UPPER CONTROL ARM EXCHANGE QUESTION
Yes, there are people with the wrong information, yourself included. I've been wrong in the past about the 9" drums, I used to think they went away in '73 but by all the factory literature it was '74.
9" drums were not available starting in 1974 according to any of the factory literature. You believe the factory literature for everything else, so, I don't see how it's not valid here. According to the factory, '74+ were all 10" drums, and those had large ball joint spindles and UCA's. If the books are wrong, show us the evidence.
Starting in 1973 all V8's got disk brakes. So, only /6 cars could have had drums up front. Disks were optional for the /6 and if you got a towing package you got disks. '73 was a transition year, 9" drums were still listed as being standard in front. But only for /6 cars without a sure grip rear, the sure grip upgraded you to 10" drums. I honestly don't know if the 1973 9" drums were small or large ball joint, although I would suspect they were small ball joint as the factory used up the remaining stock. And I haven't seen or heard of a 9" drum, large ball joint spindle (although that's obviously not proof). But that's 1973 only. The front drum cars stayed small bolt pattern the whole time, and drums went away completely for the front in January of 1975.
So-
All 1973-76 A-body disk brake cars were BBP and had large ball joint UCA's, the disks were standard for V8 and optional with a /6
All 1973-76 A-body 10" front drum cars had the 5x4" SBP and used large ball joint UCA's. And '74+ were all 10" front drums if they had drums.
1973 was the last year for 9" front drums.
As for cars 1974 or later with 9" drums, when you have one you can prove had them from the factory I'd be happy to change my statements. But just having a '74+ car with 9" front drums doesn't mean it came that way from the factory. I've swapped drums onto parts cars that came with disks just to keep them rollers, and used the disks to upgrade my other cars. I know I'm not the only one too. Of course it's possible there may have been some leftover cars at the very beginning of '74 with leftover 9" front drums and SBJ UCA's, it's Ma Mopar and there weren't many absolute cut off dates. Using leftovers was pretty common, but that typically only lasted a few months at the beginning of each model year. So, after early '74 I'd have to see real evidence. And who knows, they could have used up all the 9" drum spindles before they even got to the end of the '73 model year, since the factory was transitioning out of the small ball joint UCA's. Just as plausible. And that makes more sense, after all, starting in '73 the factory was transitioning the A-body line to use the same parts as the B/E body lines. Same upper ball joints, same lower ball joints, same rotors and bearings, same side markers (that started in '72), etc. Cost savings for the gas crunch. 9" drums require a bunch of parts unique to only 9" drums. Remember, not only did they use the small upper ball joint and UCA's (shared with the SBP disks up to '72), they used a lower ball joint they didn't share with anything else, even the SBP disk cars didn't use the 9" drum lower ball joints. And of course all of the brake parts were unique to the 9" drums and since they were SBP they were A-body only.
I've posted this info before, but here it is again. All this is from The 1970 Hamtramck Registry Home Page, the red highlights are mine. You don't have to believe me, but, "a car I saw in a junk yard" is not proof the factory literature is wrong. I've seen V8 cars with /6 K's, disk cars that had drums, 7.25's in cars that should have had 8 3/4's, BBP and SBP on the same car, you name it. That doesn't prove the factory did that, not after 40+ years. Especially with the '73+ cars because they get used as donors all the time, and people swap earlier parts on to keep them rolling and send the leftovers to the junk yard.
1973
1974
Yes, there are people with the wrong information, yourself included. I've been wrong in the past about the 9" drums, I used to think they went away in '73 but by all the factory literature it was '74.
9" drums were not available starting in 1974 according to any of the factory literature. You believe the factory literature for everything else, so, I don't see how it's not valid here. According to the factory, '74+ were all 10" drums, and those had large ball joint spindles and UCA's. If the books are wrong, show us the evidence.
Starting in 1973 all V8's got disk brakes. So, only /6 cars could have had drums up front. Disks were optional for the /6 and if you got a towing package you got disks. '73 was a transition year, 9" drums were still listed as being standard in front. But only for /6 cars without a sure grip rear, the sure grip upgraded you to 10" drums. I honestly don't know if the 1973 9" drums were small or large ball joint, although I would suspect they were small ball joint as the factory used up the remaining stock. And I haven't seen or heard of a 9" drum, large ball joint spindle (although that's obviously not proof). But that's 1973 only. The front drum cars stayed small bolt pattern the whole time, and drums went away completely for the front in January of 1975.
So-
All 1973-76 A-body disk brake cars were BBP and had large ball joint UCA's, the disks were standard for V8 and optional with a /6
All 1973-76 A-body 10" front drum cars had the 5x4" SBP and used large ball joint UCA's. And '74+ were all 10" front drums if they had drums.
1973 was the last year for 9" front drums.
As for cars 1974 or later with 9" drums, when you have one you can prove had them from the factory I'd be happy to change my statements. But just having a '74+ car with 9" front drums doesn't mean it came that way from the factory. I've swapped drums onto parts cars that came with disks just to keep them rollers, and used the disks to upgrade my other cars. I know I'm not the only one too. Of course it's possible there may have been some leftover cars at the very beginning of '74 with leftover 9" front drums and SBJ UCA's, it's Ma Mopar and there weren't many absolute cut off dates. Using leftovers was pretty common, but that typically only lasted a few months at the beginning of each model year. So, after early '74 I'd have to see real evidence. And who knows, they could have used up all the 9" drum spindles before they even got to the end of the '73 model year, since the factory was transitioning out of the small ball joint UCA's. Just as plausible. And that makes more sense, after all, starting in '73 the factory was transitioning the A-body line to use the same parts as the B/E body lines. Same upper ball joints, same lower ball joints, same rotors and bearings, same side markers (that started in '72), etc. Cost savings for the gas crunch. 9" drums require a bunch of parts unique to only 9" drums. Remember, not only did they use the small upper ball joint and UCA's (shared with the SBP disks up to '72), they used a lower ball joint they didn't share with anything else, even the SBP disk cars didn't use the 9" drum lower ball joints. And of course all of the brake parts were unique to the 9" drums and since they were SBP they were A-body only.
I've posted this info before, but here it is again. All this is from The 1970 Hamtramck Registry Home Page, the red highlights are mine. You don't have to believe me, but, "a car I saw in a junk yard" is not proof the factory literature is wrong. I've seen V8 cars with /6 K's, disk cars that had drums, 7.25's in cars that should have had 8 3/4's, BBP and SBP on the same car, you name it. That doesn't prove the factory did that, not after 40+ years. Especially with the '73+ cars because they get used as donors all the time, and people swap earlier parts on to keep them rolling and send the leftovers to the junk yard.
1973
1974