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A body upper control arms question 1973 and up #1784755
03/21/15 10:27 AM
03/21/15 10:27 AM
Joined: Mar 2005
Posts: 175
Minnesota USA
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Dart6pak Offline OP
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Dart6pak  Offline OP
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Minnesota USA
were all A body upper control arms 1973 and up big ball joint --were they different between disc and drum

Re: A body upper control arms question 1973 and up [Re: Dart6pak] #1784756
03/21/15 12:37 PM
03/21/15 12:37 PM
Joined: Jan 2003
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Rancho Cordova, California (Sa...
hemi71x Offline
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Read this from another forum that i replied to.

I just copied and pasted it to this page, to make it easy to answer your question.



Boy oh boy, has there been a lot of misinformation being thrown out here in regards to upper control arms on the A body cars.
Now everyone listen up.
On the 73 -76 A body cars there is NO difference in UCA's if the car is equipped with disc brakes, or 10 inch Drum brakes.
They are all the same thing. No difference to them at all.
They all use the big ball joint.

There are some early, odd ball, 6 cylinder, drum brake, 73 A body cars, that came off the assembly line with 9 inch drum brakes.
Those cars had small ball joint upper control arms.
Chances, coming across one of those cars in this day and age, is pretty slim, but some members report that they have one, or at one time had one.
In my 30 years of professional wrenching, and going to the wrecking yards, i have only came across two, or three, of these stripped down models.

And another thing to clear up is if you have Kelsey Hayes, 4 piston disc brakes, on a 65-72 A body car, those A body's used the Small ball joint UCA.
Those 62-72 A body's all used the same UCA wether it was Drum brake, or Disc brake equipped.

Large ball joint UCA's started on the 73 A bodys, with disc brakes, or 10 inch drum brakes.

And another thing that i read from a poster is that if your doing a disc brake swap onto the A body you can use 73 up B body ball joints.
That is totally inacutate. Not true. False, wrong, information.
73 and up B body suspension changed with the 73 model year, and is a totally different design, and won't interchange with the A body cars.

You use 73-76 A body lower ball joints when doing the brake conversion.
Lower ball joints are the same thing for disc brakes, and 10 inch drum brakes, on the 73-76 cars.

Just some things that need to get clarified here, as i had some time to kill, before leaving the house for a medical appointment, so i made this reply.

Last edited by hemi71x; 03/21/15 01:10 PM.

RF-4C Phantom 69-370 Zweibrucken, Germany

Re: A body upper control arms question 1973 and up [Re: hemi71x] #1784757
03/21/15 12:57 PM
03/21/15 12:57 PM
Joined: Jun 2005
Posts: 5,095
Western Md.
skicker Offline
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The small ball joint used in the uppers was phased out for 73. Many don't realize the conversion from 10" drum to disc for a 73-76 A does not require the new upper control arm as a 72 and back does...

There are a very select few 9" small bolt pattern set-ups that I have seen on 6 cylinder cars as late as 75. They're few and far between...


...FAFO...
Re: A body upper control arms question 1973 and up [Re: hemi71x] #1784758
03/21/15 01:33 PM
03/21/15 01:33 PM
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Lincoln Nebraska
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RapidRobert Offline
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And on the early (65-72) A LBJ's there is a different part number for drum and disc but the only difference is the drum unit holes are for 1/2" bolts and the disc unit holes are for 9/16" bolts and there is plenty enough material there to drill em larger and the set I did was soft material (iron?) & the drill bit went thru em like butter so if you have a set of drum ones and are converting to (early) discs no need for another purchase.


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Re: A body upper control arms question 1973 and up [Re: RapidRobert] #1784759
03/21/15 01:54 PM
03/21/15 01:54 PM
Joined: Feb 2015
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crackedback Online content
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The Ball Joint for 73+ A's BBJ upper is the same as a B body, K772

The arms they go in are totally different. A body upper arms are their own animal.







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