how to guide for 7 1/4 to 8 3/4

Discussion in 'Transmission and Drivetrain Tech' started by CrazyPete, Apr 14, 2012.

  1. CrazyPete

    CrazyPete Well-Known Member

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    is there a reference out there for doing this swap? i know it seems pretty simple i just wanna know what im in for
     
  2. roadrunnerh

    roadrunnerh Well-Known Member

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    I'm in the middle of this right now. Do you have questions? Maybe I could help?
     
  3. Bad Sport

    Bad Sport HALF A BUBBLE OFF Staff Member FABO Gold Member

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    Fire away with the questions, it has been done a bunch around here.

    First of all what car? Is it an A body rear that your swapping in?
     
  4. CrazyPete

    CrazyPete Well-Known Member

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    ok heres my project my swapping car is a 76 dart sport was a /6 car now has a 383 a/t it has the crappy 7 1/4 i have a project/donor car im getting the 8 3/4 from which is a 63 dart that was a makeshift project car back in the 80's the guy got parts he claims were from a 69 dart gts which included a 360/340 4 speed and a 8 3/4 rear end well ive already sold the 4 speed set up now i wanna swap in the rearend. Its a 741 weak pumpkin but what i need to know will the springs bolt up to my 76? I have several 489 housings ready to bolt in the rear also is sbp so i figured id order axles from dr diff sometime i wanna know if theres a simple pic filled guideline to removing the springs from the car to make my swap nice and easy any tips welcome
     
  5. ef8340

    ef8340 Well-Known Member

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    it should be simple take a part off put a new part on
     
  6. RedFish

    RedFish Well-Known Member

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    Unbolting the rear spring hangers then the forward spring hangers, rolling the whole thing out from under the car at once sounds easy enough but... You'll need some very tall stands if you dont have a lift.
    For some spending another 35 bucks for new U bolts is the best plan.
     
  7. sireland67

    sireland67 Well-Known Member

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    Start soaking the bolt a week or two before you are going to swap them out.
    Take the tension off of the emergency brake cables, and un hook each emergency brake cable.
    Un hook the rubber brake line where it comes down to the rear axle.
    Remove the four bolts from the drive shaft.
    There are four nuts on the front of both spring hangers, and two on each rear hanger, remove them for each spring. Pay close attention on which way the front hangers are oriented, if you switch them from side to side it will lower the car 1".
    The rear end is now ready to take out of the car.

    Your brake drums, brakes and backing plates will bolt right on the 8.75 axle, this will give you big bolt pattern brakes, and most likely 2.5 x 10" brakes. This requires the use of Dr. Diff axles.

    Download the factory service manual which will show everything. The manual is a sticky somewhere on this site.
    It is really pretty easy if you know the basics, and have a shop manual.
     
  8. roadrunnerh

    roadrunnerh Well-Known Member

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    You may want to purchase the following parts depending on condition of these on donor car, and how far you wanna go. Here's a list of what I replaced and parts I purchased:
    rubber brake hose, axle vent screw, rear axle brake lines, 20 axle/carrier nuts, a set of BBP axles from dr diff, inner axle seals, pinion seal, yoke straps, U-bolts, shock plates, shock washers, gear lube, 2 new U-joints,
    I also bought new drums, brake hardware kit with adjuster kit, and new brake shoes.
    Do you plan on cleaning up the housing and carrier, backing plates?
    You may have to get the driveshaft resized.
    I ended up getting more parts and farther into it then I initially thought I would. But I tend to be a little obsessive/compulsive....lol
    The work itself is pretty easy, you shouldn't have a problem.
     
  9. CrazyPete

    CrazyPete Well-Known Member

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    sweet thanks guys never done it is all ive replaced tons of gears axle brakes but never the whole assembly it seemed pretty simple just wanted some tips ill snap pics and do a write upas far as the brakes i got a big drum set up off a 69 newport that should stop the car very good
     
  10. Dartnut

    Dartnut I'm H.R. Shovin'stuff FABO Gold Member

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    Sounds good.
    Remember, you'll have to shorten your drive shaft.
     
  11. sireland67

    sireland67 Well-Known Member

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    If they are 11" make sure the drums are in good shape.
    11" drums are worth their weight in gold.
    Re-man ones are over 100 bucks each.
    10" you can buy two and still take your lady out to a good dinner.
     
  12. krazykuda

    krazykuda FABO Gold Member FABO Gold Member Technical Editor

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    You will need to replace the stock shock plates with 8 3/4 ones, U-bolts, and shorten the driveshaft approx. 2".
     
  13. CrazyPete

    CrazyPete Well-Known Member

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    got the old 8 3/4 out today pretty simple thank god the bolts that were on there were ingood shape...except one whoch was rounded off so it fought my cut off wheel for about 45 min.............next up is removing the the 7 1/4
     
  14. CrazyPete

    CrazyPete Well-Known Member

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    Ok im at the rear shackles do i just cut one of the studs or try to unbolt it from the frame? Im just worried about breaking the bolts
     
  15. sireland67

    sireland67 Well-Known Member

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    Unbolt the two nuts, the shackle is just a "C" with a plate on the side.
    Slide the shackle out.

    Reference mancini's racing website for an illustration of the shackle.
     
  16. CrazyPete

    CrazyPete Well-Known Member

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    simple thanks man so far everything has unbolted pretty easy the E brake cables unhooked easy too even the brake line came right off btw the car is completely original still had stock shocks which were bad its nice having an old car that comes apart easy FINALLY!
     
  17. CrazyPete

    CrazyPete Well-Known Member

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    well got it out today pretty easy o gotta say the oly issue i had was the shackles there studs not through bolts so i thought it would be a good idea to remove the shackle plate..Wrong needless to say i broke a bolt not a huge deal i guess just gotta drill it out and put a new bolt in.

    pics thanks again for everyones help and advise
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