Bad vibration when on the throttle above 15 mph

[1wickedGST]

My girlfriends 1990 GSX has a very bad vibration when I am on the throttle starting at about 15 mph and above, but once you let off the throttle or put the cruise on the vibration settles down. I have checked the front end and everything is tight and I put the wheels and tires off my 93 GSX on it and that didnt fix the problem. I have searched but nothing sounded like the problem I am having

 

[burkgonzo]

wheel bearings..balance...try those first...maybe a brake rotor..

 

[DSM1G90]

I call it more like Lower control arm problems.. -tie rods, ball sockets, et.al. ...

 

[burkgonzo]

Like busted bushings?

 

[DSM1G90]

..anything related to the main support of the front suspension. Lower ball joints are known for vibration problems when they are getting ready to go out with things being so loose in that socket area where the weight of the front end can go right through that socket and it's not fun to see a tire suddenly spay outward when a joint lets go.

 

[1wickedGST]

Ok, I cheaked the brakes and they are not hanging up, the wheel bearings are still good. I am going to check the front end agsin when it stops raining. I'll post back with more info

 

[DSM_Zak]

Crazy thing, but back when I had the same problem, after doing all of that, plus a driveline replacement thinking it was carrier bearings, it wasn't, then I thought it was rear end, changed that, still was not it. Eventually I gave up. One day I launched my car so hard, the front wheels came off the ground a little, the weight distributed back to the front when they settled down, shattered the center differential. So long story short I replaced with a Shep Stage 3, and no more vibration after driving it. Something in the transmission was vibrating the car so bad the rear view mirror rattled off!

So it IS a possibility.

 

[1g-tsi-86]

Check the wheel bearings jack up all 4 wheels place hand on strut and spring have a buddy spin the tire real fast and feel for vibrations. Do u feel in steering wheel or butt?