Lower Ball Joint taper dimension VS spindle ID

[fishnixon]

1968 C30 Conversion project underway...C30 drum to disc.

I've put in 1986 P30 ball joints into the control arms.

I called my local salvage yard, and explained I was looking for a 73-87 2WD C30 front spindle-dually disc set up and they said they had one.

I picked up the whole front end, cross member and all, and once home, I commenced removing the spindle set up. At present I have one spindle seperated from the discs as the discs need help (turning) or replacing. I stopped after looking at the one spindle and comparing to my ball joints all ready in the control arms.

Here's more set up for my questions...The O.D. of the lower ball joint at it's widest part is 1 1/8 inch and the I.D. of the respective spindle location is 1 inch. I believe that a 1/16th on either side is a lot to overcome to get the spindle onto the ball joint. Is this a normal measurement and I should continue the project and place the spindle onto my new ball joints and crank it down? Or should I look for "new" spindles? I do not want to scar up a +$65 lower ball joint without confirmation.

Could the salvage yard parts be non 73 and up and have a smaller spindle/ball joint orifice? It is a dually set up for 2WD that I picked up. Is the P30 ball joints different than a C30 of the same year, 1986?

[kieth]

Just use the whole front crossmember that you got from the salvage, replace what needs to be replace, mixing and matching is your problem right now. Kieth ps this way the tie rods, etc will work without any mods.

[Portmod7]

Your concern when matching ball joints to spindles is the taper of the stud and the taper of the bore in the spindle. The taper is usually measured in inches/foot. The spindle may or may not fit all the way down to the widest part of the stud. That being said, you usually always want the stud to fit far enough into the spindle that all of the threads on the ball joint stud are exposed once the spindle is seated on it.

You should be able to determine the taper of each by measuring the difference between the diameter at the widest point and the diameter at the narrowest point (in inches). You must also measure the linear distance between the two points where you measured the diameter(in inches) and divide that by 12 to convert it to feet. Now divide the difference in diameter (in inches) by the distance between the two points (in feet). That should give you the taper of each in inches/foot. Very commonly 1.5, or 2 in my experience.

If they don't match, you can either buy a reamer for your spindle (at least $100, and challenging not to mess up the bore in the spindle), or research different ball joints.

Hopefully this helps. Anybody else feel free to add if I forgot something, or shoot me down if I'm flat out wrong!

[fishnixon]

Thanks Keith...but I'm going to keep my crossmember, big block and tranny just where they are.

Portmod7...sounds logical, and I'll check it out. Thank you. Maybe an easier way is to find some P30 van spindles and carry on.

Others? Any more input is fine with me regarding P30 vs C30. Thank you

Rob

[fishnixon]

OK...I talked to CarQuest today, where I purchased the ball joints. Long story short, the parts clerk/owner and I were not on the same page when I told them I needed ball joints for a 73-87 Chevrolet one ton dually pickup. I may have said truck...I don't remember. Anyway, he confirms that there are two different part numbers when comparing P30 and C30...He is calling his tech guru, doing a confirmation and as he told me, "we'll fix the problem". So here I am, crossing my fingers and hoping for the best outcome. I think we all know what that would be...I keep you posted.
Rob

[fishnixon]

Here's the latest...Parts clerk/owner ordered C30 ball joints and told me to pull out the P30's and he'll make good on the exchange. HMMMM...sounds like good service in the works. (way to go Lawrence)