How do you know if your cv halfshafts are going bad?

[kbasham]

Can anyone tell me how to tell if your cv halfshafts are going bad? I have an 02 LS V6 with 78,000 miles. It has a vibration and makes a roaring noise when you get above 40 mph. I am almost positive it is coming from the rear of the car. It starts at exactly 40 mph and then stops when you fall below 40 mph. I had new rear wheel bearings installed in the spring so i don't think that is the problem. Does anyone have any suggestions. Are the halfshafts hard to replace. Is it a DIY job or should it be left for a professional?
Thanks for everyones help.
KB

 

[TheRebel]

Get under the car and see if you can move the shafts by hand. I am guessing if there is any popping or what feels like a lot of slack, then they could be bad. These is how I knew the front CV shafts were bad on my 4x4. Also check for torn boots

 

[KD00LS]

Sounds like the halfshafts to me. When my car kicked into 5th gear at a coasting speed it vibrated, and when you lightly press the gas it went away.

 

[lseguy]

Are you 100% certain it is not tire noise? If you've ever had cupped or worn tires before, then you know that they can get as noisy, if not noisier than bad wheel bearings.

 

[kbasham]

I just recently had new tires and it was doing it before and after the new tires. The halfshafts boots look good and there wasn't any movement when I tried to move them by hand. The wheel bearings also seem fine. There is not any play in the rear wheels when I jacked the car up.

 

[TheRebel]

Perhaps the ring and pinion are out of clearance specs. I don’t know of a good way to check that without taking it to a mechanic