On my 88 Bronco I have just pressed in new upper and lower ball joints and am trying to install the knuckle. The Haynes manual says to tighten the lower about 30 pounds, tighten the upper to about 100 pounds and then tighten the lower nut to about 100. The problem is the lower ball joint nut is a "prevailing torque" nut. Which means it won't go on the ball joint any further than the top of the nut. After that it just spins the ball joint. The top castle nut will go all the way on fine.
Did I somehow get the wrong part? Is this supposed to work like this? I kept the "old" nut and seems to behave the same way, but I have tighten and loosened it it the past and dont recall this strange behavior. The nut on the other wheel is below the top of the stud by several threads. Any ideas?

 

I had the same problem. I had to borrow air tools and use an impact gun to tighten the nut. The trick is to turn the knuckle all the way to one side which will put a little pressure on the stud. Hit it with the impact, then turn the knuckle all the way in the opposite direction, and zip it again. It will tighten it. I couldn't figure out any other way. I tried putting a jack under the lower ball joint, but it just started lifting the truck, not pressing the balljoint stud up into the arm.

Good luck
Jim

 

Thanks, I seemed to have solved it. I used the top castle nut to tighten the bottom ball joint. When I removed the castle nut and tried the real nut I had no problem getting the nut all the way on and tight. Using the castle nut first must have pulled the set the ball tight and it no longer spun. I will try the trick on the other side to see if it works the first time.

 

I used a shop rag on the bottom joint then put a large pipe wrench to it. Held it in place without scarring it up and I was able to tighten it up no prob.