Slight noise coming from rear axle area

[JBK]

I own a 1995 K2500 4x4 with only 43,000 orginal miles, for about the past year when driving the truck I keep noticing a slight noise coming from the rear of the vehicle. It's kind of hard to explain the noise but it's kind of a steady wub,wub noise that is very slight but noticeable. I stopped by the local GMC dealership the other day and the shop foreman took a short ride with me, he picked up on the noise also and said it did not sound like a bearing but was also at a loss as to what it was, he did suggest maybe a brake drum that was rubbing some where.

My question is: Today I jacked up each side of the rear axle (one side at a time) and put the transfer case in netural so I could spin the rear wheels as I spin the wheel about half way thru a rotation it feels like the drum and brake pad are coming in contact with each other and makes a very light rubbing noise, this continues for about 1/2 of the rotation. Both sides are the same, I'm wondering if my drums are out of round and need to be turned to true them. Would this slight rubbing be normal?? Or when spinning the rear wheel while jacked up should it spin perfectly free with no contact with the brake pads?? Thanks for any suggestions as the noise is not bad but does bug me.

[Morgan1986]

My dad once told me along time ago with drums to religh them or somthing like that you want to find a hill and back down the hill and tap on your breaks . I am not exactly sure what he said but this was a while ago. A few good breaking backing down the hill I think he told me .

[j-ten-ner]

Has the truck been sitting for a longer period with the E-brake on? (I mean 43.000 miles in 17 years ain't much)

 

Once the drum is really rusted (I don't mean surface rust) you'll have a rough surface and it wont wear down anymore.

It can even happen w/o the E-brake on. The gap between the drum and the brake shoes is sometimes so small that the water stays in (capillary action)

Just a guess.

I would just change the drum and shoes. I don't know if it makes sense to machine the drums.

 

so long

j-ten-ner

[JBK]

Although the truck has few miles on it I used it about once or twice a week for a few years, I was very lucky in that I had a company truck to go back and forth to work with. I retired eight months ago and now use the truck more often, prior to retirement the truck was parked in an enclosed garage and I think I have only used the parking brake very few times. The parking brake is never left on when the truck is in the garage. Thanks for your reply!!

[JBK]

Hopefully this may help someone in the future. I belive I have solved my problem after a test drive today I did not hear the noise. As stated prior to this post when the truck rear axle was jacked up and I spun the rear wheels you could hear and feel the rear brakes slightly rubbing the drum for about 1/2 a rotation. I pulled the drums and even thought the truck only has 43,000 miles I noticed near the top of the back shoe the top four rivets were within about 1/8" of rubbing the drums, the rest of the brake pads had plenty of space left before the rivets holding the brake pads to the holder would have rubbed. I decided that since I had it taken apart I would but new brake shoes on anyway. I also took both drums to the local Napa and asked them to check them for being round & true. When I picked the drums up the machinist said both drums were out of round and the one from the drivers side was worst. He got them back into specs without much trouble. Why the drums were out of round is beyond me as the truck has never been driven or braked hard and has only towed my 17' center console boat which is fairly light. Now when jacked up and spinning the wheel everything seems fine. Again hopefully this will help someone else in the future!! Thanks for your replies!!