Offered in late-model Dodge Viper, and Ford Mustang Cobra-R, as well as General Motors F-Body and Corvette Z06 applications, Borg-Warner (and later Tremec) T-56 6-speeed transmissions became a popular feature in factory performance cars. Their overall acceptance from both manufacturers and enthusiasts was so great that Tremec is also now producing new aftermarket versions of these original units in Ford, Viper and Chevrolet configurations. Adding a T-56 will not be the cheapest upgrade you could undertake, nor will it be the easiest. But the advantages of the T-56 will be an added feature for your street car.
Viper T-56 has bellhousing attached to the case.
The added strength of a T-56 makes it a hard worker in higher-performance and/or horsepower engines. It is compatible through all ranges of rear-end configurations, whether it’s a large tire-screeching rear gear or a shorter gas-economy rear-end ratio. The low 2.66:1 or 2.97:1 first-gear ratios mean a big advantage pulling away from a traffic light and fast acceleration. The T-56 will make your car run at a lower rpm as well, saving a lot of wear and tear on the engine. The feature of double overdrives means closer shifting ratios, and the T-56 makes cleaner shifts because of its single-rail integral shifter. The improved synchronizer design makes for a much smoother shift and better component reliability in performance applications.
Aftermarket T-56s don`t feature the F-body`s 18-degree offset.
You will find T-56 transmissions for a changeover in the following donor cars:
o 1993 and up F-Body Camaro and Firebird with V-8 engine
o 1997 and up Corvette
o 1992-2004 Dodge Viper V-10
o 2003-2004 Mustang Cobra-R w/ 4.6-liter engine
o 2004-2005 Cadillac CTS-V
o 2004-2005 Dodge Ram SRT-10 pickup
o Holden Commodore and Monaro (for you Aussie readers)
Their appearance is similar to a T-5 five-speed transmission we featured in this column a few months ago; however, the T-56 transmission identification numbers begin with “1386” (or, in the case of some Fords, “TUET”). You will recall that the T-5 used prefix numbers “1352.”
The shifter location is towards the rear and mounted on the tailshaft, and is similar to the T-5. The integral shifter also saves the cost of buying a different shifter assembly; in most cases, only a new shift lever and handle are necessary.
Because of differences in the stock production Corvette and Viper transmissions, we do not recommend trying to use one of these for your conversion project. Changing the Viper input shaft to make it compatible with the installations we will be discussing is an added expense that you really don’t need to undertake, unless these units are all you can find. Tremec does make aftermarket versions of the Viper T-56 that have the proper length and spline-count input shaft to be used in these conversions. And because of the 550-lbs.ft. of torque, many enthusiasts have adapted the Viper transmissions for high-performance applications.
The Corvette unit is similar in ratio and dimensions to the Camaro offerings, but a good 10 inches shorter than the F-body transmissions.
The original 1993 General Motors 2.97:1 first-gear ratio was the only one that used the GM standard mechanical clutch linkage. In subsequent years, the 2.66:1 first-gear ratio had a hydraulic clutch linkage. If you can find a 1983 F-Body T-5 mechanical bellhousing, this can be used to mate the T-56 to an earlier 1955 and up Chevy block. This would probably be one good reason why it’s tough to buy a good T-5 mechanical-linkage bellhousing at a salvage yard, because GM discontinued the part number several years ago.
You could also substitute a Lakewood #15015 scattershield or a McLeod modular bellhousing #8710-10 for mechanical linkage applications. 1994 and up versions of the transmission will require replacing the existing bellhousing with the T-5 hydraulic clutch unit (GM #14045722) or an aftermarket T-5 scattershield. Lakewood part number is 15020; the McLeod number is 8710-15. Aftermarket suppliers have devised a special adapter plate, which can be used in conjunction with a T-5 bellhousing to mount this T-56 transmission to the earlier Chevrolet small-blocks. This adapter re-orients the transmission to a straight-up position to mount properly to the crossmember in non-F-body applications (F-Body T-5 bellhousings mount the transmission at an 18-degree angle). The addition of the hydraulic clutch linkage is necessary as well.
GM versions of the T-56 had the 26-spline input shaft and a 27-spline output, requiring a TH-350-style slip yoke to mate to your original driveshaft. Because of the additional length of a T-56, you will also have to shorten the driveshaft a few inches, and a new crossmember will need to be fabricated or purchased. SPD manufactures a new crossmember, which is U-shaped and runs about $150. A reverse lockout solenoid is installed next to the shifter on original applications and is powered by the car’s computer. Depressing a momentary push-button switch in place of this solenoid will allow you to start the car. Several aftermarket shifters also have a button in the knob that can be used for this purpose.
F-body transmissions later than 1998 use no clutch fork; the clutch slave is part of the throw-out bearing, and the input shaft is longer than on the 1993 to 1997 models. These will be much more expensive and labor-intensive to install into a Sixties or Seventies muscle car and would have to be adapted to a mechanical speedometer drive to work in them as well. Speedometer adapter packages will run you between $40 and $120.
For the later Mustangs (1983 and up), installation of the Ford T-56 can be accomplished with the use of a 1983 and newer T-5 bellhousing. The shifter location is similar to that of the T-5; however, the output yoke would have to be changed to the C-6 automatic slip yoke, and the front u-joint would need to be converted to fit the driveshaft with an adapter-type joint. 1983 to 1986 driveshafts require a Spicer 5-460X adapter joint; 1987 to 1989 require a Spicer 5-648X u-joint to mate the driveline with the transmission. Your driveline would also need to be shortened 1-1/2 to 2 inches. The crossmember mounting would be approximately 5 inches farther back, and the original crossmember could be re-used, or a replacement double-hump crossmember is available through Ford Motorsport. New crossmember brackets would have to be custom-made for this installation, or one of the aftermarket three-piece crossmembers that you cut and weld together could be used. The Ford T-5 bellhousings used a cable-activated clutch assembly, which can be retained for this particular changeover.
Now that we have explained a little about what is involved in adapting a T-56 to your own ride, how about some costs? A used Firebird or Camaro T-56 (early style 1993 to 1997) is selling in the $800 to $1,300 range currently. The later 1997 and up F-body six-speeds are more in the $1,200 to $2,500 range. Cobra-R Tremec six-speeds are an easy $2,000, and the Viper heavy-duty units go for around $2,400. The T-5 bellhousings, which are a key piece in all of the changeovers we have mentioned, are still found at some salvage yards and specialty F-Body or Mustang used parts suppliers, and sell for somewhere in the $75 to $135 price range.
Installation of the T-56 into older Ford applications will involve a hydraulic linkage changeover, an adapter bellhousing and new or modified crossmember. Complete changeover kits and component pieces are available for Sixties and Seventies Falcon, Fairlane, Cougar, Comet and Mustang. For these applications, we would recommend you get one of these all-inclusive kits to save yourself the time and effort you would spend fabricating and tracking down parts to fit the T-56 into one of these cars.
Very little information has yet been collected for performing a T-56 changeover into Mopar or AMC cars. The only Mopar/AMC changeovers that we are aware of at this time are for complete kits, available through Dark Horse Performance. Two kits are available for the Mopar cars, one for big-block and one for small-block, and they sell in the $2,400 to $2,700 range. An AMC kit is also available. Another Mopar kit that is available is for the 1997 and up Dakota pickups. Keisler Automotive has developed a complete changeover kit for these popular truck models, to the tune of about $4,200.
If you were leaning towards getting an aftermarket complete kit, these would definitely be a lot less work in terms of fabricating and locating necessary finishing-off parts. A complete six-speed installation kit for a first-generation Camaro or 1968 to 1974 Nova will set you back $3,600; most of the parts price lists we have seen involving this changeover are running anywhere from $2,500 to $3,000 (depending on how inexpensive the transmission will be).
But enthusiasts who have performed this conversion are happy with the results, and many report fuel economy increases of 20 percent to 30 percent. This can help to justify undertaking this installation and some of the expenses related to it. As manufacturers continue to come out with new products to assist in the installation of the T-56, it will become one of the more popular muscle car upgrades to be undertaken by enthusiasts in the near future. And if any of our readers figure out a way to put the T-56 in any other cars, feel free to drop us a line, and we will post the additional information in this column in the future.
In our continuing effort to put as much information as possible into this column, even when we run out of room for it, we will offer an additional chart of gear ratios and dimensions for the T-56 transmissions. This will, as always, be available on the www.hemmings.com/parts-locator website. It will be linked to the Parts Locator page, as are the other charts from previous articles.
