Liberty’s Gears to Shift Your Own Gears with High Horsepower

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Photography by Liberty's Gears

TREMEC Elite Distributor Liberty’s Gears has been in the business of beefing-up manual transmissions since the days of bell-bottoms and mutton-chop sideburns. Today, Liberty’s Gears is a source for racers and enthusiasts wanting to shift their own gears behind ultra-high-horsepower engines.

Liberty’s Gears was started in 1971 by Joseph Liberty Jr. His career began in GM’s Cadillac division and in his spare time he was a successful drag racer. Experiments in developing improvements to manual transmissions for increased strength and quicker shifts earned him a solid reputation among racers across the country. Eventually he stopped racing and focused entirely on the manual transmission business, building Liberty’s Gears into an international supplier of upgraded manual transmissions and manual transmission parts.

Liberty’s Gears offers TREMEC transmissions to suit a variety of applications, including drag racing and road racing, in addition to street use. Since there are numerous variables between applications (even within the same performance sect), Liberty’s Gears first gathers vehicle specs and information from the customer on how the vehicle will be used. Then they pull a new TREMEC unit from the shelf and start modifying it accordingly.

Horsepower and torque are not the only factors for upgrades, but also the shifting environment and pattern. A drag racer will only shift down through the gears during a normal pass, but road racing requires upshifting and downshifting countless times. Each situation puts different stresses on the transmission itself.

As technology, manufacturing and metallurgy progressed, Liberty’s Gears updated its processes for upgrading select internals of TREMEC transmissions for extreme use to include methods like cryogenic-dipping and shot-peening for extra strength and durability. Craig Liberty from Liberty’s Gears took some time to explain these to us, which we detail in the photos and captions that follow.

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Liberty’s Gears facility in Harrison Township, Michigan, features an array of state-of-the-art equipment for improving existing transmission components or creating brand-new ones. In addition to manufacturing, Liberty’s Gears also has a team of skilled techs to help customers meet their transmission needs.
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Making the best even better: Liberty’s Gears takes the already rock-solid TREMEC TKO and Magnum manual transmissions and employs a variety of methods to further enhance their strength, reliability and shifting quality.
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One of the upgrades Liberty’s Gears offers is for the blocker rings in the synchronizer system. The factory full-brass blocker rings are upgraded to carbon-fiber-lined brass blocker rings, making them capable of handling more power and improves shifting at high RPM.
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Surface enhancement is an important element of a Liberty’s Gears–prepped transmission, and there are multiple steps in the process. First, the gears are shot-peened. Shot-peening relieves the existing stress in the gear (from the manufacturing process) and converts it to a compressive stress that enhances the surface strength of the gear and prevents chipping, especially on the synchronizer gears. The second step is to put the gears through a centrifugal surface-enhancement treatment that leaves the gears with a polished look (as seen above). It’s not just for appearances, though. This process enhances the face of the gears and the valleys within the gear teeth. No acids are used in the process – just a special formulation of soap and water.
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The gear on the left as been through Liberty’s Gears surface-enhancement treatment. The gear on the right is stock.
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Another step in the enhancement process is cryogenic treatment of certain transmission components. This freezing process converts any retained austinite from the carburizing heat-treatment process to martensite, which enhances gear hardness and toughness. To make certain that durability isn’t affected, Liberty’s does this before and after Rockwell hardness testing on cryo-treated components.
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A popular upgrade that Liberty’s Gears does for the 2003-04 Ford Mustang Cobra is to convert the factory TREMEC T-56 transmissions from a 10-spline input shaft to a much stronger 2.66 ratio 26-spline input shaft.