My girlfriend has a purple V6 RS and she let me drive it the other day. When we went on the highway, i released WOT and it shifted into overdrive. What I noticed is that when it shifts down the car starts shaking and the faster you go the more it shakes. at 50 mph its a little ok, but 60 is kinda bad.

Also about the tranny, when I shift it from neutral to drive, it makes a clunking noise from under the car sometimes. Is that a U-joint?

 

Anyone know what could be wrong with it or not?

 

clunking noise is usualy the u-joints. also inspect the mount.

Check alignment, strut mounts for wear, lower control arm bushings. Haven't realy had to deal w/drive shaft being out of balance, so couldn't tell you the symptoms......

 

Sounds like the torque converter in the transmission. The clunk itself sounds like a u-joint, like someone already suggested. Might want to make sure the tires are correctly balanced.

 

yea thats true...I told her to get new tires. it looks like all 4 of her tires are different in size but yea it shakes pretty badly ever since we got it from some other chick who did no maintainance to it. it has like 137,xxx i believe so maybe i should just look at the entire tranny. Thanks guys.

 

I bet u ur tranny mount is shot,
even if thats not causing ur symptoms.. they're cheap and easy and
will make a difference in ur ride..