Switch to disc in rear

Brakes for your Classic Mopar

  1. Originalowner73 340duster

    Originalowner73 340duster Well-Known Member

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    I have a 8 3/4 rear and want to do disc brakes in rear and better system in front ..is their a kit if so which is the way to go..and do I have to change Axel's?
     
  2. 383Scampman

    383Scampman Well-Known Member

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    There are several kits available for disc brake conversion for your 8 3/4" rear . There were several variants of the 8 3/4 and it is essential that you measure correctly . The critical measurement is from the axle flange to the face of the housing (called the brake space ) so that the caliper is spaced properly . Not difficult but important .
     
  3. Originalowner73 340duster

    Originalowner73 340duster Well-Known Member

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  4. Originalowner73 340duster

    Originalowner73 340duster Well-Known Member

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    So you must measure to get correct kit?
     
  5. Veryfastdart

    Veryfastdart Well-Known Member

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    Dr Diff makes a great F/R disc conversion.
    They are very knowledgable to fitting the correct one for you.
    Give them a shout
     
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    • AAndrews

      AAndrews Supercuda

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      I considered this upgrade but decided against it and went with Moser 4.5 bolt circle axles, and 11x2.5" rear heavy duty finned drums. Why?? Because removing the factory drum setup and going with disks removes too much weigh from the rear and further exasperates the front to rear weight bias resulting in poorer handling characteristics. In my case, I went with Alterkation front suspension and Wilwood front disk setup which is much lighter than stock. Along with the aluminium heads and intake manifold I'm taking weight out of the front and moving it rearward to even out the weight distribution. Hopefully Ill end up with a much better handling car.
       
    • Originalowner73 340duster

      Originalowner73 340duster Well-Known Member

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      I didn't consider the weight because I didn't think it would be enough to make a difference..was more worried about stopping force..but will definitely consider that in my final decision
       
    • AAndrews

      AAndrews Supercuda

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      Well , here's some other things you may want to consider as well. Your car weighs about 3200lbs. If you have disks up front and you increase the size of the rear drums, now you have even more stopping power with the 11 "drums. It was good enough for a Hemi Cuda or Roadrunner and they weighed 35-3800lbs. Remember, the front brakes will do most of the stopping anyway. A big plus is that you gain this advantage at a much lesser price , approx. 250-300.00 vs 800-1000 dollars for rear disks !!
       
    • rumblefish360

      rumblefish360 So close, yet so far away FABO Gold Member

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      this should not be the case at all. It is unsprung.
      IF anything, the disc will weigh less and allow the car to go faster.
      IF it was "Sprung weight" on the car, then you have something.

      Dr.Diff has kits that will help out. You can re-use your old wheels and tires. Not an issue. Upgraded axles can also be had at Dr.Diff but IIRC, only in the larger 5X4-1/2 pattern. Upgarding the front discs to a 5X4-1/2 is also an EZ kit away. Factory or not.
       
    • hemi71x

      hemi71x FABO Gold Member FABO Gold Member

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    • Originalowner73 340duster

      Originalowner73 340duster Well-Known Member

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      Thanks alot ..will definitely be taking his info into consideration..and the save money part is huge!!
       
    • rumblefish360

      rumblefish360 So close, yet so far away FABO Gold Member

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      I do agree with this to a point. A new proportioning valve should be used. Or an adjustable one. While itis not the end of the world, it is a helpful item to have. If cost is a consideration, stay with stock parts and retro fit them.it is mostly an E Z task.
       
    • Originalowner73 340duster

      Originalowner73 340duster Well-Known Member

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      Looking for what's best and safest not so much on saving money..but it does help to save where you can
       
    • rumblefish360

      rumblefish360 So close, yet so far away FABO Gold Member

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      Well, safer is always first in my book, but, I have no actual practical experiance with aftermarket brake systems. The stock parts have been good enough for what I was doing. Best runs were high 11's. Stopping power was not an issue @ 110+ on factory parts in a full weight E body.
       
    • AAndrews

      AAndrews Supercuda

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      I would agree to a point. The power train will have less effort in spinning lighter rotors and rebound in the suspension will be a little harsher with more unsprung weight. However, by moving more weight rearward, the vehicle moves away from being nose heavy and should handle a little better. You are still accelerating the same mass whether it is sprung or unsprung weight so Im not sure it would be faster. The biggest point I would make is that there is not enough difference made in the car's braking for the amount of money spent to convert to disk rather than bigger drums.
       
    • AAndrews

      AAndrews Supercuda

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      Yup! Have to agree here. Excellent example is that your e-body's rear brakes work fine and are completely safe. BTW , were they 10 or 11"?
       
    • Originalowner73 340duster

      Originalowner73 340duster Well-Known Member

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      Stupid question but what
      Is the e body.. thought I had a body..right??
       
    • Originalowner73 340duster

      Originalowner73 340duster Well-Known Member

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      What
       
    • rumblefish360

      rumblefish360 So close, yet so far away FABO Gold Member

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      Yes! just mentioning my E-body Cuda because it has factory braking and weighs a bit more than an A body. The "Listed" cars weight is IIRC, 3650lbs. P/S, P/B, no A/C, small block, 4 spd manual, 8-3/4 rear, S/S springs. Basic MP book build parts back from the early - mid 80's.
      No,the drums are not sprung so weight transfer is unaffected. The weight is otherwise dead mass that needs to be rotated or pushed. All of this has been writen about and proven by smart people, not smart ass smarty pants people like me.
      Stock for '73, 10 drums, small disc up front. It was a bit hairy stopping, but that is mostly a issue of nerves. Plenty of run at the strips end. A lack of vacuum has more play and is the scarry issue if it isn't there! A nervous LOL at tracks end for the new guy!
       
    • AAndrews

      AAndrews Supercuda

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      Sorry for the confusion Originalowner73, but the E body and the A-body were both available with 10"brakes. By using the backing plates and drum setup from an e-body with 11" brakes, you could upgrade to the larger brakes on your a-body.
      This is exactly what I did with my car.
       
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      • rumblefish360

        rumblefish360 So close, yet so far away FABO Gold Member

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        I did a similar move. I took the 11 inch drum set up from backing plates outwards from a Cordoba years back. I also grabbed the larger 12 inch discs. Wish I still had the disc set up! I have the drums set up.
         
      • AAndrews

        AAndrews Supercuda

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        Off the to

        Off the topic...sorry.. but that was one quick E-body for the 'eightys' !! I saw big block e-bodys run back then that you would have decimated!! Good on ya!
         
      • Originalowner73 340duster

        Originalowner73 340duster Well-Known Member

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        ..makes sense..I was lost for a second.hahaha
         
      • rumblefish360

        rumblefish360 So close, yet so far away FABO Gold Member

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        Well,
        Well, maybe! I did recieve a few real good stompings as well. I called the tech line and told them I was tired of a few ass clowns talking crap after getting whooped. After a short discusion, he told me to go with W2's and a upgraded cam &header. I never got to the W2's though. (Actually, I just picked up my first pair. Some 30 years later after the advice. But kids, house, marriage, collage, ......)
        I just followed the MP "Speed Tips" section in there publications. Get these parts, numbers listed, follow the list, skip the 6 pack, (WHOA! $$$$!!!) yadda yadda yadda.... Just lookup the part number, go down to the dealer the old club had a deal with (10% over cost on everything except cloths) and order away. 1 of the parts guys used to work on the tech line until he moved to New York. Larry was a real nice and good fella.
         
      • rumblefish360

        rumblefish360 So close, yet so far away FABO Gold Member

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        I was running this (Screwed up so it had to be welded up) MP book modified LD-340 for a long time with a big TQ and cam.
        Then I found for a stupid cheap price, the 6 pack below it. LeAnna power coated it for me as well as the MP - M1 tunnel ram.
        Then there is the W5 set up on dragging my feet on.
        YUP (I have bitten off more than I can chew at the moment. But thats OK. I don't mind these fresh parts collecting dust for a little while.)
        Soon, I'll get to play with blocks again.
        DSCN0735.JPG
        IMG_0024.JPG iPhone Pictures up to Jan 2014 173.jpg IMG_0088.jpg
         
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