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You guys have helped us more than you will ever imagine with your advise on the 460 heads. Now I have a tranny question. What are your thought on the FMX tranny. I just heard of it today as I am quit uneducated in all these fields but trying to learn from you guys. What is the choice among the dragracing folks?
The FMX is a very good trans, although a little heavy. It is basically an old cast iron cruiso with a newer valve body. It is the trans that was used in the automatic Thunderbolts in the early 60's. I've used several over the years and have had no complaints.
Honestly dude, I never had any experience outside of my own, but I will give you this little tid-bit. I have a '69 Cougar with a 351 all stock. I had it for a few years, but in that time I have gone through two FMX's. Granted neither one of them were new, but they would slip like crazy, and never had a good response. I suggest a c4. Its a very good all around auto trans if thats the way your going.
I toasted an original equipment FMX in a '71 LTD with a 351W. The thing never shifted very good, certainly not as quickly as you would need for drag racing. I literally burned 2nd gear out of it, as it would shift from low to 3rd without ever going into 2nd. My dad was real happy about it, the car was about a year old when it happened, and it was entirely my fault, no question about it. Well we had the thing rebuilt, but it was never right, not even as good as before. Dad traded the car for a '73 Caprice with the old FMX still slipping and occasionally missing 2nd. I guess it became the Chevy dealer's headache.
I also had an FMX in a '71 International pickup about 1979 or 80.
It had a 304 V8 and would burn rubber on the 1-2 shift. The 2-3 shift was just as hard, but I couldn't screech the tires with that one. This FMX was one tough customer, nothing like the LTD. I thouroughly abused it and it never failed to perform. I really don't understand how the same transmission could behave so differently in spite of the difference of application. As far as I know, the trans outlasted the rest of the truck.
Now, if you are seriously racing with a big torque mill like a 460, I don't think you even have a choice of transmissions. A C6 is the only way to go. C6s are very tough trannys, right up there with Torqueflites I think. I have a C6 in my '88 Bronco with a 351W, and I love it. It always shifts smoothly under light throttle, smoother than a Turbo 400 in a Buick (and that's smoooooth); and, when I romp down on it, it bangs both the 1-2, and the 2-3 like I've got an all-out racing valve body in it. I don't even have a crummy shift kit in it, the thing is totally stock. It's really a blast to put the transfer case in low range and smoke the tires all the way to high gear. I don't think you can beat a C6 for a hot Ford. Remember, they were engineered to take the punishment of a 428's torque, and that's a lot of punishment indeed.