FMX questions (help)

[DBH69Mach1]

Hey everyone.. I was reading an earlier post about FMX vs C4 transmissions and have a few questions. First off I have a 69 Mach1 that is getting a serious facelift. The 351W is getting an edlebrock performer rebuild but I don't know what to do about the trans. It is an FMX but i was considering tossing in an AOD or maybe going to a T5. The post I read earlier mentioned that the FMX is not all that bad of a trans. If I do stay with the FMX where can I find parts and/or do I need to do anything to it if it is sitting behind about 350Hp engine? Thanks...

 

[bnickel]

i would put in a shift kit at least, if you plan on having it rebuilt have the tranny shop put in a flex band, the weakest link with the FMX is the cast iron second gear band, replacing it with a flex band (steel) will fix that problem but makes the 1-2 shift a little softer, but the shift kit will fix that. only other thing you might need would be a stall convertor depending on what cam you plan on using, most of the e'brock performer cams can be used with the stock convertor.

as far as the AOD, that would be a really good choice, however if you are still running the factory gears which are most likely 3.00:1 i wouldn't bother with the aod. if you are running a steeper gear such as 3.50 or higher the AOD is a great upgrade.

 

[rbohm]

B&M and performance automatic both should have parts for the FMX. if you decide on an AOD, the i recomend that you checl out
www.victrans.com/aod.htm
www.transmissioncenter.com/aod.htm
http://baumannengineering.com
www.lentechautomatics.com/home.htm

these site have lots of good info on modifying the AOD to suit your needs.

 

[351carlo]

I have an FMX with a Stage II BM Shift kit. It's no longer made but I was able to find it on Ebay. I waited about a month checking every week or so. Its well worth my 37 dollar investment.

 

[FasterThenU72]

trust me when i say this, i had an fmx and its a piece of junk.....dump that iron piece of crap, and switch to a c4 or a sb c6 if possible....i lucked out and found a guy nearby that would sell me a built c4 as well as make the modified adjustments to the mount, flexplate, bellhousing etc....for cheap i think its the way to go seeing as how parts for those fmxs are especially hard to find, i mean a rebuild kit alone is so hard to get ahold of b/c i think only like 2 or 3 companies still make it....and even getting a break itll still cost you round 800 to get it done. not counting a shift kit and the high heat clutches, which are nonexistent i think for the fmx as well as those kevlar? bands....If you want his number and tell him i called, im sure hell ship you a awesome one for a good price.....just to let you know cause i racked up one hell of a phone bill trying to find a good good shop, for a good price on what i wanted to do.....those are my thoughts....

 

[1969mach1351]

I had my FMX rebuilt to stock specs 5 years ago. I have since put in a 2600 stall. I have almost 100 1/4 mile passes on it @ 360 hp. The only problem is that it acts a little funny when the engine is cold. If I had the chance again to rebuild it or go C4, Id go with the C4.

 

[D.Hearne]

Trust me when I say this: EVERY C-4 I've ever had left ME on the side of the road. If you're gonna upgrade from an FMX get a C-6. Sure you may loose a few ponies, but at least it won't leave you stranded. I'd keep the FMX if you can get parts for it though.

 

[DarkBuddha]

I'll say it again... I think the FMX is a plenty sturdy piece stock compared to a stock C4 or C6 and should be fine behind a 350 hp motor. Modifying it is a bit tougher since its just not as common as the others, but you can still get it rebuilt and there are shift kits out there from places like Transgo.

Now, with regard to going with an AOD vs. the FMX... If the FMX needs a rebuild, then I say go for the AOD. A stock AOD isn't going to handle 350+ hp very well, but a well built AOD can be done for $800-$1000. Add a converter and the cost of conversion, and you'll probably be into it for $1200-$1500, an extra $400-$600 over just building the FMX.

The question becomes is the extra cost worth having overdrive? If you wanna run a steeper rear gear and plan to drive the car regularly, the answer is probably yes. Otherwise you'd probably save money going with the FMX or a well built C4 that will handle 350hp and be durable, though the C4 may require you get a longer driveshaft.

Hope this helps...

 

[Max Power]

My FMX has put up with plenty of abuse, and now resides behind a 450hp stroker. Time will tell, but I think it will be fine. C-4s can be built to be more durable with a fair amount of cash, but I don't think it is necessary for the street.

 

[DBH69Mach1]

Thanks for all the input everyone! There are certainly alot of different opinions out there! Just for further info the rear end is 3.25:1 and I want to build the car for street driving.. I doubt it will ever see the track.

 

[bnickel]

if it's just around town driving with not much highway use, i'd say stick with the FMX for now, if you decide to go with lower gears later on then an upgrade to an AOD would be well worth the money. i have the same combo you have at the moment, 351w, FMX and 3.25 geared 9" rear. i will eventually be going to a 3.70 rear gear and will build an AOD when the time comes. even with the 3.25's i got about 20-24 mpg on the highway with my old basically stock 351w 4vwith e'brock performer intake, 600 carter carb and mallory unilite conversion in the stock distributor with about 10.5:1 or 11:1 compression or so (bored .030, decked .010, 60cc heads milled .010 and fel-pro printo-seal head gaskets) i also had the cam advanced 4 degrees which worked great on the highway but really sucked around town, since i didn't really have enough cam for that compression and 4 degree cam advance.