68 Dodge Coronet Brake issue

[ChuckBurgess]

good evening everyone, I'm new here and this is actually my first post so be patient lol

I have a 68 Superbee which my wife bought for me 18 years ago. It's been a great car but I admit i neglected it for several years. I was too busy racing cars on an oval track and then we decided to move out of country for a few years. We're now back and it's time to take care of this girl, instead of being laid up on jack stands. I redid the front-end with new brakes, rotors and calipers as well brake lines from the side to the pistons. I did the exact same thing to rear but its drum brakes on the back.

The problem I'm having is no brakes. I've bled them several times and still no luck. I must also say I let the master cylinder run dry while doing the upgrades. I re-bled the master cylinder and it seems fine. When I bleed the brakes, the wife presses the brake down several times and holds it while I release the bleeder and then reset it. I've put almost 2 qts of brake fluid into the system and don't see any leaks anywhere. Doesn't seem to have any air in the lines either.

What am I missing????? Could the MC have gone bad? Even though I rebled the MC (while still in the car). It's about 55 years old and looks original. The funny part is the brakes were working when I drove it into the shop about 4 weeks ago. Could have letting the MC run dry cause it to now fail?

Thanks for any ideas.

 

[pnora]

Did you bench bleed the master. Are your front bleeders on the top? Are the rears adjusted?

 

[Paul_B]

Master Cylinders do go bad. If your master cylinder went dry, you should bench bleed before proceeding to the typical bleeding process.

 

[jimbosride]

I have had real good luck with this. No bench bleed or wife needed (for the brakes )

But I do agree... the master needs to be looked at or bleed it first

 

[Jerry Hall]

Sounds like a master cylinder problem to me. Check your drivers floorboard, under the carpet for your disappeared brake fluid. If the master cylinder is good, it's possible to bleed it in the car. Just make sure you protect your paint. I put a plastic bag down the inner fender and plenty of rags on top of the plastic.

 

[tubalcain]

I have heard from a reliable source that you can "reverse bleed " brakes by using a large syringe, with tubing, connected to the bleeder screws. Force fluid from the wheel cylinders to the master cylinder. Do that on all 4 corners and the system is bled. As a bonus, the whole system will, now, be full of clean fluid. I have never done this, but it seems to be entirely reasonable. Give it a thought, results may vary. Search, like Amazon, large syringe. If you try, we will need a report, of course.

 

[ChuckBurgess]

thank you everyone for your great ideas. I think instead of just doing the same thing over and over and expecting different results, I'm going to go with the MC being the culprit as of now. I re-bled the MC (still on the car) and it seemed perfectly fine after. I forgot to mention that the brakes also seemed to be fine when the car is off, it's when I start the car that all indications of brakes disappear. Still taking any new ideas before I pull the MC later today. Thanks again for all the assistance everyone has provided.

 

[danf_fl]

The booster may have a problem with the diaphragm or pedal linkage adjustment.

They work okay with car off, but with car on, there is vacuum.

 

[pnora]

The booster may have a problem with the diaphragm or pedal linkage adjustment.

They work okay with car off, but with car on, there is vacuum.

The booster is just an assist. You should still have brake pedal.

 

[pnora]

thank you everyone for your great ideas. I think instead of just doing the same thing over and over and expecting different results, I'm going to go with the MC being the culprit as of now. I re-bled the MC (still on the car) and it seemed perfectly fine after. I forgot to mention that the brakes also seemed to be fine when the car is off, it's when I start the car that all indications of brakes disappear. Still taking any new ideas before I pull the MC later today. Thanks again for all the assistance everyone has provided.

Did you actually bleed the master with tubes going back into the fluid? Did you verify the caliper bleeders are on top? Did you make sure the rear shoes are properly adjusted? You ask questions but give no answers.

 

[ChuckBurgess]

Sorry pnora, I reread the prior posts and realized I actually missed your first post asking these valuable questions. Yes, I had the tubes going back into the brake fluid on MC, but I did bleed the MC on the car. I don't believe there's any reason not to. Yes, the bleeders are on top. Yes, the rear shoes were adjusted. I also should add that the brake light comes on in the car when started, but everything is full and doesn't seem to be any air in the lines. I freely admit I am new to this restoration stuff, so bear with me please. Once again, thanks all for the great input.

 

[pnora]

Sorry pnora, I reread the prior posts and realized I actually missed your first post asking these valuable questions. Yes, I had the tubes going back into the brake fluid on MC, but I did bleed the MC on the car. I don't believe there's any reason not to. Yes, the bleeders are on top. Yes, the rear shoes were adjusted. I also should add that the brake light comes on in the car when started, but everything is full and doesn't seem to be any air in the lines. I freely admit I am new to this restoration stuff, so bear with me please. Once again, thanks all for the great input.

If you are sure that both halves of the master have let all the air out you should of bled it ok. On the car or bench will not matter as long as you fully stroked the master to get all air out. You might be on the right track that the master has failed and needs replacement. Get a new master and bench bleed it. See where that leads you.

 

[ChuckBurgess]

Thanks pnora, that's my plan because I don't have too much hair anymore and this is not helping...lol

 

['68 Coronet R/T]

You say that with the car off, you have a solid brake pedal. Have you tried holding the pedal down and turning the key to the ON position?
If it still holds there but goes down after you start the car, that would cause me to think it's the booster.