Disk brake steering knuckle

[moparkrazed]

Hey guys. My uncles purchasing 2 1971/72 dusters. One has no front suspension at all. The junk yard he’s pulling from has some darts/dusters that has upper and lower control arms. Would he be able to take the upper/lower control arms from a car that had drum brakes and use a disk brake steering knuckle? Need to get something under there to move it around. Also would he be able to use my drum brake knuckle off my 71 charger if I can find the disk brake knuckle to swap over in time?

 

[mvh]

My recollection is that the disc brake steering knuckle takes one size larger bolts for the lower ball joint. So I think it would work if you got the disc brake ball joints.

 

[72bluNblu]

Depends on what year the donor cars are.

62-72 the upper control arms have small ball joints. 73-76 they use the large ball joints, which are the same as the B/E bodies.

The lower control arms are basically the same from 62-76, only the location of the sway bar mounts changed. So as long as they don’t have sway bar tabs (or you don’t try to hook up a sway bar) it doesn’t matter what year the lower control arms are.

There’s also two versions of the disk brake spindles, ‘72 down and 73+. The 73+ version uses the large upper ball joint and those rotors are 5x4.5” for the bolt pattern, the earlier disks are 5x4”.

The B/E bodies used the large ball joint for their whole run, so, you can only use the ‘71 Charger drum spindles and brakes if you have large ball joint UCA’s, or buy a set of tapered ball joint adapters from DoctorDiff. And of course those brakes will have the 5x4.5” bolt pattern, whereas your ‘72 and earlier Dusters will be 5x4”.

You can use any year just to get things rolling as long as you’re not trying to mix and match large and small ball joints and bolt pattern parts.

 

[moparkrazed]

My recollection is that the disc brake steering knuckle takes one size larger bolts for the lower ball joint. So I think it would work if you got the disc brake ball joints.

Thank you mvh I think you are correct depending on the year maybe. I appreciate it.

 

[moparkrazed]

Depends on what year the donor cars are.

62-72 the upper control arms have small ball joints. 73-76 they use the large ball joints, which are the same as the B/E bodies.

The lower control arms are basically the same from 62-76, only the location of the sway bar mounts changed. So as long as they don’t have sway bar tabs (or you don’t try to hook up a sway bar) it doesn’t matter what year the lower control arms are.

There’s also two versions of the disk brake spindles, ‘72 down and 73+. The 73+ version uses the large upper ball joint and those rotors are 5x4.5” for the bolt pattern, the earlier disks are 5x4”.

The B/E bodies used the large ball joint for their whole run, so, you can only use the ‘71 Charger drum spindles and brakes if you have large ball joint UCA’s, or buy a set of tapered ball joint adapters from DoctorDiff. And of course those brakes will have the 5x4.5” bolt pattern, whereas your ‘72 and earlier Dusters will be 5x4”.

You can use any year just to get things rolling as long as you’re not trying to mix and match large and small ball joints and bolt pattern parts.

Thanks 72. Trying to get him rolling as soon as possible but didn’t want to jump out there and replace parts on my charger ( spending money in areas I’m not ready to yet) sooner than I wanted to. I’m thinking his best bet is to find the whole drop out unit from the same car. I might start a wanted ad after talking with him. Should be fun cars. His is a basin street blue duster twister and the second one is a base model duster that’s pea green with white interior.
Appreciate your time and input with all of that info.

 

[72bluNblu]

Thank you mvh I think you are correct depending on the year maybe. I appreciate it.

It depends on the year and the brakes. 9” drums use smaller lower ball joint bolts than 72 down 10” drum brakes, which use the same bolts as the 72 down KH disk brakes. And 73+ disk brake and 10” drum brakes use a larger bolt than the KH and earlier 10” drums.

Thanks 72. Trying to get him rolling as soon as possible but didn’t want to jump out there and replace parts on my charger ( spending money in areas I’m not ready to yet) sooner than I wanted to. I’m thinking his best bet is to find the whole drop out unit from the same car. I might start a wanted ad after talking with him. Should be fun cars. His is a basin street blue duster twister and the second one is a base model duster that’s pea green with white interior.
Appreciate your time and input with all of that info.

From an ease of “getting it rolling” perspective just grabbing the entire K frame with the attached LCA’s and just disconnecting the UCA’s and torsion bars is the easiest. And if you do it that way everything will match so if it is a different year than your Duster you can keep it later and have all the parts that go together as there’s some other parts that don’t mix and match depending on the year. But the K frames and UCA frame mounts are all the same.

 

[moparkrazed]

It depends on the year and the brakes. 9” drums use smaller lower ball joint bolts than 72 down 10” drum brakes, which use the same bolts as the 72 down KH disk brakes. And 73+ disk brake and 10” drum brakes use a larger bolt than the KH and earlier 10” drums.



From an ease of “getting it rolling” perspective just grabbing the entire K frame with the attached LCA’s and just disconnecting the UCA’s and torsion bars is the easiest. And if you do it that way everything will match so if it is a different year than your Duster you can keep it later and have all the parts that go together as there’s some other parts that don’t mix and match depending on the year. But the K frames and UCA frame mounts are all the same.

I do r

It depends on the year and the brakes. 9” drums use smaller lower ball joint bolts than 72 down 10” drum brakes, which use the same bolts as the 72 down KH disk brakes. And 73+ disk brake and 10” drum brakes use a larger bolt than the KH and earlier 10” drums.



From an ease of “getting it rolling” perspective just grabbing the entire K frame with the attached LCA’s and just disconnecting the UCA’s and torsion bars is the easiest. And if you do it that way everything will match so if it is a different year than your Duster you can keep it later and have all the parts that go together as there’s some other parts that don’t mix and match depending on the year. But the K frames and UCA frame mounts are all the same.

i do remember the early stuff using small ball joints (63-66 maybe) but wasn’t quite sure on when things changed. I do remember my dart having big ball joints with the fist brakes but completely forgot about them changing over to sbp so he would have a mismatch on the bolt pattern. But that’s not a huge deal, we just need to get it so the tow truck driver and move it and we can get it in my uncles shop. There is 1 75 dart there with disk brakes so that might work. All of the other cars are missing the knuckles so prob just easier to get the front end stuff from the dart there or doing a wanted ad depending on his prices. I have more important things to replace on the charger so disk brakes on my car is further down the list. But that does give us a great cheat sheet for when we’re looking at other front ends.

 

[67Dart273]

Depends on what year the donor cars are.

62-72 the upper control arms have small ball joints. 73-76 they use the large ball joints, which are the same as the B/E bodies.

The lower control arms are basically the same from 62-76, only the location of the sway bar mounts changed. So as long as they don’t have sway bar tabs (or you don’t try to hook up a sway bar) it doesn’t matter what year the lower control arms are.

There’s also two versions of the disk brake spindles, ‘72 down and 73+. The 73+ version uses the large upper ball joint and those rotors are 5x4.5” for the bolt pattern, the earlier disks are 5x4”.

The B/E bodies used the large ball joint for their whole run, so, you can only use the ‘71 Charger drum spindles and brakes if you have large ball joint UCA’s, or buy a set of tapered ball joint adapters from DoctorDiff. And of course those brakes will have the 5x4.5” bolt pattern, whereas your ‘72 and earlier Dusters will be 5x4”.

You can use any year just to get things rolling as long as you’re not trying to mix and match large and small ball joints and bolt pattern parts.

I think you might had better read your answer?

Through 72, small upper ball joints with FACTORY drum or disk, but not if you convert to 73/ later disc

I think we pretty much decided that "maybe" 73 and later 9" drum factory use small joints, but "maybe" the 10 front drums use large ones. Not sure. There's been discussions about that. And obviously the 73/ later disk, which are single piston, are large ball

 

[AMC Diplomat]

Can't he take the knuckles off an F or M body and keep the disc brakes? Lots of 5th Aves in junkyards

 

[cudamark]

I think you might had better read your answer?

Through 72, small upper ball joints with FACTORY drum or disk, but not if you convert to 73/ later disc

I think we pretty much decided that "maybe" 73 and later 9" drum factory use small joints, but "maybe" the 10 front drums use large ones. Not sure. There's been discussions about that. And obviously the 73/ later disk, which are single piston, are large ball

All....repeat all...'73-up A-bodies used the larger upper ball joints regardless of which brakes it had. All the drum brake cars those years used the same spindle and bearings too. It's just the disc brake cars those years that used the 4 1/2" bolt pattern wheels. All the drum brake versions kept the 4" bolt pattern.

 

[72bluNblu]

I do r

i do remember the early stuff using small ball joints (63-66 maybe) but wasn’t quite sure on when things changed. I do remember my dart having big ball joints with the fist brakes but completely forgot about them changing over to sbp so he would have a mismatch on the bolt pattern. But that’s not a huge deal, we just need to get it so the tow truck driver and move it and we can get it in my uncles shop. There is 1 75 dart there with disk brakes so that might work. All of the other cars are missing the knuckles so prob just easier to get the front end stuff from the dart there or doing a wanted ad depending on his prices. I have more important things to replace on the charger so disk brakes on my car is further down the list. But that does give us a great cheat sheet for when we’re looking at other front ends.

The '75 stuff would work, if it's got disk brakes it would have the large ball joint spindles and UCA's and actually a more desirable K frame as well if you wanted to go that far. If you grab the K grab the steering stuff as well. If you just grab from the control arms out you can leave the steering stuff.

I think you might had better read your answer?

Through 72, small upper ball joints with FACTORY drum or disk, but not if you convert to 73/ later disc

I think we pretty much decided that "maybe" 73 and later 9" drum factory use small joints, but "maybe" the 10 front drums use large ones. Not sure. There's been discussions about that. And obviously the 73/ later disk, which are single piston, are large ball

No, I read my answer and it's correct. From the factory that's how stuff came, I clearly said the 73+ disk brake spindles use large ball joints and that 73+ UCA's use large ball joints. If someone swapped the car in the junk yard over to something else he'll have to figure that out by inspecting it anyway, since it could be almost anything if it's not stock.

"We" didn't decide anything of the sort regarding the 73+ drum brakes. 73+ 10" front drum brake spindles use large ball joints, and 73+ 9" front drums don't exist past early production of the '73 model year.

The factory TSB is pretty clear, the 10" drums were redesigned and used from ~ November 1 of 1972 for the rest of the '73 model year. The 73+ A-body 10" drums were redesigned B-body brakes, and the differences from the B-body brakes are listed 1- 4" bolt circle hub, 2- backing plate center hole enlarged to clear the '73 spindle (which had large ball joints and bearings, hence the larger center hole needed), and 3- 1 1/8" wheel cylinders to balance the A-body. The TSB clearly states that the 6 cylinder cars will keep their 9" rear drums. Before that date they weren't mixing and matching, if you had 10" front drums you had 10" rear drums, 9" front drums got 9" rear drums. The fact that the TSB says the 6 cylinder cars get 10" front drums and 9" rear drums would indicate the redesigned 10" front drums replaced the 9s and that the 9" front drums were gone after that date. As with everything Ma mopar maybe not EXACTLY that date, but the 9" drums were discontinued around that time.

You can read the TSB's here https://www.hamtramck-historical.com/images/TSBs/1973/05-03-73C page1.jpg
https://www.hamtramck-historical.com/images/TSBs/1973/05-03-73C page2.jpg

Can't he take the knuckles off an F or M body and keep the disc brakes? Lots of 5th Aves in junkyards

Yes, he can take the knuckles and use those. But those cars don't have a UCA he can use, and the FMJ disk spindles need a large upper ball joint. He said the car he's got "has no front suspension", and you can't use the control arms from the FMJ's.

 

[moparkrazed]

Thanks for all of the input everyone. I really do appreciate everyone’s help. You guys are awesome as always.