Rear drum brakes dragging. HELP!

[RalphN]

Hello.  Got my 72 with dragging brakes, I was thinking It was wheel cylinders.  I replaced them both and they were pretty gunked up, added some new fluid. Took it for a ride thought i had it fixed, but it still drags, bad. Lots of brake dust on my rims. What's the chance that it could be a master cylinder not releasing?? Also the brake pedal pushes HARD.  Anyone have these issues?  Or advise??

[BobW]

Check the freeplay gap between the booster and the master cylinder.

Replace the flexible brake hose to the rear end, it can deteriorate and collapse internally, keeping fluid from returning.

Hard pedal, check the booster for leaks, or a bad check valve.

[Dtret]

When you bled the brakes did you get complete pedal drop at all 4 wheels, individually of course?  

[GRAY 70 Monte Carlo]

I have many times on many vehicles seen brake hoses cause that problem.brake fluid able to flow to calipers but Not letting fluid return from calipers .

[Scott S.]

First of all, did you set the cylinders ???

There's a little port that allows you to dial them with a flathead screw driver. The "toothed" ring on the cylinder. 

Also, did you set them by driving and operating them in reverse ??

[Scott S.]

Just now, Scott S. said:

First of all, did you set the cylinders ???

There's a little port that allows you to dial them with a flathead screw driver. The "toothed" ring on the cylinder. 

Also, did you set them by driving and operating them in reverse ??

Sorry, not on the cylinder, but the spacer on the bottom. 

My mind gets ahead of itself sometimes.   

[72 Monte Carlo]

1 hour ago, Scott S. said:

Sorry, not on the cylinder, but the spacer on the bottom. 

My mind gets ahead of itself sometimes.   

That's called the "adjuster".

[stangeba]

I wonder if the parking brake cable/s are rusted causing them to stick and not fully release??

To apply, we push on the parking brake pedal but to release, I don't believe the spring has as much power as the pedal and our left foot.......

Good luck!!!

[72 Monte Carlo]

If the brakes are hard to press, then like Bob suggested, it's a bad check valve on the vacuum booster or a failed vacuum booster.

You can press in on the diaphragm rod on the booster while plugging the vacuum hose elbow fitting and look and listen to hear if the diaphragm is moving on its own. If it does, then it has failed and needs replaced to get power brakes functional again.

[FrankOC]

If nothing else has changed, (booster, master, etc), then the hose sounds like the culprit.  When the brakes drag, crack a bleeder to see if there is a quick blast of fluid under pressure.  If there is, the hose may be preventing the release of pressure.  

[RON T]

Mine was the rubber brake line hose that goes over the real end.. collapsed. Replaced and ok ✅… maybe 8-10 years ago..