FMX and C6 flexplates

Discussion in 'General Automotive Questions' started by handy_andy_cv64, May 16, 2019.

  1. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    '76 LTD, 400/FMX, it's on wobbly legs right now, it's abused, doesn't shift right, yadda yadda. The question is, if the trans gets replaced by a C6, is the flexplate the same? A yes answer would make things easier, but not impossible.
     
  2. aquartlow

    aquartlow In Maximum Overdrive

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    IIRC, they will not interchange. If I was removing a transmission from a 40+ year old vehicle I would replace the flexplate anyhow due to years of use and the occasional starter grind that could have happened during it's lifespan. For usually less than $40, purchasing and installing a new/correct flexplate is just cheap insurance against doing it again, just saying.
     
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  3. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Good reasoning, even if they were interchangeable. Thank you.
     
  4. colnago

    colnago In Maximum Overdrive

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    I agree. Had the flexplate crack on my '67. Took it to a shop (they had the tools; I didn't), and it cost $300.

    Joseph
     
  5. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Hey, bringing up this thread, since I was the OP, but I'm working on my friend's FMX for shifting problems, and one of the overlooked things, generally, is the governor. I've removed the gov assembly from his, and it is craptastically clogged with gunk. I'll also pull the modulator, just to check it, and then road test it tomorrow.
     
  6. Jeff B

    Jeff B In Maximum Overdrive BRONZE MEMBER

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    If you change your flex plate, does that affect the harmonic balancer or the balance it balances? (That is a technical question)
     
  7. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    The flexplate is more or less matched to the crankshaft and damper. My original question was if a C6 replaced an FMX, would the flexplate need to be changed to accommodate the trans. That means the new flexplate is still usable on the engine.
     
  8. Doc76251

    Doc76251 In Fourth Gear

    Messages:
    351
    Location:
    Virginia Beach, VA
    The flex plate is the big gear that makes the little gear on the starter roll the engine over. That said there are balanced cranks and unbalanced cranks that can use the fly wheel as a location for balance weights / holes. Replace what you took off with the same thing. The harmonic balancer in the front of the motor dampens the vibrations associated with the timing chain gears, belts and such. HB's are REALLY important to your "V"/ serpentine belts as my son found out on his Subaru when the freshly installed motor stared eating accessory belts. The HB had come "unglued" and the outer ring was walking it's back towards the engine block eating it's way into the serpentine housing.

    Cheers,

    Doc
     
  9. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Ouch. I had given my niece a '93 Taurus that ran great for me, but needed a bunch of repair work. I did all the work, she took it to college...and then the idiotic s#!t started happening. Dying when hot, and developing a wicked vibration like it was on four cylinders out of six, I had to go down to try to figure out what was wrong. I finally figured out a wire in the ignition was broken and would open once hot, and the damper ring slipped. I had to go from Salem up to Portland for a used damper because the three yards in Salem didn't have any 3.8L engines.
     
  10. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    So we had a choice: shag a flexplate from Pick 'n' Nose, or buy one. Amazon had one for $26, IIRC, so, buy, or bust your chops? Prime is really nice....
     
  11. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    So, we finally got the brakes working on the Galaxie, and moved it around to the driveway, facing the LTD. Then we pulled the engine (a 351 not a 400) and bad FMX, dropped the gearbox and swapped flexplates, and after discovering that the 460 perches are wider than the 351 perches, and getting them swapped, we finally got the engine dropped in today. In the rain. And the humidity. Now it only needs to be hooked up to the Duraspark box, mount the regulator, and hook up the wiring before we put gas in it.
     
  12. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
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    Also, the new flexplate we bought? It appears to visibly match the original flexplate, so if you decide to ditch your FMX for a C6, or drop in a 335-series (like we did for temporary) you likely should not have a problem with your flexplate.
     
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  13. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    We finally got the 351 bolted up to the mounts and trans fully, starter installed, alternator harness installed and getting ready to install the radiator. Bought a replacement dipstick tube and dipstick from a '71 Merc, but it's been misplaced....
    Took a look at hooking up the Duraspark, it's easy peasy. We'll get that and the radiator done this coming week, then fuel and a battery....
     
  14. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    "Hey, Friday...I found the snake...."

    We found the dipstick and tube. Apparently, the dipstick unloading the wagon set it on top of said wagon. It luckily stayed up there after three more trips elsewhere.:mad:
     
  15. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Sooooo...I've been working on wiring up the Duraspark harness to the Galaxie's harness. But, no sparky-spark. The engine ran before we pulled the drivetrain and harness, but of course, anything could've changed after that point, but I wanted to confirm I have it correctly wired to the 1973 harness.

    The module ON power (module's red wire) and one of the two wires from the coil connector connects to the harness coil wire (red-green stripe), and the module's START power plus the other wire from the coil connector to the ignition resistor bypass wire (brown-pink stripe). Does that sound correct? Is there anything I missed?
     
  16. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
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    Location:
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    So, found a slight problem...no spark on cranking, but once the key is released, the engine fired off. We immediately shut it down, as it's not yet ready for any running, but I checked my wiring crimps (temporary wiring right now), and found sufficient voltage during cranking.
     
  17. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    10,331
    Location:
    Seguin, TX
    As it turns out, I had my head wedged up my kazoo, and had the wiring all wrong. So I rethought the connections, put a couple items back the way they were, swapped in a starter solenoid with an 'I' terminal, then hooked the white wire to it, the red wire in under the dash to the red/green wire at the ignition switch, to pull 12 volts from there, and the coil red/white to the red/green after the junction with the brown/pink bypass, and it now fires, but now we have a fuel problem. Ugh.
     
  18. Lowrider

    Lowrider In Third Gear

    Messages:
    178
    Location:
    Kingman AZ.
    Did about the same thing a few years ago when I switched the ignition on my 57 Ford yblock from points to a Duraspark system. When I first wired it I had no 12v signal to the system while cranking. It was only by chance it would fire up when I let up on the key. Started fine once I straighten it out.
     
  19. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Location:
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    Yeah, I should've done more research instead of making assumptions. I should ask someone to do up a color-coded diagram, post it up for others to use.
     
  20. Kris S.

    Kris S. In Second Gear

    Messages:
    48
    Location:
    Tucson, AZ
    I ditched Duraspark for HEI. When I get it running (after receiving parts needed for the carb Edelbrock so nicely left out in our chat) I will let you know how it goes. Getting rid of the extra wire mess and the Duraspark box is a win in my books (unless you are keeping original Ford equipment).
     

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