c4 transmission "swap" ?

[GriGri 10]

Hi All,

 

the 69 mach1 (351w) I bought came without a transmission and I was thinking of putting a c4 instead of the FMX that is "correct" for the car.

 

Any advice as to waht C4 to look for ? (ie what c4 model/year would be easily be adapted in the car) ?

 

Since my budget is limited (whose isn't ?) I want to find a used one and have it rebuilt. Any idea of where and how much to expect for a c4 rebuild ?

 

Any help is welcome. Thanks

[rwcstang 201]

most c4's are pretty much the same its matter of how you are going to rebuild it. most every transmission shop can rebuild them to your specs. I got my "street fighter" c4 from performance automatic a few years back no complaints just plug and play lol :) but later on i hope to switch to a 5 speed.

 

but since your replacing the auto why not convert to a 5 speed? you would probably be spending the same amount (if you fish out the parts yourself) if you tend to keep your 351w stock with some mild mods i suggest get a 91-93 t5 or get a t5z from ford. this will place your rpms very low and save some gas mpg at the same time or if you wanna still stick with auto you can go AOD.

[TexasEd 188]

There is no reason not to at least look at going with an AOD. The only potential drawbacks I can think of are that you may want a bigger ratio rear differential and initial adjustment of the throttle valve cable needs to be done properly.

 

I currently have a C4 but if it ever needs major work I'll be swapping it out for an AOD

[GriGri 10]

Agreed, AOD would be my first choice but from I have looked around, an AOD would be about twice the price of a C4 and C4 rebuilds are less costly as well. Given I am on a honey budget (same idea as honey do list but the opposite :-). Therefore the C4 idea.

 

Even new streeftfighter's from TCI can be found for around 900 while it seems AODs are around 1600 starting price

[eatmyjeep 10]

fmx transmission is cast iron i believe . so its really heavy with limited resale valve.

 

I swapped my FMX with a tko 500 bc Like you i had a 351w, and the T5 whould have been pushed to its limits. Even the nice t5 is only rated to 300-350 foot lbs of toque.

 

If you go with a 5 speed, plan on changeing your rear end as well. $250 parts + 7 hours labor

 

The whole job cost me about 5k?

 

A c4 whould get the job done but.... if your going to stick with an auto transmission! I whould save my pennies and nail down an AOD . You will be happy for years to come!

[1969 Mach1 14]

I always thought in stock form the FMX was stronger than a C4 thats why it was used with the 351w's and the 302's got the c4's. If I were installing an automatic without overdrive I would consider either an FMX or a C6.

Edited October 14, 2011 by 1969 Mach1

[Max Power 74]

FMX is a cast iron case, but the bell and tail are aluminum.

 

C4s with some mods can be just as strong if not stronger. Biggest problem with the FMX is almost no performance aftermarket for it. One shift kit, and 1 or 2 selections in torque converters and that's it. C4s have a lot of options.

 

Depending on how you use it, it's hard not to justify overdrive of some sort.

[1969 Mach1 14]

Unless you want to do alot of mods to increase the strength of a C4 I would not use one with a 351w. For a non overdrive auto trans, go with a C6 if you are putting alot of HP through it or FMX your motor is stock or mild. In stock form, the C4 is a 289-302 trans. If you want an automatic overdrive, I don't know because again in stock form the AOD is weak like the C4 that is why Ford didn't put an AOD or its later electronic overdrive version, the AODE, behind the 351w's.

[TexasEd 188]

AOD up to 550 hp $2000 plus shipping ($110 more for up to 600hp)

 

http://www.ford-aod.com/

[PaleRider 12]

C4 will be fine. If you go used route do a 1970 or higher - larger input shaft and more options availables. Look at TCI thru summit you can get a stout c4 under $1000. It will cover more than enough tq/hp out of you mach and give you some room to grow if you want. Comes aleady with shift kit installed. I'm running it on my 1970 347 that is putting out over 400/400 hp and torque. Very happy with it. AOD would be nice if you are concerned about gas mileage or want to run small gears (3.7s or taller). I was in your boat and could not justify the cost at the time. If you have stock gears in rear end (3.0 o 3.25) should be fine. I've got 3.44s and running about 3000 rpm at 65. I also have put in a ratchet shifter (B&M Megashifter). Its great I think it provides best of both worlds - you can bang gears if you like or just let auto do its thing. I'm planning on same set up in 66 I'm building now.

Edited October 14, 2011 by PaleRider

[1969 Mach1 14]

Maybe I am anti-C4 and anti-AOD. I am referring to these trans in their stock form, not modified. My thoughts are why start with the weakest model and invest more in mods to obtain the strength you need. Especially when you are on a limited budget for the project. Lastly, I think putting a C4 in a Mach 1 is just not right and will probably reduce the vehicles value, at least a small amount.

Edited October 15, 2011 by 1969 Mach1

[PaleRider 12]

Here is the one I'm using. http://www.summitracing.com/parts/TCI-511200/

 

You can also get a c6. http://www.summitracing.com/parts/TCI-411400/

 

I think you will have more options with c4 but you have more period correct with c6. Yours could have been a FMX originally (my 1970 mach1 was). Also my c4 did not come with bell hosing. The c6 shows a picture with bell housing on it. Not sure if the bell housing is built into the case on c6s - not as familiar with them. If so may save some money going with c6. Initially I was thinking best route is c4 but now I'm leaning toward 1969 Mach1's view.

Edited October 15, 2011 by PaleRider

[RPM 1,190]

There are many C4's behind stroked 460's.

[Max Power 74]

Here is the one I'm using. http://www.summitracing.com/parts/TCI-511200/

 

You can also get a c6. http://www.summitracing.com/parts/TCI-411400/

 

I think you will have more options with c4 but you have more period correct with c6. Yours could have been a FMX originally (my 1970 mach1 was). Also my c4 did not come with bell hosing. The c6 shows a picture with bell housing on it. Not sure if the bell housing is built into the case on c6s - not as familiar with them. If so may save some money going with c6. Initially I was thinking best route is c4 but now I'm leaning toward 1969 Mach1's view.

 

Bell is integral on C6's, small block bells are not as common.

 

The reason people go with C4s is because they are the most affordale, most available and easiest to modify. They are also a lot lighter than the C6 or FMX/AOD units. People use them in drag apps behind serious HP all the time.

[1969 Mach1 14]

I know there are C4's built to handle alot of hp. In my opinion it is just not correct or for a Mach 1 and it would seem like a down grade. Similar to installing a 302 in a Mach 1 that originally had a 351W or 351C.

[PaleRider 12]

I dont think you can go wrong eitehr way. If I was going to race it I would go with C4. If a daily I would probably go with c6 - just for period correct thing.

[Max Power 74]

I know there are C4's built to handle alot of hp. In my opinion it is just not correct or for a Mach 1 and it would seem like a down grade. Similar to installing a 302 in a Mach 1 that originally had a 351W or 351C.

 

Most people don't see it that way. The FMX is usually considered the bottom of the desirable heap. It's hard to even give them away when you swap them out.

 

If you have an original show car, not such a bad idea, but I don't think most people have a problem with losing an FMX. Much different than 302 vs 351, IMO.

[LoneWolf2U 136]

I know there are C4's built to handle alot of hp. In my opinion it is just not correct or for a Mach 1 and it would seem like a down grade. Similar to installing a 302 in a Mach 1 that originally had a 351W or 351C.

 

:confused1: Thats comparing apples to oranges.......

The best reason for installing a C4 over the FMX or C6 is lower weight and parasidic loss of HP the two larger trans will have.

 

I don't build a engine to lose its power thru the trans.:nono:

[GriGri 10]

Alright, so if I read everything everybody say I could actually go C4, C6 or FMX or AOD or TKO or ...:-)

 

Considering cost is an issue right now (lots of parts to buy) I'll keep the FMX and rebuild it (rebuild kit is $100) since I already have the converter. I'll spring for a better trans (TBD) when I do performance upgrades

 

Anybody knows if the TRANSGO FMX-3 Shift kit is worth the Money ($200) or I should not bother ?

[1969 Mach1 14]

I have used both Transgo and B&M kits in Ford's 4R70W (AODE successor) in late model Mustangs and preferred the B&M. The Transgo kits came with more parts to solve inherrant driveability issues. But in the end, the B&M kits worked better. Those extra parts in the Transgo kit didn't solve the inherrant driveability issues they claimed they would. I have also used B&M kits in the Ford's E4OD trans and a Mopar's Torqueflight 727 trans. I was happy with those results as well.

 

If B&M offers a kit for your trans, I would choose that over the Transgo.