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Tech: Fox Body AOD to T-56 Magnum Conversion

Posted By Don Creason On In Drivetrain | Comments Disabled

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.

The T-56 Magnum is capable of handling 700 ft-lbs of torque. We’re essentially overbuilding the powertrian with this swap since the coupe is probably making no more than 450 ft-lbs of torque. This makes it virtually impossible to damage the T-56 Magnum.

Left: We ordered a McLeod RST dual disc clutch and flywheel set. Capable of 800 hp, this clutch is more than enough for our combination. Center: Rather than try to piece all of our parts together we ordered a complete installation kit from American Powertrain. This includes a Quicktime bellhousing, transmission spacer, shifter, driveshaft with the correct yoke, and transmission mount. Right: To make shifting easier we also ordered a Hydraulic Clutch Kit from American Powertrain, this also came with everything we needed for installation.

The Candidate

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.

Left to Right: To ease installation we removed the instrument cluster, lower dash panel (knee panel), and dropped the steering column. This allows better access to the wiring and pedal mounting area.

T-56 Magnum

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.

Left: Fox Body Mustangs have two holes in the firewall used for the speedometer and clutch cables. Since our car is an automatic the speedometer cable must be moved to the center hole, this is easily done by removing the plug, disconnecting the cable, and moving it over into the new position. Center: We used a template to mark the firewall for installation of the hydraulic clutch system's master cylinder. Right: The stock pedal assembly can now be unbolted and removed from the car. It will take some twisting and turning to snake the old pedal assembly out. Don’t forget to disconnect it from the brake pedal pushrod.

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.

Our clutch master cylinder installed easily and connected perfectly to the factory manual transmission medal assembly.

Left: Schumacher bought this Fox Body pedal assembly from a junkyard. Center Left: Side by side you can see the small differences in the two pedal assemblies. We sand blasted and painted our junk yard pedals to make them look a little nicer. Center Right: We carefully snake the new pedal assembly into place. Far Right: With the pedals in place we made the connection for the brake push rod, and also connected the wiring harness for the clutch release/safety switch. We then tightened the bolts that retain the pedal assembly in place.

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.

Swap Parts

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.

Left: With the steering column and pedals in place we reinstalled the instrument cluster. Right: Before moving under the car, we removed the covers for the AOD shifter and removed it.

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

We also opted for a Quicktime SFI bell housing, part number BHFO-28031.

Left and Center Left: Under the car the exhaust system had to be dropped. We disconnected the car’s cat-back system and then removed the H-pipe. Center Right: The trans-brake AOD has seen better days, it finally gave up after years of drag racing abuse. Far Right: We trimmed less than a half inch out of the stock floor pans to get proper clearance for the T-56 Magnum shifter.

Going Hydraulic

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:

Left: We installed the new rollerized pilot bearing, this is a must for Manual transmissions. Automatics use a pilot bushing that must first be removed. Center left: The speedometer gear must also be changed from the one previously used, this was provided in our kit from American Powertrain. Center right: Since we had the transmission out we decided to install a new crankshaft rear main seal. This is cheap insurance against a future oil leak, and only took a couple of extra minutes. Right: To get proper clearance for the clutch, flywheel, and transmission combination it was necessary to install a .250 inch spacer. This spacer was included with the kit from American Powertrain and is in addition to the thin factory spacer.

4138, 5411, 4176, 4180

Twin Clutch

 

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,.

Left: For for the McLeod RST clutch, we started by installing the flywheel. Center left: We had previously marked the pressure plate, flywheel, floater, and adapter ring to ease installation later. Center right: After the flywheel, the first clutch disc goes on, followed by the floater, and the second clutch disc. The included pilot tool is essential to getting everything lined up. Right: The pressure plate is the last piece of the clutch kit to be installed

The Swap

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.

Left: Before installing the bell housing and transmission, we made sure that our clearance from the .250 inch spacer to the face of the pressure plate is correct. Center left: Next we installed our hydraulic clutch release bearing on the input shaft. Center right: Now the transmission can go in. If you’re doing this on the garage floor, do not let the transmission hang from the input shaft, this will damage it. Right: Then we bled the clutch master cylinder. The release bearing is pre-bled making installation easier.

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.

Left and Center Left: The only necessary electrical connection underneath is for the reverse lights. We had fed the harness that came in our kit to the transmission to the reverse light trigger on the T-56 Magnum. Center Right: This installation requires a shorter driveshaft than the factory Fox Body AOD or T5 shaft. It also requires a transmission slip yoke for a 31 spline output shaft compared to the AOD and T5’s 28 spline. Our kit from American Powertrain included a driveshaft built to all the proper specifications.

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.

With the transmission installed, we moved on to reinstalling the exhaust. We did have to cut out and flip the car’s factory OEM Ford converters to get them to clear the transmission. Center Left: The Cross member supplied in our American Powertrain kit is engineered to fit the car exactly. It cleared the exhaust and easily allowed us to bolt in the T-56 Magnum. Right: We filled the transmission with Royal Purple Max ATF fluid completing our installation.

Parts List: