08 Alpha Vibration Problem Help

[StandoutAlpha]

When going 70 mph + and above my Alpha has a vibration coming from underneath the center console or center of the H3 and even more when I accelerate.

Here's the thing...
-My steering wheel doesn't shake
-My tires are new and just got balanced recently
-No vibration at all under 65 mph or less, it does only when going 70mph+
-My Alpha has a slight off alignment to the right<-----can it be the cause??

--Bad drive shaft? (it has no play if I move/wiggle/shake it around with my hand)
--Bad engine mount or tranny mount?

What do you all think the problem is?? Thanks in advance

 

[4speedfunk]

Put the T-case In 4HI lock...pull the front driveshaft...run it up to 65mph...see if the vibe goes away.

The front driveshaft has a CV joint on the aft end, that is a known problem. Look for tears in the boot and/or grease flung all over the underside of the trans tunnel.

 

[jakesz28]

Also block the wheels, put it in neutral with the engine off. Then slide underneath and grab the front of the rear driveshaft. Check to see if the bushing is worn out in the transfercase for the slip yoke.

 

[4speedfunk]

Standout states in a separate post that he had his tranny freshly rebuilt. If something wasn’t installed correctly that could also be the source of vibes. I’m not a tranny guy but I have heard of bad torque converters causing vibes at highway speeds.

 

[StandoutAlpha]

Standout states in a separate post that he had his tranny freshly rebuilt. If something wasn’t installed correctly that could also be the source of vibes. I’m not a tranny guy but I have heard of bad torque converters causing vibes at highway speeds.

Vibrations was already there when I first bought the H3 back in September 2020. I just started this thread to see what others think the problem is.

 

[StandoutAlpha]

Rebuilt transmission wasn't the problem. I plan to just hook up a GoPro under the H3 and drive up to 70mph to check whats shaking.

 

[Hubbs]

I agree that driveshaft vibes are the most likely. Look for any damage as well. Dented tube?

 

[Happy Hummer]

Trans mount, motor mount, CV axle?

 

[Chris Laun]

I've had a similar problem for the past ~30k miles and wrote it off as wheel-balancing weights getting kicked off. Only slightly noticeable by me, passengers have no idea. Very curious to see what you find