We devote a fair amount of coverage to transmission swaps, often for the sake of gaining an overdrive. When these swaps concern manual transmissions, it seems that most guys go for the sex appeal of a six-speed gearbox, sometimes with multiple overdrives and often providing additional strength. However, there is still something to be said for the often overlooked five-speed. Most five-speed boxes provide overdrive while maintaining underdrive ratios similar to the four-speeds of musclecar lore. Don't let the bad experiences your buddy had while power-shifting his stock '86 IROC deter you--today's five-speeds are much more durable than the original manual overdrive boxes. We've gathered the most popular offerings and listed their features and specs along with where to find them for your perusal. Just a little more food for thought as you ponder future upgrades.
Borg-Warner/TTC T5
T5-Z
The Borg-Warner T5 manual five-speed transmission has been used in a wide variety of applications since it was first put into production in the late '70s; in fact, there are currently over 260 part numbers for T5 assemblies on the books. This has resulted in numerous variations over its production 20-plus-year lifespan. The original intent of this gearbox was to provide a relatively lightweight (under 80 pounds), smooth-shifting manual transmission with overdrive for improved fuel efficiency. But it wasn't long before it was providing an excellent bridge between performance and economy. The two versions most familiar to car crafters are the '83-'95 Ford Mustang 5.0L and the '83-'92 V-8-powered Camaro and Firebird. Despite the similar parameters of both of these vehicles, the gearboxes used in each are significantly different from one another, and to make matters even more confusing, there were changes to each during their respective runs. The upside is that these changes were almost always done in the name of increased durability, as the Detroit horsepower race escalated.
The primary differences in T5s for both the Mustang and the F-car can be split into two classifications: World Class (WC) and non-World Class (NWC). The term World Class is often thought to be reserved for the best T5s built, but actually there were further upgrades after this nomenclature was first applied. The World Class upgrades consisted primarily of caged needle bearings for First, Second, and Third gears, compared to the gears riding on a solid shaft as they do in NWC versions. The counter gears in WC boxes use tapered roller bearings in place of the standard rollers in the NWC. World Class boxes also use fiber-lined blocker rings on First through Fourth gears to improve synchronizing for smoother shifts. Despite these upgrades, the first WC boxes carry the same 265-lb-ft torque rating as the NWC units before them, probably since the changes were actually aimed at improving the transmission's operating performance rather than its integrity.
T5 WC
The NWC gearboxes use a 2.95 First gear while the later WC units have a 3.35 First. This holds true for both Camaro and Mustang boxes, though the Mustang went to the WC for the '85 model year while the Camaro didn't make the switch until '88. For the '90 model year, Ford worked with Borg-Warner to further upgrade the T5, resulting in new Second and Third gearsets using course-pitch gear teeth and higher nickel-content steel. These changes raised the torque rating to 300 lb-ft in Mustangs. Later, the T5 was further upgraded to harness the power of the '93 Mustang Cobra. This version, dubbed the T5 "Z" because of its Ford part number designation, has tapered output bearings and a steel front-bearing retainer (versus aluminum) among other things, pushing its torque rating to 330 lb-ft.
Speaking of the T5's durability, this gearbox has garnered a reputation as being wimpy and incapable of handling the power of a typical street machine. In truth, the better variants of the T5 can handle a healthy V-8 just fine--until it comes to full-on power-shifting, particularly with sticky tires. In those situations, the pinnacle of T5 development may be necessary: the G-Force T5 (see G-Force sidebar).
Tremec/TTC 3550/TKO
Tremec 3550
The Tremec gearbox has the appearance of an OE-designed assembly, yet most of its uses have been in aftermarket applications. Primarily built as an upgrade for Ford manual transmissions, the initial version of the Tremec 3550 used a Ford "Toploader"-style bolt pattern and center spacing merged with a 10-spline input shaft and a 28-spline (Ford C4-type yoke) output. Thanks to heavy-duty features like tapered roller bearings for the countershaft and caged needle bearings under First through Third gears, the 3550 carries a 350 lb-ft torque rating. The next evolution of this gearbox is the TKO, which has a 425-lb-ft torque rating, due mostly to its 26-spline input shaft and 31-spline (Ford C6-type yoke) output shaft. The TKO II is further upgraded with gearsets made from higher-grade steel, raising the torque rating further to 475 lb-ft. The TKO II can also be had with a 0.83:1 ratio in Overdrive, which many road racers favor since engine rpm doesn't drop dramatically in Fifth gear, often permitting the use of Fifth on long straights.
One of the features of the Tremec gearbox that makes it favorable for swapping is its multiple shifter locations. There are three possible shifter locations on the gearbox, though each position requires a specific shifter. Most Ford applications used the rear mount, and this is the position most aftermarket shifters for Tremec are designed to fit. However, since many muscle-era cars are better served by mounting the shifter in the center position, many of the outlets for swap kits offer center-mount shifter hardware.
There are now Tremec gearboxes available for applications other than Ford, including GM and Mopar. Some of these are factory-produced while others are modified after production. If you're considering a Tremec swap, make sure to find out exactly what you'll need to complete the job, including any modifications that may be necessary to accommodate shifter positioning, transmission crossmember modifications, bellhousing and clutch requirements, driveshaft yoke and length specifications, and speedometer cable/gear adapters. Currently, there are a number of very complete kits on the market to simplify Tremec swaps for various applications.
D&D Performance
D&D can meet all of your late-model drivetrain needs, covering a full line of T5, Tremec, and even T56 gearboxes, parts, and accessories. The Z-spec T5 is available from D&D as a new assembly, as is the Tremec 3550, TKO, TKO Plus, and TKO II. D&D also offers shifters, clutches, driveshafts, and just about anything else you'll need to convert your classic to a late-model overdrive manual trans, or simply to upgrade or service your late-model performance car.
Forte's Parts Connection
Forte's offers a diverse array of performance parts for various makes, but is best known as a manual transmission one-stop shop for replacement parts, complete gearboxes, and trans-swap parts and pieces. Today, Forte's carries a full line of overdrive manual transmissions, including the Z-spec T5, the Tremec 3550, TKO, and TKO II, plus Forte's also offers every version of the Tremec, from the typical Ford small-block applications to swap-oriented gearboxes for GM applications, including specific kits for third-generation Camaro/Firebird, plus the Ford FE, Mopar small- and big-block, and even AMC. Also available are mid-shift conversion parts for Tremec boxes to relocate the shifter, application-specific shifters, driveshaft components, crossmember conversion parts, clutch linkage, speedometer cable parts, and much more.
G-Force Transmissions
The name "G-Force" may not be immediately recognizable to the average hot rodder, but this high-performance transmission company is actually a division of Long Tool & Machine, the parent company of Long Shifters. Long and G-Force are well-known in professional drag racing and in NASCAR for producing incredibly durable transmissions and shifters. As a government-contracted aerospace components manufacturer, Long is well-versed in precision machining and absolute consistency of specifications and tolerances. Recently, G-Force added a complete internal shaft and gear arrangement for T5 gearboxes to its list of offerings. This kit replaces the stock T5 guts with G-Force's own components, and when fully outfitted, raises the T5's torque rating to roughly 500 lb-ft or 600 hp. There are two main versions: a fully synchronized unit and the race-bred trans using dog-ring engagement. The power rating remains the same for both. G-Force sells the components for the upgrade, can provide a complete ready-to-run transmission, or can rebuild your T5 with the G-Force internals.
Keisler Automotive Engineering
What began as an outfit dedicated to restoring the electrical bits of vintage Mopars has grown in just over 10 years into a diverse outlet for classic auto restoration and modification parts. The first musclecar transmission offerings from Keisler were for Chrysler products, enabling the use of the popular Tremec five-speed in place of vintage A-833 four-speeds and even as an alternative to Torqueflite automatics. Since then, the applications for five-speed swap parts has grown to include kits for classic GM cars, including kits specifically for first- and second-generation F-bodies, Chevelles, Novas, and even Corvettes. These kits are intended as bolt-ins that don't require cutting or other "permanent" modifications. Keisler offers choices of Tremec 3550, TKO, or TKO II boxes in its swap kits (depending on desired power capacity), and also offers new reproduction steel floor humps for manual transmission Chrysler applications as well as reproduction shifter handles, replicating those used on original Mopar musclecars, though designed to fit the Tremec shifter base. All necessary bellhousing, driveshaft, speedo gears and cable, and other driveline parts needed for the Tremec swap are also available through Keisler.
Hanlon Motorsports
Pennsylvania-based Hanlon Motorsports (HMS) is headed up by noted Mustang drag racer Bob Hanlon. Hanlon's racing efforts have involved successfully running manual gearboxes in classes where automatics were thought to have a distinct advantage, and to date, Hanlon Motorsports prides itself on serving the fastest five-speed racers in the country. Hanlon's knowledge of manual gearboxes is the driving force behind the business, and late-model overdrive boxes are a specialty. While rebuilding and upgrading gearboxes is the bulk of Hanlon's business, HMS also offers a full line of new gearboxes and replacement parts for the T5 and the Tremec line. For the T5, HMS offers the Cobra-spec "Z" trans, with 2.95:1 First gear and 330-lb-ft torque rating. This is a brand-new gearbox, ready to replace your weaker production T5. If you want something stronger, HMS can set you up with a Tremec 3550, TKO, or even the TKO II. HMS can also convert your Tremec to a mid-shift shifter location with its own billet adapter kit, and offers a Tremec girdle for increased strength. Of course, all service parts and full repair and rebuild services are also available.
Ford Racing
Although known for its wide array of performance parts for Ford vehicles, Ford Racing also carries many of the best factory pieces, to allow for updates and upgrades of earlier models. One perfect example of this is Ford Racing's Z-spec T5 gearbox (M-7003-Z), presented as a brand-new assembly ready to bolt in. The Z-spec trans was originally developed for the '93 Mustang Cobra to handle the additional output of the Cobra-spec 5.0 engine. Internal upgrades and a change to different gearsets (including a 2.95:1 First gear in place of the standard World Class 3.35:1) raised the torque rating of the Z-spec box to 330 lb-ft, up from the standard World Class T5's 300-lb-ft rating. Similarly, Ford Racing also offers the Tremec 3550 (M-7003-R58) as an upgrade, using the parts put into production on the '95 Mustang Cobra R, where the beefy trans was called on to harness the additional torque of the R's GT-40-equipped 351W. Ford Racing also carries bellhousings, clutch kits, flywheels, driveshafts, and other related parts to complement your new trans. Plus, Ford Racing has rebuild kits for the T5 along with service replacement parts to convert your standard World Class T5 to Z-spec.
