MIRADA FLEXIBILITY

J Body General Discussion

  1. CM360

    CM360 Well-Known Member

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    Cam across 1980 Mirada /6. Car is in reasonable shape. Are these cars as foreign to the B body as the F to the A body? I'd like to put a 360 in it. K member change? What B body 8 3/4 would be a direct swap? Overall weight of a Mirada? Thanks
     
  2. 80mirada

    80mirada Well-Known Member

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    Schumacher makes conversion mounts to drop in a v-8, otherwise all fmj k-members are interchangeable. Miradas run from 3300 to 3600 pounds depending on options. 66-67 fits the best, next is the 68-70 b-body rear. Other years can be used, depending on what you are willing to do, 71-79 can be used if a deeper back space wheel is used, and pre 65 rears can be use if you either are willing to deal with the odd hubs or do a shaft and brake change.
     
  3. Joe12459

    Joe12459 Well-Known Member

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    66-70 B Body 8 3/4 is an easy fit. I used a 67 with B Body shock mounts, but you can keep the iso setup as well.
     
  4. CM360

    CM360 Well-Known Member

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    Can you use the B body SS spring if moving to a 8 3/4 or Dana 60?
     
  5. Joe12459

    Joe12459 Well-Known Member

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    I don't think the B Body spring is the right dimensions. I know you can use E Body springs if you use different front hangers (Firmfeel has the hangers). I just bought a new set of heavy duty J body springs from ESPO Leaf Springs, Coil Springs and Suspension | ESPO Springs n Things
    and used B Body shock plates. I had a new set of perches, so I welded them in the right position on the 67 housing, but a slight modification of the existing holes, less than a half inch, is all that's necessary.
     
  6. 4speedjim

    4speedjim Well-Known Member

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    Its not a Mopar, I know. But it is a piece of cake. An 8.8 out of an Exploder, any Exploder will do. '95 up are 11.25 disc brake, and have cable parking brakes that connects to your current cables. Same exact width, and bolt pattern as you stock axle. Spring perches are .25" inboard of J bodies, slop takes that up. And there cheap. All over for $200 complete with rotors and calipers. I live near Buffalo. Don't know if it matters, but lots of them around here have posi. All Exploders have 31 spline axles. I think they come with like 3.08 - 4.10's. Most I see were in the 3.20- 3.55- 3.73 range. Same size ring and pinion 8.75" vs 8.80". Incase you finished the car and haven't landed an 8 3/4. The 8.8 with disc brakes is a very solid substitute.
     
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  7. Oldiron440

    Oldiron440 Well-Known Member

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    I used the 8.8 from an Explorer in my Ford, I had Quick Performance in Ames Ia. narrow the housing weld on Billet 9" ends and weld the tubes to the center. $300 A pair of axels $300, clutch kit for limited slip $70 I replaced the brakes with disks $325
    total cost $995
    cost of 8.8 from yard $100
    grand total $1095

    The 8.8 is a strong rear axel assembly, there are Fords in the 8 and 9s on stock gears.
     
  8. BudW

    BudW Moderator Staff Member

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    https://www.dippy.org/forum2/index.php/topic,209.0.html
    Is a good source for leaf spring details.

    Note: Changing differential does not directly affect the leaf spring usage (or vice versa) - with one minor detail/exception.

    The differentials that use Iso-Clamps have a bigger hole to locate itself on the spring pin. The Iso-Clamp cars, the hole is (I think) 1-7/16” (but might be off). The pre-IsoClamp differentials have a ½” hole (again, I think – but might be wrong).

    It is not too hard to make differential perches at 1-7/16”, if wanted – but personally, I highly recommend tossing the Iso-Clamp system as far as you can toss it. The pre-IsoClamp shock plates are easy to find, a lot less complicated, less prong to failure and will make car handle so much better.

    If using a FMJ differential and using the older shock plates, then a person will need to find or make something to fill the 1-7/16” hole with and weld it into the existing holes. Then drill a ½” hole in center of your gap filler.

    If using a ’65-70 B-body differential, elongating the holes 0.22” outwards, per side – will do the trick.
    I have discovered that spring flex will allow you to install a ’65-70 differential without any modifications at all.
    Matter of fact, a ’66-70 B-Body Dana 60 will bolt right in place – if a person wanted something stronger (and had a lot of extra coin burning a hole in your pocket).

    Just keep in mind that propeller shafts are different lengths for no matter what differential you use (ie: 7¼” prop shafts are longest, 9¾” (Dana 60) would be the shortest, 8¾” next shortest, 9¼” middle length and 8¼” second longest).
    I don’t know how the Ford 8.8” falls in there – but a safe bet is you’ll need a different length shaft than what you currently have on hand.
    BudW
     
  9. BudW

    BudW Moderator Staff Member

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    On a different but related note: this TSB is for ’69 Road Runners/GTX with 383 4-bbl, 8¾” differential and with a 4-Speed.
    The TSB says “. . . The 3.91 ratio 8-3/4” ring gear sure-grip with 383 cu. In. (4-bbl.) engine and 4-speed manual transmission, only slightly exceeds our durability standards”.

    It goes on to say “If you should experience any structural failure of gears, shafts or housings within warranty, the axle should be replaced with a 4.10 ratio, 9-3/4” ring gear “Dana” axle”.

    I respect the Dana-60 differential – for it is one extremely tough unit – but expensive (and heavy).
    After reading this TSB and looking at what some of the cars are driving now (500+ strocker big blocks) and using much much better tires than they had then – I wonder if the factory is trying to tell us to, um, go Dana 60?
    AIFB 913 p1.jpg
    AIFB 913 p2.jpg
    BudW