Time to rebuild the FMX?

[LoveThatHood]

After getting the engine running decent, I decided to drive the 71 into town for ID/OD inspection. (Just picked the old gal up last month after previous owner had it since 1989, and he only put 2k miles on it since 91) I noticed the transmission wasn't real sharp at shifts, so I picked up some F type fluid and a new filter and gasket to swap out when I got home. Next 5 miles was even slipperier, and the last mile, I literally couldn't keep it moving up hill to my house. Fortunately, it still is strong in reverse, so I did a bit of creative reversing to get it up the hill from the driveway and rolled it forward to work on.

Note that fluid seemed to be above the add mark, so I don't think it was low. I pulled 4 quarts out of the pan with an evacuator and then dropped the transmission pan with another quart or two. I have seen/smelled worse, but what was left in the bottom of the pan was what I would refer to as sludge with a light dusting of metal flakes. (by sludge, I mean I had to use brake cleaner and a lot of rags to get the stuff off of the bottom of the pan) I replaced the filter, and replaced the transmission pan, filling the fluid up to a point where it was at the full mark when idling in park. Tried again and reverse is strong, but no forward gears. Looked at modulator and while the vacuum connection was on, it was kind of loose-ish so I ran back to the store and got a new modulator and some vacuum hose. Replaced both, but still no forward motion. Literally, even with the car in the air, putting it in gear and reving the engine does not move the tire on the drivers side, but it hops right into reverse.

After reading a bit of comments on this and a few other forums, it seems that after sitting that long and the slippery drive back home, the seals may just be toast. Anyone have any other troubleshooting ideas I may want to consider?

Question 2 - I'm fortunate that there is a transmission shop just up the road that seems to have a random assortment of non-computer controlled vehicles there all the time, so I suspect they may be decent for an FMX rebuild if it comes to that. However, I also am a bit torn between the idea of dropping money into rebuilding the FMX vs moving to a manual transmission. Got a quote from Modern Driveline on the T5 setup, but they did call out that I may be happier with a re-gear to go with the 5 speed. (Came with 2.75's per the Marti) Any of you who did the conversion who regret it, or inversely, any of you who rebuilt the automatic only to regret it later? My back of envelope math is probably $3k difference not including a possible future regear.

Always appreciate everyone's feedback!

 

[Sheriff41]

Well, if you are planning to change out or rebuild the transmission, you could try some K & W Trans-X transmission treatment to see if it will soften up the seals a bit. We used to use it back in the '70s to buy customers a little more time before having to spend $$ on a rebuild.

There are quite a few auto-to-5-speed conversions done by members on here. Do a search and read through the threads. You'll also see recommendations on axle ratios - lots of opinions on this! I'm in the process of swapping out the AOD (AODs/AODEs are other options to consider) I put in my '72 decades ago for a T5 from MDL. MDL seems to be very easy to work with and their prices are competitive.

 

[Steve McMahan]

Sounds like Sheriff41 has an AOD to sell. Best change I ever made to a car to just drive. Love the low freeway RPMs.

 

[LoveThatHood]

After quite a few discussions with various transmissions shops near me, I have come to realize there is only one (so far) who will rebuild a FMX, and they are almost 2 months out. Seeing the cost to rebuild the FMX is within 2k of the quote for the T5 setup from MDL, I am somewhat certain I'll just pull the trigger and change over to the manual now. Hoping the learning curve isn't too steep!

 

[giantpune]

After quite a few discussions with various transmissions shops near me, I have come to realize there is only one (so far) who will rebuild a FMX, and they are almost 2 months out. Seeing the cost to rebuild the FMX is within 2k of the quote for the T5 setup from MDL, I am somewhat certain I'll just pull the trigger and change over to the manual now. Hoping the learning curve isn't too steep!

I got the email from MDL, for most of july they're running a sale. Transmission swap kits are $250 off and you get some free swag.

 

[Paul M]

That sludge build up with some metalic particles is your friction discs worn out. The seals may be old and brittle limiting their ability to function properly, however, you aren't going anywhere with no friction on the discs, the plates between them will be severely blued. I'm not familiar with the FMX, just don't see a problem with buildability for any tranny shop that does the older ones. The only problems are not having parts on hand, so the wait to complete it may take a couple of weeks extra. My GM 400 turbo was acting up & I did some research got the line pressures and did a line pressure check to find it was toast. I rebuilt it after my findings. I ran some high-pressure hose from a fitting on the side of my tranny and hooked up a gauge n drove it and noticed the pressures were subpar. They were fine in reverse, reverse is usually a bit higher pressure.

 

[Cleveland Crush]

After quite a few discussions with various transmissions shops near me, I have come to realize there is only one (so far) who will rebuild a FMX, and they are almost 2 months out. Seeing the cost to rebuild the FMX is within 2k of the quote for the T5 setup from MDL, I am somewhat certain I'll just pull the trigger and change over to the manual now. Hoping the learning curve isn't too steep!

You'll be very happy with the OD swap. As others have stated, start checking on "better" rearend gears also.

 

[LoveThatHood]

Yeah... gears are on my list too, but it is a slippery slope. If I'm spending the cash to regear, then I should probably find a 9" to put them in, and if I'm replacing the axle then it's probably a good time to move from drums to discs and then ....

I've done this dance before when I bought my first jeep. What started as a 2" budget lift turned into replacing everything between the frame and the ground over the course of the next few years.

 

[Spike Morelli]

On the other hand...... The FMX is a relatively stout automatic. There are components today and "reprogramming kits" from Trans-Go that really work well with this trans. If everything were like new with your trans, you'd likely not be considering a swap out. You could plan a trip to Hawaii with the money saved on not doing a conversion. Just another .02 opinion.

 

[midlife]

On the other hand...... The FMX is a relatively stout automatic. There are components today and "reprogramming kits" from Trans-Go that really work well with this trans. If everything were like new with your trans, you'd likely not be considering a swap out. You could plan a trip to Hawaii with the money saved on not doing a conversion. Just another .02 opinion.

Just don't plan on driving to Hawaii as there are only a couple of gas stations along the way...

 

[giantpune]

And when you get back from your Hawaiian vacation, you can hop back in your car and net be able to cruise around at 80MPH.

I think the cost is a wash. Sure, the FMX (or C4, or C6) will be cheaper to rebuild now. If you drive the car much over 50MPH, eventually the gas savings and lower wear and tear thanks to the overdrive will pay for itself.

 

[Paul M]

Yeah... gears are on my list too, but it is a slippery slope. If I'm spending the cash to regear, then I should probably find a 9" to put them in, and if I'm replacing the axle then it's probably a good time to move from drums to discs and then ....

I've done this dance before when I bought my first jeep. What started as a 2" budget lift turned into replacing everything between the frame and the ground over the course of the next few years.

The AOD concept is tempting, however, not in my budget at the moment either. There's nothing wrong w/the FMX they are a lil heavy but durable. I personally would put some blocks under my wheels n pull it & rebuild it myself. It pays to have a hydraulic press if needed. You'd need the tool to compress the discs in the drum. (under 100) I personally would look into some basic upgrades, like kevlar band, shift kit, decent frictions n steels ..prob. alto reds. a Torrington replacement in the back to eliminate some drag. Probably only the front pump & rear tail shaft bushings (depends on wear) Disassembly is where you find what is needed. Usually they are basic seals, frictions n steels for wear items, however, you have some failing component. This is most likely a weakness in your tranny. You'll most likely find one drum with excessive wear in the frictions n steels. That is the one I'd modify to get 1 more friction and steel in. That will be your weakest point when you add hp down the road. You either buy a new drum from $Sonnax or do what I do buy a used one with a higher ring groove or find a smaller machine shop who'll take the time to cut a new one. They aren't that expensive the C6 one that I got was a nice used one at a local transmission parts dealer.(@50 bucks) Pay a lil for a nice new converter, I'd increase the stall a bit myself.

 

[ib4stangs]

To bad you're not closer to me!

https://washingtondc.craigslist.org/mld/pts/d/bryans-road-1970-ford-fmx-trans/7637208236.html

 

[Paul M]

And when you get back from your Hawaiian vacation, you can hop back in your car and net be able to cruise around at 80MPH.

I think the cost is a wash. Sure, the FMX (or C4, or C6) will be cheaper to rebuild now. If you drive the car much over 50MPH, eventually the gas savings and lower wear and tear thanks to the overdrive will pay for itself.

And when you get back from your Hawaiian vacation, you can hop back in your car and net be able to cruise around at 80MPH.

I think the cost is a wash. Sure, the FMX (or C4, or C6) will be cheaper to rebuild now. If you drive the car much over 50MPH, eventually the gas savings and lower wear and tear thanks to the overdrive will pay for its

And when you get back from your Hawaiian vacation, you can hop back in your car and net be able to cruise around at 80MPH.

I think the cost is a wash. Sure, the FMX (or C4, or C6) will be cheaper to rebuild now. If you drive the car much over 50MPH, eventually the gas savings and lower wear and tear thanks to the overdrive will pay for itself.

I noticed 3 of you rec'd the AOD. Which AOD are you using? I have one in my FX4 it only has 10k miles and needs rebuilt already. This time I'm doing it myself. I want to see what is failing. I'm not forking out another 2400 for only 10k miles. You guys must be buying them built to handle a few horses.

 

[Cleveland Crush]

I've run a manual OD (tko 600) for 15+ years about 1000 miles per year with a high horsepower engine. 100% positive experience.

 

[giantpune]

I noticed 3 of you rec'd the AOD. Which AOD are you using? I have one in my FX4 it only has 10k miles and needs rebuilt already. This time I'm doing it myself. I want to see what is failing. I'm not forking out another 2400 for only 10k miles. You guys must be buying them built to handle a few horses.

I haven't done an AOD swap. In old fords, the only overdrive swap I've had is a manual T-5. Will hopefully be doing a TKX in another car, soon.
In old chevys, I've done a couple 700r4 swaps that are holding up great.

 

[Paul M]

I've run a manual OD (tko 600) for 15+ years about 1000 miles per year with a high horsepower engine. 100% positive experience.

manual OD (tko 600) yep lighter and much more fun. I could see the 3k+ investment in the future, if I keep this. That's the best of both worlds.

 

[Sheriff41]

I've been running an AOD out of an 1986 Mustang in my 72 Q-code for a couple decades. No issues at all. I don't race the car, but don't baby it either. The AOD was rebuilt to stock specs and I added a B&M torque converter (~2600 stall). When I put the AOD in I made sure to set the pressures per the factory shop manual. I think this is where most people have problems, they don't set up the TV cable to the required pressure setting and they end up burning up the AOD.

When I put the AOD in my car, the AODE wasn't really an option. Now there are ECUs available for retrofitting an AODE (rather the and TV cable on the AOD) into our cars and is the way to go. The AODE incorporates a lot of the evolutionary improvements from the AOD and, with the ECU, you can tailor the shift points to your set up.

The AOD, like a manual with OD, allows you to run a lower gear ratio and still get decent or improved gas mileage. I've been running a 3.89 gear and it makes for a fun drive. I'll keep the 3.89 as I change to a T5 setup.

I'd recommend either the AOD(E) or the manual swap. I've been happy with my AOD and am only swapping to the T5 because I've always wanted a manual in the car (I've owned it since 1977).

Good luck with your choice!

 

[Paul M]

I've been running an AOD out of an 1986 Mustang in my 72 Q-code for a couple decades. No issues at all. I don't race the car, but don't baby it either. The AOD was rebuilt to stock specs and I added a B&M torque converter (~2600 stall). When I put the AOD in I made sure to set the pressures per the factory shop manual. I think this is where most people have problems, they don't set up the TV cable to the required pressure setting and they end up burning up the AOD.

When I put the AOD in my car, the AODE wasn't really an option. Now there are ECUs available for retrofitting an AODE (rather the and TV cable on the AOD) into our cars and is the way to go. The AODE incorporates a lot of the evolutionary improvements from the AOD and, with the ECU, you can tailor the shift points to your set up.

The AOD, like a manual with OD, allows you to run a lower gear ratio and still get decent or improved gas mileage. I've been running a 3.89 gear and it makes for a fun drive. I'll keep the 3.89 as I change to a T5 setup.

I'd recommend either the AOD(E) or the manual swap. I've been happy with my AOD and am only swapping to the T5 because I've always wanted a manual in the car (I've owned it since 1977).

Good luck with your choice!

got to love the drivability w/a 3:89 gear. I have to rebuild a AODE in my truck & will be learning the improvements in the process... I may become a fan. Not sure I'm wanting to go manual in this car. I have two manuals and love them for the cars they are in. They are fun, however, continuous activity.

 

[LoveThatHood]

In a strange twist of fate (and guided by my impatience to wait for parts) I found a gentleman selling a FMX that had been rebuilt for a great price. I picked it up today, drove home, and started working to take out the old one. I'm down to the last steps of removing it before I quit for the evening (dark and bugs), but if all goes well I hope to hook up the rebuilt FMX tomorrow and get it road ready again. I've never swapped a transmission before, so this is a bit of a learning curve.