Hey all,
will appreciate your input on this im rephrasing my words, its not vibration, its not shuddering, the truck shakes

i have a 2007 suburban 1500 5.3L with 107k miles on it

so for a while i would have aggressive shaking coming from what seems like the front of my car when driving between 55-70 mph, and then when slowing down from those speeds same shakes coming thru until i got to a lower speed.

a while back my front carrier axle seal was leaking and i was delayed in repairing and changing the fluid. I could hear clicking when changing from drive to reverse and back.

2 weeks ago i gunned the car from a complete stop and hear a clunk / heave pop from what sounded like the front. after that the burb was just shaking hard at speeds higher than 15mph.

i thought this was the front diff which had given out, previous noises had come from this area and i went ahead and bought it used and replaced it.

unfortunately that didn't fix it. The heavy shaking is still there, it is strong and shake the entire car. I doesn't come thru the steering wheel but rather through the floor of the car and from the rear of the vehicle.

i haven't jacked up the car, but tried checking the ujoints, they dont have any play and the counter weight on the drive shaft is still there. my suspicion is the rear diff so i will be opening that up to check it out.

Also suspect at this point is transfer case

I can accelerate but the shaking just gets stronger, the car in idle there is no shaking at all, in park if i rev the engine, no shaking at all.

again it feels like its from the rear, but i can't tell for sure if its the back of the car or the middle, i will need to sit back there and have someone drive the car while i feel for this, but im not sure if that will help as oppose to physically opening up the rear diff to rule that out.

i can get provide more information if needed any help or ideas would be greatly appreciated.

one last thing when i reversed out of my drive and turned my steering wheel clock wise it felt as if the front driver side wheel slipped for a second, which again leads me to transfer case.

thanks again!

 

cracked Flex plate (flywheel) maybe ?

 

run your car through all the 4 and 2 wd modes, then lube your drive shafts.

 

thanks let me check that out, im down there anywhere i'll see if i can look at it.

my only thing is that the shaking seems to be coming from the back but i'll have a confirmation once i get home today to check it out

the acceleration of the car only seems to be lowered by my hesitation to give it more gas. would the flexplate kill acceleration?

 

thanks already did that, gonna grease up the drive shaft around the u joints just to cross that off the list

 

New update,
So i had my wife shift the gears from park to reverse to drive and back and forth and the transfer case was doing the loud cracks and clicks. just int he shifting this was happening. now im too cautious to want to jack up the back and put this thing in drive simply because of the shaking but with the cracking coming from one part only i think i have narrowed down the problem to the transfer case.

comes the question, does the transfer case motor have anything to do with the shifting or is this cracking simply the failure of the internal mechanics.

any recommendations on where to get a used transfer case?