Driveshaft wobbling

In 1st gear, if i floor it, it wobbles, you can feel the vibration under the car, but other gears are fine. And when cruising on the highway going 120, its constantly wobbling. At first i thought it was my one of my tires, but when i let go of the gas and put the car in neutral, it goes away. Couple nights ago, it got real bad, it felt like something was gonna snap, i had to slow down and it went away. How do i fix this? Has anyone experienced that before? Is it safe to drive the car like that as long as it's not wobbling or should i get this fixed ASAP?

Any help would be greatly appreciated.

Thanks,

Sebastien

My general rule is to get something like this checked out immediately if I'm uncertain of the cause. I think everyone else will agree with that statement, especially if it feels really wrong and/or unsafe.

I'D CHECK IT OUT! DRIVESHAFT COULD BE OUT OF BALANCE OR YOUR CARRIERS BROKEN, OR WORN U JOINTS AND OR LOBRO JOINT . IF YOU KEEP DRIVING IT YOU COULD MAKE THE REPAIR ALOT MORE EXPENSIVE BY MANGLING THE DIFF OR TRANSFER.

"when i let go of the gas and put the car in neutral, it goes away."

If that's the case, it's not your driveshaft. With the car rolling, and the transmission in neutral, the driveshafts are all still spinning.

The driveshafts are spinning but there is little load on them. I'd check the carrier bearings first off and the u-joints while you are down there. Almost sounds like first gear launch driveshaft thump.

Is the whole car vibrating or can you tell if it's coming from the front, centre, or the rear?

What does it do when decelerating while in gear?

Ha, sounds a little too familiar!
FIRST thing I would check is to see what transmissoon you have in the car, JDM tranny ???

You say its in 1st gear and 120 cruising, could be the diff binding up due to a wrong final drive.

If tranny checks out fine and is stock, then check what everyone else is telling you to.
Bad CV shafts will vibrate under load, or a very bad u-joint or carrier.

If it just happened all of a sudden, and you do have a JDM tranny, look into that first.

In my case of this symptom, it was the passenger rear CV shaft. It would go right crazy under any load in fifth on the highway.. feeling almost undriveable. I thought for sure it was the driveshaft and replaced all the carrier bearings and the u-joints. I finally bought some new axles for the rear from a junkyard and fixed it. I have since found that bad carrier bearings and U-joints in the driveshaft manifest themsleves as a "rubber band" effect when taking off in low gears, or driveshaft thump under hard acceleration in first.

I never even thought about the differences when under load! (obviously) Sorry, ignore me.

Thanks for all the advice guys! This does sound a lot like mine tho...hmm...the vibrations come from the middle and sometimes feels like its rear passenger...They havent made the car feel undriveable except once...On the highway in 5th gear, its noticeable to the driver, you can feel it when holding the steering wheel etc..But its coming from mid rear. In all other gears its fine, or maybe its so light that its not noticeable. And in first gear under hard acceleration its very noticeable. Other then that, i never feel it.