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Six-Speed Science—TREMEC Magnum vs. T-56 Six-Speed Manual Transmissions

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Although undeniably similar, particularly to the untrained eye; the T-56 and Magnum are two very different transmissions inside.

Introduction

Of all the misnomers we encounter in the aftermarket, one of the most common stems from the confusion that surrounds the T-56 6-speed and its Magnum 6-speed protégé. Granted, one could argue that the two models have more in common than they do setting them apart; however, they are in fact completely different transmissions. If you think you might be in the market for either, then it is important to know what those differences are. This, in order to prevent you from wasting money on the wrong hardware, and ultimately falling short of your performance objectives.

Background

The TR-6060/Magnum design hinged largely on two key elements; the first of which was a new synchronizer assembly that featured a significantly narrower cross section than that of the T-56 (right), leaving more space between gears.

Appreciating the difference between the Magnum and its T-56 predecessor starts with knowing the transmissions’ history and the context that gave birth to the Magnum in the first place. We’ll start in the late-1990’s, when TREMEC was well on its way to becoming a household name amongst stick-shift enthusiasts, thanks to the growing popularity of its TKO transmission in the budding 5-speed muscle car conversion market. During this same period, following the acquisition of BorgWarner’s manual transmission business in December of ’96, TREMEC was successfully producing the T-56 for use in just about every factory performance car coming out of Detroit (as well as some not from the Motor City).

Fast forward a few years and the muscle car ‘restomod’ market had completely exploded. While the TKO (re-released in 2004 as the TKO-500 & 600) continued to lead the charge, particularly amongst those with early engine combinations; enthusiasts who had embraced more recent GM LS and Ford Modular offerings saw increasing appeal in the T-56 for similar early model swaps. Moreover, salvage yards had become flush with the factory offerings, making LS1/T-56 drivetrains from wrecked Camaros or Trans Ams in particular, a very popular swap.

The only problem was, much like today, was the fact that factory T-56s were tailored specifically to and for the OE applications from which they came—meaning that gear ratios were sometimes undesirable, shifter locations were often less than ideal, forcing the use of awkward-looking custom consoles; and last but not least, speedometer provisions on the trans were typically incompatible with the classic application. In short, the swap left a lot to be desired. Add to that the limited torque capacity of some factory units, and the fact that many had been severely abused before ending up in a bone-yard, the need for an aftermarket solution was clear.

As fortune would have, the timing was just about right for a response from TREMEC. Prompted by ever-increasing torque demands, and the desire for improved shift quality from its OEM-customers, in 2004, TREMEC began work on a replacement for the T-56; and in 2006, the TR-6060 6-speed was released. Debuting in the Shelby GT500 for model year 2007, the 6060 quickly became the new go-to performance box of the industry, and by 2008, had superseded the T-56 in pretty much all performance applications. Addressing the need for a more flexible solution for the custom car market, TREMEC engineers also got to work a on an aftermarket-only version of the 6060; taking swap-friendly features from the TKO, and modeling the input side of the trans after popular T-56 applications, in order to leverage existing market support (“GM” versions of the Magnum were modeled after ’98-02 F-bodies and “Ford” versions after the ’03-04 Terminator Cobra). In 2009, TREMEC released the new T-56 Magnum. “T-56” to let customers know the trans was not some brand-new, gee-whiz, unproven design; and “Magnum” to signify that this new unit was indeed something special—unique from all T-56 transmissions that came before it.

Unfortunately, all this did was confuse large portions of the market that didn’t know the Magnum was actually more TR-6060 than it was T-56. In addition, the T-56 name itself had so much goodwill in the market that many enthusiasts chose to drop the Magnum part of title and continue using the T-56 moniker instead—rather than the other way around. With all that said however, now that we know some of the history leading up to the Magnum, and that it is in fact NOT a T-56, let’s take a deeper look at what separates the Magnum and its TR-6060 sibling from the T-56 that came before them.

The second crucial element was the design of the speed gears themselves. Whereas T-56 gears (right) were carved from complicated 1-piece forgings that required generous amounts of space to be left for machining of the clutching teeth, the 6060/Magnum (left) advanced to a more sophisticated 2-piece construction. The clutching ring and the gear are forged and machined separately. They are then interference fit and laser welded together. This type of construction does away with the previously wasted space, and combined with the new snychro design, allowed TREMEC engineers to substantially increase the face widths of the gears, thereby increasing torque capacity.

 

Yet another significant benefit afforded by the 2-piece construction was the ability to optimize tooth angles and profiles on both clutching ring and the gear. Note the raised ‘shelf’ area at the heel of each clutching tooth. These are built-in stops which eliminate the possibility of an ‘overthrow’ during a shift activity.

 

Going back to the synchronizer, the improvements were much more than a simple trimming of fat. Here you can see the detents that control the fore-and-aft movement of the slider over the synchronizer hub. The T-56 design (right) used a crude but effective hoop style retainer to hold three stamped steel ‘keys’ in place, attempting to put equal pressure at three points of a circle. Though it worked, the designed was prone to uncontrolled movement which in some severe cases could allow the keys to dislodge. The ball-and-spring loaded ‘crows feet’ arrangement in the 6060/Magnum (left) is far superior at locating the slider and controlling the motion between shifts. This translates in to greater durability and a noticeably improved shift feel.

Here you can see the blocker and friction rings from the 6060/Magnum at left and the T-56 at right. Though again narrower in design, the 6060/Magnum more than makes up for the loss with increased diameter and a standard triple-cone arrangement for substantially more surface area than the double cone setup found in the majority of T-56s. In the case of the TR-6060, the friction materials themselves vary by application. Here the material shown is what is known as sintered bronze. The T-56 also used several different materials. Shown here is a ‘particlized’ carbon. All 6060/Magnums feature triple-cone baskets in the 1-2 position, and double-cone arrangements throughout the rest of the box (including reverse). The T-56, conversely, offered a mix of double and triple cones (depending on the application) for first and second, and in many cases, a single cone for all other gears.

Like the T-56, the 6060/Magnum uses a simple yet highly effective single-rail internal shift mechanism. When you push or pull the shift handle in the vehicle, the rail operates these forks—again with the Magnum at left and T-56 at right. A common complaint from those that like to abuse their T-56 was the unit’s propensity to bend aluminum shift forks; making the installation of steel forks a favorite upgrade for many. The problem, however, was not so much with bending the prongs of the forks, but rather an issue found at the shift rail bore. A keyway cut into the bore for placement of the shift plates, or ‘z-links’, had a tendency to wallow out and allow the fork to deflect on the rail, opening the door to a host of secondary shift-related issues. In the 6060/Magnum, these links are cast into the fork, eliminating the concern and negating the need for ‘heavier duty’ materials.

Though there is some visual trickery on account of the composition, here you can see some of the differences between the T-56 (rear) and TR-6060/Magnum (front) input shafts. Most notable is the bearing hardware, which is much larger in the 6060/Magnum. This of course, helps the transmission endure significantly increased torque. In addition, all Magnums (and most 6060s) use a 26-spline input shaft for maximum surface area and subsequent strength.

Although some of the heavy and/or heavy-hitting T-56 applications did receive a 1-piece ‘cluster’, or ‘countershaft’; for more common applications like the Cobra and 4th Gen F-car, 2-piece clusters (left) were standard fair. In the 6060/Magnum, however, all cluster gears are of the 1-piece variety. Here again you can also see the difference in gear face widths.

 

Significant differences exist outside the transmissions, too! Of the more notable, 6060/Magnum main cases benefit from additional webbing and substantially thicker flanges at each end. This is the one of the easiest was to tell the difference between a 6060/Magnum and the T-56. It all contributes greatly to strength and sealing.

 

Going back to the application concerns in our story, perhaps the greatest difference between the Magnum and all other OEM units (6060s included), is the wide range  flexibility features the Magnum offers with the explicit intent of being more swap friendly. Here you can see the Magnum’s three available shift locations, versus just one on the OE units, which varies according to application. This image also shows the skip shift solenoid on the T-56, which is required hardware for OE-applications to meet emissions standards—not so on the Magnum. Other Magnum features not shown include dual (electronic & mechanical) speedometer pickups, the dual-pattern crossmember mount area, and a commonized 31-spline output that trumps even the toughest T-56 in strength.

Though not a secret, a little known fact about the Magnum is that GM-types (left) are modeled after ’98-02 F-car T-56s, and Ford-types (right) follow the formula from the ’03-04 Cobra (minus the factory 10-spline input shaft). What this means is that, up front anyways, Magnums will interface with nearly any of the stock or aftermarket hardware intended for those applications; which leaves a ton of options on the table and makes swaps to nearly any engine or application possible.

 

There’s still a lot of ground we could cover, and perhaps in later story we will, but hopefully now (if you didn’t before) you understand and appreciate some of the critical differences between the Magnum and the T-56 it replaced. Although the T-56 was a great transmission, and continues to serve faithfully in many a heavy-hitting street car, it’s simply no match for the Magnum transmission that it ultimately inspired.

 

TREMEC       www.TREMEC.com       248/859-6500

Mike Galimi
Mike Galimi is the Director of Content & Marketing at ProMedia Publishing and Events with nearly 20 years of experience in motorsport writing and photography.
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