FMX to AOD swap. Complete report.

[MechEng]

Can someone tell us whether the aod's suck more HP than an fmx or are they about the same.

Will I notice the extra HP by going to a 5 speed manual?

You'll almost always notice a perceptible HP gain when going from an automatic to a manual because you cut out the inherent losses of the torque converter. The Manual is more of a direct lock-up so it's going to feel a little snappier and a bit more responsive off the line.

In terms of an AOD taking more HP than a FMX I couldn't offer more than an educated guess on this one. I would assert that they should be pretty equal if an identical TC is used, meaning that most of the variation would come from internal losses in the transmission itself which would be mostly limited to the gear frictional losses and the transmission fluid pumping losses. But this is only an assertion, if someone had good access to a dyno and a lot of free time they could put some better numbers on the table to deal with.

For me, the potential minimal loss of HP (or possibly gain since that could also be true) of switching from an FMX to an AOD is pretty easy to overlook for the sake of more gas mileage. This is coming from someone who drives nearly 200 miles a day so every bit of MPG helps a lot. If I drove less my opinion might be different.

 

[Mister 4x4]

Since the FMX's gear ratios are essentially the same as the AOD's (excluding OD), the biggest difference should be in the torque converter. Admittedly, what I know about TCs could fit in a thimble, but I would think that the TC might be application-specific. For instance, if you got an AOD set-up from a Crown Vic, its TC might be 'less aggressive' than one from say, a 5.0 Mustang GT. If that's the case for Luxstang, it could be the cause of his perceived horsepower loss. As for the shifting points, I suppose it could have a similar effect, assuming the cable was set-up properly (correct pressures at various rpms).

I'm kind of almost starting to lose a little faith in wisdom of my own AOD conversion now. Even though I got the AOD with its actual TV cable, and didn't mess with the settings (from the Ford factory as it was removed intact), I'll definitely be checking it with the pressure gauges before I take it out on the road for the first time... just to make sure.

 

[luxstang]

If I remember correctly my AOD came from a pickup truck. If they did indeed have application specific TCs, then that could be the issue.

It feels like the engine and trans don't communicate properly. I don't know how to put it in words.

It used to feel like the whole drivetrain, engine, trans and rear axle was one unity.

Now it doesn't feel like it.

I took a long drive today and I noticed that the car is indeed still fast. I only need to force it with my right foot whereas it used to be eager to respond.

When I floored it today, 2nd gear did last until 65mph on the AOD. Like I said, I have to force it.

Performance felt like it was the same as before the swap. It just lacks the ease. Maybe that is the way an AOD works. Shift up, keep low rpms unless the driver really, really means it.

The FMX was more eager to please and would support you going fast.

I'll try and get more info on application specific TCs, if there was such a thing. Then we'll see.

 

[Mister 4x4]

No sir - I think you are communicating what you've discovered just fine. And I believe you might have 2 separate problems here.

1. More thinking on torque converters, if a lighter-duty TC had a different stall speed (or lock-up point, or whatever they call it), that could account for the slushy response you're getting. When you step on the gas, if it's constantly trying to slip rather than lock-up, you'll just be losing power to the slippage. As far as stall speeds and whatnot, I have no idea what to use for the transmission's 'butter zone,'

2. As for the shift points, though - that sounds more like it would be a TV cable adjustment to me (I know Lokar's instructions say to hook their cable up according to their specifics, but then it will most likely require some fine tuning to get the shift points just right). Especially, since it seems to shift early through the entire range. It probably all seems compounded with the 3.00:1 rear gears (especially when OD kicks in). I don't believe you're very far off from being perfectly set-up, though.

There's a lot of information about how the TCs work in Mercury Marauders here. http://www.mercurymarauder.net/forums/showthread.php?t=39220

But I just read something about there being different AOD TCs for different applications. Factory AOD TCs were:

• 1300-1900 (stall speed) for low-performance/better economy/towing applications (Ford F-150, Econoline E-150, et al)
  
• 1600-2200 for mid-performance applications (stock 5.0L H.O.)
  
• AOD-E TC for 5.0L Mustangs had 2400 stall speed
  

A good article for overall information about the AOD for use in early-model Cougars and Mustangs:

http://www.hemmings.com/mus/stories/2006/05/01/hmn_feature5.html

Something of note I found interesting in this article (assuming you have a standard TV cable... I'm not sure if it would apply to a Lokar cable or not:

"The throttle valve linkage or cable adjustment is very important to allow the AOD to shift properly. Start with a good bushing on your throttle linkage and check this bushing often after installation. Many complaints of improper shifting can be traced to this bushing. New bushings are less than $3 and can be obtained from your dealer or you can purchase aftermarket aluminum replacement bushings, which will last much longer.

To correctly adjust the TV cable assembly, release the locking tab on the TV cable and have someone hold the throttle full to the floor. Lock the tab down and mark this setting on the cable casing. This will be your maximum TV setting. Measure 5/16 in. back from that mark (with throttle still wide open) and scribe another mark as your minimum throttle valve setting. Then make a third mark halfway between both scribe marks (5/32 in. from either mark). Unlock the locking tab again and set the adjustment at this halfway mark to have a properly adjusted TV cable."

Sorry to hijack - your thread has gotten me into wanting to know more about mine. Hopefully, there's something you can use here.

 

[Jeff73Mach1]

Keep in mind all transmissions are not created equal. A FMX has a parasitic loss of only 25 horsepower. A C-4 has a loss of about 30 horsepower and a C-6 has a parasitic loss of 50-55 horsepower. WHile it isn't scientific, I found some AOD estimates of appx 40-45 horsepower parasitic loss. So what you are feeling is that the car isn't as "lively" because you are having to overcome an additional 20 horsepower in drag before you ever get to overdrive. That's damn near 10% on a stock engine!

 

[Qcode351mach]

2. As for the shift points, though - that sounds more like it would be a TV cable adjustment to me (I know Lokar's instructions say to hook their cable up according to their specifics, but then it will most likely require some fine tuning to get the shift points just right). Especially, since it seems to shift early through the entire range. It probably all seems compounded with the 3.00:1 rear gears (especially when OD kicks in). I don't believe you're very far off from being perfectly set-up, though.

Agreed your going to need to adjust the shift points..But I don't think your going to be able to adjust each point by itself like the 4r70w from the controller ..it's the entire curve ..The entire curve may need to be moved..to kick in later(more rpm /mph) vs earlier

 

[Mister 4x4]

2. As for the shift points, though - that sounds more like it would be a TV cable adjustment to me (I know Lokar's instructions say to hook their cable up according to their specifics, but then it will most likely require some fine tuning to get the shift points just right). Especially, since it seems to shift early through the entire range. It probably all seems compounded with the 3.00:1 rear gears (especially when OD kicks in). I don't believe you're very far off from being perfectly set-up, though.

Agreed your going to need to adjust the shift points..But I don't think your going to be able to adjust each point by itself like the 4r70w from the controller ..it's the entire curve ..The entire curve may need to be moved..to kick in later(more rpm /mph) vs earlier

Exactly what I was thinking. ::thumb::

You know, if my AOD hadn't be literally given to me, and after all the research we've been throwing around on this site, I would probably be going with a 4R70W.

 

[JimNiki]

I have read that the 4r70w are even more parasitic.

 

[Luke]

I have read that the 4r70w are even more parasitic.

Toploader is looking good jimbo

disregard the other negative stuff i posted the wrong link before sorry.we know the aod is a good choice for street cars. I too believe Mike is very close to a sweet set up it would only be tweaking the shift points to come a little latter

 

[luxstang]

Thanks Mister4x4

That's a lot of good info.

I found a video on how to fine tune shift points and kickdown response with the tv cable.


With higher pressure the AOD will shift at higher rpms and react faster to the kickdown. I guess that will make it feel much livelier and lighter to the touch.

I found out that the AOD delivers but you have to convince it that you're serious about revving it up.

So I guess the fine tuning should do the trick.


Parasitic loss is another factor. I figured it would be the same as a FMX but if the loss is actually 20 hp more then that will make a perceptible difference.

 

[mustang7173]

All,

The valve body in the AOD is suspect due to Fords cost cutting in the transmission. According research on the web, the stock valve body is the culprit to sluggish performance. Here is one article from Hot Rod Magazine that describes the issues. Replacing the stock valve body with the performance enhanceed AOD valve body is option to look into!

Ford AOD Transmissions - The Bulletproof AOD

http://www.hotrod.com/techarticles/drivetrain/hrdp_9903_ford_aod_transmission/

I did replace my valve body with a performance enhanced valve body and I can tell a difference. I got my performance valve body from Broader Performance!

http://www.broaderperformance.com/

mustang7173

 

[luxstang]

All,

The valve body in the AOD is suspect due to Fords cost cutting in the transmission. According research on the web, the stock valve body is the culprit to sluggish performance. Here is one article from Hot Rod Magazine that describes the issues. Replacing the stock valve body with the performance enhanceed AOD valve body is option to look into!

Ford AOD Transmissions - The Bulletproof AOD

http://www.hotrod.com/techarticles/drivetrain/hrdp_9903_ford_aod_transmission/

I did replace my valve body with a performance enhanced valve body and I can tell a difference. I got my performance valve body from Broader Performance!

http://www.broaderperformance.com/

mustang7173

Thanks! Definitely worth looking into.

 

[CZ-75]

That must be why I'm not havi ng any issues. Mine came with a customized valve body from Dan at Silverfox Transmissions.

 

[luxstang]

That must be why I'm not havi ng any issues. Mine came with a customized valve body from Dan at Silverfox Transmissions.

Yeah, yeah. Go ahead, rub it in.

 

[Qcode351mach]

I also installed a reprograming kit (shift kit modded valve body) when I had the tranny built even though it's a 4r70w..Was recommended by Baumann=tranny controller electronics

 

[will e]

While I went a different route (put a GV on the back of my C6) I have to agree with Mike. The highway is much more enjoyable with the OD gear. Even cruising a neighborhood street at 30 or 35 is just nicer. I run 3.50 gears.

 

[tfowler9]

I have a 1971 with a 351 Cleveland and FMX transmission. I have modified the engine with an Edelbrock manifold, 4 barrel Holley, Mallory Distributer and Jacobs Ignition system. I have also swapped out a 9" 2.79 rear for 3.50 posi. I have been seriously thinking about the AOD swap vs. a T5 manual.

Did you find it a straight forward swap and do you think it will work for my application? What was the total cost for all the parts including the transmission - which I assume you bought through a dealer, rebuilt.

Thanks Tom

 

[luxstang]

Of course, it would work. I think that the parts needed would be the same, because you have an FMX.

The 3.50 rear would be a perfect match.

I bought the trans from another mustanger who had it rebuilt by a friend of his.

As for the costs for the parts, check the links in my first post.

All in all it cost me a little north of 4000$ but I am in Europe. For someone in the US it should be less than half of that.

 

[mus72]

Mike I'm curious as the cost of that conversion would have bought a Gear Vendors and given an overdrive in every gear, was there a particular reason for going down the AOD route?

Thanks Stephen

 

[mustang7173]

mus72,

Once you mentioned Gear Vendors, I had to go price out the FMX part and the cost was $ 2795.00. It is a bit expensive, but considering the approx. $4000 already put in, this might have been a cheaper alternative, depending on what it would cost to ship international.

http://www.gearvendors.com/cgi-bin/shop/detail.cgi?id=10721&1.%20MANUFACTURER=FORD&2.%20VEHICLE%20TYPE=CAR&3.%20MODEL=MUSTANG&4.%20YEAR=1973&5.%20TYPE=PERFORMANCE%20STREET&6.%20FUEL%20TYPE=GAS&7.%20WHEEL%20DRIVE=REAR%20WHEEL%20DRIVE&8.%20TRANSMISSION%20TYPE=AUTOMATIC&9.%20TRANSMISSION%20MODEL=3-SPEED%20FMX%2012.75%22%20TAILHOUSING

mustang7173