Topic: 70-Upper and Lower Ball Joints

[1970 Snake]

I rebuilding my upper control arms and want to use the original ball joints, but am a little confused as to the type of the original ball joints used by the factory on my cars suspension. Looking at the design of the 1970 mustang front suspension, I would assume the upper ball joint is a loaded type ball joint and takes the weight of the car because the front coil spring is mounted on it via the spring perch, where the lower ball joint should be a follower joint. I have cleaned and degreased the original upper ball joints and they are very snug in their sockets but when put in a vise will collapse a spring under the ball and take it off its seat at least 1/8" or more. This would indicate they are of a follower design which makes no sense. I have some new replacements that do not collapse in the vise. So what am I missing here, as I am sure the original is not wore out but is a follower type because of the spring under the ball.

[70cj428]

Not sure what your asking, the upper ball joint is a loaded type joint, the stud faces down in the spindle and the weight of the car seats the stud in the joint. That's why Ford tells you to check the upper joint loaded. The lower control arm joint is a "follower" type joint......

Hope this helps, John

[1970 Snake]

So what I am saying is that I can collapse the ball joint about an 1/8" in the vise and because it takes a bit of pressure with the vise to do that and when released out of the vise it goes right back into place because it has a spring inside to do that. Because of this I am assuming it is a follow type ball joint and not a loaded type. Yet it is for the upper control arm and it should be a loaded type ball joint without a spring inside, correct. So I am wondering why Ford would use a spring in the ball joint in a loaded joint location and my concern is the weight of the car could likely collapse it. If the ball joint is correct with a spring inside holding the ball in place, is there a method of testing the ball joint to see if it is still OK??

[70cj428]

I've also noticed that there's a spring that moves the stud off the seat when the joint is unloaded, I'm guessing that it permits  lube to enter the joint when the joint is temporarly lightly loaded. Once the cars weight is compressing the joint, the stud is completely seated and any radial play disappears ...

JMHO, John

[1970 Snake]

Yes so you have noticed this too, that is why I have started this thread, as I am surprised that an original Ford upper ball joint would be what I would consider a Follower type joint in a location where a Loaded type joint is required to take the spindle load/weight/pressure of the car suspension.

I have attached a picture of the ball joint with some joint detail comments as I see them on the original joint. The loaded side of the joint when installed is the internal spring sided of the joint and the ball seat area seems very small, which does not make sense when that area would be taking the entire car suspension load and the unloaded side of the joint where the ball joint internal spring places the ball when the joint is unloaded, is a large seat area for the ball which you would expect for a loaded seat area not unloaded seat area.

So before I spend all the money to send my upper control arms away to get these original ball joints correctly rivetted to the arm, I definitely want to make sure that they are correct and will function as Ford designed and hoped someone could clearly explain why this type of ball joint was used on the upper control arm by Ford and why.

[1970 Snake]

Can anyone advise how the ball joint boots are attached to the ball joint, is it glued? I also see there is no method of venting the grease in the boot so the boot is not over pressured when filling how does this happen with the repro boots?