The axle tubes are machined for an ideal fit inside the centersection. With the axle tubes cool, they’re easily brought home inside the heated centersection. The ends of the tubes are coated with sealant, and then the tube is fitted into the centersection using a BFH, or Big Freakin’ Hammer. A plate is placed over the end of the axle tube so that the BFH does not hammer directly on the tube. When the centersection cools down, it contracts around the axle tubes and creates a permanent bond to establish a second line of defense. There are also setscrews between the centersection and the axle tubes.