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Discussion Starter #1
I've never ran across this before and am not sure what happened. I took the rear drums off and the rear brake shoes linings had almost disintegrated. The pads were very thin. I have seen them before and they weren't very worn down then. The drums were scored up but can be turned. The axels got hot enough to turn the silver rally wheel paint brown where the surface of the wheels by the lug nuts were touching the axels. The right was slightly darker. The front hold down springs in the brakes had come loose and the strut bar spring and other springs appeared to have gotten hot enough that they either compressed, stretched or broke. I had taken the Camaro out on the turnpike and had been doing 75 and when I took an exit I heard some metallic noises that didn't sound good. ( A shop had changed the open 12 bolt to a posi a couple of years ago and I thought at first that it had made the noise.) I drove at not over 55 to where I was going to and the noise had quit. I noticed the back trim rings were covered in a light brown dust. Later when I got back home I pulled the drums and was surprised to find what I mentioned. I'm trying to figure out what caused the brake failure. Both wheel cylinders appear to be Delco but I can't imagine they are the originals but the rubber dust boots were gone. Whether they burned off or had rotted off from age I can't tell. So is it possible that the cylinders were starting to leak and caused the linings to get sticky while I was driving and caused the damage? The back brakes have never locked up. Or I had trouble getting the differential clutches to stop chattering and I used synthetic lube and it seemed to have been a lot better but can the gears get hot enough to transfer heat to the wheels and brakes? I appreciate any thoughts.
 

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The shop should have poured in GM Limited Slip Additive for the clutches as this would quiet the clutches slipping upon turns.
If rear brakes adjusted correctly - a slight drag will be heard when turning wheel - rear brakes should lock up upon heavy pedal.
 

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I saw this before. The owner had driven with the E-brake engaged.

Guessing that’s the case here or it wasn’t properly adjusted.
 
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OP

don't use synthetic oil in a clutch type limited slip differential. Use conventional oil and a 4oz bottle of GM or Ford (aka soy sauce) friction modifier.

To me it sounds like you drove with parking brake engaged which burned up your rear brakes and surrounding components. Might want to closely look at your outer wheel seals also
 

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Discussion Starter #7
Here's an update. I checked the parking brake and it wasn't on at any level. I replaced the wheel cylinders, shoes and springs with new components. I checked the emergency brake cables and they both move freely. HOWEVER, there are 2 things going on. First, I thought that who I bought the Camaro from 11 years ago said he replaced the brakes which I assumed he meant the rear too. The cylinders say Delco Moraine and looks like 7/8 5464 079 which I'm guessing are really old and the shoes also. The Camaro has a little over 100K miles. I thought they may have been leaking but here's the other part of the story. I proceeded to bleed the brakes with the assistance of a helper and neither cylinder will bleed at all. The pedal stays hard even with the bleeders out. I changed the master cylinder a while back and had a hard time getting it to bleed. At the time, I noticed a damp rusty residue coming out of the back of the metering valve under the rubber cap. If the metering valve has frozen could that make it so there is no pressure at the rear brakes?
 

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Check your lines. Did you replace any of those? Rebuilt cylinders could have Delco on them, not that it matters now. Open all your brake lines and let the "self bleed" over night then proceed in the proper order to bleed RR, RL, FR, FL. Were the brakes working correctly before the mishap? I usually add 2 small bottles of GM Non slip additive then conventual oil.
 

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If the metering valve has frozen could that make it so there is no pressure at the rear brakes?
a clogged/restricted metering valve will prevent proper hydraulic pressure form applying brakes correctly....and can also "hold" that pressure. "Something" caused excessive heat which generally is brake shoes dragging because parking brake is engaged some...and conversely if the pressure is not "relieved" because of either a restricted line or block holding pressure against the wheel cylinders causing the brakes to drag

You might want to make sure the home run long line from MC to the rear split block on top of the pumpkin flows freely and your rear soft line has also not collapsed

another reason your heat can be caused is failed wheel bearings. They will just melt wheel cylinders and certainly score axles to the point they can cut right through the axle
 

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Discussion Starter #10
I think I found it. The rear brake hose. Nothing comes out of the T end and the forward ends squirts fluid freely by just being loosened a little bit. With that hose being blocked inside I'm thinking that at some point when I applied the brakes the pressure may have held some on the rear brakes thus, being too tight on the shoes, heated up too much. The pad material was down to the rivets.
 

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Hope you found the problem. I would get it all replaced and bled. Then jack up the rear and apply the brakes several times then spin the wheels by hand to see how they feel.
 
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