Third gear is the furthest gear out on the mainshaft( fourth gear locks the input and main shafts together) hence third gear has the most deflection of all the gears in the trans. A hard hitting clutch will and does enhances the deflection. That is why a clutch that is set up with a little slip on the hit and locks up after the hit will save the trans and keeps the rpm's up to make the car accelerate quicker off the line and each gear change.