How to tell '73-up UCAs?

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'74 Sport

'74 Sport

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I know the '73-up UCAs are the ones hunted for by those wanting to
upgrade to disk brakes, but I don't know how to tell the difference in
them vs. the earlier ones. Doesn't it have something to do with the size
of the ball joints - what do I look for? Anything for me to measure so
I will know?

Jerry
 
Great question.......I "think" it's just the size of the ball joint but....? :scratch:

Give me a couple of days, I'll take pix.
 
That's kind of what it boils down to, C. Is it determined by the top of the ball joint (the part threaded and screwed into the UCA), or is it the tapered stud on the bottom of the joint?

Any help is appreciated.
 
Jerry, It is both the diameter of the stud and the diameter of the upper control arm opening.

Thank you for the speaker grill...... Worked perfect :thumbup:
 
Excellent! Glad you like it. It's a cheap fix for a simple problem.

I'll stand by for the measurements.
 
Most used upper arms will have the ball joint still in them so you cant measure the threaded hole. My plan would be to measure the hex on the top of the ones you have and then seek something larger. The larger ball joint required a larger socket :)
 
Here's a few pics for you.....If you need more measurements or can't read these, let me know. As far as I can tell, the only difference in the control arms is the size of the opening for the ball joints. There is however, a big difference in stud diameter and length of the ball joint stud which accounts for different spindles between early and late.

72 A-Body UCA 007.jpg

72 A-Body UCA 001.jpg

72 A-Body UCA 003.jpg

The above 3 pics are of a 72 and earlier UCA.

73 A-Body UCA 005.jpg

73 A-Body UCA 008.jpg

73 A-Body UCA 006.jpg

These 3 pics above are of a 73 and later UCA.



72 and 73 A-Body UCA 009.jpg

Here's the 2 of them side by side. 72 and earlier on the left and 73 and later on the right.

72 A-Body UCA 007.jpg


72 A-Body UCA 001.jpg


72 A-Body UCA 003.jpg


73 A-Body UCA 005.jpg


73 A-Body UCA 008.jpg


73 A-Body UCA 006.jpg


72 and 73 A-Body UCA 009.jpg
 
Bingo, you win the Kewpie doll. As it turns out, I found a pair of each like yours in the trunk of a parts car I bought. It never occurred to me to compare the ball joint tapered studs. I was focusing on how there wasn't much obvious difference in the top of the ball joints. As you pointed out, there isn't any noticeable difference in the shape of the UCA itself.

Thanks for the measurements. They jive with what I am finding on mine.
Another mystery solved.

Thanks much,
Jerry
 
Glad to help.......I'll PM you my address for the Kewpie doll ;)
 
wow I never realized just how different they really are.
Thanks for the good post
 
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