Feature Article from Hemmings Motor News
February, 2008 - Jim O'Clair

The ''Big 4'' American manufacturers couldn't agree on too many things in the 1950s and '60s. Everyone had a better idea for horsepower, engine displacement, rearend ratio and carburetion requirements to make their cars more appealing than the others.

One thing they could agree on, however, was the Borg-Warner T-10 four-speed transmission. Each of the manufacturers used the T-10 at some point during these years, and GM even brought it back for a few years in the late '70s and early '80s. Because the transmission was used in so many production vehicles, they were easy to find, as well as being a reliable and strong four-speed, sought after by many racing enthusiasts of the time. They are still very popular with classic car and muscle car restorers today.

Beginning with the 1957 Chevy Corvette, this transmission was used by Ford, GM, AMC and, on a limited basis, by Chrysler in the early '60s. By 1963, GM and Chrysler developed their own replacement four-speeds (based in part on components of the T-10); however, Ford and AMC continued to use this transmission for quite a while afterward. Pontiac also continued to use the T-10 in '64 full-size models, because their replacement four-speed supplier, Muncie, could not keep up with GM's production demands in that year. Ford installed it in their full-size models (both Ford and Mercury), Mustangs, Falcons, Comets and Fairlanes until '65. AMC continued to use it in their Javelin and AMX cars until '74. Borg Warner started supplying to the original equipment market again in the early '70s with its release of the Super T-10. These were used on the GM A- and F-Body muscle cars and Corvettes up into the early '80s. Super T-10s incorporated shifting improvements over the T-10 design.

Their unique nine-bolt side cover can identify all versions of the T-10. This cover is a "D" shape with the curve of the "D" facing toward the ground. The T-10s came with a 10-spline, 1.125-inch input shaft. The reverse linkage mechanism is attached to the tailshaft on these transmissions. The four-speed design came about when B-W moved the reverse gear to the tail shaft on a Borg Warner T-85 three-speed, to make room in the case for the additional fourth gear used in the T-10. Borg Warner also released that same T-85 manual three-speed in '57. Late '50s and early '60s Corvettes used an aluminum case, while the full-size GM units from '57-'60 used a cast-iron case. GM used all aluminum-cased units after 1960, and all manufacturers used aluminum cases up until 1974.

Cars to look for, which used this transmission as an original equipment unit, were:

1957-'63 Corvette 1957-'63 Chevrolet full-size sedan 1961-'63 Pontiac, Olds F85, Buick Specials 1960-'65 Ford and Mercury full-size, except station wagon 1960-'65 Ford Fairlane, Falcon, Mustang, Mercury Comet 1963 Dodge and Plymouth V-8, except Hemi 1968-'70 AMC Rambler, Rebel, Ambassador, Marlin, and American 1971 AMC Hornet and Matador 1968-'74 AMC Javelin and AMX

Original Manufacturers specified different shift ratios for their own cars; and there were several for each manufacturer available. Ford used a 2.73 first gear in the Falcon, Comet and Mustang models, and a 2.36 first gear in their larger cars and the Shelbys. Chrysler used both a 2.54 and a 2.20 first gear in the 1963 production year, depending on engine size and rearend ratios. GM also used a 2.54:1 ratio and a 2.20:1 in the Corvettes, initially, and added the 2.64:1 and 2.43:1 ratio in both their aluminum and cast-iron cased versions. AMC used a 2.23:1 ratio as well as the 2.64:1 and 2.43:1 ratios. Production of the T-10 continued as an aftermarket replacement transmission for all American makes, and improvements to its design continued in each later updated version.

The most popular version of the T-10 among enthusiasts is the Power Brute Super T-10, which was used on the 1974-'82 GM A-Body and F-body cars. The Super T-10s used a 26-spline input shaft and were built to withstand the higher rpm requirements for the larger muscle car engines. These can be easily identified on 1974 and up GM data tags as an M-18, M-21 or M-24 transmission designation. These later Super T-10s can be retrofitted into the earlier T-10 applications by changing the clutch disc to a 10.4 inch, 26-spline disc. You will also need to change the slip yoke on your driveshaft. Super T-10s have a 32-spline output, which is the same size as a TH-400 slip yoke. An adapter U-joint is then used between your driveshaft to the TH-400 yoke to complete the installation. Advantages to the Super T-10 over the older units were hardened gears, hardened cases, and the additional ratios. Super T-10s came in several ratios depending on the year:

1974-'77: 2.43 1977-'79: 2.64 1979-'81: 2.88 1980-'82: 3.42

If you want to get a new four-speed unit instead of a used one from the salvage yard, Richmond Gear also manufactures a new Super T-10 for GM-only applications. Richmond Gear owns the rights to the B-W T-10, which they purchased several years ago. Other T-10 race-ready four-speeds are also available from other suppliers, but they run in the $1,200 to $1,500 range for an off-the-shelf unit. A quick check with some online salvage yards indicates you can find a used one for between $300 and $800, depending on application and condition.

This article originally appeared in the February, 2008 issue of Hemmings Motor News.