• 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Transmission advice
#1
I am in a bit of a dilemma and wanted to get your suggestions. The FMX on my 73 with a 351C was suffering from “morning sickness”, but the last time I took it for a drive around the block it was slipping and I even thought I might not make it back home. In the end I did make it home but have decided it is time to do something about it.
 
About a  year ago I bought a used AOD that came out of a 92 mustang with about 50k miles that included the transmission, torque converter, cross member, flywheel, cooling lines, radiator, fan, shifter, dipstick, TV cable (no bracket), and driveshaft (I think that covers everything I got). I was told it was running fine and the guy selling it was only doing so because he was going to swap in a T5. I saw the mustang, the T5 and he seemed like an honest guy. I bought it thinking I would eventually swap this into my Mustang in the future. However, I do not believe I have the ability to do the swap myself. I have worked on cars with things like suspension, changing belts, intake/carb swap; but nothing as involved as a transmission swap. I read Mister 4x4’s AOD conversion thread and kind of have an idea of what is needed, but still think it is a bit too much for me to do in my garage. I am especially worried about having to modify the cross member, cooling lines, neutral safety switch/shifter and adjusting the TV cable since I have never done any custom fabrication work. I have asked around in some shops that specialize in classic mustangs in Houston and the price they quote me for the swap is way too high for me (close to $3-$4k).
 
I have also asked about getting the FMX rebuilt and it comes down to two options with two different shops:
Option 1 costs $700 (which includes a rebuild kit with clutches and bands; and labor to remove/reinstall the transmission, but does not include rebuilding/replacing the torque converter or any other hardware that is not included in the rebuild kit which would be additional if required) with a 1 year warranty. He said he would check the torque converter and if it still has “more than 50% life in it”, then there is no need to rebuild/replace it.
Option 2 costs $1200 and is a full rebuild that includes anything that might be needed (including torque converter and any other hardware he might need to pull off from an FMX transmission core he has), includes labor to remove/reinstall the transmission and comes with a 2 year warranty.
 
The only mods to the 351C 2V is a 4 bbl intake and Edelbrock carb. It also came with a duraspark 2 ignition and a flowmaster exhaust system (with stock manifolds) from the previous owner. It currently has a 9 inch open differential with 2.75 or 3.0 gears. I really only plan to use it as a weekend cruiser that I can step on and  enjoy a little power. My current future plan (other than the transmission) would be to install 3.5-3.89 gears and possibly change to a locking differential.
 
After writing all this I come to realize that I should probably just rebuild the FMX and sell the AOD. As far as my two options with the rebuild: option 1 leaves me with an extra $500 IF (and that is a BIG “if”) nothing else needs to be replaced. If the torque converter needs to be replaced then that would add about $200 to the total if I buy one from Summit or any other online store. While option two includes everything being rebuilt for the extra $500 and an extra 1 year of warranty. As far as the warranty is concerned I would assume that since this is only a weekend cruiser (and I only really drive it every 2-3 weeks), the transmission would probably not suffer too much wear. What would you guys suggest?
  Reply
#2
To save on costs, why not remove and replace the trans yourself and just pay for the rebuild? It is pretty straight forward and lots of info here on how to do it. Good luck.

Jeff
1972 Q Code Convertible
  Reply
#3
Doing the trans swap is really not that hard. I swapped out my FMX for a T5 so converted from an Auto to a Manual in my garage with no issues. I had never tackled anything like this before and just did my research and only ordered the individual parts I would need. I think you would be amazed at the difference in feel driving with the AOD Vs the FMX even without changing the rear gears. I had 2.75 gears and the difference was with the T5 was night and day. I eventually swapped out the rear gear for a 3.70 traclok and holy crap what a difference. If you are looking to go to a 3.50 or higher gear eventually the AOD would be a huge benefit if you do any type of highway cruising. Also do some research, but I believe I read somewhere that the FMX crossmember bolts up to the AOD.

'73 Grandé H Code. Headman long tube headers, T-5 Transmission, 3.70 Traclok, Lowered 1" all around, Aussie 2v heads w/ 2.19 intake, 1.71 exhaust, screw in studs, full roller cam 608/612 lift 280/281 duration LSA 112, Quick Fuel 750 CFM double pumper, AirGap intake.

'73 F code convertible. Bright red. Needs total restore. (IE HOT MESS)

- Jason
  Reply
#4
(11-27-2018, 04:01 PM)jeff8877 Wrote: To save on costs, why not remove and replace the trans yourself and just pay for the rebuild? It is pretty straight forward and lots of info here on how to do it. Good luck.

Both shops said they have to remove/install for the warranty to be valid.
  Reply
#5
(11-27-2018, 04:29 PM)Tataocb Wrote:
(11-27-2018, 04:01 PM)jeff8877 Wrote: To save on costs, why not remove and replace the trans yourself and just pay for the rebuild? It is pretty straight forward and lots of info here on how to do it. Good luck.

Both shops said they have to remove/install for the warranty to be valid.

That's standard in the industry. No one wants to stand behind a tranny when they have no idea if the installer knows what they're doing. 

I'd say the $1200 option is pretty reasonable with the 2yr warranty. Make sure he uses a new/reman converter and get him to install a shift improver kit.


  Reply
#6
How much do you plan on driving it ???  If your planning on doing alot of highway, the AOD would be nice, other than that, stick with what you got. 

I have no advice on which way to go with the rebuild except  - flip a coin

73 ragtop, 1999 Mustang Bright Atlantic Blue Paint, Phoenix Engine 302-335HP,  Edelbrock Carb & Performer manifold; c4 with 2000 stall and shiftkit; 3:55 auburn limited slip differential, Hedman shorties; Car Chemistry Exhaust

Classic Air; Tilt Steering Wheel; 1999 Chrysler Sebring bucket Seats ; power windows;
  Reply
#7
I have been in the exact same position as you and our cars sound very similar. Mines a 73 convertible with 351-2v with eldebrock intake, I switched the eldebock carb for a Summit and couldn't be happier. 2.75 open rear end with 245/60 BFGs.  Originally intended to swap the FMX for an AOD but then changed my mind to a 4r70w. No question that an upgraded trans is a huge improvement, IF you need it to match the use of you car. If you go that way be aware that you will definitely need to change rear gears also to get the benefit.

While still on the "wish-list", I have found that I really didn't need to make the swap to be happy with the car. I use my car as a daily driver. It has almost 95000 miles on it but the engine was rebuilt approx 13000 miles ago by the PO. Runs pretty strong but not a race car by any means.

I had the FMX rebuilt last year. Full rebuild with a stage 4 shift kit was $900. Shifts are firm but not too harsh. Even with the 2.75 gears, it will spin the tires(tire) anytime I want to. After driving it every day rain or shine for a year now everything from stop and go city traffic to 85 mph highway runs I have found that for now the FMX suits my needs.  Last Mustang I had I did swap a C6 to a Tremec 3550 and 3.89 gears. Huge improvement and was perfect with the built 427FE in that car but I used it differently - it was definitely a hot rod.
  Reply
#8
I just went through the same issue.  I ended up buying the rebuild video from Bad Shoe Productions and an FMX rebuild kit.  The video was about $40. (an excellent product).  The kit was about $100.  I paid a local tranny shop $20 to reinstall a piston seal.  I have not reinstalled the rebuilt FMX  yet, so i can't comment on how it works.   Rebuilding is not difficult.  You just need to be organized and pay close attention to details when working on the valve bodies to make sure you get everything back in the same way it came out.  

After all of my research, If I had an AOD, I would do the swap - since nobody seems to regret upgrading to an AOD (or a manual).  

If you decide to rebuild yourself,  I have a homemade spring compressor you can borrow (i'm on the SW side of Houston).

Good luck.
[Image: 20180715-135633.jpg]
  Reply
#9
@mudbilly - don't plan on using it as a daily driver so probably less than 200 miles a month I would say.

@mbrew2 - sounds as if you were describing my car. It is also a 73 convertible. I have come to believe that the FMX fits the use I have planned for this car and do not really need to go with the AOD swap. It would be nice to have overdrive, but not an absolute necessity. I am glad to hear you are able to spin your tire at will with a very similar drivetrain to mine.
  Reply
#10
You can always add a Gear Vendor overdrive to your FMX later, not cheap, though.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
  Reply
Share Thread:  


Possibly Related Threads...
Thread Author Replies Views Last Post
  engine build advice kusanagi 16 912 11-21-2018, 02:17 AM
Last Post: Robsweden
  Advice on cheap headers? scgamecock 21 651 10-31-2018, 06:01 PM
Last Post: barnett468
  Which Auto Transmission is this? GeoBW 9 593 09-29-2018, 07:44 PM
Last Post: GeoBW
  FMX to C4 Automatic Transmission fangstang 7 452 09-17-2018, 12:44 AM
Last Post: Studdley
  Advice on rebuild parts / kits brands Vinnie 11 534 09-16-2018, 01:12 PM
Last Post: Vinnie
  Compression test advice needed crzyfun 14 630 09-06-2018, 09:13 PM
Last Post: Don C
  C6 Transmission Shift lever - ??? timsweet 12 743 09-02-2018, 10:07 AM
Last Post: timsweet
  transmission questions isaac300 9 447 08-22-2018, 04:02 PM
Last Post: secluff



Users browsing this thread: 1 Guest(s)