Vibration

[snarkee]

my friend has a 09 sierra cc 4x4 18,000miles

 

under moderate acceleration, around 30ish mph, there is a driveline vibration (can feel its under the seat towards the rear of the truck)

 

i took it for a drive and it is only felt that that speed

 

sound like u-joints???

[focijoe]

Nevermind. Read the post too fast. Thought maybe it could be the rear tires out of balace but you said it only does it under acceleration.

[snarkee]

yes the tires were rebalanced and are fine....its only lasts a second on acceleration only

[jro909]

i have this problem on my 04( i know you have a 900) anyway its the exhaust making the vibration in mine..its more profound when its cold outside

[Slabi]

yes the tires were rebalanced and are fine....its only lasts a second on acceleration only

 

Could definately be U-joints, or maybe the hanger bearing. Better to get it checked soon before it causes any other trouble.