Tech: Fox Body AOD to T-56 Magnum Conversion
Swapping out an AOD transmission for a manual transmission has been a modification that many Fox Body enthusiasts have performed for years. It used to be that the parts to do such swaps were easily sourced from swap meets, the local junk yard, or even your neighborhood Ford dealer. It’s been 20 years since a new Fox Body rolled off a Ford assembly line, and as such new or even used parts for these swaps in good condition can be harder to come by these days.
A dream swap for many Fox Body owners has been the Tremec T-56. This often proved a tricky proposition, as the T-56 presents a few issues over the traditional T-5 swap. That being said, with Tremec now offering the stout T-56 Magnum transmission to the aftermarket, swapping one into a Fox body is more tempting than ever. We recently performed such a swap on a ’93 Mustang coupe, owned by Power Automedia’s own Eric Schumacher. This was made possible with the help of Tremec, McLeod, and American Powertrain. The components offered by these companies made this swap a straight forward, bolt on affair.
Schumacher’s car is one that has seen a lot of drag strip duty, but is now being converted over to a corner carver. With a stock short block, some bolt on parts, and a Vortech supercharger pushing 15 psi, this engine is estimated to make around 475 hp to the rear wheels. With a full suspension from Maximum Motorsports on board, the car hooks well.
The car has been running a manual valve body AOD equipped with a trans brake. Unfortunately the AOD decided it had undergone all the abuse it would take. The slushbox finally failed and has been stuck in first gear, leaving the coupe unusable.
Schumacher was faced with two options, either to rebuild and repair the worn out AOD or go a different route. He elected to row his own gears at the track, hatching the idea fort a T-56 Magnum swap.
When we developed the Magnum, we had three key things in mind, synchronizer capacity, smooth shifting, and torque handling -Kevin Ryan, Tremec
The T-56 Magnum is the same internally as the TR6060 or T-56 Magnum XL used as original equipment in the GT500. The Magnum line from Tremec was developed as the the evolution of the original T-56. For years the original T-56 was the go to transmission for hot rodding, muscle car, or pro-touring swaps. Repeated abuse would often take a toll on it’s smooth shifting capability, and eventually cause a synchronizer failure. To remedy this Tremec developed a carbon particle lining for the synchronizers, the second generation T-56 featured this lining, however the trade off for improved durability was a lessened smooth shifting characteristic.
Moving on, Tremec knew that racers and enthusiassts wanted to have their cake and eat it too, they wanted to develop the next version of the T-56 to offer both slick shifts, while maintaining durability. “When we developed the Magnum, we had three key things in mind, synchronizer capacity, smooth shifting, and torque handling,” says Tremec’s Kevin Ryan. The T-56 Magnum was born. With the ability to handle 700 ft-lbs of torque, while still offering silky smooth shifts, and the smooth ability to change gears quickly the T-56 Magnum should provide Schumacher’s coupe with reliable shifting for years to come.
“This is the ideal transmission for someone who wants to be able to cruise the boulevard, but still go to the track and really use the car,” says Ryan. The 26-spline input shaft offers improved strength and greater surface area for the clutch disk to grip than the standard 10 spline of the Fox Body era T-5.
The gear spacing of the T-56 Magnum should also make a world of difference in acceleration when compared to the AOD it replaces. With closer spacing of the gears, Schumacher should be able to keep the engine in the sweet spot of the engine RPM range longer as he makes his way around the track.
The upgrade to the T-56 Magnum will also cause less parasitic power loss through the drivetrain than the AOD. Like so many OEM parts, when it was designed the AOD had to fit a variety of vehicles from your grandmother’s Town Car to Mustang GT’s. While some variations exist for each particular application, the AOD is a transmission not always best suited for high performance Mustangs.
With so many potential applications for the T-56 Magnum, Tremec has yet to come out with a swap kit specifically for the Fox Body Mustang. This leaves those trying to do the swap with a couple of options. You could try to source each part individually and adapt others, which may require hours of parts hunting, or even fabrication.
Instead of tracking down one piece at a time, we turned to American Powertrain. Grey Frederick from American Powertrain tells us, “We put our kits together so that you don’t have to pull your hair out trying to get the right parts and make everything fit.” They offer everything needed to get the job done in a bolt on manner all in one place. There’s no hitting the junk yards for sometimes questionable parts, and no trying to assemble everything needed from multiple sources.
Our installation kit, part number, PFFO-30002, included:
We put our kits together so that you don’t have to pull your hair out trying to get the right parts and make everything fit.-Grey Frederick, American Powertrian
- X-Factor aluminum cross member
- Transmission mount (polyurethane)
- Speedometer gear
- Pilot bearing, fully rollerized
- Shift knob
- Slip yoke
- Seamless DOM driveshaft (race balanced, solid U-joints)
- Reverse light wiring harness
- Reverse lockout wiring harness
We also opted for a Quicktime SFI bell housing, part number BHFO-28031.
Until the S197 platform came along for 2005, Mustangs had always been equipped with mechanically actuated clutch systems. The hydraulic system that is standard equipment on the S197 allows for much easier clutch effort, without the worry of stretching or breaking a cable. Schumacher wanted this feature on his coupe as well, and American Powertrain was able to provide all the necessary parts. Frederick tells us, “The hydraulic system is also something new that we’ve put together for the Fox Body market.” The complete kit, part number HMFO-01101GT, includes:
- Concentric slave bearing, which comes pre-bled for easier installation.
- Stainless steel braided teflon lined hydraulic lines
- 3/4 inch bore clutch master cylinder
- Hydramax firewall mount
- Reservoir kit
- Pedal rod and hardware -model specific with adjustable length
- Necessary fittings for installation
The Purpose of Marcel
Marcel is the wavy pattern you will see on many street oriented clutch discs. Marcel acts as cushioning when you engage the clutch, smoothing out out the transition into the next gear. The RST clutch uses a disc with Marcel at the flywheel, and a second disc without Marcel between the floater and pressure plate. With the floater plate attached to the adapter ring using straps, the floater actually exhibits some Marcel characteristics. What this means to drivers with an RST clutch is that in stop, go and low speed engagement situations the RST clutch acts more like an OEM type of clutch, rather than the hardcore, high horsepower capable unit that it is.
Schumacher’s coupe needed a clutch that can take the abuse of drag racing. It also needed one that will allow for the 26 spline input shaft of the T-56 Magnum. For that we went to McLeod for a RST twin disc clutch and flywheel setup, part number 6913-07C.
The RST clutch package is a twin disc clutch that is designed for high output street cars such as the coupe that we’re doing this install on. The setup offers incredible clamping ability for engines making up to 800 hp, while still allowing for a comfortable pedal effort that won’t leave you crying after sitting in a traffic jam. “It’s the type of clutch you can use at the track and then comfortably drive your car home on the street,” says McLeod’s Fred Taylor.
The RST also features a shorter release distance than many older clutch designs. Most OEM, and some aftermarket clutch designs require .500 of an inch of pressure plate finger throw to travel to release once the pressure plate is acted upon by the throwout bearing. The RST and RXT clutches require only .350-.375, making them ideal for Schumacher’s coupe and his weekend racing exploits.
Included in the RST clutch kit is the correct flywheel, McLeod adapter ring, floater plate, pressure plate, friction discs and pilot tool. The clutch discs feature an organic friction material designed to be tough while engaging smoothly, and not chattering,.
A swap of this magnitude is pretty much an all day job if you have a lift, possibly all weekend if you’re doing it on the garage floor.
We were surprised by how well the T-56 Magnum fits in the Fox Body transmission tunnel. We had to clearance one of the transport tabs on the bell transmission case to get it to fit properly. We also trimmed less than a half inch of material out of the back side of our shifter location in the floor pan allowing the shifter to fit nicely.
This car is still running the factory catalytic converters. Being a California based street car it’s subject to emissions regulations, meaning it must continue to use converters. The Ford OEM converters for a Fox Body are reversible, so they flow in both directions. We actually cut them out of the exhaust and reversed them to allow for proper clearance. This moved the converters back three inches, giving us the room we needed to clear the new T-56 Magnum. If you’re running non-factory converters and doing this swap you’ll need to check with the manufacturer before doing anything like this. Off road pipe owners shouldn’t have anything to worry about.
We’re anxious to see what kind of ET’s the car is capable of with a few more horsepower at the rear tires and more ratios to spread out the power down the track.
On the street, the coupe is more drivable than it has been in years. With two overdrive ratios the Vortech hardly touches the boost in sixth gear. Schumacher can’t wait to get back to the drag strip and road courses, plus we wonder if he will be driving the coupe on the street a bit more now that it has a more street friendly transmission.
- Tremec T-56 Magnum 6 speed manual transmission
- McLeod RST Clutch and flywheel kit: 6913-07C
- American Powertrain T-56 Magnum swap kit: PFFO-30002
- Quicktime bell housing from American Powertrain: BHFO-28031
- American Powertrain hydraulic clutch activation kit: HMFO-01101GT
- Royal Purple Max ATF