K.J. Jones
June 13, 2007
Photos By: Patrick Hill

Horse Sense: Looking back at 'Stang-trans history, most of the five-speed transmissions found in early Foxes weren't rated higher than 300 lb-ft of torque. In the early '90s, Borg Warner developed a Super-Duty T-5 featuring a 2.95 First gear that was able to withstand 330 lb-ft of torque. Unfortunately, with the advancement of power adders and the fact that engines in hard-core Fox Mustangs pumped nearly double the amount of torque to the rear tires, 330 lb-ft still wasn't enough. Although aftermarket transmissions were developed and were capable of handling higher horsepower and torque levels, enthusiasts complained about the modifications that were necessary to install them and the difficulty they experienced when trying to shift the crash boxes into gear at high rpm.

Every once in a while, we have to acknowledge the fact that on occasion, there's a slight disparity in the type of Mustang racing we talk about in 5.0&SF.

After a thorough cleaning process, A-Five assembly begins with installation of the reverse idler gear. In a stock transmission, a rubber O-ring is used to distance the idler from the second countershaft gear. All the gears on an A-Five countershaft are much wider than factory pieces, so wider spacers and bushings are required. Astro replaces the O-ring with a bronze bushing to space the reverse idler gear toward the back of the transmission and away from the second countershaft gear. Without the bushing, the reverse idler would rub against the side of the second countershaft gear, which will wear the gear material and make noise inside the transmission. A-Five countershaft gears feature press-fit bearings at each end.

While there are many different racing disciplines that Mustangs participate in and usually dominate using products that we test and report about in our tech articles, we're sometimes guilty of making the assumptive generalization that our readers share our 'Stang-racin'-is-drag-racin' mentality.

We begrudgingly admit that not all competitive 'Stangbangers are diehard drag fans. Some enthusiasts prefer to challenge their Mustangs and driving skills by going up and down hills, around hairpin corners, and across long straightaways on a road course. Road racing, autocrossing, and other forms of non-straight-line competition is cool when it's all said and done, as long as it's being done in a 'Stang.

The road course at Willow Springs and the canyons of Southern California's Malibu area are asphalt playgrounds for Mason "Mase" Rowland when it's time to give his 500hp, Vortech-blown, '93 Cobra exercise. If Mase's name sounds familiar, it's because you've read it in this mag on more than a few occasions. He's the lead technician at B&D Racing in Canoga Park, California-a 'Stang-specific installation and dyno facility that assists us with tech projects.

While Mase is better known for upgrading 'Stangs, he also has a bit of a reputation for breaking World Class and standard T-5 transmissions. In fairness, we can't put all the blame on Mase alone, as the rigors of road racing-constant up- and downshifting and high-rpm-to-clutch-action preciseness required for smooth, grind-free shifts-can play a huge part in the destruction of a 'Stang's stock, stick transmission's internals.

Gerry uses engine assembly lube on all the bearings used in an Astro transmission. The lube keeps the bearings' cones and needles from rusting or pitting if the tranny isn't going to be installed immediately after it has been built.

After explaining Mase's dilemma with Tony Sarvis of Astro Performance Warehouse in Tavares, Florida, Tony suggested we try one of Astro's five-speed trannys ($1,995 without core) as a stout remedy for the input-shaft and Third-gear breakage that has plagued Mase's Cobra.

According to Tony, our best bet is to go with a bulletproof gearset that features his company's new "A-Five" First- through Fourth-gear package ($1,095). The gear kit features helical-cut gears capable of supporting double the amount of power and torque the factory pieces will stand up to (650 hp/525 lb-ft based on a 3,400-pound Mustang). The larger, wider, and thicker gears will accept the synchronizers, dog rings, and sliders of a stock World Class T-5, which keeps the upgraded tranny's shift quality smooth and relatively quiet. We think this deal will be perfect for Mase's daily driven 500hp 'Stang. Our project tranny will also be upgraded with a 9310-alloy output shaft ($395), countershaft support-plate and bolts ($45), First- through Fourth-gear shift-fork lugs ($49.95), and an all-steel bearing retainer.

Here's a closer look at the installed countershaft. Notice how wide the second gear is? This greater-than-stock width makes installing a bronze bushing mandatory on the Reverse idler gear.

Since Mase likes powering through turns, we had his Astro-prepped transmission set up with a Road Race Fifth gear ($239), featuring a 9310-alloy, 0.79 percent Overdrive. The Road Race Overdrive is currently the only synchronized gear of its type, designed for hard-driving enthusiasts who want their 'Stangs to pull hard throughout the First- to Fifth-gear powerband. Thanks to this unique Overdrive, revs continue to climb in top gear instead of dropping off to the fuel-conscious, sub-2,000 rpm that are common for the 0.59 Fifth gear found in stock T-5s. Astro also offers remanufactured T-5 units that include the A-Five gear kit, starting at $1,595 with core exchange.

We had the good fortune of following Astro's shop foreman Gerry Hoffman as he went about building Astro's A-Five five-speed. The hardware differences compared to the factory gearset are dramatic, as you'll see in our photo coverage of the process.

Once the bearings are lubed and installed, Gerry adds this stout heavy-duty countershaft reinforcement plate. This brutish retainer is capable of standing up to 500 lb-ft of torque. It fortifies the rear part of the tranny's main case and allows a prescribed 2 in-lb of preload on the countershaft gear.

With the countershaft installed, Gerry moves onto the A-Five's mainshaft assembly, and begins by positioning the First-, Second-, and Reverse-gear slider on the mainshaft's hub. On the Second-gear side of the shaft, synchronizer/blocking rings are installed and secured with spiral locks. This allows Gerry to flip the shaft over and position First gear, its synchronizers, and bearings.

A clamp-style shaft collar is used to hold the First-gear components in place on the mainshaft.

Third and Fourth gears are added to the mainshaft and this synchronizer assembly follows. Each synchronizer is overhauled with new dogs and springs prior to installation.

The A-Five mainshaft assembly, installed over the countershaft.

After pressing the input-shaft bearing against Fourth gear, Gerry installs 15 needle bearings in the pocket of the input shaft. Transmission assembly lube works well at holding needle bearings in place.

A Torrington bearing, washer, and the Fourth-gear synchros and dog rings follow. Gerry pushes the Fourth-gear/input-shaft combination through the front of the case.

Astro's all-steel bearing retainer is slipped over the input shaft and secured with only two bolts, allowing for completion of the trans assembly.

A rear, mainshaft bearing and race must be installed before the 0.79 overdrive Fifth gear is added.

By completely encapsulating the Fifth-gear snap ring (an OEM piece), the mainshaft spacer shown here literally locks the Road Race Fifth gear. A second snap ring is installed in another groove cut into the mainshaft, creating what Astro calls a double snap ring.

The double protection assures us that Fifth and other mainshaft gears won't break a snap ring under high-rpm shifting.

Astro offers its own upgraded shift-selector plates for the tranny's two shift forks for First through Fourth gears. The plates, made of 4140 alloy steel, are less likely to crack under high-rpm shifts.

Check out the difference between the factory shift-selector finger (top) and Astro's upgraded finger. Stock, press-fit pieces can twist under the stresses of torque and hard shifting. Gerry makes sure the bulletproof fingers are installed in our transmission.

Here's our finished A-Five five-speed transmission, ready to handle all the horsepower and torque that Mason's blown Cobra will throw at it. With this A-Five's 0.79 overdrive, Mase will now have Fifth-gear acceleration that wasn't possible with a stock transmission. This unit weighs 82 pounds once two quarts of Synergyn Syngear II gear oil (required), and one quart of Red Line Oil's high-temp ATF have been poured in.

Bet you didn't know that gaskets aren't used to seal T-5 transmissions. Gerry applies high-temp RTV silicone between the case halves and near the O-ring on the rear part of the top cover. This ensures there won't be any leaks between the main case, top cover, and tailshaft housing.

The steel bearing retainer must be removed briefly-remember, we only secured it with two bolts earlier-to allow Gerry to install shims that will eliminate input-shaft endplay. When this step is complete, the bearing retainer is resecured with all four bolts and installed on the main case.

Installing parts in 'Stangs is what B&D Racing's Mason "Mase" Rowland does best.

After taking delivery of his Astro Performance A-Five, Mase had the complete transmission swap complete in about three hours. Granted, B&D Racing has all the equipment on-hand to make this type of operation go smoothly, but there's no reason why a mechanically adept enthusiast won't be able to install a new stick trans in the driveway in about the same amount of time.

This is the type of transmission carnage that became somewhat normal for Mase after a day of hard driving at Willow Springs Raceway. Note how Fourth gear is completely obliterated-a perfect example of stock equipment that can't keep up when big-time torque and horsepower meet high rpm.

Per Astro's recommendation, we're installing McLeod's Series 500 10 1/2-inch clutch disc (PN 260570) for the new tranny. Installing an A-Five unit requires stepping up to a 26-spline clutch (stock is 10-spline). The Series 500 clutch is designed for heavy-duty street use and some off-road applications. It features a bronze-button surface on the flywheel side and organic material on the pressure-plate side. We're also adding a blower-friendly 10 1/2-inch aluminum flywheel (PN 563100-50), a throw-out bearing (PN 16100), and a diaphragm-style pressure plate (PN 360048) to the mix.

Mase separates his broken T-5 from the factory bellhousing. Astro doesn't provide bellhousings with its A-Five trannys, so the original must be reused or a newbellhousing needs to be pro-cured before you begin.

Mase uses a tranny jack to pump his new transmission into its new home. This part of the install procedure is straightforward. Once the trans unit is in place and the crossmember, clutch cable, and exhaust are reinstalled, the Cobra is lowered and ready to test.

"This tranny isn't going to break," is the assessment Mase gave us after a few weeks of driving with Astro's A-Five in his Snake. "It shifts smoothly, and it's really cool having an overdrive that lets the car continue to pull in Fifth gear instead of having to downshift." Astro recommends putting about 500 easy miles on an A-Five tranny before turning the wick up.

Astro Performance's A-Five gear upgrade is all about width and thickness. Here's a look at how stock T-5 gears match up against the super-stout helical-cut cogs that went into Mase's new transmission.

A-Five First gear (right), OEM First gear (left).

A-Five Second gear (right), OEM Second gear (left).

A-Five countershaft (right), OEM countershaft (left).

A-Five countershaft (right), OEM countershaft (left).

A-Five input shaft and Fourth gear (left), OEM input shaft and Fourth gear (right).