FMX vs C4 vs C6
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Senior User
Joined: Apr 2005
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From: Burkburnett, Texas
FMX vs C4 vs C6
I just figured out that my son's truck has an FMX instead of a C4 like we originally thought. The tailshaft on the FMX is cracked, so should I try and change the tailshaft or look for a C4 or C6 (running an old 302)? Does anyone know the difference in the lengths of these different transmissions; I'd prefer not to cut the driveshaft if I don't have to...
Thanks for your input,
Vern
Thanks for your input,
Vern
Elder User
Joined: Sep 2004
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From: Grain Valley Mo.
I had a FMX/302 in a Ranchero one time and never had any problem with that tranny. If the tranny is working fine other than that I'd just fix it. If you don't want to weld it, run by your local tranmission repair shop, they probably have one.
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xfordman
'53 F 100
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xfordman
'53 F 100
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Joined: Jan 2004
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From: Lancaster CA
I have run with an FMX and put it through hell. Its pretty tough and will take a licking from any kid. The tailshaft should be aluminum along with the bellhousing. Thats what mine is, any way I do believe that the tail is actually a c6 if you cant find a direct replacement for FMX. Good luck either way.
Cargo Master
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From: Somewhere Saskatchewan
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Elder User
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From: Floriduh
The FMX is a decent trans. I raced with one behind my 302 for about 2 years before I bought a small block C-6....There are very little performance parts for the FMX. Personally, I would take it out and put in a C-4.
When I changed to the C-6, I had to shorten the drive shaft by about 4 inches(if memory serves...usually doesnt though, so the exact measurement may be different) But I know I had to shorten it a bit.
When I changed to the C-6, I had to shorten the drive shaft by about 4 inches(if memory serves...usually doesnt though, so the exact measurement may be different) But I know I had to shorten it a bit.
Posting Guru
Joined: Dec 2004
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From: Shasta Lake, Ca.
Originally Posted by fatfenders56
rumor has it that it takes a lot more power to turn a c-6, but I guess that's only a factor if you have a girly motor
In 90 I hyped up a 87 Stang that had a 302 in it and changed out the tranny it had( Dont remember what it was, Just know I killed it with all the engine mods ) And I installed a C6 from a 90 F20.. It worked great .. And it was great for getting off the Line.. It smoke the tires right off the thing.. And that Little 302 did kill the C6 also... I went thru 6 tranny with that thing....
More Turbo
Joined: Nov 2003
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From: Peoria, IL (more or less)
The C6 vs. C4 debate is probably responsible for more posts & Net arguments than anything else Ford related. They both have strengths & weaknesses in factory form. The C6 does have more rotating weight, but is a physically stronger trans. Mustang guys seem to feel that they pick up about a tenth in the quarter mile by switching to a C4, in a high-hp application. On the street I doubt it makes a nickel's worth of difference. OTOH the C6 is heavier & larger, which can make a difference in some swaps.
Stuart, are you the same Stuart from the transmission forum? (I mean, how many Canadian Stuarts are there who are transmission rebuilders/experts from Saskatchewan?) If so, you know more about this subject than any of us.
Stuart, are you the same Stuart from the transmission forum? (I mean, how many Canadian Stuarts are there who are transmission rebuilders/experts from Saskatchewan?) If so, you know more about this subject than any of us.
Last edited by Homespun91; Apr 15, 2005 at 10:52 PM. Reason: typing mistake
Cargo Master
Joined: Jun 2003
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From: Somewhere Saskatchewan
Originally Posted by Homespun91
The C6 vs. C4 debate is probably responsible for more posts & Net arguments than anything else Ford related. They both have strengths & weaknesses in factory form. The C6 does have more rotating weight, but is a physically stronger trans. Mustang guys seem to feel that they pick up about a tenth in the quarter mile by switching to a C4, in a high-hp application. On the street I doubt it makes a nickel's worth of difference. OTOH the C6 is heavier & larger, which can make a difference in some swaps.
Stuart, are you the same Stuart from the transmission forum? (I mean, how many Canadian Stuarts are there who are transmission rebuilders/experts from Saskatchewan?) If so, you know more about this subject than any of us.
Stuart, are you the same Stuart from the transmission forum? (I mean, how many Canadian Stuarts are there who are transmission rebuilders/experts from Saskatchewan?) If so, you know more about this subject than any of us.
X is an unknown factor and spurt is a drip under pressure.
Well on the other hand you may be on to something.
Post Fiend
Joined: Feb 2001
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From: Iowa
Originally Posted by fatfenders56
rumor has it that it takes a lot more power to turn a c-6, but I guess that's only a factor if you have a girly motor
I believe that's a good rumor Tim. I don't know physics, but it seems easy to understand in spite of that. Go to a performance forum and you can see evidence of power loss from using different transmissions. (DYNO rear wheel power numbers). Even different manual trannys will consume more or less power.
That said, the C6 has got to be one of the toughest trannys on this earth, but a street 302 guy doesn't really need one. 95% of all 302s out there make less than 350FT/LBs of TQ. A sound C4 can handle that much power easy. (I would probably use a C6 behind anything but a very mild bigblock, but I'm paranoid).
IMO, all of the other transmissions mentioned on this thread are a better choice in this case. Anytime I have the chance to shave 50+ pounds off my truck I am going to take it.
parasitic power loss.