Hi Guys,

Which transmission is stronger? FMX or C4. I just had a chance to buy a transmission for a back up, but was wondering which is the better choice for a 4bbl 302.

Thanks

 

Both bone stock? Gonna have to say the FMX.

I'm no expert, however. I do know that These guys are experts and give great info.

I've recently built a C4 w/ a PA street /strip valve body and after my problems were resolved, it is doing as advertised by my builder behind my 289.

 

the FMX is what was used before the C-6, but its pretty heavy I think. Youd be better off with the C-6 for availability of parts and more importantly aftermarket stuff. Try and find a nice cast aluminum pan for an FMX!

 

get a nice race prepped c4 if ur worried about it breaking i the fmx is heavy and costs a lot more to beef up and have to do some searching to find parts

 

Thanks guys. Nice car Bulldog.

I just found out that Ford made a smaller C4 bellhousing for Mustang IIs. I measured the bellhousing on the FMX, and it is deeper than my current C4 transmission. The FMX might be from a truck, not really sure, as it has the torque converter, but don't know how big the flywheel was. 157 tooth vs 164.

 

I would get a C4, since that's what you have now. Then, you don't have to worry about the bellhousing...just transfer it from the one in your car should you need to do a swap...

 

i like c-4 and c-6 but i wish they had overdrive and i know you can buy an overdrive for either one but for the money of the overdrive you could buy a noce aode and beef it up strait from the junk yard

 

If you have a C4 and dont have a high output engine, like over 350hp a C4 with a stock rebuild will work fine for a long time.

The C6 was designed and built YEARS before the FMX was, way back in the 60s. FMX was behind the Cleveland and some 351 Windsors. It will handle plenty of abuse, but they tend to leak because cast iron and aluminum expand at different rates, and the FMX has iron main body with aluminum tail shaft extension and bellhousing. A stock pan with the gasket done correctly with a resonable amount of RTV will seal up just fine.


The difference between an AOD and an add on OD like Gear Vendors is strength. Sure you can build an AOD to handle massive power, but doing so will far exceede the cost of the GV unit. Building a C6 to handle serious power isnt all that expensive, and the price comes out about the same but a little less than a max build on AODs but without the split input shaft issues and no lock up converter.

A stock AOD is good for 350-400hp, provided you arent using a high stall converter and you have the tougher inner input shaft. More power means you need to get rid of the split input and use a solid billet one. I cant remember where the power break is, but its there.. lol