Front 11 x 3 HD Brakes

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It is not hard to do a side to side drum swap. We did that often in the old days to chase a vibration.
If the problem only happens after the brakes warm up, think about this. What parts are warming up ? The backing plates ? or the drums and/or lining ?
Also steer clear of riveted lining. Cracked shoes are common at the rivet holes.
The same backing plates were there before the brake service and didn't make noise then so why now?
Lets say you replace the backing plates and the noise is still there ? What then ?

All the linings so far have been bonded.  Man, if I did replace those backing plates and the problem persisted the "what then" is me checking into a mental institution.  Virtually everything else is new.  And I am fairly certain it is the brakes since it consistently happens at the same time and under light pressure I hear the noise that coincides with a tire rotation.  I let off then it disappears.

I thought I was the only west coast, IE guy out here.  I'm in Cucamonga.  Small world!  Did you make Fall Fling?

[MoparLeo]

For the last 20 + years. I have a space at the Fall and Spring Flings. I sell Mopar rebuild door hinges. I have done several sets for members here and also on Craig's List, FABO, FBBO, FEBO, EBAY, and others. I am also a member of Inland Mopars and we just had a very successful "Mopars in May" show in Ontario during the summer.
Can you take a cell video with sound of your issue and post that ? Your description sounds like a drum/hub issue.
Did you have the studs replaced when you changed the drums ? The originals drums were swegded onto the hubs and the assemblies machined as one unit.
Swap the drum/hub assembly to the opposite side and retest. I was a Firestone company store manager for several years, and other companies back in the seventies. Brake noise were number one service complaint.

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For the last 20 + years. I have a space at the Fall and Spring Flings. I sell Mopar rebuild door hinges. I have done several sets for members here and also on Craig's List, FABO, FBBO, FEBO, EBAY, and others. I am also a member of Inland Mopars and we just had a very successful "Mopars in May" show in Ontario during the summer.
Can you take a cell video with sound of your issue and post that ? Your description sounds like a drum/hub issue.
Did you have the studs replaced when you changed the drums ? The originals drums were swegded onto the hubs and the assemblies machined as one unit.
Swap the drum/hub assembly to the opposite side and retest. I was a Firestone company store manager for several years, and other companies back in the seventies. Brake noise were number one service complaint.

I'd probably recognize you if I saw you.  I've been going to that show since the late '80s.  I went to your clubs Ontario show this year too.  That was a nice little surprise out my way and a trip saver from the usual spot.

I don't think a cell video would pick up the sound very well.  I appreciate the thought though.  The studs haven't been changed.  That's a good idea about switching those around too!  If you were still working at the Firestone, I'd bring it in for sure.  Good mechanics out here are hard to come by.

[Filthy Filbert]

Can you duplicate the problem on jack stands...maybe after a drive to warm things up? 

Checked for witness marks from something like the shoe retaining pin making contact somewhere?  It's not something dumb like the wheel bearing nut cotter pin contacting the grease cap is it? 

I'd be looking real hard at the bearings and preload and what not if the problem only happens after driving and things have warmed up some.

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That's a great idea to try and duplicate it on the jack stands, but I don't think it would work well trying to do.  I think getting it at that temp and trying to spin that wheel fast enough with someone's foot on the brake wouldn't be easy to duplicate.  I'll try it though as on paper it sounds good. 

I can't say for sure that it's not a bearing problem though.  Does what I describe sound like it could be?  It sounds like a good clank of metal on metal almost like a hammer hitting the drum or something, but not severely hard when I come to a light stop.

I think I'm good on the bearing torque and cotter pin.  I've had that off a few times subsequent to the problem and retorqued it and that didn't change things.

[Ebody Edgar]

 
Worn out backing plate? Doubtful but possible, a dial indicator mounted on the hub can be used to check the height of the pads to each other.
How are the shoes set to the drums? Light - even drag?
Self adjusters on the front? I hope not.
Are the shoes arc lined to match the drums?

Are you sure the wheel bearings are set properly?
The old school way has been superseded by people smarter than me.
They recommend using an inch pound torque wrench and setting the bearing torque to 90-120 INCH pounds after seating the bearing with 15- 20 ft lbs.
I have tried it and it works fantastic

Do not use OEM/asbestos linings try some new technology. Metallic linings as i recall
I have tried those linings - fantastic.
I am  not here to reinvent the wheel but I do follow good advice

[MoparLeo]

OK. Now you have given a much better description of the noise. Try this. After the brake warm up, try to back up and hit the brake firmly. Now go forward again and re-apply the brake to try to make the noise again. This will check for drum shift on the hub. As I said before, the drum/hub assembly was designed to act as one piece. That is why the new studs being sweged after the drums are replaced is important.
Also what wheels are you using and are they torque to factory specs.

[moreparts]

Worn out backing plate? Doubtful but possible, a dial indicator mounted on the hub can be used to check the height of the pads to each other.
How are the shoes set to the drums? Light - even drag?
Self adjusters on the front? I hope not.
Are the shoes arc lined to match the drums?

Are you sure the wheel bearings are set properly?
The old school way has been superseded by people smarter than me.
They recommend using an inch pound torque wrench and setting the bearing torque to 90-120 INCH pounds after seating the bearing with 15- 20 ft lbs.
I have tried it and it works fantastic

Do not use OEM/asbestos linings try some new technology. Metallic linings as i recall
I have tried those linings - fantastic.
I am  not here to reinvent the wheel but I do follow good advice

I'll have to look for my dial indicator.  That would be a good test too. 

Yeah, I think I have the shoe to drum drag set pretty well.

The car does have the self adjusters in the front.  Why is that a concern?

I used this guys technique for setting the wheel bearings.  It was pretty easy and worked well.  It looks close to what you describe.

https://www.youtube.com/watch?v=M9auq-2fDQk

New linings are bonded metallic

[moreparts]

OK. Now you have given a much better description of the noise. Try this. After the brake warm up, try to back up and hit the brake firmly. Now go forward again and re-apply the brake to try to make the noise again. This will check for drum shift on the hub. As I said before, the drum/hub assembly was designed to act as one piece. That is why the new studs being sweged after the drums are replaced is important.
Also what wheels are you using and are they torque to factory specs.

You know, the last time I drove my car (about a week ago) I did the back-up and hit the brakes firmly routine.  I did it for the self adjuster activation.  That was after hearing the noise a bit.  I drove it home after that and didn't notice the noise again.  I did that the previous time I did my brakes and didn't notice it making a difference in the long term.  How does doing that indicate I'm having drum shift?

I didn't put new studs on either, so no sweging.  I've never heard of that term as well.

The car has the factory 14" rallye wheels.  I made sure I torqued them back to spec.

[Filthy Filbert]

You should have self adjusters on the front brakes, but they should be installed so they are on the rear facing shoe, not the front facing shoe.   That's what he meant.

[MoparLeo]

OK Next time you remove the wheels take a closeup picture of the brake drum at the center where the studs come though.
Next remove drum and take a good closeup picture of the brake assembly.
Remember that I am not there and can only see what you show me. The more I can see, the easier to find the problem.
With the drum set back on the hub lightly install a few lug nuts. Not tight, just enough to hold the drum from falling back off. Check the fit of the holes in the drum compared to the diameter of the wheel studs.
If the holes are bigger than the stud protruding through the holes, the drum will shift back and forth when braking.
That was the purpose of backing up and braking. The drum would shift to the direction of rotation. That in turn would cause the drum to snap back when braking the other direction.
In the old days the stud would act like a rivet and the drum would be "sweged" with a press at the shoulder of the stud causing it to swell and lock the drum to the hub. The drum/hub would be removed as a single unit.
Most new drums now have lug stud holes that are oversized to clear the original studs and can sometimes have too much play/slop in the hole/stud fit. Noises are common. Nobody does things like they did 50 years ago.
Now you will usually notice especially on import cars that have drum brakes is the there are usually extra holes in the drums. One is usually counter sunk and a screw is inserted in the drum. This serves to retain the drums on the assembly line before the wheels are installed and to firmly lock the drum to the hub when braking.
The drum is sometimes threaded in another hole(s) to allow installing a screw to help remove sticky drums from the hubs acting like a steering wheel remover.

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Thanks Leo, and to everyone else contributing to this thread.  You've all given me some good things to look at and lots of good idea! 

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Well Leo, I took it out for a drive.  After warming the brakes up, that noise came back.  I did your put it in reverse suggestion and hit the brakes a few times.  The first time I did it I could swear I heard a very similar noise to what I was getting from the low speed stop.  After I did it the noise went away.  I don't know if it was coincidence as it would sometimes go away on it's own anyway, but even after driving quite a bit more it did not return.  Now I really want to get those wheels off to get some pictures for you.  This is the biggest step forward I've had and I thank you and everyone else in this thread for helping me with this!  Just a side question...if this turns out to be a snug-lug issue is that the sort of thing we live with or is there some way to make more of an interference fit with the studs and drum?  And it's not the type of thing the coroner is going to flag as my cause of death is it?

[MoparLeo]

If it is because of excessive slop between the lug holes and the wheel studs, the only solution is to get another brake drum and check the lug hole size first. You just need a tight fit. You can see another reason the manufacturers went to disc front brakes on every car in the mid 70's. No brake adjustments, fewer parts and superior stopping. And cheaper to manufacture to boot.

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Here's a couple of pics.  This is of the front right.  It's hard to tell from them, but there wasn't really any slop between the lugs and the drum holes.  You can mostly see the shoulders and some shadows in the pics.  When I tried putting lug nuts on they wouldn't seat there was maybe a 1/4 inch or so gap from the end of the nut and where it could seat.  I'd guess to accommodate the wheel.  That was the same on both sides.