Silverado Strange Noise

[thundercat]

My 03 Silverado 4 wheel drive is making a strange rattle almost grinding sound coming from the rear of the truck whenever you hit a bump,it sounds like the rear end is about to explode,but the truck runs fine,I went under the truck yesterday and looked for something loose and hitting the drive shaft and found nothing loose,then I pulled wheels and rotors nothing,pulled the pumpkin cap no damage every thing looked good,put in new fluid,changed the transfer case fluid nothing spooky came out Iam running out of ideas any thing you can think of would be appreciated.RH

[SouthCo]

How did the suspension look? If you only hear it when hitting a bump I'd look there 1st.

[98 Z71 SLT]

Look for a broken leaf spring

[thundercat]

How did the suspension look? If you only hear it when hitting a bump I'd look there 1st.

Yea looked fine everything in place,the noise is almost like a vibrating,grinding rattling noise and does not change pitch with speed and after you hit the bump can last a few seconds,its bazaar I have never heard this on any vehicle I owned,tomorrow Iam off so going to put it on ramps and look it over end to end I cant believe that its not obvious its quite loud,I will post up what I end up finding no matter how stupid,this is not my first rodeo and it should be a simple find but for some reason I must be looking past the obvious.RH PS I was just informed by the better half that it made the noise without hitting any bumps today when she pulled out of work.

[thundercat]

One more possibility after some thought about that hideous noise that seems to emit from the rear,if something was going south in the transfer case the sound might travel down that big aluminum driveshaft and make it sound like its was in the rear this may be a job for Mr Goodwrench.

[jro909]

sure its not the sound of the springs bouncing back after a bump?

[thundercat]

Thanks guys for the responses Iam fairly certain it is in the transfer case,I changed out the fluid a week ago,went to the local bowtie dealer and he provided me with the Blue fluid,the change out went smooth no issues and now its hit and miss noisy I have had plenty of four wheel drive trucks but none with the auto feature.So I assume there must be some sort of clutch pack in there and was wondering whether the fluid change had a effect or is there a additive I should have bought like a friction modifier.RH

[papastoy]

Have you gone back and rechecked the level in the T case?

[thundercat]

Okay guys mystery solved and I feel like a idiot,like I had said the noise was quite loud it sounded like the pinion was falling out of the truck,the truck is in my shop and coming apart the whole issue is in the emergency brake shoe,finally after backing up and pulling forward with my head hanging out the door I could place the noise to the LH rear wheel and if I applied the emergency brake a little it went away so I assume that the shoe more like a band has come loose from its fasteners and is rattling around sometimes its fine but when you hit a bump it got out of place and made a terrible noise,I would have swore that bearings were gone,anyway its out to the shop and get dirty,thanks again for all your input sooner or later I might make a bowtie expert,coming from years of owning Fords you would think I would be use to things falling apart.LOL hope my fumbling around helps somebody else..Hound

[natecompton]

[CapitalTruck]

That "drum in hat" e-brake system can be a little sassy bitch at times. I'm on a first name basis with mine.