K.J. Jones
November 2, 2007
Photos By: Courtesy Of All Mustang Performance
Hurst's short-throw, five-speed shifter peeks through the trans tunnel of Dave Shephard's '05 Mustang GT. The sight of this shifter may not immediately trip your excitement meter, but once you consider the fact that the gear-selector handle of a 5R55S automatic originally occupied the same space, you have to give props to the crew at AMP Performance for pulling off the first auto-to-manual S197 trans swap known to 'Stangbanging.

Horse Sense: AMP Performance has one of the largest one-stop Mustang salvage operations in the country, so OEM parts necessary for this type of project might be in stock when you're ready to try the transmission swap-or any other, for that matter.

We've been fortunate enough to be in the loop with folks who have turned us on to first-time installations and swaps of various replacement or performance-improving parts for 'Stangs. Since cluing you in on the things we learn about is one of our primary jobs, we're always on the lookout for cool, new developments in 'Stangland, be them tech-related or pertaining to some other aspect of the hobby.

With the S197 now in its third year, the upgrade/modification hits seem to keep coming for this 'Stang, which has quickly become one of the most popular editions of the breed. For reasons we're still not able to ascertain-but we're certainly not upset about-owners of '05-'08 Mustang GTs and Shelby GT 500s seem to be OK with making radical changes to their new rides long before the cars are anywhere close to being out of warranty. Power adders are at the forefront of S197 mods, but enthusiasts are installing parts for other areas of a drivetrain in an effort to make Ford's Pony cars even better.

When David Shephard of Gold Canyon, Arizona, wanted a few more horses and performance from his '05 GT convertible, he dropped the car off with Tom Thompson and Mike Gallo of AMP Performance in Phoenix for a hearty roundup of go-fast upgrades.

The AMP crew, led by master technician Chris Ciolek, bolted on a Saleen VI supercharger and its related accessories: a Steeda cold-air system, a 90mm mass air, fuel pumps from a Ford GT, 39-lb/hr injectors, a 9-pound blower pulley, and a custom tune. Dave's ragtop rocket hit the dyno's rollers with 398 hp and 382 lb-ft of torque. That's definitely more than a respectable power gain, especially since Dave's 'Stang was equipped with an automatic tranny.

Yes, the '05 we're talking about left the assembly line with Ford's 5R55S automatic transmission, and we don't doubt for a second that the trans and its torque converter were working against the blower upgrade in a major way-not only on the dyno, but on the street as well.

What happened when Dave coupled his 'Stang's somewhat hindered performance with the auto trans and his true penchant for rowing gears? The result is AMP's successful transmission conversion from a 5R55S to a Tremec 3650 five-speed gearbox.

To our knowledge, the project is the first successful transmission exchange of this type for '05-to-present 'Stangs. In the spirit of this issue's report on cool swaps of all sorts, it goes without saying that this landmark endeavor should be included.

AMP's Jim Ray handled the assignment of identifying and gathering the parts needed for swapping the auto trans in an S197 with its five-speed cousin. Along with the Tremec 3650 transmission and bell housing, a two-piece driveshaft, the aforementioned Hurst short-throw shifter and shift boot, an '05 Spanish Oak PCM (for manual transmission), and wiring harness are all required components of the project.

Naturally, a new pedal box is required for this procedure, along with a slave cylinder and line for the hydraulic clutch. The actual reservoir for the slave cylinder is shared with the hydraulic brake system, so some of the brake fluid must be drained before connecting the clutch line. A harness that bypasses the automatic transmission position sensor is also required, as it completes the starter circuit when the clutch pedal is depressed, allowing the engine to start.

Todd Uzzell and Mike Akerlund are the AMP technicians responsible for performing the swap. Once the 'Stang is secured safely on a hoist and the negative battery cable is disconnected, the project begins with disassembly of the top of the engine (wiring harness, Saleen supercharger, transmission cooler, and so on). Temporarily taking away the blower allows the transmission to be tilted downward for easy access and removal. The complete wiring harness for the auto transmission is removed, as well as the shifter, starter, O2-sensor wires, exhaust system, and driveshaft.

An engine plate, flywheel and hardware, and McLeod 11-inch clutch kit replace Ford's S197 torque converter and flexplate. Two clutch switches must be installed with this conversion. Note how the wiring harness is routed from the engine compartment down to the transmission area. Once the transmission is in and the exhaust is reinstalled, the blue connectors on the harness will be matched with the GT's O2 sensors.

Once the Tremec is in its new home, the crossmember is positioned and secured and all of the tranny-related wiring is connected to ensure that the PCM keeps up with all the kickin' and stickin'.

When you glance inside the cockpit, the finished product looks factory with the Hurst shifter in its proper location and the 'Stang's original center console returned to its home. Some modifying must be done in order to pull it off cleanly. While a lower boot is incorporated into a stock, manual shifter on S197s, shifters on automatics don't have them-nor do Hurst's short-throw shifters for '05-'08 Mustangs. To fix this, AMP uses lower shifter boots from '84-'93 'Stangs, which keeps noise and heat out of the interior. With the trans tunnel sealed off, the OEM console is returned to its place and topped off with a factory leather boot and surrounding trim plate (for stick-shift cars).

AMP selected and installed 4.10 gears in the 8.8 rear to enhance Dave's performance and seat-of-the-pants driving experience with the 'Stang's Saleen huffer and new Tremec stick trans.

Final steps include installing a new engine harness that will accommodate the five-speed transmission. AMP recommends setting the harness on the engine first to make sure all the plugs are correctly installed. With that task complete, reconnect the supercharger and the remaining wires and hoses.

Chris Ciolek uses a Dynojet chassis dyno and DiabloSport tuning software to bring out the best in 'Stangs that are brought to AMP for performance upgrades. Dave's S197 certainly didn't disappoint. With a custom tune, including reprogrammed key fobs (for the vehicle's security system), the former automatic 'Stang produced a stout 470 rwhp and 430 lb-ft of torque with its new five-speed tranny setup.