FMX to C6 swap?

[1973mach1]

Has anyone ever done a FMX to C6 swap? Is this the route to go if IM planning a 400+HP 351c 4v build? I have a chance to buy a c6 with 5k miles on it, the tranny has a shift kit and a tranny kit. He said it was always used as a street car daily driver and never raced. Is there alot involved in the swap? Will the driveshaft I have now fit? Or should I hold out and try to find a C4? Will I need to change all the linkage and that stuff or will it bolt right in?

Thanks,
Jim

 

[69stang351]

Well seeing as noone has replied to this post, I figure it's time i must...

For starters, why in the heck would you want to swap out one of the most heavy duty trannies out there for a light duty C6 or C4?? I say the FMX is better for your setup with the 400+ HP 351c 4v because it will take more and wont wear out as easily as the C6 and the C4 will. That is why they put the FMX in the police interceptors and the mach1s because they have bigger engines and more power, so they need something that can take some heat and be powerful. This is just from my experiences though, someone else might want to add to this or correct me if I'm wrong... which I'm pretty sure I'm right on this one...

 

[GaPonyFarm]

You're right about the FMX... You can't hardly break one with a sledge hammer. The only disadvantage is weight, but in a 400 hp 351, I'd gladly swap pounds for reliability.

I'd use a C4 before I'd use a C6.

 

[dartthower]

no kidding.i'm at the same point.ive always heard that an fmx wont stand up to the hp.i'm stroking my 351 to 393 in a 69 mach 1.i was looking for a trany to replace my fmx. do i need to rethink this or what?

 

[69stang351]

no kidding.i'm at the same point.ive always heard that an fmx wont stand up to the hp.i'm stroking my 351 to 393 in a 69 mach 1.i was looking for a trany to replace my fmx. do i need to rethink this or what?

No, I think you misunderstood what GaPonyFarm and I [69stang351] were saying, the FMX is one of the strongest automatic trannies out there, in other words, dont swap a C6 or C4 for it if you have a high output engine or are planning on building one... the FMX is the way to go with lots of HP, am I right GaPony??

 

[1973mach1]

Thanks for the reply's The only reason I was planning on swapping is I hear alot of crap about them, people saying how bad they were and a few told me that it would fall apart the first time I ran it at the track. Usually the first thing I hear after I say I have an FMX is dump that thing. I really cant afford a new tranny so im glad to hear someone say keep it. Dind't they use C6's behind most of the big blocks though?

Thanks,
Jim

 

[Edbert]

I'm not claiming to be an expert on them but I've heard for the last ~20 years that the FMX was crap and should be removed in favor of ANYTHING but a 3-speed manual. In other words you'd better seek professional advice!

As far as the C4/C6 goes...they are the way to go unless you decide 3 speeds arren't enough. A C4 with the proper parts can take 1,000HP and weighs considerably less than the FMX or C6.