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Rubbing brake drum


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ronnieg63
New User

Jul 11, 2009, 3:06 AM

Post #1 of 6 (3024 views)
Rubbing brake drum Sign In

Hey everyone. I have a 1995 2wd chevy 1500 pu, 5.0, with north of 160k miles on evrything but the engine, which was new in the crate some 12k miles ago. While trying to diagnose a scratchy noise coming from the right rear (suspected a brake issue), I found that a small portion of the inner lip on the brake drum is rubbing the back plate. I feel like it may be a wheel bearing issue, but don't know how to find out other than tearing it down...I'm an electrician, not a mechanic...but I do as much as I can. Remember, we are in a recession. Any advice is appreciated..


Loren Champlain Sr
Veteran / Moderator
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Jul 11, 2009, 4:00 AM

Post #2 of 6 (3021 views)
Re: Rubbing brake drum Sign In

Ronnie; The bearing would have to be really bad to allow the drum to make contact with the backing plate. Don't think I've ever seen it and I've seen some REALLY bad bearings! I have seen rust buildup on the drums/backing plates that will cause what you are describing. Remove the brake drum and closely inspect it, the backing plate, brake hold-down springs, ect. Also, keep in mind that sounds can travel; It may sound like it's coming from one area, but may be just transmitting the noise elsewhere. Not that this is the case, here, just a thought.
Loren
SW Washington


Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 11, 2009, 4:34 AM

Post #3 of 6 (3020 views)
Re: Rubbing brake drum Sign In

Ronnie - along with Loren's advice I suggest routinely taking drums off for inspection of both wear and condition of hardware. Clean out drum by dropping it squarely down on hard surface to get all the rust and dust out which causes problems. Clean up that mess and dispose carefully as it's nasty stuff. Wipe good shoes with a paper towel soaked in brake cleaner then treat that as a nasty towel also.

Bearing?? It would have to have some serious troubles to allow that much motion! If so I would be near certain you'd hear that just driving along,

T



ronnieg63
New User

Jul 11, 2009, 11:57 PM

Post #4 of 6 (3011 views)
Re: Rubbing brake drum Sign In

Thanks guys. The fact that it is probably not a bearing is great news. A brake job I can handle. Without actually having torn into the brake assmbly, I can tell you that the return spring looks extremely stressed, possibly weakened, and the shoes seem glazed over, but not worn, almost as if they were not in play for some time. The drums give the same indication, almost new looking wear wise. While the above checks were done with only the rr off the ground, I couldn't actually check how the brake operated, so I will have to get the entire rearend in the air to further evaluate it. One more thing I noticed. There was a light coating of some kind of fluid on things, but not bad as if the cykinder was bad or anything. I have been told not to try the brake with the drum off, so I didn't check it to see if it works. But this may be a case of not self adjusting maybe? Mechanic friend told me the oily light coating can be a result of the shoes not making good contact, or being stuck in a position that JUST makes contact, causing the pad (shoe ) to overheat and breakdown epoxy in the makeup, leaving the film...I am thinking that a breakjob is the best way to go further on this. Got brand new brakes up front, may as well do the same on the back. Any other thoughts are appreciated. Glad I found this place.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jul 12, 2009, 2:25 AM

Post #5 of 6 (3004 views)
Re: Rubbing brake drum Sign In

Thoughts: Ya - do a whole brake job including hardware and wheel cylinders. Make certain the parking brake is properly functional, releases fully and the connecting bar is slightly loose indicating park cable has retracted. With a helper watch the cable pull in and fully extend - they can be the problem spot or bent hardware. I've seen intermittent wheel cylinders too that can stay on.

More: larger (one with more lining) goes towards the REAR! I've seen that done backwards too.

Your call on machining drums or new ones. Rust can be an issue also.

Some lining material can drag or make a noise if wet like after a hard rain but usually that quits with first stop.

Make sure brakes are adjusted properly before ever touching the parking brake cable adjustment which isn't always needed to adjust! Good luck,

T



Loren Champlain Sr
Veteran / Moderator
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Jul 12, 2009, 6:54 AM

Post #6 of 6 (2994 views)
Re: Rubbing brake drum Sign In

Ronnie; The only thing that I don't agree with is the evidence of some type of moisture on the linings. If there is any moisture (be it brake fluid or axle grease) it needs to be investigated and repaired. I have never seen or heard of the 'epoxy' theory, and your brake linings should be riveted, anyway. The glazing of the linings is indicative of heat. A leaky wheel cylinder or an axle seal can cause this. You don't sound like the type to skimp, so buy NEW premium quality brake linings. Riveted only (not bonded). If you need assistance on brake bleeding or axle seal replacement, don't hesitate to ask.
We'll help the best we can. Have a great weekend.
Loren
SW Washington






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