My gtu is vibrating like crazy at around 75mph and if I go higher it gets worst. I checked:

dirve shaft joints (its got a new drive shaft with changeable joints)
tires (got them all to right preassure and they were all resently balanced)
motor mounts (brand new)
wheel nuts(good and tight)
its not engine
its not tranny
I checked the cv joints and they were good, but not sure

I have no idea what it is but it scares the crap out of me and its so bad that I cant see through my mirrors because they vibrate too much. HELP!!!

 

did you check for any loose or worn front suspension components? tie rod ends, ball joints? did you check your diff fluid(while you're back there) and mount? do you feel the vibration through the steering wheel or the whole car? are you POSITIVE that your u-joints are good?

 

No I havent checked for anything on the suspension Ill do that today, I havent checked the fluid lately and there is almost no vibration on the steering wheel its all in the body, and to tell u the truth I changed the drive shaft two days ago (if those r the u joints u r talking about)

 

sounds like the driveshaft.. .i would stop driving on it, it will **** your tranny up if it breaks while moving

 

but how can it be if its brand new?????could it be out of balance or somethin???

 

it can be out of balance. where did you get the driveshaft from? also, is the driveshaft secured tightly to the diff? make sure of that.

 

it could be that one of your struts is out, i think driveshaft vibration is when your slowing down and when your going at high speeds its the pilot bearing?, and the tranny does **** up if you let the driveshaft break the bolts on my linkage just broke right off =\

 

Does the vibration stop if you put it in neutral? That would help indicate/rule out the driveshaft, depending on the outcome. Also, it it an all-over vibration, or can you feel it especially in the steering wheel?

 

I also have that problem right now. My friend at Wyotech took mine out for a test drive and he said that its probably the tranny mount. My vibrations occur around 60+ mph and they get worse up until 80. He said that if the tranny mount is messed up, then I probably need to get a new driveshaft.

 

Huh? My tranny mount was totally screwed, and I never had vibrations at speed.

 

yeah my tranny mounts are a bit soft and the thing doesnt vibrate (just put in tranny last week, old one went boom and that one WAS vibrating bad, bad bearings inside) its just fine.

 

When your car starts to vibrate do you have any trouble streering the car? Or does the wheel jerk around? If its a suspension issue you will have issues steering.

 

the pilot bearing is doing nothing unless you have the clutch in... it is not the pilot bearing.

driveshafts going bad usually make a noise and are their worst under load or engine braking... and why the hell would you need a new driveshaft if you have bad trans mounts?

have you checked wheel bearings?