Re: Drum Brake Troubleshooting
[Re: BcudaChris]
#2134344
08/16/16 02:07 PM
08/16/16 02:07 PM
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Posts: 36,041 Lincoln Nebraska
RapidRobert
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first replace the leaks which I believe you have done then a visual to see if everything looks copacetic on all 4 corners (everything assembled correct/no damage) then spoon up the shoes then bleed the MC then bleed the corners. EDIT gotta find out what that "clunk" is
Last edited by RapidRobert; 08/16/16 02:19 PM.
live every 24 hour block of time like it's your last day on earth
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Re: Drum Brake Troubleshooting
[Re: BcudaChris]
#2134728
08/16/16 10:16 PM
08/16/16 10:16 PM
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Posts: 36,041 Lincoln Nebraska
RapidRobert
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the 2 halves (front discs or drums and rear drums are still hydraulically seperated even with a combo valve which likely includes a metering valve and a proportioning valve (I forget their exact functioning). I'd "keep it simple sam" & find/fix the clunk & confirm no leaks/spoon em up then bleed the MC then the corners
live every 24 hour block of time like it's your last day on earth
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Re: Drum Brake Troubleshooting
[Re: BcudaChris]
#2135020
08/17/16 11:37 AM
08/17/16 11:37 AM
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Posts: 403 Colorado front range
BcudaChris
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Well, I pulled the rear wheels off and inspected everything against a detailed photo. The lower retract spring on the driver's side had either not been properly attached or had somehow come loose. I put a hardware kit in both drums and all the springs I pulled off were noticeably wimpier than the new ones, clunk eliminated.
On to bleeding. Re-bled the master in place using the brake pedal. No fluid drop. Bled the RR with the mighty vac and sealed it. Attached mighty vac to the LR and could get no fluid. left the catch can hooked up and used the pedal, appeared to work. Went back to the RR, opened the bleeder, attached the catch can and gave it a couple of pumps, repeat once again for the LR. On to the front, the pedal goes to the floor both sides, properly bled.
So, the pedal would only go halfway down on the rears, and with the whole system sealed, the pedal only goes halfway down. I am befuddled. I think it either has to be a partial blockage in the rear channel or that 2yr only combo valve that I had replaced some of the seals in years ago. At any rate the situation is a bit improved, but more work required.
Any ideas here regarding the valve/blockage?
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Re: Drum Brake Troubleshooting
[Re: BcudaChris]
#2135072
08/17/16 01:09 PM
08/17/16 01:09 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
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what I would do is get some brass male inverted flare plugs & cap the MC ports & if the MC is bled out and it is holding pressure the pedal will be rock hard with virtually no travel (eng idling-these are PB correct?). the fittings are 9/16-20 and 1/2-20 & your parts house would have em in the "Edelman" fittings cabinet. then onto the prop valve & I would unscrew the rear brake(s) "out" line & cap the prop valve female open port with a 3/8-24 similar male brass fitting & work on the fronts & see if you can get them bled out and have the same high and tight pedal that you have with the MC capped. that'd be a good start. I would put a block of wood under the pedal so it dont go to the floor but stays pretty close to its normal range of travel. holler back when you can
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Re: Drum Brake Troubleshooting
[Re: BcudaChris]
#2135845
08/18/16 02:00 PM
08/18/16 02:00 PM
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BcudaChris
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OK, Isolated the master - Good Blocked rear output at the combo valve - 1\2 pedal Rear hard lines, flex line and y-block - clean and clear
I pulled the combo valve, disassembled it as much as possible, cleaned and soaked with penetrating oil. I then used a small screwdriver to move the shuttle valve, but was unable to move it back non-destructively (even with compressed air). It looked like it was stuck open, so there would be flow to the rear. I thoroughly cleaned and reassembled the valve, installed it and bled the brakes. No more air, the pedal is rock hard, but only goes down half way. I'm thinking it is hydraulic lock in the combo valve. The slider must be disadvantageously stuck and when the valve opens the rear channel, no flow.
Any other ideas or avenues to explore? I'm almost ready to get one of those Wilwood adjustable combo valves and plumb it in...
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Re: Drum Brake Troubleshooting
[Re: BcudaChris]
#2136151
08/18/16 08:54 PM
08/18/16 08:54 PM
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Posts: 36,041 Lincoln Nebraska
RapidRobert
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blocked off the MC & was high and tight & rehooked things up and capped output to rear & pedal goes down 1/2 way? does the travel seem excessive or OK? does it pump up?
live every 24 hour block of time like it's your last day on earth
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Re: Drum Brake Troubleshooting
[Re: BcudaChris]
#2136384
08/19/16 01:52 AM
08/19/16 01:52 AM
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RapidRobert
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see if I am reading this right, you unhooked the forward (closest to radiator) line in the MC (for rear brakes) & hooked the short bleeder line to it (the MC port) & run it back into the MC bowl (just like you are bench bleeding (that half) of the MC) & the system felt "normal" as far as the front pads engageing? If all good on that & the other half (for rear brakes) of the MC is bled out then there has to be a blockage from that half rearward as you said. if we're thinking the prop valve is fubared I'd almost wanna go back to your parts house & get a short length of prefabbed 3/16 brake line with the male inverted flare ends and a double female inverted flare union and a 3/8-24 male inverted flare plug to cap the hole in the prop valve that the rear line was in that you took out, to bypass it COMPLETELY & see if the prob is there or further downstream. it'd be some work but that is my 2 cents worth at the moment
live every 24 hour block of time like it's your last day on earth
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Re: Drum Brake Troubleshooting
[Re: BcudaChris]
#2137552
08/20/16 11:55 PM
08/20/16 11:55 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
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yeah on a toughie if the MC (& booster if PB) is high and tight when capped then we wanna move outward downstream till we find the issue
live every 24 hour block of time like it's your last day on earth
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Re: Drum Brake Troubleshooting
[Re: BcudaChris]
#2139537
08/23/16 09:02 PM
08/23/16 09:02 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
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anytime bro, can the prop valve be dissassembled to see what is stuck. might be an easy fix. then you can sell the wilwood valve plus no brake line fabbing would be needed for the wilwood
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Re: Drum Brake Troubleshooting
[Re: BcudaChris]
#2143948
08/30/16 03:53 PM
08/30/16 03:53 PM
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Posts: 403 Colorado front range
BcudaChris
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Got my project interrupted by a little vacation!
On the factory prop valve, on more than one occasion I have removed, disassembled, cleaned and reassembled it. It is one of the oddball 73-74 B&E body valves, as far as I know. No reman available. Problem is, it is iron and the little brass flare disks can not be removed non-destructively, at least without proper tooling.
This time, I was unable to free up the shuttle which is contained by the flare disks. Previously, I pushed it to one end of its travel with a small screwdriver and soaked the inside with penetrating oil. I would then be able to push the valve back with a piece of coat hanger through the flare disk. Repeating this process three or four times would get it moving again. Not this time though, I got it stuck at one end and couldn't push it back with a hanger. I left it soaking in penetrating oil for a couple of days, same deal. Couldn't even move it with compressed air.
I've finally got the Wilwood spliced in (and am going to purchase a 3/16 flaring tool instead of the bar for lines on the car in future) and am now on to the bleed. Good times!
WIll report back.
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