c5 Transmission

[dpuwookie79 11]

Long story short, I bought a '69 mustang vert a couple of years ago and have been restoring it ever since. The guy who sold it to me took the existing C4 transmission out of it and put an early 60's fmx (2 speed) into it. I wanted to go back to a c4, so I called a transmission shop down town to find and rebuild one for me, so I'd have something with a guarantee on it. So, the guy calls me and tells me they have found one, so I tell him I'd like it rebuilt...and pay him half of the rebuild fee up front. A couple of days later, he calls me and tells me it's a c5 transmission...but the c4 & c5 are identical...only differing on the internals of the torque converter. I told him that's fine, as long as it will swap out directly for the present 2 speed FMX.

A couple of days after this interaction, I called a transmission shop closer to where I live (these two shops are franchises of the same parent). I ask the guy there about installation of the c5 into the present set up...and he tells me that there may be some necessary modification, and it could be more complicated than just a simple swap out. One of these two guys isn't telling me the whole story...or just they plain don't know. I'm new to transmissions and am learning, but I'd like to run this by you more seasoned veterns. Who's giving me the complete story? Will a c5 more or less bolt into the same setup I have now? I appreciate your help :)

[Max Power 74]

I don't think there were any 2 speed FMX trannys, you have something else in there. I do think there are some differences to the C5s relating to the lock up of the converter, you can Google up the differences and go from there. I would go to the C-4, or if you are going to modify something to fit, get an AOD.

 

http://en.wikipedia.org/wiki/Ford_C4_transmission

[dpuwookie79 11]

I really wish I knew more about these, because I feel like I've gotten myself in a bind...having given the guy a check for half of the the rebuild fee on what was supposed to be a c4. I've been to the link you posted trying to figure out more about the differences, myself. I agree, if there must be mods, I'd much rather get an AoD, but I am unsure of how much that would cost to have someone else do. Ideally, this c5 would "just fit", without additional modifcation to the drive shaft, and just slide in using the existing parts....but I feel like I am stuck now. UGH, this has certainly been draining.

[Max Power 74]

My guess would be that the physical dimensions of the C5 are nearly identical. My concerns would be the mount, what they did to lock up the converter and if a standard converter would work in there, and probably most likely, linkage. C5s probably mostly came in cars with column shifts, and definitely came in cars with locking steering columns, so the linkage would be different, and since you have a 2 speed in there, you don't have the correct C4 linkage either. It could be sourced, of course, probably used, but you would have had to do that with a C4 anyway.

[Hoover 12]

Don't know if this will help, but this link has info on which vehicle used a C4 or a C5

http://mmerlinn.tripod.com/trans/fdc4f/fbdc4_a0.htm

[ashleesmach1 28]

It's probably a mx tranny. I think they were 2 speed. The fmx is 3 speed and the case is cast iron. A heavy mother... :) go with c4

[MikeStang 247]

Simply call the bank and cancel the check, then call the fellow and tell him you want your c4 that you requested, if he doesn't agree tell him the check has been cancelled and find another shop.

If he agrees and builds the tranny be sure. And run the numbers on the tranny to ensure that it is a c4 and not a c5 before you take delivery of it :)

I will make a call and see if i can find out what the diff are between the two so far as interchange goes.

mike

[MikeStang 247]

Well it seems that the flywheels and bell housings can be different, along with the shift selector location, and the Torque converter.

You will need a longer driveshaft, and a crossmember, along with a new starter, and a different converter, and probably a new fly wheel......

The good news is it is a direct bolt in LOL meaning it will fit with no issues, you just gotta have all the new parts to go along with it lol.

I was also informed that the c5 is a bit heavier duty than a c4 but that is just about it, and if your not throwing any power at it then a c4is the best option.

The fmx crossmember you have will directly bolt into a c6 if you can find one.....I had one i gave away ;(

Also being told that those lock up converters are getting tough to find depending on the year model.......I would say tell the guy you want your c4 but who knows what other parts you will need even if you get a c4 because your not sure what ya got in there now.

All the above info comes from a local mustang junkyard parts guy that has been doing this stuff for more than 30 years and who I totally trust and call on a regular basis so you can take the info to the bank in my opinion.

Your call now......you could always tell the guy hey man I want you to put it in for me and show me how much of a direct swap it is ;) then he will be forced to admit he's wrong it he cant make it work Lol but i would not leave my car anywhere with any shop unless you have had work done in the past with them.

mIke

[Max Power 74]

I am confused why the guy couldn't find a C4. They aren't exactly rare.

[Trav_450R 10]

I am confused why the guy couldn't find a C4. They aren't exactly rare.

 

There almost a dime a dozen on car-part.com!

[Handegard 10]

The C5 should be almost a direct swap. It's essentially a C4, but with a lockup torque converter.

 

I'd personally explain that you paid for a C4, not a C5, and request what you paid for. Like was said, I'd cancel the check if need be.

 

That said, if the C5 does directly bolt in, the lockup TC is basically a upgrade. Little better fuel mileage perhaps.

[dpuwookie79 11]

The C5 should be almost a direct swap. It's essentially a C4, but with a lockup torque converter.

 

I'd personally explain that you paid for a C4, not a C5, and request what you paid for. Like was said, I'd cancel the check if need be.

 

That said, if the C5 does directly bolt in, the lockup TC is basically a upgrade. Little better fuel mileage perhaps.

 

 

The shop is going to try the install for me, to make sure it will fit. All indications seem to point to it being a relatively easy install. I appreciate all of your input guys...I'd still be hung up, if you weren't around ;-)

[MikeStang 247]

They going to cover the cost of the new tranny mount, and converter, and possibly a new drive shaft?

[RPM 1,190]

the only diff between a c4 and 5 is internals. c5 has better oiling. my fmx crossmember works for the c5.