I'm thinking front flex hoses, master, booster, in that order of likelyhood.
Dragging calipers on my '73 conversion
- Thread starter Zymurgy
- Start date
mr. fix it
Old Man with a Hat
Were the flex hoses not changed out earlier?
He said yes, but they still could be defective..
mr. fix it
Old Man with a Hat
True but in all the years I've been in the trade i have changed out less than a dozen flex hoses just because... most are dry rotted and still work.
The ultimate test is to pump the brakes
Then crack open the line at the MC.
If there is lots of fluid released under pressure then it is at the MC or booster.
If not then it is in the lines(flex hoses too) or the calipers
One last thing to inspect.
Make sure the flex hoses are not twisted when the caliper is mounted
Agreed - same experience for me, however he needs to systematcally stwp through sourcing where the issue stems from. Tricky in some ways.
70bigblockdodge
Old Man with a Hat
I really do think it is in the pushrod under dash or booster
I think so too. The push rod adjustment is a giant pain in the *** to get it right. I was hoping Mike wouldn't hafta go through that. . . Still hoping. . .
Ok I got to my shop. I pumped he brakes(engine not running) and the wheels are froze and will not spin. I released the line for the smaller rear line first a lot of fluid flowing out. I opened the larger fluid released not as strong as the rear. The wheels would spin but still a small amount of resistance.
Tried it again opening the larger line about the same as before and then the rear and got a stronger flow as before.
I opened rubber brake lines on both ends and closed them backed never got the calipers to release.
Now to bench bleeding. First the '73 I which I originally installed in the conversion, after 45 minutes still lots of air gave up went to the '67 master which is currently on the car.
The video. No real air, bled quickly. For reference during the first 1/8" of depression can make a gusher if I push quickly, after the 1/8" no matter how quick no activity in the reservoir. No aggessive movement at all in the large reservoir, but fluid is moving.
Tried it again opening the larger line about the same as before and then the rear and got a stronger flow as before.
I opened rubber brake lines on both ends and closed them backed never got the calipers to release.
Now to bench bleeding. First the '73 I which I originally installed in the conversion, after 45 minutes still lots of air gave up went to the '67 master which is currently on the car.
The video. No real air, bled quickly. For reference during the first 1/8" of depression can make a gusher if I push quickly, after the 1/8" no matter how quick no activity in the reservoir. No aggessive movement at all in the large reservoir, but fluid is moving.
I forget I reinstalled the master still reacting the same.
Mike. Are you sure that the push rod is bottoming in the M/C piston without being stuck in that piston when it is bottomed? That little rubber band "wigget" on that push rod can screw you up bad. IF IT'S ON THE PUSH ROD GET RID OF IT. YOU WANT THAT PUSH ROD TO BOTTOM IN THE PISTON AND BE A BIT SLOPPY SIDE TO SIDE AND UP AND DOWN. The 1/8th" Ross mentioned is real close to perfect where it needs to be before the push rod moves the M/C piston when you're bolting up the M/C to the booster. That 1/8th" is roughly .060 and that ain't much. Please understand that as little as 1/16th" of one revolution of the push rod adjustment can take you from dead on to being dead off. The length of the push rod to the M/C piston is that critical. One other thing I'd check and I hope I do not get an argument from our friendz on this. If their is a brass valve of either of the exit ports on the M/C, Get a dry wall screw, screw it into the hole on that brass port, get a pliers and get 'um out of there. Some re-builder's install them and some do not. Some re-builder's play that brass port both ways when the re-build their M/Cs. Cordone comes to mind as one that does it both wayz?? They used to be domiciled in New Jersey up until a couple yearz ago and paid their workers maybe $8-$10 an hour. Now their headquartered some where in Mexico and paying what? $3.00- $3.50 an hour. Check out the prices between Re-Manufactured and Brand New M/Cs and see how close they are, Jer
OK... If I'm reading this right... Jer is on track. Check for the valve and remove it (front circuit only). There shouldn't be one under the line seat. Then try again.
If no change wind that pushrod in as far as it can go and see what happens.
Let us know how that turns out.
At his point you would be into the booster, or the pedal assembly.... UNLESS... do you have the missing spacer back on between the booster and master? Traintech55 mentioned it in post #42
70bigblockdodge
Old Man with a Hat
They don't take much either. I put a 71 Newport master cylinder on my Challenger (larger diameter piston), to try and raise the pedal height, was not satisfied with height so I started adjusting and then after a couple of adjustments less than half a turn adjustment everything started getting hot.
I am feeling better I talked to the booster rebuild guy it seems as though my my push rod has most likely been dislodged he said it should be protruding about an inch, and I said it's an inch and 3/8, he says that's it. He actually said tap it with a hammer if I need to. I hope this is it, but he seemed pretty confident, after I explained the whole situation.
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What was refreshing, while talking to the guy who rebuilt my booster, he never once tried to blame me or another component as the problem. He just wanted to explain what could be wrong with the booster.
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This was one of the first things he asked me too. I told he I didn't see one pictured in the service manual and didn't have one. When I told him which master it was he said it doesn't have one.
Excellent!! Keep us posted!!
70bigblockdodge
Old Man with a Hat
Now we are getting somewhere.
I know it's been a slow process, Mike... but you're doing great!
Enough poking, prodding and headbanging and anything can be figured out. I'm just glad you were on top of things and didn't drive her to a failure.
I am surprised the push rod didn't reseat itself while you were applying pedal pressure, but I will be thrilled to hear it is resolved if that is the cause. Just think of how ready to fiddle with the final adjustments you are now
Enough poking, prodding and headbanging and anything can be figured out. I'm just glad you were on top of things and didn't drive her to a failure.
I am surprised the push rod didn't reseat itself while you were applying pedal pressure, but I will be thrilled to hear it is resolved if that is the cause. Just think of how ready to fiddle with the final adjustments you are now
YES YES YES YES! Problem solved and it wasn't my fault.
I got to my shop this afternoon, first tried to tap the push rod in while the booster was still in the car, didn't move at all. Took it out got a bigger hammer tapped it 3 or 4 times. Previously it was 1" 3/16, now at 7/8" yes. One more tap for good measure, no change. Twisted adjustment nut to 1" reinstalled. It passed every test, including a pretty hard test drive.
Bring on the summer, I am ready.
Thanks everyone for being there for me through this whole experience. I would have never been able to do it without everyones input.
I got to my shop this afternoon, first tried to tap the push rod in while the booster was still in the car, didn't move at all. Took it out got a bigger hammer tapped it 3 or 4 times. Previously it was 1" 3/16, now at 7/8" yes. One more tap for good measure, no change. Twisted adjustment nut to 1" reinstalled. It passed every test, including a pretty hard test drive.
Bring on the summer, I am ready.
Thanks everyone for being there for me through this whole experience. I would have never been able to do it without everyones input.
70bigblockdodge
Old Man with a Hat
Cool see you at the Nats.
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