Ok guys, the time has come to wake the old '78 up from hibernation. Her main problem at the moment is that she has only 1 forewrd gear (1st), and no reverse. The last time I had the FMX rebuilt the shop that did it, as far as I can tell, locked out second gear (I was 18 at the time, needed the car fixed in a hurry, and the place took advantage of me big time!), and the thing lasted until the warranty was up, then started acting up. I've got two other FMX transmissions, one recently rebuilt and the other with 30,000 miles on it since a rebuild (or so says the guy I bought them from). Now, I'll have a little quality time to spend with the car over Christmas, and I'd like to swap the one in the car our for one of my other transmissions. I've never done anything more in depth than alternators, water pumps, ect. Is this simply going to be an unbolt-the-old-one-and-bolt-in-the-new-one proposition, or is there more to it than that? Anything that's not obvious to a first timer, I need to know before I take my car apart. Will the engine mounts hold the engine up without the transmission, or do I need to support it with something? Thanks for any advice.

My FM3 (predecessor to the FMX) has a torque convertor with a 1 3/8" hub and 8 1/4" center to center on the converter bolts. Most V8 C4's have a converter with 1 1/2 hub and 7 1/2 between converter bolts. I recently discovered that the 12" lockup converter on the C5 has 1 1/2 hub and 8 1/4 in on the converter bolts, so you might be able to bolt up a C5 without changing flywheels. The only difference I can find between a C4 and a C5 is the diameter of the bell housing and the converter. C4-C5 have different valve bodies and modulators, but either will work with either bell housing and converter, total interchange. As far as length goes, it is pretty close, you may have to put a transmission plate (sheet metal) from your crossmember to the rubber pad on the transmission like I did, but the reason mine was moved forward was the C5 converter housing didn't fit under the car floor ('59) and I moved the engine forward 2" to compensate. The shift lever is a bolt up but you will have to kluge the kickdown lever- hint on the FM3 the lever is very important, as is sets the shift points like a modulator, but on the C4/5 you can leave it unconnected if you don't need the kickdown feature.
I wish I knew 2 weeks ago, I was in Texas and have been kind of looking for a cheap rebuildable FMX to put in my '57 bird, since the FM3 went underwater in the flood. Note FMX parts are still available, but it takes a good shop to want to deal with something they don't work on a lot. Sonny's Tmission on Campbell in Houston did my FM3 and a good job, if he is still in business. But then, shops don't like doing C4's either, thats why I did my own for $200 in stead of $800 like the shop wanted.

Well, I've already got another FMX to go into the car, so I don't think I'll swap to another transmission at this point. As finances improve, however, I eventually want to put in an E4OD (overdrive transmission based on the C-6), but to get a computer that will work with my 400M motor will set me back about 2 grand on top of acquiring the transmission and it's perhiphials. I know the logical thing to do would be to go to a 460 engine, but then again, I've never been logical. The 400 is sort of the ugly duckling of small-block Fords, and so it has a perverse attraction to me, but the parts are there to wake it up, you just have to know what you're doing. Anway, sticking with the 400 makes it that much simpler getting a new (read rebuilt) engine into the car when the time comes. So for now, I'm going to put another FMX transmission into the car and get it running again, and as time and money allow, acquire a rebuildable 400M and an E4OD, and have the new drivetrain ready to go into the car when I yank the old. And if you're still interested in an FMX, shoot me an e-mail, cause if all goes well, right after new-years I'll have a transmission or two (one of which I know will need work-the one in the car now) that I might just be willing to sell.

Having done a couple FMX swaps in the past, here's one very important word of advice....find an assistant. The FMX has a cast-iron case which makes it ridiculously heavy...underneath a car it's not likely you'd be able to move it around by yourself. Also, get your car up as high as possible at all four corners. The 335- and 385-series engines have a very tall bellhousing.

Aside from those oddities, it's a pretty simple job. Here are a couple other tips:
If you're swapping torque converters, make sure the converter hub is engaged with the front pump of the tranny. Put the converter on the input shaft and slowly spin it, putting a little pressure on the converter. You should hear and feel two small "thuds" as the flats machined onto the hub engage with the pump. Make sure you hear two.

Secondly, I've notice it's easier to cut the tranny cooler lines with a tubing cutter rather than wrestle with trying to loosen the lines where they go into the tranny (most times the clearance between the transmission tunnel prevents you from swinging a wrench to get them loose). Then, when you have the tranny in, get a couple compression fittings at your favorite discount auto parts store to hook them back up where you spliced them.

One last thing....make sure your dowel pins to locate the transmission are still in the engine block.

Changing a tranny is fairly simple, but it's a PITA. You might want to look for a shop manual so you know where all the nuts and bolts are at.

Hope this helps a little...
Pat

Sounds like a cool idea there is one potential problem I see though: will an E4OD fit under a marquis? The housing on them is HUGE... see for yourself:


I never heard the E4OD was based at all on the C6 but it could be true. I do know that the E4OD is computer controled and will therefore need some custom electronics to work... assuming of course it will even fit under a car.

Slap the transfer case back on, and let's go muddin'!

Yeah, I know the E4OD is one honkin' big transmission, but my '78 is one honkin' big car. (You know this Cowman, you've got a '77 nearly identical). Anyway, I will have to measure underneath there before I go out and buy one.

That transfer case comment got me thinking (RED FLAG RIGHT THERE!), what would it take to put F-series 4x4 running gear into an old Grand Marquis?

Your whole idea about an E4OD has had me thinking again since I had a very similar idea myself way back that I'd abandoned. I do have one resource that I didn't have then though... a truck with an E4OD under it to measure

These are crude measurements since it's hard to measure a tranny while it's on a vehicle but it will give some idea... the length of the thing from the start of the bell housing back to where the transfer case bolts on is about 33" I believe I read somewhere a C6 is 20" long so that means custom driveshaft... most likely the cheapest and easiest part of the swap!
This was hard to measure but it looks to me like the thing is basically round.. at least as far as fitting purposes are concerned and between 16" and 12"(diameter varies). The diameter(height) clearance is what I'd be most worried about when installing it on a marquis. Marquis are big yes but if you look at them they're not very tall. E4ODs are designed for trucks with clearance to spare. Still... it may be possible. Sometime in the next month I'll have my car up on jack stands to change the tranny flluid and I'll measure it while I'm down there.

Another option I looked at which is very apealing and might be a lot easier is an auxilary transmission from gear vendors. These bolt onto the tailshaft of your transmission and essentially double your gear ratios. It's kinda like on a 10 speed bike where you have the two gears on the pedals and setting it in one position makes the other set of gears 1-5 and then the other setting gives you 6-10. Here's their site: http://www.gearvendors.com/
Pricy yes, but go look up what a rebuilt or new E4OD + the electronics you'd need to run it would cost. Ends up being about the same difference I think.


Oh... I like the idea of a 4x4 marquis but having seen the frong suspension setup on a marquis and several 4x4 F-series trucks up close I'll just say they are not even remotely similar.... There are 2 wheels on the front and they steer and there are brakes and shocks and springs..... that's all they have in common
a simple example: I've noticed on my marquis that the steering linkage is entirely behind the front axle vs in front of it like just about every other setup I've seen.... I wish I had a pic to show people but the front suspension on a marquis is quite unique in some ways

anyway, since we're the only 70's marquis owners on this site that I'm aware of and we're both doing some custom projects let's keep in touch in here. These old cars have a lot of potential it's just going to take some work to get them there.

A C6 is a lot longer than 20". The 2WD big block versions had two different extension housing lengths. I'll measure one and post some dimensions here when I get a chance.
Some of the E4OD internals can be used in upgrades to the C6, but of course the C6 remains a 3 speed.

Many years ago I saw about a '74 Impala that was 4WD. Someones home brew project. They kept the tire sizes reasonable, so it looked like a taller car. It really looked nice. I saw it on a snowy day. They probably used a Suburban chassis or something like that, and dropped the Impala body onto it. That would be a quicker way to do it.

The steering linkage being behind the engine crossmember was used on big Merc's, Lincolns, and maybe big Fords too for the 70's. That changed when the box bodies came out, it went out in front. Sure is easier to work on stuff with the steering out front! Its easier to get to out in front, and its out of the way of the starter, and the exhaust pipe connections, etc.

I didn't want you guys to think you were all alone here

C6 is 37 inches long with the long extension housing. The long ext housing is 17 inches of that.