Slowly depress the brake pedal until the brake warning light goes off, signaling that the pressure differential valve is centered. Then tighten the tube connector and recheck and correct the fluid level in the master cylinder reservoirs".
I guess this won't help if the bulb is missing or burnt out.
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Lead Driver
Joined: Dec 2012
Posts: 7,877
Likes: 49
From: Tennessee
Wanna attempt to re-center it?
Here's the note on brake bleeding out of my vintage Clymer manual (1979 Copyright!):
"If the brake warning light remains on after the brake system has been bled, loosen the tube connector of the pressure differential valve opposite the circuit that was bled last. Slowly depress the brake pedal until the brake warning light goes off, signaling that the pressure differential valve is centered. Then tighten the tube connector and recheck and correct the fluid level in the master cylinder reservoirs".
I guess this won't help if the bulb is missing or burnt out.
Here's the note on brake bleeding out of my vintage Clymer manual (1979 Copyright!):
"If the brake warning light remains on after the brake system has been bled, loosen the tube connector of the pressure differential valve opposite the circuit that was bled last. Slowly depress the brake pedal until the brake warning light goes off, signaling that the pressure differential valve is centered. Then tighten the tube connector and recheck and correct the fluid level in the master cylinder reservoirs".
I guess this won't help if the bulb is missing or burnt out.
Whatever you call them , a split brake system has one .
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
Marc, this may have already been covered, but when you went from the drum to disc brakes in the front, did you change the proportioning valve?
What about the master cylinder?
Both of these are different between drum/drum and disc/drum.
What about the master cylinder?
Both of these are different between drum/drum and disc/drum.
Thread Starter
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Postmaster
Joined: Oct 2010
Posts: 4,656
Likes: 4
From: Northern and Southern Cal
Yup, bases covered.
.
Thread Starter
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Postmaster
Joined: Oct 2010
Posts: 4,656
Likes: 4
From: Northern and Southern Cal
Ok, now I'm going nuts.
Took the distro block out of the system, and separated the front and back totally.
Took the booster out of the system.
Have a non power, disc/drum mc (there are different numbers for boosted and non boosted) hanging on the firewall. A Wilwood rear bias valve inline to the rears with a 10lb. residual valve in line.
So I have the simplest possible system.
Same symptoms. Pedal almost to floor, can pump it and get pedal and hold it fine. Let go of the pedal, no pressure again.
If you're thinking about the residual valve, i've used them before with no problems. They help greatly keeping the shoes and drums close.
No leaks anywhere.
So, where does that put me? Back at the mc.
Either there's air in the mc, or it's bad.
I bench bled it for at least 15 to 20 minutes and am sure I got all the air. I know how to bench bleed, done it many times with no issues.
Yet it's hard to believe I have two bad mc's.
In the morning I'm going to pull the lines and hook up my little truck bleed system that pumps fluid out to the lines then up into the bowls via clear lines so you can see if there is bubbles, so bench bleeding on the truck.
Never had a brake system act like this before.
And still remembering, it worked for a week.
Gonna beat it.
Took the distro block out of the system, and separated the front and back totally.
Took the booster out of the system.
Have a non power, disc/drum mc (there are different numbers for boosted and non boosted) hanging on the firewall. A Wilwood rear bias valve inline to the rears with a 10lb. residual valve in line.
So I have the simplest possible system.
Same symptoms. Pedal almost to floor, can pump it and get pedal and hold it fine. Let go of the pedal, no pressure again.
If you're thinking about the residual valve, i've used them before with no problems. They help greatly keeping the shoes and drums close.
No leaks anywhere.
So, where does that put me? Back at the mc.
Either there's air in the mc, or it's bad.
I bench bled it for at least 15 to 20 minutes and am sure I got all the air. I know how to bench bleed, done it many times with no issues.
Yet it's hard to believe I have two bad mc's.
In the morning I'm going to pull the lines and hook up my little truck bleed system that pumps fluid out to the lines then up into the bowls via clear lines so you can see if there is bubbles, so bench bleeding on the truck.
Never had a brake system act like this before.
And still remembering, it worked for a week.
Gonna beat it.
Thread Starter
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Postmaster
Joined: Oct 2010
Posts: 4,656
Likes: 4
From: Northern and Southern Cal
Ok, just truck bled the mc.
Can't get the air out of it.
When bench bleeding it looked like it was just pumping fluid no air.
However it's obvious with my little set up that it's putting out air.
Even if you account for plastic leaking, it's just to much air.
And no matter how long I pumped I couldn't get the air out.
I have a vid.
I'll figure out how to post.
But everything is telling me that that mc's are bad.
So I'm going to order one from a totally different source and see how that goes.
And since I feel like treating myself after this crap, it's gonna be chrome.
Can't get the air out of it.
When bench bleeding it looked like it was just pumping fluid no air.
However it's obvious with my little set up that it's putting out air.
Even if you account for plastic leaking, it's just to much air.
And no matter how long I pumped I couldn't get the air out.
I have a vid.
I'll figure out how to post.
But everything is telling me that that mc's are bad.
So I'm going to order one from a totally different source and see how that goes.
And since I feel like treating myself after this crap, it's gonna be chrome.
