jcchevy

Never seen the "gas cap less" feature. Can you take a pic of it? does it still have the "threads" to screw a cap on?

@PMmury, only if experiecing a rumble strip type hum/feel between 55-72mph. I see on prev post you had the less then 55mph issue which would not apply to the front and sounds like you got that taken care of via rear axle resolution. I must have misread and thought you were experiencing new issue. It is funny how some of the different distuiquished issues are determined by common speeds, which is helpful in narrowing at least where to start looking. The dealer can also hook up a vibration analyzer on the powertrain components to distinguish the faulty area. Im pretty mechanically inclined and had my issue narrowed down to the front diff, was just a matter of convincing dealer. Since the wheels still turn on the truck, its not considered broken/faulty to them.

What you have described (tiny rumble strip feel) is your front differential. Needs replacement or complete overhaul. You may find this thread /post linked below more useful and related. This is not the resolution to all, but for those SPECIFIC to "tiny rumble strip" feel issues, its worth reviewing. We have several members (including myself) who got their dealerships (NOT EASY) to replace the entire front differential assembly, which resolved the issue and for most part trucks rode smooth as glass again. http://www.gm-trucks.com/forums/topic/154976-2014-sierra-humming-noise/page-9?do=findComment&comment=1607902

haha, looks like the a ghost took my words that should have been there. I was referring to wind noise. Did you notice an increase in wind noise with those bigger/flatter mirrors on the truck?

Nice. You notice an slight increase with those? Also was the harness (assuming their powered) adapter PNP with original?

I found "GMC The Magazine" online using my crafty search skills ;) Enjoy http://gmc.mynetworkcontent.com/

I finally uploaded some pictures on my build thread, but here you go for this Suspension Lift Thread. This is with the 8" Fabtech suspension performance kit and 35" x 20" tires and wheels. Soon I will be swapping out the Dick Cepek tires with Toyo Extreme tires soon and will provide new pics then.

Yes, your issue will no doubt be different as you do not have the cv joints/diff etc.. spinning/mass friction etc.. which is the vibration/harmonic noise MJ (well assuming his is 4WD) and I are likely experiencing. Reading through some of the unique issues forum users have added, there clearly multiple unique issues in this 144+ Page thread .

MJ , this verbiage explains EXACTLY what i have occuring as well ....there is a harmonic component and I can sense a low woom, woom, woom thats much slower cycled than tire rotation. My gut says these tires heat up, lose their shape, and start a wobble that begins a harmonic vibration that you're feeling on top of the tire wobble All was good even after the 8" fabtech lift and 35" tires were installed. It wasn't until about 800 miles AFTER putting on my lift and 35" dick cepeks (only had 3K on the truck itself). that this starting occuring, so i think this was going to occur with/without the lift/tires. 4 trips to the service dealer and their accessories dept (who installed, lift, balance etc..) came down to that is "normal" road vibration throughout the cv joints, differential and front drive shaft as when they removed the CV joints, the noise disappears. So i guess thats good news for 2WD fans as they should not have this issue. Either way, i am getting less aggressive tires as the floor vibration and "woom, woom" that occurs is a little ridiculous (starts at 45, continues to get more noticeable, longer harmonic rotation etc... faster you go). I had 36" x14.50 tires 9" of lift on my last 2004 Silverado and never had this problem. I think it really comes down to these 2014 drivetrains/frame specs etc.. are so dam tight/within specs etc that this is going to occur more often then not and does have a lot to do with tires, but again this did not occur on previous trucks. Well previous trucks were also not this dam quiet. So it is what it is. Just thought i would chime in since your the first to describe what only a few people can describe.