The only way I have been able to eliminate driveline vibration completely and at all speeds is to set the driveline angles up at "net zero". I've tested this up to 187mph.
Correct me if I am wrong here but if the trans tail flange is not parallel to the crankshaft something is not right???
Interesting, what type of bushings are you using? What are your rear spring rates? What type of angle finder are you using? Is the car on a drive-on lift, or jackstands? I would never say that is not possible, as I have seen weirder things happen, but it definitely is not common.
This. I'm still trying to figure out why you're bolting all these high-end performance parts onto a car that is "99% street-driven." You're never going to even get close to driving the car hard enough to see the difference all those parts can make.
I recommend quite a few people to keep the stock upper stuff.
Now, if someone's car is lowered, I absolutely recommend an adjustable UCA. It is not good on the pinion parts. You may have "luck" for 50K miles, but it still is not good to have the drivetrain angle off.
