Drum brake howl- can't seem to get rid of it

[the original honcho]

So I've been putting in a lot of effort on my '91. My Dad convinced me to pay his friend, allegedly a mechanic, to do my brakes because the guy did a good job on the brakes on my Mom's Durango.
Well the next day the drums were howling; right before it comes to a stop. It sounds like a bus, or some other big heavy drum brakes. I drove it another day hoping it was just a coating or something. No change. I tried calling the guy but he said he was in Houston. I never got ahold of him again, and needless to say he never showed up. When I checked the drums, they were filthy and the drum was glazed. I wouldn't have believed he had them machined if I didnt have the receipt. I bought new drums, shoes and hardware kit. 2 days later...
This time I took it into a brake shop that used to work on my Camaro. He put new shoes and fixed some springs he said I installed backwards. 2 days later same story. I took it back, and he told me to buy $150 Wagner shoes or get used to it. The rear passenger side locks up with very little effort now, too. What gives?

[Tatsadasayago]

When you say the drums were filthy/glazed, did you mean from brake dust or something else?

I'd be inclined to look at the bearing seal(s) for weeping enough lubricant into the drum as a possible cause. Gear lube/bearing grease can mix with the brake dust and turn it into goop that turns black when it gets hot, it bakes into the shoes and drum which causes sticky/rapid braking and chattering. Brake fluid from leaking wheel cylinders does a similar thing.

Another possible fix is to pull the shoes and bevel the leading and trailing edges with a grinder similar to how modern brake pads have. The bevel reduces the square edge that acts like a snow plow blade as the shoe contacts the drum.

I've had larger GM drums that came off the brake lathe looking like a vinyl record from the operator feeding the tool too fast that set up a harmonic vibration. That caused a low frequency 'thrumming' sound at low speed when applying the brakes.

[the original honcho]

Filthy with brake dust... There is SLIGHT seepage on one side, but only noticeable to some one with ocd like me... and probably not enough to make a drop. The shoes came beveled, and I'm labratory- clean when I changed them. Could bad wheel cylinders make uneven pressure on the drums? Only thing not brand new

[carnuck]

Try sticking flatwashers on the wheel studs under the drum and see if the noise goes away. If it does, then the shoes are wrong width.

[the original honcho]

Try sticking flatwashers on the wheel studs under the drum and see if the noise goes away. If it does, then the shoes are wrong width.

Is that a problem with discount auto parts stores???
I'll give it a shot! The shoes are from O'Reilly, and I wouldn't be the least bit surprised if it were the shoes.

[Tatsadasayago]

If the shoes are too wide you should see a rounded wear groove/pattern at the outer edge that matches the shoe lining.
I'd forgotten about that one! Stock and proper replacement shoes will stay about 1/16" or so in from the edge where the drum makes that 90 degree turn.
Another cause might be the shoes are out too far from the backing plate. I vaguely remember finding that someone had installed the wrong length pin on the shoe retainer springs which caused the shoes to angle outward in the middle--thus causing the shoe to rub against the edge of the drum.

[carnuck]

The correct shoes should be the same as '77 Chevy Blazer

[the original honcho]

The correct shoes should be the same as '77 Chevy Blazer

The shoes O'Reilly sold me are part #462; according to their website a '77 Blazer shoe is part #450. No size detail is given on the Jeep; the Blazer is 11.16X2.75