Soft pedal first push

[TA head 69?]

69 dart
73 front end brakes, suspension, k member.
New Calipers
New stainless flexible lines all
New rear disc calipers
New proportioning valve
New 1 1/8 master cylinder
No leaks
Line lock
Bench bled master cylinder, 3 times.
Manual bleed with the wife many times.
Bled with vacumn tank 3 times.
Bled every fitting.
First pedal 3/4 push soft. Hard and holds second pump. 1 minute later, first push soft. What am I missing? Thanks.

 

[4spdragtop]

You started at furthest fitting on car? Rear pass i believe.

 

[TA head 69?]

Yes sir. Have bled many makes and models. New and old. First experience like this.

 

[MV8]

Don't be insulted if I say something basic you know by heart.

Bleeding technique is important. I work the bleeder back and forth between tiny bubbles sucking air around the seat versus actual bleeding, while I keep squeezing the hand pump to keep a vacuum on the jar.

Are you driving to check? Loose wheel bearings act like extra runout in the rotors, pushing the pistons back more in the calipers so there is more travel to take up when the pedal is pressed initially. I would not expect a second pump right behind the first to go as far.

Can't see how it is but the truck/van master rear port is for the front brakes like most masters.

New (china?) master may not be as good as it should be for the bore and seal, but then it would leak down/not hold. Looks like you ran hard line and just replaced the flex with stainless so that's good. I assume no vertical loops to trap air.

 

[Oldmanmopar]

Check the master cyl. push rod travel. Is it returning all the way or is the stop lamp switch holding it from returning.

 

[nutz]

see if your pads retract on the rear
after you step on the brake see if you can see the rear brake pads retract a little
if you take a screw driver you shouldn't be able to push the rear pads back (parking brake aculator problem seen a few bad new ones )

 

[TA head 69?]

Cars on blocks. Rear rotor held tight with lug nuts. Push rod moves free in the car and out of it. Plugged the master cylinder ports with brass plugs after bleeding. Hard, no bleed down in the car and out. BUT. You know what? And I hate to say it but the lines are backwards if the rear port is for the front brakes. Won't be able to try for a few days, work calls. I'll swap them and give it a try. Will let everyone know. Will be very relieved if it's this, no matter how embarrassing! Thanks very much!

 

[nutz]

yes rear master to front brakes
so if you pump the brakes do they get hard (or still too much travel)

 

[TA head 69?]

Haven't swapped them yet. As is, first push goes down 3/4 of the way and gets hard. Every push after the 1st one is hard at the top. Neighbor has a Cuda with a speedway power master/booster. His front port is going to the front brakes. Looking forward to swapping them. Car has been done for a month except for this brake situation and a blow thru carb battle!

 

[nutz]

Yea
Check rear pads and see if the bounce back
Stupid question but all your bleaders are on the top of your calipers........

 

[TA head 69?]

Bleeders are all up. All 4 disc's release when the brakes are let up.

 

[nutz]

Oh yea some have front going to the front
The brake pads will sometime pull back from the rotors when you release the pedal
So need to have someone pump up the brakes and when they let off the pads will pull back 1/16 "or less then when you step on the pedal it needs to travel that much more ...common on parking brake calipers

 

[nutz]

80s gms had square cut seals that pulled the pistons back slightly
Than had a valve in the master to hold pressure on the pistons
Thats why I'm thinking rear
Look like gm calipers

 

[TA head 69?]

Had the same rear disc bake set up on a 52 dodge pilot house truck. Believe your right on the gm. I believe early cadillacs. If the swap doesn't work I'll try a residual valve in the back. worked the emergeny brake many times to adjust it. Same on the dart. Very good parking brake on the dart.

 

[Kegan B]

Is it possible it needs a distribution block vs a proportioning valve? I know Dr. Diff lists proportioning valves for front disc set ups and distribution blocks as 4 wheel drum or disc. I also had a similar issue but car is rear drums, ended up having to bleed it a bunch.

 

[nutz]

Like i said if you see the caliper piston pulling back that's your problem

 

[nutz]

Is it possible it needs a distribution block vs a proportioning valve? I know Dr. Diff lists proportioning valves for front disc set ups and distribution blocks as 4 wheel drum or disc. I also had a similar issue but car is rear drums, ended up having to bleed it a bunch.

Oh yea sometimes have to jack the back or front of the car if the bleeders aren't in the top of the piston bores

 

[RustyRatRod]

It has air in the system. Pay attention to @Oldmanmopar's post, because that could be the reason. If the pushrod isn't making the full travel, you wouldn't be able to bleed all the air out of the system. Don't think about it. Check it. Because of machining tolerances from one master cylinder to another, even same part numbers can differ.

 

[TA head 69?]

Have the adjustable mopar pushrod kit. Coming out all the way for sure. Oldmanmopar do you agree with swapping the port lines?

 

[TA head 69?]

Hello friends. Back on the car today. Took out the brake pedal push rod bolt out to double check it's coming all the way out. Good to go oldmanmopar. Mv8 I swapped the port lines. Front to back, back to front. Vacumn pumped the entire system (2 quarts thru the system), manually bled the system ( 2 quarts). Same results. Looked up a rebuild kit for the 79 to 84 Eldorado caliper and it is a square seal nuts. Wife just pushed to pedal while I watched the caliper puck and there it was. Puck comes out around .080 (i measured it with a feeler gauge),touches the pad and the pedals hard. Pump the pedal quick twice, hard at the second push and holds. Have a stock distribution block not proportioning valve. So. Would appreciate suggestions. Residual valve back, what psi? Adjustable proportioning valve to the back. Thanks for all your suggestions!

 

[nutz]

residual check valve
Not sure on the psi
Think they were 6psi

 

[TA head 69?]

Decided on 2 psi valves. Back first with a proportioning valve. Then see if I need the front valve. Lehgo!

 

[nutz]

Yea only rear if the front is tight

 

[TA head 69?]

So we have brakes! 2psi front, 2 psi back residual valves. Proportioning valve to the back. Waiting on a custom blow thru carb! Listing a dc power jr dragster roadster project if someone is adventurous. Thanks all.

 

[nutz]

Just need to make sure they don't drag
Plum crazy purple....yes
More pics......