sfilion

In the process of installing CV axles I broke one of the lower ball joints on my 95 Accord. I slipped the lower ball joint back into the steering knuckle, I attempted to tighten the castle nut. Once the nut started to resist torque, but long before it was cinched down, the ball joint stud started to turn, making it impossible to tighten the castle nut. I assume that the ball joint is broken and needs replaced. I purchased a replacement ball joint, and rented the ball joint press C-clamp tool, too; however, there is insufficient clearance around the top of the ball joint to fit the cylindrical receiving cup in the press tool. Is there a special tool needed for this?

Fuse

Take it all apart and use an air hammer it feel strange but it workers. Your ball joint may not be broken just because it spins. Use a pry bar between the lower arm and the knuckle put some tension on the ball joint hit the nut with an air impact.

JimBlake

It's normal for that thing to spin.

Another way...
Put a jack under the lower control arm. Crank it up just enough to put some compression load holding the balljoint's tapered stud into the hole. That should prevent it from spinning enough to tighten the nut.

Be careful you don't crank the jack enough to knock the car off the stands...