I am looking for some help on my 2004 bonneville Se with 38,000 miles because it has a vibration at 60 to 70 mph like alot of the information on the internet states about this car. I have put new brakes & rotors, motor mounts, force balanced all tires twice, new inner & outer tie rods, wheel bearings, replaced the tires and it still has this vibration and it just about drives me crazy so please help?

you said that you had the tires forced balanced, is it possible the wheel and tire assembly might be bad (i.e. bent rim or seperated belt in the tire) does the car pull at the higher speeds?

This may apply to your car as well but, GM just released a TSB that will take effect in 2011 that states that if the wheel hub isnt cleaned rust and debris can cause a wheel shake.

Also, which wheel bearings have you had replaced?

All the tires are brand new and when we balanced them we checked the rims very good and all seamed to be good. the force balanced the front to 8 and the best we could to is 12. I changed the front wheel bearings. What is really odd is after the balaning was done it seams the shake is worse but tonight I put it up on jack stands and it really seams to come from the front passenger side. as I had it up in the air and a freind in the car while I was looking underneath and it looked like both tires are ok but I did notice some shaking on the passenger side motor mount so I removed it and it move back and forth kind of easy and looks like there is a little crack in the rubber looking into the bottom side of the mount but I am not sure what they are supposed to be like???

I also was looking at the engine cratle mounts and the rubber part is real soft so is this normal?

I am about to crazy from this car !!!

Motor and tranny mounts will cause vibrations like you are experiencing. Based off what you wrote cast, I think you found the problem.

After I install the new passenger mount I will post the results.

Do you think the cradle mounts have anything to do with this?

They could, but its unlikely on a 2004. Check them out anyway.

A common problem I've seen is failure of the CV shaft/axles. If those have too much play, they will vibrate under higher speeds. The way to tell is to get on the highway when its vibrating, then let off the gas and coast. Pay attention to the vibration. Then accelerate hard. If between your coasting and acceleration the vibration changes, goes away, or gets heavier, then one or both of your CV shafts are bad.

I have replaced the right cv-shaft already and i still get the vibration. When I had it on the jack stands last night you could see the right motot mount moving with the vibration and the wheel, tire brake calipers are running perfectly straight. also looking at cv shaft when it is running it does not vibrate or shake ir seams like the motor is causing the vibration because of the crappy design to not have the dogbone mounts on the top of the engine. Do you think it would help to retrofit a dogbone motor mount from a gran prix to work at the front left? i would have to fabricate a bracket to attach it to the core support?

I have great news...
After about 2 and a half months and about $500 or more of trying to figure this vibration out I changed the passenger side motor mount and the vibration is gone.

did the shake seem like it moved all around the car?

The vibration allways felt like it was in the right front wheel area but now just about everythng is new on that side.