Identify Disc Brakes on Dart?
Those are definitely 73+ disks.
They do increase the track width, there was even a TSB about it
And as you can see, not even the pre-73 track widths matched front to rear. That was true for both the drums and the earlier KH disk set ups as well.
In the back, the next question is if your bolt pattern matches. You car had the 5x4" bolt pattern from the factory, your front disk brakes should have the 5x4.5" bolt pattern. So, either your bolt patterns aren't the same front and back, or someone has also changed the rear brakes and axles as well. They can either be re-drilled SBP axles and brakes, or possibly have been upgraded to the later 10x.2.5" BBP brakes and axles. The BBP brakes and axles also increase track width compared to the SBP stuff.
While that's a great article for identifying brake components, Ehrenberg was completely wrong about the geometry issues with the B/R and F/M/J spindles. That was something he just speculated, and he never bothered to actually check. Because if he'd bothered to check he wouldn't have said any of it.
Fortunately, someone actually DID bother to check the change in geometry of the FMJ spindles compared to the 73+ A-body spindles. The result was that the change is minor, and depending on you application, possibly even beneficial. Ehrenberg was wrong about the geometry of the FMJ spindles.
Here's the article and the actual geometry numbers
Swapping Disc-Brake Spindles - Mopar Muscle Magazine
The majority of aftermarket brake kits increase the track width by some amount. It depends on the kit and manufacturer. Obviously anything based on the 73+ mopar disks moves them out the same amount as the factory 73+ disks. But most of the wilwood kits change the track width as well, you have to check the specifications of the kit you're going to use because many of them change the offset different amounts depending on which kit it is.
Those are definitely 73+ disks.
They do increase the track width, there was even a TSB about it
And as you can see, not even the pre-73 track widths matched front to rear. That was true for both the drums and the earlier KH disk set ups as well.
In the back, the next question is if your bolt pattern matches. You car had the 5x4" bolt pattern from the factory, your front disk brakes should have the 5x4.5" bolt pattern. So, either your bolt patterns aren't the same front and back, or someone has also changed the rear brakes and axles as well. They can either be re-drilled SBP axles and brakes, or possibly have been upgraded to the later 10x.2.5" BBP brakes and axles. The BBP brakes and axles also increase track width compared to the SBP stuff.
While that's a great article for identifying brake components, Ehrenberg was completely wrong about the geometry issues with the B/R and F/M/J spindles. That was something he just speculated, and he never bothered to actually check. Because if he'd bothered to check he wouldn't have said any of it.
Fortunately, someone actually DID bother to check the change in geometry of the FMJ spindles compared to the 73+ A-body spindles. The result was that the change is minor, and depending on you application, possibly even beneficial. Ehrenberg was wrong about the geometry of the FMJ spindles.
Here's the article and the actual geometry numbers
Swapping Disc-Brake Spindles - Mopar Muscle Magazine
The majority of aftermarket brake kits increase the track width by some amount. It depends on the kit and manufacturer. Obviously anything based on the 73+ mopar disks moves them out the same amount as the factory 73+ disks. But most of the wilwood kits change the track width as well, you have to check the specifications of the kit you're going to use because many of them change the offset different amounts depending on which kit it is.