I am swapping a 74 Duster from nine inch small bolt pattern drum brakes to the disc brakes. I bought a kit to do this from the same guy i bought the car from, but, upon opening the boxes for the first time today, I discovered I do not have the upper control arms in the disc swap kit.

Parts catalogs only show one upper ball joint for 74 Dusters. Does this mean that I don't need to swap upper control arms to put the disc brakes on? Will the disc brakes work with the 74 drum brake UCAs?

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Casually looking for a Clifford hyperpak intake for cheap.

'74 FPC shows:

-Same part number for the upper ball joint, regardless of disc or drum brakes

-Different part numbers for the upper control arm depending on disc or drum brakes

-Different part numbers for the knuckles depending on disc or drum brakes.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I'm not questioning the parts books, but I'm having trouble figuring out what that means. If the upper ball joints are the same, then what significant difference could there be in the upper control arms?

One thing to note, on the 74, changing to disk brakes will mean changing to large bolt pattern.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

Not necessarily, maybe this is a kit for the 72 and earlier cars meant for a KH style SBP brake setup? Would make sense why they didn't include the UCA because that conversion didn't require a UCA/UBJ since they were the same (72 and down disc vs drum).

Reed, any info on the kit? Part#, brand, etc ?

It's always been my understanding that:

1) Three mopar ball joints-
One small one for all drum brake cars, and pre-73 disk brake cars
One medium one for most of the RWD passenger cars (1973+ disk brake cars, FMJ, etc...), I think these are used on the 10" drum brake A-bodies as well.
The large one for Trucks and C-bodies

2) Drum spindles are cast one way, and disk brake spindles are a bit different

-D.Idiot

Hmmm. These are definitely large bolt pattern rotors and single piston calipers.

I wonder if the part number for drum vs. disc UCAs is like different part numbers for engine blocks or cylinder heads? Meaning the part number is different but the parts are dimensionally the same and interchangeable? If not, then I am looking for some UCa for my disc brakes.

At lest the spindles and rotors and calipers are clean and painted already.

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Casually looking for a Clifford hyperpak intake for cheap.

Donno, but this is interesting; the '73 FPC says all A-bodies take the same upper control arms (3402 702 right, 3402 703 left). The '74 FPC says drum brake A-bodies take those same arms, but disc brake A-bodies take 3722 460 and 3722 461. I don't have a '75 FPC, and my '76 FPC isn't accessible at the moment.
That's probably not it. Often you'll find different P/Ns for functionally identical parts in different-year FPCs, but not side by side in the same FPC with an equipment differentiation (e.g., w/drum brakes vs. w/disk brakes). Sometimes the distinction does not relate directly to the differentiation. For example, in some years you'll have two speedometers listed, one "100mph" and one "140mph". Easy enough. But in some years those same two speedometers will be listed as "6 cyl" and "8 cyl". The maximum speedometer calibration has nothing direct to do with the engine type, but if all 6-cylinder cars got a 100mph speedo and all V8 cars got a 140mph speedo, they may be listed by engine size. Likewise, you might find lower control arms listed as "6 cyl" vs. "8 cyl" with the difference being the absence/presence (respectively) of sway bar mounting tabs.

But in this case, there probably is a difference of some description. I'll look and see what the '76 FPC says the next time I have it in hand.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Hmmm. Ok. I will stay tuned. If someone who has some loose late disc brake UCAs is willing to take some measurements and shoot some pictures I will be happy to reciprocate with the upper control arms on my brother's Duster Maybe we can figure out what is different between the two styles.

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Casually looking for a Clifford hyperpak intake for cheap.

Well this will be interesting...

A-body UCA:

Disk Brakes up to 12-1-75 and after 3402702/703
Drum Brakes all 3722460/461

>Disc Brakes HD after 12-1-75 3722460/461---

Upper Ball Joint all cars except C-bodies 2298534


One of the things I had heard in local mopar circles is that about late 1974 or so that the UCA's had been "standardized", and that the UCA for the 10" drums is the same as the disk brake arms... so for the late A-bodies a swap from 10" drum to disks would just involve a spindle/rotors/maybe propblock/rear axle change out.

I'm not sure about the 9" drum cars in the 1974/1975 frame, I doubt they still would use the same UCA their 1968 counterparts would have.

Hmmm....

-D.Idiot

I have some out of the car, in fact I just got finished cleaning and painting them a few minutes ago. I don't know what year they are but I do know that they are from a disk brake equipped Duster in the 73-76 year range. They are identical in appearance to the UCA's from the 62 Valiant, other than the ball joint. I'll be happy to take some pictures after the paint dries.

As far as measurements go, I don't know what you would expect to learn. We know that the pivot point attachments are the same for all A-body cars from 62 on; I'm not sure about 60-61. The ball joints are the same for all A-body cars, 73-76 regardless of brake configuration. That only leaves the length from the pivot centerline to the ball joint pivot center. Since the lower control arms are identical there can't be any material difference or it would be impossible to align the front end. If it were me I would just use them.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

According to the broadcast sheet for the 74 Duster, the code for the front brakes is 0-5. Where do I look to find the build date?

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Casually looking for a Clifford hyperpak intake for cheap.

I'm not sure but were nine inch drums even offered that late? Most all of the '73 and up a-bodies I've seen have 10" sbp drums or the lbp discs. I'm pretty sure the UCA and ball joints are the same for both.

-James

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Reed,

Is the new disc brake ball joint the same size across the wrench flats as the old ball joint? The smaller ball joints take a smaller socket.

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Joshua

I'll need to check that.

I went out and peeked, and I think I was wrong about the front nine inch drums. I think it actually has ten inch finned small bolt pattern drums:



The "kit" was a bunch of parts pulled form a disc-brake equipped A-body. All Mopar. Looks like almost everything is there. I don't have a disc brake master cylinder or proportioning valve, either. I can get those new, though.

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Casually looking for a Clifford hyperpak intake for cheap.

Post the fender tag contents.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.