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FMX to AOD swap. Complete report.


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So, finally the Mustang is back on the road.

Maybe some of you noticed the update on my "idle pressure to high" thread. It turned out it was a stuck valve in the valve body. Once that was taken care of everything went smooth.

I'm gonna post both the effect of the swap and the parts we needed (and did not need). The latter is important because the Internet is full of "you need this" and "you don't need that" and in the end we were none the wiser.

 

Before we start, let me remind you some basics on my car: It has a 351W from Ford Racing, the stock FMX and 8 inch rear axle.

All the info below was true for MY car. Don't blame me if it turns out to be different on yours. :)

The suppliers listed below are the ones I bought from. There are others out there, you may wanna check with them. The links are for better reference.

 

Before and after:

 

It is amazing how much of a difference it makes. The first three gears are the same in ratio on the AOD and the FMX, so not much difference there. But as soon as the OD kicks in it's a different world. No engine noise, no exhaust noise, only the wind noise on the convertible top.

One ting to remember is your rear axle ratio. Mine is a 3,0:1 which is a little low for this setup.

At 35 mph You will have a little under 900 rpm, which is actually idling rpm.

But, on the other hand, it is cool for freeway cruises.

Remember, I am in Europe and can have fun on German autobahns. :)

When going 110 mph, rpm is 3000!

At 65 mph it is 1700 rpm instead of the previous 2500 rpm with the FMX.

 

I will change the rear axle ratio to a much shorter one, probably 3,8:1 after I got the car on the dyno. Then I will know at what rpm the engine delivers best and I will match the rear ratio accordingly.

 

Oh, by the way, the positions of the stock shifter lever can be made to match precisely. It takes a little setup but no modification is necessary.

 

Parts I needed:

 

Lokar KD2AODHT - Lokar Hi-Tech Kickdown Kits

http://www.summitracing.com/int/parts/lok-kd2aodht

 

Lokar SRK-4000 - Lokar Throttle Cable Brackets

http://www.summitracing.com/int/parts/lok-srk-4000

 

Lokar ATA-1000 - Lokar Ford AOD Selector Shaft and Arms

http://www.summitracing.com/int/parts/lok-ata-1000

We ended up making a custom part and did not use this one. Reason is the hole in it was too small to accept the original shifter rod.

It was also pretty hard to align the shifter positions with this one. You may wanna try the one with only a slot and no hole, maybe that one will work better but I can't say for sure. Link:

http://www.summitracing.com/int/parts/lok-ata-1001/overview/

 

Ford Racing M-4841-B - Ford Racing Transmission Yokes

http://www.summitracing.com/int/parts/fms-m-4841-b

My FMX had 32 spline and required this new yoke. Problem is that it is a 1330 yoke and the driveshaft had 1310 ones, so we also needed:

 

Ford Racing M-4635-A - Ford Racing U-Joint Conversion Kits

http://www.summitracing.com/int/parts/fms-m-4635-a

 

 

From http://www.transmissioncenter.org/classic_mustang_to_aod_conversion.htm:

 

#29 CARBURETOR ADAPTER

 

FOUR FORD TORQUE CONVERTER NUTS

 

Inspection plate (for bottom of bellhousing)

 

New AOD conversion crossmember

(you can modify the existing FMX crossmember to fit but this is a direct replacement and much sturdier than the flimsy stock crossmember. Plus I think it is not a good idea to cut parts off of structural parts. By the way Summit have their own version of this part but as I ordered other parts from PATC I got this from them too.)

 

AOD conversion trans mount.

 

 

Things we did NOT need:

 

OD NEUTRAL SAFETY SWITCH PIGTAIL as that switch is built into the shifter on a 72 Mustang.

New speedo gear (the stock one fit and works precisely)

Engine block off plate. The original one from the FMX worked fine, only the inspection plate at the bottom did not fit and needed the aforementioned replacement.

New starter. Although many posts on the web say you need one, we did not. The stock one fit perfectly.

New flexplate. Stock one worked fine.

New shifter and new shifter rod (and rooster comb or whatever shifter related parts). The stock ones work perfectly and the positions of the shifter match.

 

Modifications:

 

We needed to shorten the drive shaft for about 3/4 inches and the transmission cooling line has to be reworked. The front one will fit but the rear one will need to be shortened.


Here are a few pictures:

First, the new transmission crossmember (and mount). Sorry, it's a pretty crappy cell phone pic. you can see how this is much better than the original flimsy crossmember used by Ford. This looks like it even adds rigidity to the seat platform area of the chassis compared to the original one.

 

IMG_4008.thumb.JPG.32695c431faeb35d9dc238a7a706cd42.JPG

 

Here's a pic of the cooling lines before they were shortened. You can see the in and outlets on the trans and how one line will fit and the other one goes all the way to the rear of the trans body and will need to be shortened.

 

IMG_4009.thumb.JPG.0550634440ece0c2501aeef17acf8522.JPG

 

Here's the Lokar Selector Shaft. Compare the diameter of the hole to the rod and you see that it won't fit.

 

IMG_4013.thumb.JPG.2c16b34132cd12d33c84b5da0350d833.JPG

 

This is the custom made part that replaces the Lokar thingy.

 

IMG_4042.thumb.JPG.c402d1929b8cea04857db74d0cc1e248.JPG

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Mike
"If I were you...... I´d rather be me." 😛
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Awesome! I will be doing this very soon, I have all the components sitting in the garage ready to go.

1972 H-code Mach1

2010 GT Premium

2015 Hyundai Sonata Sport 2.0T

1995 F150- The "home depot" machine

2012 Harley Davidson Road Glide Ultra

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Great write up. I really appreciate the pictures. ::goodjob::

Ron

The Rickster, a 1973 Mach 1, being restored as a tribute to my brother who passed away with COVID in July 2020.

Billy, a 1976 Ford Bronco, also needs a lot of work.

El Guapo, a 1986 F150, frame-off Resto-Mod.

Also, in the queue, a 1950 Ford F1 Panel truck and 1962 Falcon Ranchero

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Very nice! This is something I've been considering down the line for my car (I can dream big right?) did you keep the stock torque converter or go with a different one?

2013 Ford Focus SE Flex Fuel 5spd - Daily Driver

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Glad it all worked out so well. How about trans lines. Did you need to alter yours?

 

Look carefully. The trans lines needed to be shortened. :)


did you keep the stock torque converter or go with a different one?

 

Good question. I used the one that came with the AOD.

To be honest, after driving it for two hours today, I think the car has less power than before. It used to take the gas pedal better.

I may be wrong because I had the car sitting over the winter and I did not drive it got 3 months but something tell me it lacks power.

Could be the torque converter.

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Mike
"If I were you...... I´d rather be me." 😛
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Could be the torque converter, but it could also be just a perception. Does your gas pedal feel like it takes more pressure to push it down? MIne did, due to having a TV cable versus the kick-down lever.

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Could be the torque converter, but it could also be just a perception. Does your gas pedal feel like it takes more pressure to push it down? MIne did, due to having a TV cable versus the kick-down lever.

 

Not really. The motor revs but there seems to be some drag in between the motor and the wheels. Does that make sense?

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Mike
"If I were you...... I´d rather be me." 😛
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You don't mention changing the torque converter and it should have the same reaction as with the FMX considering the gear ratios are the same. Is it up shifting too quickly?

 

I used an 1800 street fighter in my 69 vert with a 3.55 TruTrac rear end. IMO, its a really nice combination for get up and go and highway cruising.

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Could be the torque converter, but it could also be just a perception. Does your gas pedal feel like it takes more pressure to push it down? MIne did, due to having a TV cable versus the kick-down lever.

 

I noticed that adding the TV cable to mine has resulted in requiring more effort to cycle the throttle than before I'd hooked it up. I was a little concerned over that because I was mostly just blipping the throttle with my hand, but when actually got in the car to move it onto the trailer, I didn't notice any crazy extra effort needed to push the gas pedal... it kind of feels just about right, actually. I was kind of expecting it to be really tight, but not so bad.

 

I can't speak to the stock converter being any more or less slushy than what was with the FMX, since mine was all seized up and nasty. I do know that my AOD's previous owner had no complaints and just wanted a 5-speed - it ran just fine, otherwise.

 

Luxstang - good to know about the rpms at speed. I used an rpm calculator to get a WAG on what to expect, and it sounds pretty much spot-on. What is your overall wheel diameter? I was using 27 inches as my wheel diameter to get the 1700 rpm @ 65mph statistic.

 

Excellent job! ::thumb:: I might just get that cross-member for mine, since I simply notched my FMX cross-member to clear the pan.

Eric

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It's definitely shifting up too fast.

I was thinking too that there shouldn't be any difference since the gear ratios are the same but the car now feels heavier, less eager in terms of throttle response. It simply feels like the trans is eating HP.

As I said, I used the torque converter that came with the AOD. Don't know what it is exactly.


Oh, regarding the wheel diameter: your 27 inches come pretty close. I think mine is 26.8 or something similar. I'm typing on my phone right now but if you wanna look it up, the tire size is 285/40/18.

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Mike
"If I were you...... I´d rather be me." 😛
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Luxstang,

I use the same combo of a cleveland & AOD in my Model A and it goes like hell !!! I have an B&M "holeshot" converter in mine. It only weighs 2200 lbs. I have found that the TV cable (lokar also) has adjustments for the shift points. Do adjustments a little at a time either in or out not to much to possibly change the actual pressures.

Good luck.

Thanks, Jay

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Thanks for your input guys. We'll look into that shift point issue again. Like I said, I've had the car for two days now. Maybe it needs a little fine tuning.

Right now it shifts into 3rd at 35 mph with medium acceleration. It used to go 45.

With hard acceleration it would stay in 2nd until 65 mph. Now it won't go over 50, no matter how hard I stomp on it.

We'll see after we tinkered with it.

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Mike
"If I were you...... I´d rather be me." 😛
Check out my video:
http://www.7173mustangs.com/thread-my-mustang-in-action

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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.

2013 Ford Focus SE Flex Fuel 5spd - Daily Driver

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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.

Eric

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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.

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Mike
"If I were you...... I´d rather be me." 😛
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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.

Eric

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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!

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"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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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

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