driveshaft vibration

I put in a one piece driveshaft (steel)Between 115 and 130mph it shakes the car pretty good.I have also installed a new centerforce clutch and pressure plate.Car was smooth with the factory clutch and driveshaft.Any ideas.I may put the factory shaft back in and give it a try.I run with some of the vette guys and these speeds are fairly common.

If it came with a mating flange you have to be sure that it is completely clean on the pinion side where the two pieces mate together. If that's good you may need to adjust your pinion angle.

The car has been lowered,i'll check that tonight.

You'll need an adjustable upper to achieve the correct angle. If you don't have one Hector has one for sale.

You say the had the driveshift on without any problems and then installed the clutch and had the vibration? Or did you put them in at the same time?

It is pinion angle off real bad or driveshaft out of balance. This is my one fear of going to 1 piece driveshaft, no vibrations with my 2 piece. If you don't have the upper adjustable control arm, get one as stated.

Plus one on Adjustable upper for pinion angle....would be my guess

same time of course.pinion angle is right on.Drive shaft runout is near perfect.Will have balance checked,but is very smooth from 0-110 mph.

Thats right I am bringing this thread up from the dead but was curious if Tony ever determined root cause?

Yes,it was a loose tranny mount.