1961 Newport brake bleeding problems .

Bucket

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My Newport has power assisted 4 wheel drum brakes and a dual pot master cylinder.
It has a later model differential with self adjusting brakes .
Front brakes are standard and everything has been replaced,new wheel cylinders , shoes and flexible brake lines.
Rear brakes are almost new with no signs of weeping wheel cylinders .
Over a few weeks i have been trying to bleed the brakes with no success .
I follow the FSM pattern when bleeding , i have backed off the adjuster cams on the front brakes .
The back brakes bleed up well and i get good pedal feel.
When i try to bleed the front brakes there is unusual amounts of air bubbles which don't stop no matter how long i bleed them .
All pedal feel has gone once i try try to bleed the front brakes .
No brake lines appear to be weeping .
Any ideas ?
Cheers,
Greg
Photos of master cylinder
MC 1.jpg
MC 2.jpg
 

413

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Why did you back off the front adjuster cams? Did the service manual say to do that? You can blow the pistons out of the cylinders doing that.
 

Bucket

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I may have been bleeding wrong.
I was getting a friend to pump the peddle 5 times then hold it to the floor.
Then i would crack the nipple and let the fluid and air flow for a few seconds.
This is how i have always done it with no problems on previous cars .
Weird thing is this method worked on the rear brakes but as soon as we started on the front brakes we got lots of air bubbles which just kept coming and lost brake pedal pressure .
The FSM says differently .
BRAKE BLEEDING 2.jpg
 

Davea Lux

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On full contact brakes, you do need to back off the adjuster cams, that is the correct procedure as the adjusting cams hold the shoes out which in turn allows the cylinder pistons to remain farther out. If you are getting lots of bubbles trying to bleed the brakes, you have likely got an air leak some place. Start by checking all line connections to be sure that they are tight. Check the bleeder screws to be sure they are properly seating. There have been issues with the ChiCom wheel cylinders being poorly machined to where the bleeder screws to not make good contact with the seating surface. Be sure that the copper sealing rings for the brake hoses are present. Missing coppers will cause the connection to the cylinder and hose to suck air when the brake pedal is released. It is also possible that you might have a master cylinder with a bad front brake piston. Grab a bench bleeding line and hook it to the port for the front brake and see if the front piston will expel all of the air, if it does not, you have a bad master cylinder. The other end of the bench bleeding line goes into the fluid pit for the master cylinder. Have a helper press down and then release the brake pedal several times, this should expel the air from the master cylinder piston. If you are satisfied that the master cylinder has expelled all of the air, reconnect the front brake line and proceed to bleed the brakes again. Have the friend push the pedal down and crack the bleeder screw, let it spit and then close the bleeder, let the brake pedal recover and repeat as necessary to purge the system. Putting a hose from the bleeder screw hose bib to a clear container of brake fluid is a good visual aid to check for bubbles.

Dave
 

Bucket

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Thanks Dave
I have have checked all the line connections and nothing appears to be weeping.
Front lines are new and copper rings are present .
I will try bleeding the master cylinder and see what happens .
Do you or anyone know where i could get a kit for that twin pot master cylinder in the photos above .
I don't know what year it is and Rock Auto only seem to have single pot master cylinders listed .
 

Davea Lux

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Thanks Dave
I have have checked all the line connections and nothing appears to be weeping.
Front lines are new and copper rings are present .
I will try bleeding the master cylinder and see what happens .
Do you or anyone know where i could get a kit for that twin pot master cylinder in the photos above .
I don't know what year it is and Rock Auto only seem to have single pot master cylinders listed .

That looks to be about a '68-'68 drum brake master cylinder. The kit will cost you almost the same as a new master cylinder, might be farther ahead to just order a new one. That will save you buying the kit and then finding out the master is pitted and not rebuildable.

Dave
 

Bucket

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Dave
Have been looking on Rock Auto .
They have this one listed for Power Brakes .
More Information for CARDONE 131323
They have this one listed for Manual Brakes .
More Information for CARDONE 131323M
This is the rebuild kit .
1969 CHRYSLER NEWPORT Parts | RockAuto
My brakes are 4 wheel drum/manual power assisted (bellow set up above the master cylinder),
Which master cylinder would i need ?
I know disc/drum master cylinders are different as they don't have the residual valve in the disc port .
Unsure of the manual and power brakes MC's listed .
 

Davea Lux

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Manual brakes on the later mopars usually had a slightly smaller master cylinder piston. The smaller piston gives more leverage to stop a car without the power assist. You could probably run either master cylinder as they both run the same mount flange, but I suspect the smaller piston would stop the car better. The increased stopping power comes at the cost of more pedal throw being needed to apply the brakes as the fluid volume applied is less with the smaller piston, so you would maybe need to adjust the brakes more often to keep the shoes close to the drums. If you have been driving the car and it stopped ok, you can measure the MC piston diameter and keep the same size. Note: Cardone rebuilt units have a very bad reputation for quality, best to specify a new MC rather than one of their crappy rebuilds.

Dave
 

Bucket

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Thanks Dave
The only time i have driven the car is off the tilt tray truck to underneath my house .
So i don't really know how the brakes worked as i found out all the front components need replacing .
 
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