Justin Fivella
May 14, 2014
Photos By: Courtesy AED Motorsports, Steve Raymond, Nate Garland

It's been dubbed the unbreakable one and the last transmission you'll ever buy. Countless people have compared the smoothness of its shifts to laying a hot knife though butter, its brawn to a Sherman tank. It's the most versatile manual transmission on the market and blends the best of the OEM industry with aftermarket performance. Simply put, in the land of manual transmissions, the Tremec T56 Magnum is king.

In 2009, when Tremec debuted the big-boy of stick shifts, it had large shoes to fill—after all, the original T56 is legendary. Thankfully though, Tremec was up to the task. How, you ask? Tremec took the OEM TR-6060 found in such legends as the Shelby GT500, ZR1 Corvette, and ACR Viper, and hot-rodded it to withstand more abuse and more torque, which allows you to rip off high-rpm shifts. Just ask anyone who's driven one and they'll confirm the obvious: If you're looking for one box that can withstand serious abuse and shift with the precision of a Swiss watch, then look no further.

Out with the old and in with the new: Look how much beefier the T56 Magnum is than the outgoing T5. The swap added 57 pounds over the old T5 setup, but the fact the Magnum shifts like glass, has better ratios, and can handle 700 lb-ft of torque more than offsets the additional weight.

The Company, The Myth, The Legend

You'd have to be living under a rock to not have heard of Tremec transmissions, and just as the T56 Magnum is to its competitors, Tremec is the big dog of the manual transmission industry. From countless OEM applications with the older T56s, the current TR-6060, and the new seven-speed TR-6070, to the legendary aftermarket transmissions like the TKO; when it comes to manual transmissions, nobody beats Tremec. In fact, it has been around for 50 years, currently serving a global client base in 70 countries and employs over 1,800 associates.

What makes this box so special? Although the beastly T56 Magnum might be based on the TR-6060 transmission found in the GT500, the Magnum is its own animal, with a unique case, shifter, and other components.

"The T56 Magnum is a completely new transmission, much different from the older T56s and OEM TR-6060s. It's more versatile, with its multiple shifter locations and various electronic hook-ups to suit a wide variety of cars," explained Jim Averill of Tremec Transmissions.

While most T56s are good for 450 lb-ft of torque, the Magnum pushes that capacity to 700 lb-ft and still keeps the shifts as smooth as glass. The Magnum uses triple-cone synchronizers on the First-Fourth gears and double-cone synchronizers on Fifth, Sixth, and Reverse. The syncros have also been narrowed for a stronger, wider gear face that's 6-24 percent wider than a standard T56. The wider gear faces allow for greater torque capacity, high-rpm shift capabilities, and shorter throws. In fact, the Magnum is said to have the shortest shift throws of any Tremec box. It also uses burly 26-spline-input and 31-spline-output shafts to transfer torque into forward motion.

Speaking of throws, the Magnum features a TKO-style moveable shifter for different shifter positions, so it can be moved between multiple projects even if, for example, you decide a classic Mustang is a better fit than your current Fox-body. No worries here. Bring your T56 Magnum—it's welcome at almost any party. The Magnum also gives enthusiasts the ability to use an SFI-approved bellhousing instead of the OEM TR-6060's cast unit. It even employs dual speedometer pickups, one for a mechanical unit and the other for an electronic example. You get the point, it's as stout as it is versatile.

01. The T56 Magnum comes with multiple shifter locations and all kinds of hook-ups to ensure no matter what speedometer, tunnel shape, or OEM connector your car has, the Magnum will slide into place.

02. Here are some of the quality parts that come with the legendary D&D Performance T56 swap kit. In addition to the transmission, the kit comes with an SFI-approved QuickTime bellhousing, all of the required connectors and plugs, along with custom pieces like the Dynotech aluminum driveshaft, and offset cross-member and mount.

03. Here’s a closer look at the stock T5 crossmember against the D&D Performance unit. Note the added offset of the D&D piece to compensate for the added length of the T56 Magnum.

04. Look at the custom Dynotech Engineering aluminum driveshaft compared to the old aluminum FMS unit we removed. Again, notice the difference in length of the Dynotech unit to offset the size of the T56.

05. The Dynotech Engineering driveshafts are some of the best in the industry. We’re talking top-rate components, unbeatable craftsmanship, and a team of engineers behind every unit.

06. Speaking of quality, the Quick Time T56 bellhousing is like Snapple—it’s made from the best stuff on earth. All jokes aside, it’s a high-end unit that’s SFI- approved and has excellent fit and finish.

07. John Rankin of Rankin Performance Machine in Martinez, California, helped us dial in the mating surfaces of the Quick Time bellhousing. Although it didn’t need much, it’s always good to have a quality machine shop like Rankin Performance ensure everything is true.

08. As a wise man once said, always test-fit everything before proceeding with the install. Jack test-fitted the bellhousing to the transmission.

It's All About Ratios

Thankfully Tremec was thorough with the design of the T56 Magnum and took into account the different ratios enthusiasts might want. Believing that one size doesn't fit all, Tremec offers two distinctly different flavors of gear ratios: one wide-ratio and the other a close-ratio. The wide-ratio version (PN TUET11011) has a deep 2.97 First gear with tighter First-Third gears and a land-speed-racing, tall 0.50 Overdrive for Fiesta-like fuel mileage on the super slab. The wide-ratio box is said to be better for drag racing applications with steeper rear gears.

The other available gear set is a close-ratio version (PN TUET11010) with a taller Terminator Cobra-style 2.66 First gear and a shorter 0.63 Overdrive. It's said to be better for road-race applications or closed course roll-racing, it trades wider ratios in the first couple of gears for a tighter spread in the upper gears. Remember though, both Fifth and Sixth overdrive-gears can be mixed and matched by a Tremec dealer for a custom combo of your choice. See how the two ratios compare (Chart 1).

Chart 1
First Second Third Fourth Fifth Sixth Reverse
Wide ratio 2.97 2.10 1.46 1.00 0.74 0.50 2.90
Close ratio 2.66 1.78 1.30 1.00 0.80 0.63 2.90
For reference, the T5 we removed had this spread:
First Second Third Fourth Fifth N/A Reverse
2.95 1.94 1.34 1.00 0.59 2.76

Thankfully Tremec has an online gearing calculator (see accompanying photos) that helped us get a better idea of the gearing in relation to road speed. After careful consideration of our engine's powerband, rev ceiling, desired tire height, and intended use, we decided on the close-ratio combination with the taller 2.66 First. With over 500 lb-ft of torque available in Smog Legal Killer, we felt the wide-ratio box with its 2.97 First was just too short on the street.

The outgoing T5 had a 2.94 First gear, and while it was nice for cutting killer 60-foots, it was so low that it was nearly unusable on the street, causing a double shift just to cross an intersection. Some might think the close-ratio box with its taller First gear will hinder our 60-foots at the track, but we think it's nothing a 500-rpm higher launch won't solve. Instead, the tighter ratios in the upper gears will help keep the Vortech V3 Si-blown 347 in the meat of its powerband instead of falling out of boost between shifts. Stay tuned for track results soon.

A quick search on the Internet proves that there are people on both sides of the fence. Some feel the 2.66 First gear is too tall, while others feel the 2.97 First gear is uselessly low. In reality, while the difference between the two gears is noticeable from the cockpit, the difference isn't that big. To prove our point, we used Tremec's online gear-ratio calculator to get a better idea of the peak speed in each gear using our 27-inch-tall tire and a conservative 6,200-rpm redline. See how they compare (Chart 2).

Chart 2
Max speed (mph) in each gear at 6,200-rpm redline
First Second Third Fourth Fifth Sixth
Wide ratio 44.95 63.58 91.45 133.52 180.43 267.03
Close ratio 50.19 75.01 102.7 133.52 166.9 211.93

This means there's only a 5-mph difference in speed between the 2.66 and the 2.97 First gear ratios at a 6,200-rpm redline. Like we said, the wide-ratio transmission is going to feel more eager out of the hole, while the close-ratio version will have a tighter spread once the car is moving. For reference, Terminator Cobras came with 2.66 First gears in their stock T56s, so it's not like we're talking Bonneville Salt Flat gearing here.

Since we just love crunching numbers, here's one more graph to chew on. This is the drive in each gear in miles per hour. Again, you can see the wide-ratio transmission has tighter First-Third gears, while the close ratio box has tighter upper gears. The closer the ratio, the smaller the drive per gear. See how they compare (Chart 3).

Chart 3
Speed (mph) per gear
First-Second Second-Third Third-Fourth Fourth-Fifth Fifth-Sixth
Wide ratio 18.7 28 42.2 47 86.9
Close ratio 24.9 27.8 30.9 33.5 41.8

Even though our AFR-headed CHP 347E motor and Vortech V3 Si blower combo makes big torque, like most centrifugal blown combos, it makes the most power during the last 1,000 rpm. In order to maximize our combo, we needed to make sure the tach never dipped outside that window, and that's exactly what the close-ratio box achieves. Save for the wide spread on the lowest gears, the close-ratio T56 Magnum keeps the motor up in the powerband where it really counts, on the Second-Third and Third-Fourth shifts.

Now, about that little snag. You knew there had to be something, right? As we'd been previously warned during the installation of our monster Ram twin-disc, its added thickness (height) can result in minor clearance issues with certain transmissions. Some calls to industry pros revealed this was a common issue with many twin-disc clutches and not really a hard fix, just a time- consuming one that requires the transmission be installed and uninstalled a half-dozen times in order to achieve proper clearance.

What happened? Well, several things. The added thickness of the twin-disc clutch caused the throw-out-bearing retainer to contact the pressure plate. This made it impossible to disengage the clutch.

Thankfully Drew and Greg Wallace of AED HP in Shingle Springs, California, were on hand for the install. Easily some of the most skilled Mustang techs on the West Coast, the Wallace brothers knew exactly what to do.

"The front case of the transmission has to be removed and the collar turned down roughly 0.2 inch to adequately clear the pressure plate," said Drew Wallace of AED.

That 0.2 inch was just enough to seat the transmission against the motor, but the next and last hurdle was getting the clutch fork to extend far enough away (backwards) from the motor to disengage the clutch. After a shorter ball-stud didn't do the trick, some of the webbing on the front case had to removed in order to allow the fork enough travel to disengage the clutch.

"Trimming the webbing because of a big twin-disc clutch isn't uncommon, it's a necessary evil since you need the twin-disc for high horsepower drag applications, but in order for it to work with many transmissions there needs to be some fabrication work," said Greg Wallace of AED.

Thankfully, Smog Legal Killer was in good hands with AED, and after numerous trips with the transmission in and out, the T56 Magnum was installed for the final time. The last of the modifications were then made and everything was buttoned up. The results were nothing short of spectacular.

09. Due to the additional thickness of our massive Ram twin-disc clutch, the throwout bearing collar on the T56 Magnum contacted the pressure plate. AED verified the amount of contact with clay and deemed the collar need to be trimmed so the clutch could disengage.

10. Since AED had to remove the front cover to gain access to the throw-out bearing collar, it gave us a chance to see the inner workings of the T56 Magnum and it’s a beast. Have a look.

11. Here’s further proof the T56 Magnum is in its own league. Unlike standard T56s, the Magnum even has this spring-loaded plunger with a roller that was designed to produce that positive “click” during each gear engagement. Like we said, there isn’t anything Tremec didn’t consider when designing this box.

12. AED turned the collar down 0.2 inch and it was enough to clear the pressure plate on our twin-disc clutch. Then it was time to reassemble the transmission.

13. We ran into a few more snags when the additional thickness of the twin-disc clutch wouldn’t allow the D&D clutch fork to move backwards enough to allow clutch disengagement. Here you can see the fork contacting the transmission case.

14. After a shorter ball-stud didn’t create enough space, AED did what it does with many twin-disc installs, it clearanced the case so the fork could freely travel. The areas in green have been addressed.

15. A great transmission calls for great oil, and in this case we used Amsoil ATF since it’s seriously good oil. That’s no typo—some Tremec boxes call for ATF.

16. Since D&D’s T56 kit comes with a Dynotech Engineering driveshaft, we took the appropriate measurements from the included spec sheet and sent them off to Dynotech. A few days later, the custom driveshaft arrived.

17. Don’t forget to apply Locktite and the appropriate torque when tightening the rear driveshaft bolts. We wouldn’t want any problems with the bolts coming loose.

18. The D&D Performance T56 kit comes with all of the appropriate connectors to ensure the reverse lights and the other associate connectors will work like factory. Check out the accompanying sidebar for a cool reverse lockout solenoid fix.

19. The T56 Magnum comes with multiple speedometer hook-ups, electronic and mechanical. The D&D kit also comes with a new cable.

20. Greg Wallace of AED trims the old mounting tabs from our BBK catted X-pipe since the T56 no longer uses such mounts.

21. The Tremec shift-knob is subtle but classically hot rod, and hints at the bad box that lurks below the floorboard. Only a keen eye will catch the six forward marks on the classy shift-knob.

22. After Dynotech selects the best quality components, they are cut to length and pressed together. Then it’s time to weld them to utter perfection. Note the dial indicator that ensures NASA-like precision.

23. Here’s how the flawless welds are created. Pretty cool, huh?

24. Dynotech is known for its ability to high-speed balance its ‘shafts to tolerances others could only dream of. This not only leads to less NVH, but far superior strength since unwanted harmonics can kill a ‘shaft in no time.

Driving Impressions

As one would expect, Smog Legal Killer is a new animal with the T56 Magnum in place. First gear is certainly taller, but the added road speed in First is a welcomed addition. From there the ratios get tighter with each shift, and now a 60-140 roll comes startlingly quick because once we roll into boost, the car never stops pulling.

As for shift action, it's like a precision Swiss watch: light, positive and smooth. It's hard to imagine ever going back. Don't get me wrong. There are some endearing qualities to a T5, but it only takes one drive with a T56 Magnum to never look back. You're never hunting for a gear, the gates are positive and there's a satisfying "click" with each shift. In all honesty, this could be one of the best mods to land on Smog Legal Killer if not for the added speed, but for the simple joy it brings by way of buttery smooth shifts and revised ratios that maximize our combo.

Although we ran out of time to hit the track before press, stay tuned because we have more big news to release before we let it fly. Stay tuned, we're back in the driver's seat and ready to rip with Smog Legal Killer.

Samoco T56 Reverse Lockout Controller

Since the T56 Magnum has its Fifth and Reverse gears in the same neighborhood, Tremec built a lockout solenoid to prevent grabbing Reverse unless the solenoid is open. This is to stop someone from catching Reverse when they're going for Fifth—an undoubtedly dangerous mishap.

D&D provides the appropriate harness, but most connect the solenoid to either a remote switch or the brake light. This means every time you want to use Reverse, you either have to flip a switch or hit the brakes—both annoying extra steps. The other common alternative is to hammer the shifter through the lockout, but this tears up the internal components of your new T56.

The fix? Samoco Industries' ingenious T56 Reverse Lockout Controller that connects to the factory vehicle speed sensor and only unlocks the solenoid under 5 mph, just like a stock setup. The nifty box is easily mounted and is built from high-quality components. Seriously, if we hadn't stumbled into this clever contraption we'd be hitting the brakes and flipping switches, instead, it's just like factory. This should be considered mandatory with every T56 Magnum swap.

T56 Magnum Vs. Standard T56

Ever wondered what makes the Magnum so much better than a standard T56? Lets just say it's all about strength! Here's what's improved on the Magnum.

The Main Case
On the surface it may look similar to a standard T56, but there's more material in high-stress areas, stout webbing where it's needed and more connections for different shifters, speedometer hook-ups and other electronic bits like vehicle-speed and reverse-light sensors.

The fact the Magnum can hold 700 lb-ft means a lot has changed from its ancestors, especially in the gear department where the cogs received increased face-widths and are now two-piece laser beam welded for greater strength instead of the older one-piece forged units. The change in production allows for tighter tolerances on the tooth angle, alignment and pitch of the gears for greater strength and smoother shifting.

The massive one-piece countershaft is also a ton more burly, which means it's more resistant to distortion and rides on larger bearings for more support and again, smoother operation.

Input shaft
The hefty 26-spline shaft is far stronger than the stock 10-spline factory T56 unit not only because it has more splines, but because it's made from thicker material for increased face-width and a larger input bearing.

The gargantuan gears called for smaller syncros that could still hold the abuse. The all-new gears are narrower than the standard T56 units and also have a fine pitch angle on the teeth for shorter throws between gears. The spring-loaded ball-type inserts also cut friction for easy shifts.

Shift Forks
The Magnum-specific shift-forks have integrated shift keys to eliminate the possibility of bending the shift-forks. There's more material on the Magnum's shift-forks for greater strength and the new design does away with the problems previously associated with high horsepower, quick shifted T56 units that experienced shifter-fork problems.

Gone are the snap rings of old on the standard T56, instead the Magnum implores a split-ring design with tighter tolerances.