FMX to C4/C5 swap, and a modulator rod question...

Discussion in 'Transmissions' started by facelessnumber, Feb 16, 2012.

  1. facelessnumber

    facelessnumber Drew Pittman

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    So I drug this C5 transmission out from under an '83 Fairmont in a junkyard to replace an ailing FMX in my '73 Ranchero. It is almost indistinguishable from a C4. No idea whether it's any good, intend to find out this weekend... (Life's just no fun without that element of risk!) But it came from a grandma-fresh looking little car with a 200 inline six, so I just don't see that transmission having a hard life. I've read somewhere that all C5 transmissions were built to "V8 spec," so if that's true it should be suitable for a new life behind the stock 2v Cleveland in my Ranchero. (And if not, well, I'm out $75, some fluid and a day's work.)

    It should be alright... With the large C4 bellhousing and converter I'm going to use on the 164-tooth flexplate it already has, the overall difference in length between this transmission and the FMX is insignificant. That just leaves the yoke... I grabbed the yoke off the Fairmont driveshaft, and provided the bearing caps are the same I should be able to pop that onto the Ranchero driveshaft. If not, a conversion u-joint should take care of it. Got to fab some kind of a bracket to get the stock shifter cable onto the bellhousing since the C4 bell lacks the bolt holes for it, but that should be no big obstacle. The crossmember on this car has multiple holes to install it in different places, so no doubt one of them will work. I think it will do fine. I'm pretty sure I even have a C4 valve body around here somewhere that will help it out.

    One problem. I noticed when I pulled it, the modulator was missing. No problem, I thought, I'll get a modulator. Oh wait, there it is under the car... But, where's the rod? I'm guessing someone must have needed just the rod and pulled that sucker out for me. I've read somewhere that a certain size nail of a specific length and diameter can be used. This sound familiar to anyone?
     
  2. Jsarnold

    Jsarnold Senior Member

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  3. facelessnumber

    facelessnumber Drew Pittman

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