have a vibration you can feel at your feet while in 4 high..starts at 85kmh and dosnt stop or get worse with speed increase..only does this in 4 high..pulled drive shaft and drove..vibration gone..front diff tight no play..front shaft and ujoints all 100%.vibration goes away if you take power away..also seems to go away once you hold it at a steady speed...any suggestions..dont want to dissasemble front diff if possible as you have to split it.not like the old ones where you could just remove cover and inspect

get you drive shaft balanced. Have you looked at you u joints?

been there done that..all 100%...had it in at gm dealer and they cant find it either..they say not to worry as most new ones are like this...my point is to them it never used to do this and want it gone...there is only 110000 kms on truck with very little 4x4 use and when it is used it . it is hiway only truck

Have you had your front diff apart? Probably not? Pull the cover off and see if the gears have a chip on them, maybe the pinion? When my 99 do_g_ had was at the 160,kkm's I had Valley Fuel check the rear diff bearings as well and the kid chipped the pinion and it took till 220,kkm's to find it!

this truck dosnt have a front cover like the old staight axles..you have to split it in half and drop it down to inspect it..wont go this far unless i am 100% sure vibration is diff related...if it was a chipped gear wouldnt it vibrate at all speeds..truck only does it above apox 85kmh and pretty much stops at 115kmh...would drive it above 115 but could be costly in fines and if i am running it in 4x4 due to road conditions this speed could be hazardous...already checked for bearing slop externally by truing to detect movement by hand on pinion bearings and axles ..all seem very tight

are you lifted?

are you lifted?That would be my question. If CV angles are much worse than stock (are torsion bars cranked) that would more than likely be the source of the vibration..That or worn CVs would do it too.

truck is not lifted...did a 4 wheel alignment due to the new tires i installed .cv joints have been inspected and both front wheel brg assemblys have been changed.due to the left one had some exess slop and done the right one at the same time.( would have just done bad one if i knew what they were worth. but told mechanic to do otherside also) .new bfg all terrains 265s x 16s on all four corners still vibrates

Maybe you could swap the tires front to rear and see if it goes away.If it does at least you'll know it's a balance issue.

done that already with old tires..no differance...never liked old tires very much so i purchased 4 new ones as stated...also to eliminate any possible balance problems i had dyna beads installed in all tires...and besides that if it was a tire balance issue it should do it in 2wheel drive as well as four but it dosnt.

I have exact problem, 08 CC long bed, the issue been there since I bought it at 400 miles.

Mine has a very slight vibration in 4X4 on dry pavement, I believe it is normal. It is a little worse than my 97 but this is a 1 ton drivetrain as oposed to 1/2 ton. I think it is normal. Is yours less in a heavy rain or on snow? Good luck.

Normal for a lot of trucks to have this. Is a little noisier and just a little more vibration at highway speeds. Mine start at about 65mph. And I know my parts are all in good shape, had it all apart.

If I'm correct these trucks dont have a CV joint on the front shaft at the transfer case like the older solid axle trucks do. Maybe try greasing every thing that moves from the T-Case to the front Diff.Is it possible you may have hit something and put the front shaft out of whack a bit?

Idevey and other with the similar issue:

I sat next to Jeff on my flight back to detroit last week, jeff was engine designer for big detroit engine coms and he was with SAE to test the engines etc.
so I was telling him about detroit's fine quality, namely chevy truck with roaring/vibrating front diffy/driveline.
this is his 2 cents:

"a vibration and roaring sound with increasing amplitute and frequency indicates that a grear surface is not smooth, a diffy has 17 gears (not sure if he said 17) and could be one or more of those have one surface that is not smooth."

what do you guys think?
how do I explain this to the dealer? or what should I ask them to check/change?

have the same problem on my 04 got it check 2 days ago pull the plug to drain the oil full of little metal shade stuck to it my mechanic said it woul pobably be a cage bearing
will take it apart this week will get back to you with more details .but if a was you i would check your diff oil and plug to see.

have a vibration you can feel at your feet while in 4 high..starts at 85kmh and dosnt stop or get worse with speed increase..only does this in 4 high..pulled drive shaft and drove..vibration gone..front diff tight no play..front shaft and ujoints all 100%.vibration goes away if you take power away..also seems to go away once you hold it at a steady speed...any suggestions..dont want to dissasemble front diff if possible as you have to split it.not like the old ones where you could just remove cover and inspect

When you pulled out the front shaft did it slide good and easy out of the transfer this is providing you have a 246 transfer case that is! You did not say! Check front prop shaft to see if it is "free", as in not stuck, in the front output of the t-case as this is also a common problem that will cause bearing, prop shaft failure in the tcase. I never seen to many issues in the front differential on these. some but not many ussually other problems leading up to it remeber noises transmit threw the driveshaft vibrations can be bearing but I look back first before going to the frontend you should be able to check the front diff with the shaft out and see how it feels as well as the out put of the transfer but I do this after I took out the rear shaft and put the vehicle in nuetral
I would also run the front shaft to a driveshaft place and have it balance they are nutorious to out of balance right from the factory!

just finish rebuilting my front diff had a few bad bearing but wasn't the source of my noise check the drive shaft slide fairly well on the output of the t-case dont think it would be out of balance cause it aint a steady vibration that follow the speed it only does in in overdrive worse is at around 90km/h can bearly notice it in 2x4 but really clear in 4x4 and just when you accelerate on or let the pedal go to slow down so go check a few more things tomorrow and let you guys now

been reading a little about the pumps rub problem could that be the cause of my vibration even if i dont have a have a hole in my t-case