I'm wondering why is it when I'm going 80 (in 5th) the car just starts to shake really strongly.. I know it's not the driveshaft.. I just paid 200$ for a custom built one.. anyone possibly tell me what's going on here..
thanks for the help.
God Bless.
John W.

 

It could be that your tires are out of balance, your drive shaft could be out of round, your alignment, just to name a few.

 

try checking your gearbox mount, my car had a vibration that i couldnt find.