Brake Changes on A Bodies

[SpriceyStuff]

Hey guys. Is there a knowledgeable fellow in here who could tell me what braking systems were standard in A Body Mopars and at what times? I have a 1974 Dart Sport, drums all around. I don’t know if it’s the 9” drums or if it’s one of the 10” variants. If it helps, it’s a slant six car with a 7.25” rear end

 

[Dana67Dart]

Your best way is to measure the ID of the drums.

 

[Kern Dog]

The slant six cars were standard with drum brakes, front and rear even through late 1975. I'm told that January 1, 1976, New cars sold in USA had to have front disc brakes.
I once had a 1976 Dart Swinger....225 slant six, 904 and 4 wheel 9" manual drum brakes. If it was original, it would have had to be built before the end of the year 1975. It looked original. It had rubber floor mats and an AM radio. It was pretty basic.
I've mentioned that car numerous times and have had a few argue that the car could not have been built that way. Since I did not order the car and own it since it was new, there is no way to know for certain that it was 100% stock but in my years of junkyard crawling, I've seen many 73 and later A bodies with 4 wheel drums. I had a slant six 73 Dart Sport with 10" front, 9" rear drums. I had another slant six car...a 74 Dart Sport with 4 wheel 9" drums and 14x4" steel wheels. I've never seen a 4" wide 14" wheel before....that was a weird one.
Usually, the 318 cars had 4 wheel 10" drums as standard.

 

[Professor Fate]

You could fill a book with what was available at different times, and differences between "same size" brakes in different years...
Basically, 9" drums on slant cars, 10"drums on V8s, discs optional on all... and different versions of discs and bolt patterns on '73 and later. And I know there's exceptions and variables...
Heck, I've got an 8.25 I yanked out of a '74 Dart Sport that has factory 11" drums- never officially available, but there were times the assembly line just used what they had in order to keep things rollin'...

 

[72bluNblu]

Probably 10” fronts with 9” rears. But the max diameter is cast right into the outside of the drums, that’ll give you the basic diameter.

This is the factory TSB on the redesigned 10” drums for the front on the A-bodies. November ‘72 everything had been changed over per the TSB, so the front drums had gone to a redesigned B body style brake- large upper ball joints, 10” drum with a larger outer wheel bearing. They still used the small bolt pattern.

https://www.hamtramck-historical.com/images/TSBs/1973/05-03-73C page1.jpg

‘73+ only /6 cars came with front drums, all the V8 cars got front disks standard ‘73+. And the drums went 10” front, 9” rear.

I’m not gonna argue what somebody saw. All the 9” drum spindles used a small upper ball joint. But 73+, after November ‘72 according to Ma Mopar (TSB), they would have been large ball joint UCA’s on both the disk and drum cars, no more small ball joint UCA’s after that. Now we all know Ma Mopar wasn’t great about dates, so, maybe some small ball joint UCA’s went out after that using up the discontinued leftover parts. But we’d be talking within weeks or months of the TSB, not years.