Disc question

-
D

DusterOnaDime

Member
Joined
Aug 5, 2024
Messages
21
Reaction score
27
Location
minnesota
I have a 73 duster with the 5x4 pattern in the front. I bought a set of used complete spindles with the rotors and calipers still attached off of a 73 a-body. Can someone tell me if these will bolt right in meaning balljoiints and stuff will interchange. Thanks in advance
 
Last edited:
I believe the 73 will be bbp, but it's a complete setup so u should be good? Oh longer flex hose is needed I believe.
 
DusterOnaDime said:
I have a 72 duster with the 5x4 pattern in the front. I bought a set of used complete spindles with the rotors and calipers still attached off of a 73 a-body. Can someone tell me if these will bolt right in meaning balljoiints and stuff will interchange. Thanks in advance
Click to expand...

What is the bolt pattern of the 73? That was a transitional period.
 
doug 371 said:
No. You will need upper control arms or upper ball joint adapter sleeve. You need to use the 73 lower ball joint also
Click to expand...
So my 73 small bolt pattern drum, uses different ballpoints or control arms than a 73 big bolt pattern does? I believe that’s what your saying?
 
DusterOnaDime said:
Mine has the 5x4” drum setup. A buddy gave me a set complete 73 spindles with the 5x4.5
Click to expand...
the 73~76 spindle uses a larger ball joint than the earlier 64~72 smaller bolt pattern. so you either need 73~76 upper control arms with the larger ball joint or you need "ball joint adapters" that enable you to use the small ball joint upper with the larger spindle.

everything else bolts on.
 
4spdragtop said:
You'd think I'd learn to keep my mouth shut and oven mitts on! :lol:
Click to expand...
haha! I too have put my foot in my mouth more times than I care to admit. I always "thought" that 1972 was the cutoff year on most sbp stuff when it comes to brake and suspension parts. I'm a bit more cautious now in my old age before I speak and have to chew on my toes again.
 
The 73 was the first year for BBP with disc brakes, with drums you still had SBP till 76 I believe. So I would say the 73-76 drum brake setup still used the small upper ball joint.
 
lemondana said:
The 73 was the first year for BBP with disc brakes, with drums you still had SBP till 76 I believe. So I would say the 73-76 drum brake setup still used the small upper ball joint.
Click to expand...

Except it didn’t.

The 1973-1976 drum front brakes remained SBP, but the spindles and drums changed over in November (ish) 1972 (73 model year production started August 72). From that point on all the A bodies used large upper ball joints. Disk brake cars were large ball joint and big bolt pattern, drum front brake cars were large ball joint but remained small bolt pattern until front drums went away entirely.
 
72bluNblu said:
Except it didn’t.

The 1973-1976 drum front brakes remained SBP, but the spindles and drums changed over in November (ish) 1972 (73 model year production started August 72). From that point on all the A bodies used large upper ball joints. Disk brake cars were large ball joint and big bolt pattern, drum front brake cars were large ball joint but remained small bolt pattern until front drums went away entirely.
Click to expand...
Thanks-I didn't know that. I have never dealt with the 73-76 drum brake setup.
 
junkyardhero said:
the 73~76 spindle uses a larger ball joint than the earlier 64~72 smaller bolt pattern. so you either need 73~76 upper control arms with the larger ball joint or you need "ball joint adapters" that enable you to use the small ball joint upper with the larger spindle.

everything else bolts on.
Click to expand...
But mine is also a 73. Just with drums and sbp. So ur saying the ball joints are the same size in 73 regardless of disc or drums?
 
DusterOnaDime said:
But mine is also a 73. Just with drums and sbp. So ur saying the ball joints are the same size in 73 regardless of disc or drums?
Click to expand...

Depends on whether or not your '73 was built before ~ November 1, 1972. If it was built before 11/1/72 then it is probably small ball joint and you will need ball joint adaptors or large ball joint UCA's. If it was built after 11/1/72 then it most likely has large ball joints and the 73+ disk spindles will bolt up to the UCA's. It's Ma Mopar we're talking about, so that date may have exceptions. If it's right around 11/1/72 it could be either one, but the further away from 11/1/72 you get the more likely it will be one or the other.

You can also check the actual drum brakes that you have. If it has 9" drums, you have a small ball joint. If it has 10" drums, then the small ball joint drums will be 10x2.25" and use smaller wheel bearings. If you have large ball joint drums the drums will be 10x2.5". It's in a factory TSB that can be seen at hamtramck-historical

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


05-03-73C page1.jpg


05-03-73C page2.jpg
 
lemondana said:
The 73 was the first year for BBP with disc brakes, with drums you still had SBP till 76 I believe. So I would say the 73-76 drum brake setup still used the small upper ball joint.
Click to expand...
Welp, the disc brake setup bolted right in. So my 73 with sbp obviously uses the same ball joints as the 73 bbp.
 
DusterOnaDime said:
Welp, the disc brake setup bolted right in. So my 73 with sbp obviously uses the same ball joints as the 73 bbp.
Click to expand...

So you have the 73+ 10x 2.5” drums with the later spindles and UCA’s.

Just FYI, that particular set of spindles is used for several aftermarket brake kits, and is more desirable than the 67-72 10” drum spindles.

4spdragtop said:
You would have to measure to be sure. Maybe you got lucky and the stuff u bought was from early 73 build? Either way, that's awesome! :thumbsup:
Click to expand...

If he’s got BBP disks then it’s not a small ball joint set up, it would have to mean his drums were large ball joint. Which most ‘73’s were.
 
72bluNblu said:
So you have the 73+ 10x 2.5” drums with the later spindles and UCA’s.

Just FYI, that particular set of spindles is used for several aftermarket brake kits, and is more desirable than the 67-72 10” drum spindles.



If he’s got BBP disks then it’s not a small ball joint set up, it would have to mean his drums were large ball joint. Which most ‘73’s were.
Click to expand...
so are they worth hanging on to? I couldn’t get the drums off when I wanted to measure the brakes like you were talking about. So I just removed the entire assy. I was just going to toss them, cuz I figured no one would want drums
 
DusterOnaDime said:
so are they worth hanging on to? I couldn’t get the drums off when I wanted to measure the brakes like you were talking about. So I just removed the entire assy. I was just going to toss them, cuz I figured no one would want drums
Click to expand...
But thank you for your great knowledge
 
DusterOnaDime said:
so are they worth hanging on to? I couldn’t get the drums off when I wanted to measure the brakes like you were talking about. So I just removed the entire assy. I was just going to toss them, cuz I figured no one would want drums
Click to expand...

The spindles are. I'm not sure if anyone wants the drums/hubs, they are unique to the 73+ drum set up though. The drums will be swaged onto the hubs, but you should be able to remove the whole hub assembly from the spindle by removing the wheel bearings.

It's not like they're "gold mine" type parts but people do look for those particular drum spindles because of their use with some of the aftermarket disk brake kits.
 
DusterOnaDime said:
So my 73 small bolt pattern drum, uses different ballpoints or control arms than a 73 big bolt pattern does? I believe that’s what your saying?
Click to expand...
maybe, if it is a very early build '73 and they were using up '72 parts.... my drum brake '76 used the same UCA and ball joints as the disk brake setup.
 
You must log in or register to reply here.
-

Back
Top