Rear Drums Drag

[Darter6]

I myself am very stumped (no pun intended) the only thing left is to check axle play up and down that may cause the drums to drag.That along with axle end play if it is still tapered bearings.If the adjuster and lock is still there set end play to .008
These are just thoughts going thru my head. I'm still thinking of things that have happened in the past.
Also check the parking brake cables that go to the drums. Had a car that the cables were part frozen and wouldn't release all the way. Removed them,lubed them and that cured it.
I got a car once and the spreader bar for the parking brake was for a 11'' drum and installed on 10'' drum.
Shoes would not retract completely. ????

 

[Darter6]

wish I could find out what my master cylinder and booster are from/for… I really wonder if it’s not correct for this car..

I too keep going back to a master cylinder problem or a crimped metal brake line that allows pressure to the wheel cylinders but not allow pressure to release. Just another thought.

 

[Stumper]

Where’s a good place to measure axle play? I did. loosen it a bit awhile back thinking it was too tight but didn’t go by a measurement.

 

[Darter6]

Dial indicator with a magnetic base attached to the backing plate to face of axle flange.
Or the old school way. Remove all movement and loosen till you just "Feel" slight movement.

 

[Stumper]

Dial indicator with a magnetic base attached to the backing plate to face of axle flange.
Or the old school way. Remove all movement and loosen till you just "Feel" slight movement.

 

[Stumper]

Did the old school method. Wanted to check my “feel” since I don’t do it very often…

 

[Darter6]

I just looked up .013 to .023 end play from a 1968 Dodge service manual for the 8 3/4'' rear.
So you have some room to work with. I still like .008 but that's just me.

 

[Stumper]

One more “clue” to this brake dragging problem, maybe. I had backed my adjusters off quite a bit and took the car out for a drive. Drove twice the distance as my previous runs and when I got home the rear drums were still hot….
Pulled the drums off and backed the adjusters off to where they barely touch the shoes. I’ll try it again later to see if any change..
The possible “clue” I mentioned is that after each test drive the the brake dust is concentrated at the top of the shoes, front and back, both sides. Is this more evidence of hydraulic binding??

 

[Darter6]

Try fitting the shoes inside the drums. I know this means disassemble time and see how they fit inside the drum.
Where they hit and if any gaps. Are they touching only at the top and bottom of the lining?
A practice that is no longer used was to taper the top and bottom of the new shoes to fit so the lining has full contact to the drum.
I know NO ONE does this anymore.Why ? I have no idea. Back in the 60 we even had a machine to chuck the shoe in to do this.
(Yeah I'm really old) Gosh dang it (family friendly) something got to be causing this..

I got home the rear drums were still hot….

How hot is hot ? Smoken' hot ? Burn your fingers hot ? Burns all the paint off hot ? Way hotter than the front drums ?
Smells like a Semi Truck on a long down hill hot ? Not making fun,being serious.
I even have a Blue Point brake drum gauge to set the proper shoe to drum size. If I can find it, I'd send it to you.

 

[Stumper]

Try fitting the shoes inside the drums. I know this means disassemble time and see how they fit inside the drum.
Where they hit and if any gaps. Are they touching only at the top and bottom of the lining?
A practice that is no longer used was to taper the top and bottom of the new shoes to fit so the lining has full contact to the drum.
I know NO ONE does this anymore.Why ? I have no idea. Back in the 60 we even had a machine to chuck the shoe in to do this.
(Yeah I'm really old) Gosh dang it (family friendly) something got to be causing this..


How hot is hot ? Smoken' hot ? Burn your fingers hot ? Burns all the paint off hot ? Way hotter than the front drums ?
Smells like a Semi Truck on a long down hill hot ? Not making fun,being serious.
I even have a Blue Point brake drum gauge to set the proper shoe to drum size. If I can find it, I'd send it to you.

Hot as in uncomfortable to hold your hand on for more than a couple seconds. Fronts are not warm at all.
Just back from another test run. 12 miles and back are still hot - this with the adjusters backed all the way off so they put no pressure on the shoes. Of course now I have no peddle. Tomorrow I’ll pull the drums and there will be dust caked on the tops of the shoes…

 

[Darter6]

I'm out of suggestions. You got me on this. Let us know when you get it solved.

 

[Stumper]

I'm out of suggestions. You got me on this. Let us know when you get it solved.

I guess I start replacing parts…. My tool for setting the rod should be here in a few days so I can verify that’s set right. From there I start replacing stuff…. Wish I knew for sure if it was mechanical or hydraulic so I knew where to start…

 

[Darter6]

The biggest thing that gets me is when you stated that the brakes released after cracking the bleeder screw.
I still think Master cylinder rod adjustment OR a stuck piston in the 2 pot master cylinder.
I installed a aftermarket booster/master combo with a Chevy style master. Dragging front brakes.
Took the master apart thinking dirt or machining is hanging the piston up.
Did it twice, still the same. Swapped master for another and problem solved. Machining problem ?
Could have been.
I guess it's just you and me trying to figure this out. But I have no more ideas left...

 

[Stumper]

The biggest thing that gets me is when you stated that the brakes released after cracking the bleeder screw.
I still think Master cylinder rod adjustment OR a stuck piston in the 2 pot master cylinder.
I installed a aftermarket booster/master combo with a Chevy style master. Dragging front brakes.
Took the master apart thinking dirt or machining is hanging the piston up.
Did it twice, still the same. Swapped master for another and problem solved. Machining problem ?
Could have been.
I guess it's just you and me trying to figure this out. But I have no more ideas left...

I should clarify. The guy that had my car rebuilding the transmission had claimed that he determined the problem was the collapsed rubber hose to the rear T block by opening a connection someplace - probably the hose to the T. That line was replaced and supposedly the hydraulics was working fine afterwards… Don’t think he test drove it though afterwards because they obviously still drag. If it’s a hydraulic problem it has to be somewhere from that hose back to the MC.. The primary line that runs the length of the car looks really old - as in possibly original. Could be that or the MC itself.
I am looking into something else this morning. My rear drums are post 66’ style. I installed Dynamic Friction 581 series shoes. Rock auto showed they fit front and rear for 66 -67 but as I look at the 68 and 69 they start showing a different number shoe…. I don’t know what year these drums and back plates are….

 

[T Brashears]

my 65 had the entire brake system replaced then sat for 13 years before I got it.worked great for about 150 miles,then random sticky brakes. Rust in master cylinder and 3 wheels. The springs rusted and particles would stick a piston.it’s all new and flushed again.

 

[Danomt]

I too keep going back to a master cylinder problem or a crimped metal brake line that allows pressure to the wheel cylinders but not allow pressure to release. Just another thought.

If you crack your brake line loose at the master cylinder and the wheel frees up it is not a hose, shoes draging or bearing asjustments, it is a master cylinder not releasing. Usually bad rod adjustment or rubber cups inside swelling up and not letting fluid return.
Simple

 

[Stumper]

If you crack your brake line loose at the master cylinder and the wheel frees up it is not a hose, shoes draging or bearing asjustments, it is a master cylinder not releasing. Usually bad rod adjustment or rubber cups inside swelling up and not letting fluid return.
Simple

At this point I don’t think I could notice a difference as it’s more of a slight drag by the time I get the rear jacked up. Hopefully my tool for the rod adjustment will be here tomorrow so I can rule that out. If it’s good and I have to break the hydraulic system I’ll probably just replace the MC, line and wheel cylinder. Make sure the whole system is new and clear.

 

[Danomt]

At this point I don’t think I could notice a difference as it’s more of a slight drag by the time I get the rear jacked up. Hopefully my tool for the rod adjustment will be here tomorrow so I can rule that out. If it’s good and I have to break the hydraulic system I’ll probably just replace the MC, line and wheel cylinder. Make sure the whole system is new and clear.

We are trying to help you but are getting mixed messages on what is going on. This should not take 40 post to get to the bottom of the problem Post 1 and 33 said that the brakes release when the bleeder is cracked. After any stop the brakes are usualy to hot to touch... You justify all suggistions as not your problem. You do not need a tool to check MC pushrod free play. You just need some. .002 is enough so the cylinder returns so the bleed hole is open. This problem would be fixed in 5 minutes at our shop...

 

[Fran Blacker]

If you crack the rear brake line at the master cylinder and it relases rear brakes is there an internal residual valve in master or as said push rod problem.

 

[Stumper]

No, I never said the brakes released when a bleeder was cracked. I said the shop guy told me they released when he opened a line in the rear (Post 1). Since he determined the hose was plugged I assume it was the hose to the T connection - maybe both ends of the hose?
I appreciate your help with this mess Danomt. I wish your shop was close by so you could look at this thing.
After a test drive, when I get back to the garage, the wheels are hot. By the time I get the rear lifted the wheels rotate without much drag. I assume what ever is holding the pressure, IF in fact that is what the problem is, releases the pressure after a couple minutes. I don’t know if the problem is hydraulic for sure. I think I’ve ruled out adjuster issues. Heck, I’m still trying to figure out if the shoes are correct.

I probably should hold my comments until I’ve ruled something out instead of blow by blow posts every-time I try something or see something. i really do appreciate the help as my knowledge is pretty limited.