I know this has been covered a lot. And I apologize. I did this conversion years ago on my 70 Dart. I just picked up a 73 Duster last month. However, it's got factory drum front brakes on it. I'm confused reading tech articles and what not. They say you will need "73-76 upper control arm". Does that mean all I need is the spindle setup? Obviously I'd need calipers etc. What do I need to scavenge for my 73 drum car? Thanks guys. I appreciate it.

Some people seem to have the false belief that all A body cars were built with front disc brakes after the 1973 model year began. This is simply not true, as I have personally owned and seen several A body cars all the way to their last year, 1976, with drum brakes at all 4 corners.

The 73-76 A body cars with 10" front drums or 11" discs did use the same upper control arms and the same upper ball joints. The 1973-76 cars with 9" front drum brakes used the same small upper ball joint as all A body cars built from 1960.

Right. Even I found that out last week. So my upper is good though it sounds. Thanks.

You will only hear of some very early build 73 A body cars with 9 inch Drum brakes.
That's it, all other ones after that were 10 inch drums, if so equipped.

They used up all the leftover 9 inch stuff on the assembly lines for a short while, until they were gone.

I have only ever come across 2 1973 A body cars, with 9 inch brakes, in the 40 years that i have been around these cars.

What are the odds that your going to come across one of these odd ball's in 2016?
Slim to none.

All of the above info is correct but only applies to 4 1/2" bolt pattern stuff.
I found a 4" bolt pattern 9" drum 76 Dart last year. Car was a 4 door /6. Story I got was 4" b/p stuff was used on 4dr /6 cars only as far up as 76.
Never say never with any of the older stuff...
As earlier mentioned I've never ran across a 4 1/2" bp with a 9" drum...

This has been beat to death numerous times in many postings, in various sites throughout the years.
You are only going to find 9 inch drums on early build 73 cars ONLY.
6 cylinder cars, were the only ones to get DRUM brakes on all 4 wheels and the 4 inch bolt pattern.
DISC brake cars all are the 4 1/2 inch bolt pattern.

If anyone came across a 74, 75, 76, A body car with 9 inch Drum brakes on it, It did not leave the assembly line like that.

There were no more 9 inch drum parts available after early 73, and certainly not in 74, 75, 76.

In 40 + years some old cars got repaired, swapped, with parts other than they were originally born with.

I don't care about the drum size war. I was just trying to co firm that I have the big ball joint upper and I don't need to change it.

Check the size of the upper stud nut

Small is about 5/8

Large is 13/16

IIRC

Thread diameter of small ball joint UCA's are 7/16 inch.
Thread diameter of large ball joint UCA's are 9/16 inch.

Wrench size nut for large ball joint is 7/8 inch.

That's a very easy way to determine, large, or small, ball joint UCA's while installed in the arm.

Why the change? Bolt pattern? Unless your running 150 mph drums work fine.

I was hoping you'd chime in. My memory on some of that stuff isn't as good as it used to be. Thanks.

I owned a 76 Dart 2 door, slanty automatic. 4 wheel 9 inch drums NON power, small bolt pattern.

One hard and fast rule: All 4 wheel drum A body cars were small bolt pattern, every one EXCEPT the Hurst Hemi 68 Darts and Barracudas.

I don't care what the service manuals list, I have personally seen 9 inch front drums on enough 73-76 cars to know that it wasn't all the result of owners changing stuff around. What are the chances that 10 or more people just in one part of my state decided to remove 10" drums to swap 9" versions on? It isn't as simple as changing drums...The spindles are different along with the control arms. This makes DOWNgrading from a 10" drum or 11" disc (Which too many people incorrectly state as being the only possible combination) as a swap that would also require awheel alignment. Think of how little sense that makes.

Just to clarify:
73 to 76 A Body
4 1/2" (big bolt pattern)
I've only seen 10" front drums when drums were used with 4 1/2" bolt pattern.
(making all 4 1/2" bolt pattern 73-76 A Body cars to use the large upper b/j...disc or drum)

I have seen the 9" drums on cars as late as 76 when used with the 4" pattern as earlier mentioned. (/6 cars only using the smaller upper b/j typical to the 67-72 upper control arms)


So are we in agreement or disagreement?

Your post may be clear to you, but all the icons and everything clutter up the post.The only 4 1/2" bolt pattern A body cars were front disc 1973-1976 cars. There were no "big" 4 1/2" bolt drum brake cars built in the A body platform.

The op's topic has gone off track, and he stated has no interest in the "Drum Brake" war.

He found out what he want's to know, and has big ball joint UCA's, for his needs.

And there is NO SUCH THING, as a 4 1/2 inch DRUM Brake A Body automobile.
Drums were 4 inch bolt pattern, to the very end.

No emoticons and all your words...which is it?

Maybe I'm missing something here but from what I've read from hemi71 and yourself is there is no 4 1/2" bolt pattern drum brake A Bodies. How can that be?

How can it be? My car has factory drums and is confirmed a 4" bolt pattern. Not saying never, but my car is 4" bp front and rear. As for keeping the drums ... Why? Disc, simpler, easier, better. I can't tell you how many times I've driven drum front vehicles and they pull to one side or the other on initial brake. That's just a short list. Disc are the way to go.

I have a 74 dart sport that has 5 on 4 1/2 bolt pattern from the factory.

That's because you have a Disc brake car.

Yes, being 4 inch I would change out too. Just thought you had 4 1/2 drums.

The only 10" drums with the 4 1/2" bolt pattern used on A body cars were the rear drums. All 4 1/2 bolt pattern front brakes were disc brakes.

The 9" 4 wheel drum brakes used on A body cars are all 4" bolt pattern. These 4" bolt pattern 9" 4 wheel drums were available up to the end of the A body production in 1976. The upper ball joints have different size studs between the disc brake A body cars and all the front drum A body cars. Gene

^^^^
Yes.

I always point folks to this article.
http://www.moparaction.com/Tech/archive/disc-main.html

You'll need disk brake spindles and believe it or not, E body spindles will work! If you don't mind 15" wheels, the 1976 up 11.75" unicast cop disk brakes are the bomb to do on the cheap, provided you can source the calipers and disks still. If not, there's info on stock A body disks in that article too. I did this swap on the Bee. Easy Peezy.