Drum Brakes... assembly

I detest drum brakes. Really. The brakes on my Dakoturd started grabbing. Investigation showed very thin friction material, and drums that were way over diameter. So, I bought new shoes and drums and reassembled exactly as it was disassembled. In fact, I did the smart thing and took photos.

I did everything like I always do, including cleaning the new drums with brake cleaner to get the oily film off first. I also properly bedded them in.

They howl like a school bus. Not a squeak, a howl. Not just a polite little howl, but an embarrassing roar that turns off prostitutes faster than a broken condom. So I pulled the drums again to check and make sure they were properly adjusted. Very light drag, even scuffing on the entire shoe. Gave the pads and drums a quick hit with sandpaper (not the proper thing to do, i know) just to change something. They still howl.

the shoes I got are semi-metallic Duralast Gold. Again, not the best shoes, but I didn't expect this level of noise.

My question is... I assembled the shoes exactly like the old ones came off, which puts the shoe with the longer friction material on the rear side of the drum. I thought it was supposed to go on the front? I was going to try putting it on the front, but the pin on the shoes that holds the adjuster actuator prevents that from happening. The pin has to be bottom rear, facing out... which means the long friction material is toward the back.

Here is the photo I took Before so I had a reference for reassembly. In this photo, the front of the truck is to the right. (this is the back right brake) It shows the long friction material on the back. Is that right?

Big shoe goes to the back of the drum.

What are the parking brake cables like? And was the parking brake adjusted?

Park brake cable wasn't adjusted. It was a bit loose before, but with the thicker shoes it was operating properly. The howl only happens under about 20% braking - normal daily braking. If you brake harder or softer, it won't do it. But right in the normal braking sweet spot, they howl.

Just found this on googles. This is exactly what mine look like now.

Try giving the adjusters a couple more clicks out and take it for a ride.

I did try that but not with a specific purpose. When I had them off to re-examine I readjusted. I tightened up the adjuster a few turns until I had a little bit more drag. I also did several brake cycles in reverse so the adjuster could work its magic.

I'll try again with a little more adjustment.

I hate drum brakes. I have to do the rear brakes on my van and I've been putting it off like forever. I think this spring I will have to do them or have no brakes back there.

Dumb question.... Does the backing plate contact the drum anywhere or vise versa?

Did you put a dab of anti seize on all the shoe contact points? You could also try taking a file and chamfering the leading and trailing edges of the shoes. Speaking of, you didn't mix up the leading/trailing shoes did you?

Interesting. I've never had drum brakes roar, and in googling it I find only a few clear complaints of it, and not a single fix.

So, using my vague musical and engineering background, I'm going to say you've got to get some vibration going to get a roar. The only area to get vibration from is rubbing surfaces, and the only ones you've got are the brake shoes and the drum itself.

So, if it were my brakes:

I'd make sure the brake shoes ride smoothly and with light lubrication on the backing plate. This would eliminate backing plate resonance.

I'd file the leading and trailing edges of the brake shoe lining. It could help reduce vibration between the shoes and drum.

I'd hold the pads against the drum to see if they match radius. Looking especially for gap in the center, with the leading and trailing sections of the lining contacting only. I'd consider adjusting them with my belt sander if necessary. Air gaps can create some wicked resonance that could lead to brake drum ringing.

I'd consider how to zip-tie / wire-tie some sort of damper ring onto the outside of the brake drum. Just like damping a trumpet bell.

you may try new hardware/springs, may be weak and causing the pads to contact the drum in a weird way.

and yea the big pad is always in the rear, my old auto tech teacher always use to say "the little guy rides up front"

and i agree to the fact that drum brakes are the worst brakes that could be put on a vehicle next to flintstone-ing

There used to be a spring to go around the drum to dampen noise. don't know if they are still available.

Ah, that gets good google hits "brake drum spring around". Lots of threads about the use of this spring, images, and links to shops that still make and carry them.

Curtis, I think that's going to be your answer. A spring around the drums.

Put the old drums on and try them.

Seriously. Drums are never round. They flex and warp with the strength of your hands, I am sure they bend and flex when the shoes are applied. I'll get the drum has some flaw or error and it's making noise against something, perhaps the backing plate. I drove hundreds of thousands of miles on drum rear brakes and I have never swapped a drum. Ever.

Go find some old stock shoes that are made using asbestos, or see if Porterfield makes semimetallic shoes. Modern organic brake shoes are all E36 M3, and almost always groan when they are cold or damp.

Is the top edge of the front shoe beveled?

Make sure that the contact points between the shoes and the backing plate are lubed. Most common cause of noise in drum brakes.

In reply to tuna55:

Might be worth flipping it over on the hub and settign up an indicator to check, or putting it on the brake lathe and taking a really light cut to reveal any issues.

Kenny_McCormic wrote: In reply to tuna55: Might be worth flipping it over on the hub and settign up an indicator to check, or putting it on the brake lathe and taking a really light cut to reveal any issues.

I wouldn't bother. They are NEVER round.

Could you have them trued on a lathe? Or would all the roundness go away again as soon as its bolted back on the axle?

Been doing my own shadetree drum brakes for 30 yrs. and never experienced the howling described. Any chance of mismatched parts? Trucks can have different width shoes and drums. I'd measure old vs new drums and shoes. Drum contacting backing plate like Ranger said?

I've had rotors mushroom the outer edge when dropped/ damaged in transit that needed cut, never experienced drums that bad but maybe it's possible, maybe take a clean up cut on the brake lathe but I doubt it's the problem.

No words of wisdom, but I've been there...

http://grassrootsmotorsports.com/forum/grm/drum-brakes-ugh/43509/page1/

If all else has failed, get some Wagner shoes. I've heard several complaints about Duralast pads, can't see the shoes being any better.

Ranger50 wrote: Dumb question.... Does the backing plate contact the drum anywhere or vise versa?

Nope... at least there is no evidence of it on the drum or the plate.

Kenny_McCormic wrote: Did you put a dab of anti seize on all the shoe contact points? You could also try taking a file and chamfering the leading and trailing edges of the shoes. Speaking of, you didn't mix up the leading/trailing shoes did you?

I used hi-temp brake grease in little tiny dabs. Shoes came already chamfered. Didn't mix up leading and trailing but that was my first thought.