that was NOT what i meant. You are right, i have never done this before so it is just pure speculation and guessing on my part. What i MEANT was that there is slop between the splines on the shaft and the splines on the impeller, so even with it bolted on tight (the bolt bottoms out against the shaft, not the impeller) there is still a small amount of play between the two sets of splines, allowing a small amount of movement of the impeller. Man you really gotta calm down, you are the only person i have EVER had any resistance with on this site.