DCAWD.com

My car (sti08) started developing a interesting slope in the drivetrain, where if i push the clutch in and change gears slowly, the transmission / drive shaft feel like they droop down (disconnected feeling) until i get back on the power. I have changed my trans and engine mounts about 5k ago with group n to tighten up the drivetrain, and also did some inserts on the rear diff.

Fast gear changes don't have the same effect but in traffic and when im being lazy its starts to get really annoying.

Any guess as to were the problem could be originating from? im about to pull the trigger on getting a 1 piece driveshaft to just get this issue over and done with.

Did you replace the driveshaft carrier bushings as well when you did the engine and trans bushings?
It would stand to reason that if you replaced the others with urethane units, teh carrier would be the only thing absorbing the increased vibration and "shock".
They could be a bit hollowed out and allowing the driveshaft to "sag" until it is loaded again.
Worst thing would be if it is the bearing itself has gone bad. If it is still the same as earlier years, the carrier is welded onto the driven half of the driveshaft. Easier to replace than to repair. Mine failed about 4 years after I did my trans and suspension bushings, I do believe as a direct correlation.
At that point, replacing with a solid unit would be worth the price. (I found a newly used stock replacement and saved a wad of cash)
Then the problem is clearances... the aluminum ones that I remember tend to be a bit oversized, and if you have a larger diameter exhaust, you can get into space competition under there. That then leads you to a multi-thousand dollar carbonfiber unit. Which is a bad thing if you want to compete in certain track activities, and some safety bodies require the welding of a driveshaft cage... But at that level of competition, this would be your dedicated track car and you wouldn't be driving on the roads with it.

Not that I have thought about this or anything, no.

I have to say, I've never seen or heard of this problem. Have you had someone walk along the car or anything when it's happening? They might be able to see what's going on.

Does look like the driveshaft carrier bushings are going out. Still not sure if its the actual reason behind it. It mainly happens when applying power to the drivetrain from an idle / low throttle position.