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Brakes not working

rrod

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Helping a club member with a brake upgrade. He upgraded a 72 barracuda from 4 wheel drum brakes to front disc and rear drum power brakes. The entire brake system has been replaced. After market front disc kit (rotors, spindles, calipers, pads). New brake lines/hoses, master cylinder, booster, brake pedal linkage, reinforcing bracket, power brake combination priority/distribution valve. Having a hard time bleeding the system. Firm pedal when bleeding but pedal is soft and goes to the floor with engine running. The front calipers will not lock up the wheels. There are leaks that I been managing to stop or slow to a weep. Can that much air be in the system or is there something else going on? Sorry for the long thread. I was told by the owner the master cylinder was not bench bleed.
 

Challenger RTA

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Try jacking the rear or the front of the car up to get the master cylinder level. The mc is mounted at an angle. so air will be trapped at the front. Have someone push on the brake easy, to see if there are any bubbles. this might be the problem air trapped. That's why it is suggested to bench bleed the mc.
 
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Challenger RTA

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Leaking lines or components can mimic master cylinder problems. Check the fluid level in the master cylinder first when any brake issues develop. If the reservoir is full, you're not experiencing an external leak. If your foot slowly sinks to the floor with normal pressure on the brake pedal, the master cylinder is leaking internally.
 

rrod

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Leaking lines or components can mimic master cylinder problems. Check the fluid level in the master cylinder first when any brake issues develop. If the reservoir is full, you're not experiencing an external leak. If your foot slowly sinks to the floor with normal pressure on the brake pedal, the master cylinder is leaking internally.
Helping a club member with a brake upgrade. He upgraded a 72 barracuda from 4 wheel drum brakes to front disc and rear drum power brakes. The entire brake system has been replaced. After market front disc kit (rotors, spindles, calipers, pads). New brake lines/hoses, master cylinder, booster, brake pedal linkage, reinforcing bracket, power brake combination priority/distribution valve. Having a hard time bleeding the system. Firm pedal when bleeding but pedal is soft and goes to the floor with engine running. The front calipers will not lock up the wheels. There are leaks that I been managing to stop or slow to a weep. Can that much air be in the system or is there something else going on? Sorry for the long thread. I was told by the owner the master cylinder was not bench bleed.
Good suggestions. I‘ll give them a try in a few days when we go at this again.
 
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Challenger RTA

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On top.

20180924_172213.jpg
 

isettakurt

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Hello, Did you check the booster rod to master cylinder piston clearance
 

greatscot3

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I've got a '74 Cuda 440 clone with a lumpy cam and I had to put a vacuum accumulator tank kit on it because of low manifold vacuum.
Summit sells their tank, a check valve, mounting bracket, hardware, plenty of hose and a vacuum gauge for about $135.00 I think.
Worked really well.
 

RJH72Cuda

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Checking the rod clearance is a good idea. A friend had the same problem on his older Vet. loaned him my power brake bleeder. The system had a lot of air in it. I suggest using a power brake bleeder. It is much easier and will get all the air out of the system. Also need to stop all leaks first that is a must. I work at a Dodge dealer, Brakes and suspension is what I do at work. I hope this helps.
 

rrod

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Checking the rod clearance is a good idea. A friend had the same problem on his older Vet. loaned him my power brake bleeder. The system had a lot of air in it. I suggest using a power brake bleeder. It is much easier and will get all the air out of the system. Also need to stop all leaks first that is a must. I work at a Dodge dealer, Brakes and suspension is what I do at work. I hope this helps.
Will be checking rod to master cylinder clearance and eliminating leaks tomorrow. Thanks for all the suggestions.
 
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