Cadillac CTS-V - Big Problem

I need some help.

Today when I was leaving work it was raining hard on the way home.
Top speed on the freeway was 40 -. About 30 min. driving slow my car (05 CTS-V) was shaking hard in 4th gear. I was thinking the rearend was letting go but I put the clutch in and the shaking went away. It did it 3 more time on the way home. I look under the car and every thing looks good and the car drives fine now.

If taking the clutch out eliminated the issue, then I would think it would involve your flywheel and/or associated parts. Are you sure it went away when you pressed the clutch pedal in?

If taking the clutch out eliminated the issue, then I would think it would involve your flywheel and/or associated parts. Are you sure it went away when you pressed the clutch pedal in?

I think so.
I could not hear any noise b/c of the rain. I could just feel it shaking from the rear.

You're sure it wasn't just a tire/wheel out of balance or something? The weights they use to balance a wheel can sometimes fall off. But if you're SURE that the shaking goes away when you depress the clutch pedal, than it's definitely something else.

Maybe something to do with anti-slip diff & traction control.
You did say it was raining hard.

You said it was raining hard.

Any chance you could've been Hydroplaning and the Traction/Stability Control was kicking in? Maybe even some wheel hop if you were accelerating?

Rain plus your Corsa might be the problem, they arre really tight to the driveshaft. When I hit enough water, the exhaust would cool on one side and pull it over to where the driveshaft counterweight would bang into the pipes. I thought the whole car was coming apart. Slow down a few MPH or let off the gas and it was fine.

I had some wheels and tires on my car that hated the rain. Not sure what the deal was but in heavy rain they would shake hard. I though my wheels were loose. Once it dried up, all the vibes when away. Strangest thing I have ever seen. I sold those wheels and tires lol

Traction Control??