Hi, I made a second ride, and now I suspect vibrations in all gears, however first and second less noticable. Flex plate can be an issue indeed. During the build up of the engine I found one thread of the crankshaft shot, so I had to apply an helicoil. Maybe it got loose again? The flange of the cranckshaft has not much depth, so easy to overstrengthen the flexplate bolts. I am busy pulling the transmission and I will find out if it is a loose flexplate?