Jimmy

Just purchased a 70 Mach 1 for the wife and it goes in for body work this winter, while drivetrain is out plan on upgrading a few thing such as rebuilding rear from a open 3.00.1 to a posi with 3.50.1, then adding some upgrades to the engine which is bone stock to get a little more HP but I've been told the FMX trans is a weak link to any performance gains elsewhere. So I was going to find a C4 as I don't think I will need a C6 as she is not going to race it but if I'm behind the wheel who knows.

My questions are can the FMX to C4 swap be done in this car, what cars and years should I be looking at for a donor and is this a bolt in deal or are major complications ahead ?

69mach1377

I cannot break my FMX no matter how hard I try...it is not the weak link, but is damn heavy because of its cast iron case. I did more than add a little more HP to my engine as you can see. The hard part for the FMX is getting a shift kit and torque converter, hard to come by. The C4 is weaker in stock form, but can be built up by throwing $$$ at it. That is why it was used on 302s and smaller...

Jimmy

Thanks for that info,so if I keep the FMX you are saying I will have a hard time getting the shift kit & converter, so I take it B&M or TCI don't offer these. Do you have any sources that I could look into, I have the time as this project will not begin until November. Thanks for any info you can offer.

Jimmy

harald

hi jimmy, just wanted to say that 69mach1377 is right about the parts being hard to come by, but i did see an advert somewhere not too long ago about shift kits for the fmx.... will look into it and let you know if i find it.

have fun with the project, (but i wouldn't buy it for my wife haha)


harald

73Cleveland

Hey 69mach, Ditto on the durability of the FMX! I have never took things very easy in my 73 Mach and have never had problem one with it (knocking on wood). I'm guessing my car is a bit heavier than yours so if it can take that kind of punishment, it has to be a decent tranny. I haven't tried to find parts for it cause I've never had to. Just changed the fluid & filter.

Harald, I know what ya mean about not wanting to buy something like that for the wife!

69mach1377

Mine has a B&M shift kit, but it was one of the last ones in the country quite a few years ago. It made a huge difference in shifting speed and quality. Maybe transgo makes one now.
My converter was built by a local converter dude who knew what he was doing, but I've seen one in the SummitRacing catalogue that should be fine.
Good luck on your project...

jrrhd73must

The FMX was originally built as a beefier transmission for the Shelby. Since they quit making that line, the started using them up by stuffing them into the 71-73s. The case is stonger than the C6, however it is harder to find upgrades.