Identify Disc Brakes on Dart?

Brakes for your Classic Mopar

  1. MoparGuy68

    MoparGuy68 Member

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    I have a question about a 68 Dart, that has manual front disc brakes and 14 inch wheels. The car appears originally to have had manual drum front brakes and 14 inch wheels, according to the fender tag.

    Can anyone identify what disc brakes these are from the photos?

    If a late 60's Dart that had drum brakes, is upgraded to disc brakes (that aren't late 60s vintage), will this move the front wheels out, further away from the inner fenders, causing the wheels to protrude further out of the wheel well? The front wheels on this car look like they are further out from the centerline of the car, than the rear wheels which are mounted on an 8 3/4 rear, with drum brakes.

    Aren't front and rear wheels, of same rim size (14 x 5.5) and tire size, going to be inline front to rear with a stock factory brake setup?

    I've mostly owned classic Mopars with drum brakes, so I am not very familiar with the front disc brakes and their effect on wheel positioning, spacing..

    68DartDiscSmall1.jpg 68DartDiscSmall2.jpg
     
  2. Dubob

    Dubob Well-Known Member

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    They sure look like the 73+ disc brake set up from an a body. But there are other factory set ups that will also work. Yes the disc brakes did increase the track width front to rear with the front being wider. Should be the 10.87” diameter rotor.
    Here’s an article that may help you further. It does state that the 73+ B/R and F/J/M spindles cause geometry issues. I’ve not personally used these but others here have said they have so might want to search FABO.

    DISC-O-TECH: Stop on a dime from Mopar Action and Rick Ehrenberg
     
    Last edited: Feb 7, 2018
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    • rustycowll69

      rustycowll69 Well-Known Member

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      very common complaint about the track width larger in front. It doesn't bother me that much, as long as it can stop.
      yep, that's the single piston caliper conversion you got going there.
       
    • dano

      dano Evil Handy Man

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      As stated those are 73- newer discs. Yes it widened your front track, 3/8" per side is what I call. It can be an issue depending on the car model. 67-69 Darts are some of the worst for fitment. I ended up with custom wheels because of this and going LBP rear on an A-body 8-3/4.
       
    • Veryfastdart

      Veryfastdart Well-Known Member

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      Do the aftermarket brake conversion kits move the wheels outboard also?
      Thanks
       
    • Dubob

      Dubob Well-Known Member

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      I believe any that use the factory “style” disc would. So any of the reproduction kits. When you get into wilwood etc I have no idea. It is something that’s inherent on the factory stuff.
       
    • replicaracer43

      replicaracer43 Old school member

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      The track width is wider on the front than it is the rear, regardless of which brake setup you use, but the 73 up stuff is wider than drums and small bolt disks as has been mentioned.
       
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      • 72bluNblu

        72bluNblu FABO Gold Member FABO Gold Member

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        Those are definitely 73+ disks.

        They do increase the track width, there was even a TSB about it
        02-04-73d-20p2_zpsfn5ocjuz-jpg-jpg.jpg

        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.
         
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        • Dubob

          Dubob Well-Known Member

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          Thanks I’ll add that to the history folder. I knew there was something with them, that’s why I stated it.
           
        • 72bluNblu

          72bluNblu FABO Gold Member FABO Gold Member

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          Yeah it's a real shame, because that article is very useful for identifying all the Mopar brake parts and is really helpful for doing a front brake conversion using the later 73+ parts. I mean, yes, the geometry does change if you use the FMJ spindles, but none of the doom and gloom he put in that article about using them is correct. And the FMJ spindles used to be a lot more prevalent in the wrecking yards, I hate to think how many folks passed up on an FMJ conversion because Ehrenberg speculated about the changes instead of doing his due diligence in actually checking the differences.
           
        • Mopar Tim

          Mopar Tim FABO Gold Member FABO Gold Member

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          I was one of those passers!
           
        • 72bluNblu

          72bluNblu FABO Gold Member FABO Gold Member

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          Exactly! It's a real shame, because a whole lot of FMJ conversions got melted down and turned into Toyota's instead of providing an inexpensive BBP disk conversion for our old Mopar's. Even just 5-6 years ago there were a decent number of B/R and FMJ cars in the yards. Fortunately I didn't subscribe to Ehrenberg's theory, and I pulled a few conversions out of the yards for my cars.

          At least now the 73+ spindles and brake parts are being reproduced, since they're mostly dried up in the yards, but still.
           
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          • MoparGuy68

            MoparGuy68 Member

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            Thanks for the responses guys!

            Is the "track width" different from front to rear only on A-Bodies?

            I owned a 71 Challenger for over 12 years, and never noticed a difference in width from front to rear.. This Dart, I could tell when I first laid eyes on it..

            After reading all the replies, it seems like I should have had some issues with wheels on my Challenger that I didn't have..

            The Challenger had its factory manual drum brakes front and rear. It came from the factory with 14 x 5 steel wheels, with dog dish caps and trim rings. I had 225/70/14 tires mounted on them.

            Back in 1992, I wanted to replace those wheels with 15 x 7 steel wheels. I knew absolutely nothing about small bolt pattern / large bolt pattern, or that there even was such a thing or a difference. I went to two junk yards in Southern California, where I was living at the time. The first yard had a pair of 15 x 7 wheels marked as coming off a "73 Dodge Van". The second pair of 15 x 7, that I found, at another yard, were marked "77 Chrysler Cordoba".

            The 73 Dodge Van wheels would mount on my Challenger's drums both front and rear without issue. The 77 Cordoba rims would only mount on the front drums, they would not mount on the rear drums. So the Van rims were on the rear, and the Cordoba rims on the front, for the last 6 years I owned the car, with my factory dog dish caps mounted on them, sans trim rings. All I needed to do to the rims, was have them sandblasted, then I painted them the body color GB5 Bright Blue Metallic. I mounted 245/60/15 Goodyear Eagle ST tires on them and the car looked pretty cool after that. Only issue was my turning radius was reduced somewhat with the wider rims / tires on the front.

            From what I read, it sounds like my 73 and 77 rims should have been large bolt pattern, and my car's drums and original wheels should have been small bolt pattern..

            And I just don't recall ever noticing any difference in track width from front to rear.. And I looked at the car a lot! I never tired of looking at it lol.
             
          • RustyRatRod

            RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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            I think the added width in the front adds a certain amount of stability. 3/8" per side is certainly nothing I would ever think of complaining about. Especially for good brakes.
             
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            • rustycowll69

              rustycowll69 Well-Known Member

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              70-74 Challenger is an E-body, and they are all big bolt pattern. It's sister E-body car was the 70-74 Barracuda, which was also big bolt pattern.
              I believe all early, and some later A-body 63-"about" 72 cars came with small bolt pattern, drum and 4-piston disk brakes. The gray area comes when Ma Mopar began to install the single-piston floating caliper disks around '73(I think). They changed to BBP on the A-body cars with the optional single-piston floating caliper installation. Of course, in order to have BBP rear wheels to match, those cars had to come with BBP rear axles. I THINK, they came with the so-called 8-1/4" rear axle. I don't think there ever was an OEM A-body BBP 8-3/4" rear axle. I believe at some point, maybe '75 they ran out of all the SBP drums, and axles and ALL the last A-bodies came with just BBP.
               
            • 72bluNblu

              72bluNblu FABO Gold Member FABO Gold Member

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              The 5x4", small bolt pattern wheels only came on A-bodies, nothing else. All B/E bodies came with the 5x4.5" bolt pattern, so did the C bodies and the later R and FMJ bodies, most vans, all the half ton the trucks, you get the idea. Your '71 Challenger would have been BBP regardless of what brakes it had.

              As far as the track width difference front to rear, it's not unusual. A-bodies have a much larger front to rear difference than the other Mopars of the era though. The E-bodies were pretty close to the same front to rear for track width.

              The A-bodies all had the 5x4" bolt pattern up through 1972, drum or disk. In 1973 the disk brakes were redesigned to be more uniform across all the car platforms, using single piston calipers and the same rotors, wheel bearings, and upper ball joints. So, all of the A-bodies 73+ with disk brakes were BBP, and they could have either a 7.25" rear axle, which also came in BBP starting in 1973, or the 8.25 rear axle, which were all BBP. There was never a factory BBP 8 3/4 A-body rear axle, 1972 was the last year for 8 3/4's in A-bodies. The weird part was that the front drum brake equipped A-bodies continued to be SBP even after '73. The spindles changed, so they used the same large ball joint UCA as the disk brake cars, and larger wheel bearings, but the front drums stayed SBP. All of those cars had /6's and 7.25" rear axles. V8 cars all got disk brakes from 73+, so, they were all BBP cars. Even /6 cars with certain options got disks and the BBP rears, my /6 '74 Duster did. The SBP drums went away for sure in January of 1976, when a federal mandate kicked in and all cars went disk in the front.
               
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