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.