How much tension should there be on the flex discs on the ends of the drive shaft? I replaced the drive shaft and discs recently and if I loosen the bolts holding up the center bearing, bolt up the discs and tighten the big nut on the drive shaft, the flex discs are no longer flat. Should they be or is this OK? The only way I can see to make them flat is to loosen the big nut on the drive shaft which doesn't seem like a good idea. Any suggestions?