The T-56 transmission is a six-speed manual transmission designed for high-performance vehicles. Though it was first used in the Dodge Viper, it was also used in two fabled Mustang models: The 2000 Cobra R and the Terminator Cobra.
Borg-Warner built early T-56 transmissions, but the production transferred in 1998. Since then, Tremec has manufactured T-56 transmissions.
Tremec’s modern Magnum, Magnum XL, and TR-6060 transmissions are considered part of the T-56 family. Though there are some variations from the original transmission, the lineage is clear.
Drivers praise the T-56 and its modern iterations for their short, notchy throws and crisp feel.
T-56 Transmission Features
In 2000, having six-speeds was enough to make a manual transmission stand out. The T-56 had a little more than that to distinguish it though.
The T-56 transmission is more closely geared than the T-5 and T-45 transmission that came on other 2000 Mustangs. Transmissions geared with a close ratio have less RPM drop between gear shifts. The close gear ratio was an advantage on drag courses.
"The close gear ratio was an advantage on drag courses."
The T-56 also had a much heartier torque capacity since it was built for Viper-level engines. This was a huge benefit, especially considering how powerful the Cobra R was.
Hydraulic and Mechanical Clutches
While almost all T-56 transmissions have hydraulic clutches, the Cobra used a mechanical clutch. There are pros and cons to each clutch system and fierce advocates for both.
While a mechanical clutch uses a cable to engage and disengage, hydraulic clutches use a fluid system. This hydraulic system is similar to the one used for braking. Hydraulic and mechanical clutches are equally responsive.
Just like brakes, a hydraulic clutch can get air bubbles that will need to be bled. Having water in the system can also lead to rust, which is why many people use silicone fluid.
While hydraulic clutches need less repair early in their life, any repairs needed will be more expensive. The only complaint many have about older T-56s is that they can make a grinding noise. This is frequently due to a poorly maintained hydraulic system and doesn’t seem to affect the mechanically-clutched Cobras.
Because the 2000 Mustang Cobra R was reserved for people with a racing license, the SVT team determined owners would want the freedom to adjust it. This also made it easier for drivers to conduct their own repairs, another feature important to Mustang owners.
When the Terminator Mustang came on the scene, it kept the same mechanical clutch setup that had been so popular for the 2000 Cobra.
For T-56 owners who want a hydraulic clutch, there are clutch conversion kits available.
Lightweight Aluminum Build
If you’re interested in performance driving, then a light vehicle is crucial. On average, transmissions weigh between 100 and 400 pounds. Transmissions that are feature-heavy tend to also be physically heavy. Though the T-56 couldn’t cut back on features, it needed to keep its weight down.
Despite its overwhelming list of features, the T-56 has a dry weight of 115 pounds. This isn’t much more than the T5, which has around a 95-pound dry weight depending on the model. Considering the T-56 has six gears, extra features, and durable internal materials, it’s impressive how close their weights are.
An aluminum transmission housing is the secret to the T-56’s low weight. Even the bellhousing was made out of aluminum.
More Durable Synchros
Once upon a time, if you drove a manual transmission, you had to double-clutch.
Double-clutching allowed the transmission’s collar and the desired gear to reach the same speed before re-engaging. This meant hitting the clutch, shifting to neutral, hitting the clutch and then shifting again. Failing to do this could create some horrible noises and damage your transmission.
Fortunately, starting in the 1930s, synchromesh transmissions became standard. Before the teeth of a gear engage, the cone clutch does. Using friction, the cone clutch and a blocker ring bring the clutch and gear to the same speed. Until the two are synchronized, the teeth of the gear won’t touch.
Because of their role in shifting, synchros can become worn out quickly. The type of material used in synchronizer rings forecasts their lifespan. GM and Ford both used brass synchronizing rings with their T-56 transmissions.
There is still a lot of dispute as to whether brass or carbon-fiber lined synchros are “better.” There’s no discussion about whether or not the T-56 transmission’s brass synchro rings were better than the T-45 or T-5's rings. The overall construction of this transmission’s synchromesh required a high degree of precision. Owners who have “upgraded” to carbon-lined synchros have felt that the responsiveness wasn’t as good post-upgrade.
Brass is a durable, malleable, and corrosion-resistant material. Like all metals though, it has its Kryptonite. Brass can break down if exposed to GL-5 specification oil because of the extreme pressure additives in this oil. If you’re purchasing a scrapyard T-56, you’ll want to check to see if it has brass synchros before adding transmission oil. A GL-4 oil is a better choice.
Two Overdrive Gears
Overdrive gears are designed for cruising. These gears have a lower gear ratio than direct gears. This allows them to be incredibly efficient and provide good fuel economy. While most transmissions at the time had one overdrive gear, the T-56 offered two.
In general, additional gear selections allow vehicles to stay in an optimal performance range. For cars that are going to be traveling at high speeds, two overdrive gears makes sense. Without an overdrive gear, the lowest gear ratio was a 1:1 direct gear. This was loud and inefficient at highway speeds.
The Cobra offers two overdrive speeds so you have one for highway speed and one for above highway speed. Not that you’d ever drive above highway speed of course.
The overdrive gear ratios have changed on different models of the T-56. On the T-56 Magnum the top overdrive has a ratio of .50:1, perfect for those who frequently travel over 70 mph.
Other T-56 Notable Features Included:
- Tapered Roller Bearings
- Advanced Synchronizer Technology
- Integral Clutch Adaptor
The Cobra R and Terminator Cobra’s T-56 Transmissions
The 2000 Cobra R and the Terminator Cobra were the only Mustangs that came with a T-56 transmission. Though they were made only 3 years apart, the T-56s used on these two Cobras were different.
The Cobra R was designed to be a very limited run race vehicle. To even purchase one, you needed a valid race license. The Cobra R was as noteworthy for all the comfort features that were stripped out as for the performance features added.
By contrast, there were many more Terminator Cobras manufactured. Though they weren’t as geared for racing as the Cobra R, they had almost as many performance features.
The John Coletti-led SVT team produced both Cobras. They are two of the most famous Mustangs made by someone other than Shelby.
Transmission Ratios for T-56 Transmissions
|Transmission||First Gear||Second Gear||Third Gear||Fourth Gear||Fifth Gear||Sixth Gear||Reverse||Torque Capacity||Input Shaft||Output Shaft|
|Cobra R T-56
|Terminator Cobra T-56
|2.66 T-56 Magnum
|2.95 T-56 Magnum
Tremec T-56 Magnum
When Shelby did step back-up to the plate in 2007, it was with a TR-6060. The TR-6060 was the updated version of the T-56 and is what led to the production of the Magnum and Magnum XL.
One of the issues with the T-56 is that each model was a little different. And there were over thirty T-56 models produced between 1992 and 2004. Each T-56 was designed specifically to work on the vehicle it was commissioned for. When people tried to swap a T-56 into a Fox Body Mustang, the results weren’t great.
The other issue with the T-56 is that it’s not the type of transmission most people want to buy from the junkyard.
The T-56 only went in performance vehicles, like Cobras and Vipers. If those vehicles landed themselves in a scrapyard, it was unlikely it would be with a well-functioning transmission.
So, when the TR-6060 launched, Tremec thought about how to correct the issues that made the T-56 less than swap-friendly.
The Magnum is the result. The T-56 Magnum is a modernized aftermarket T-56 designed to address the weaknesses of the original.
Tremec T-56 Magnum XL for S197s
It makes sense that you’d want a Magnum if you have an S197 Mustang as well. Afterall, the S197 Shelby Mustangs all had a TR-6060.
If the Magnum is a modernized aftermarket version of the T-56, then the Magnum XL is the same for a TR-6060. The Tremec Magnum XL is essentially the same as the Magnum. The only difference is that it’s made for the S197 chassis.
Benefits of T-56 Magnum and Magnum XL Transmissions
There’s only one part of the Mustang’s T-56 transmission that got less than rave reviews. For whatever reason, the original Cobra Mustangs only had 10-spline input shafts. This makes the input shaft one of the most likely parts to break. Upgrading the T-56 to a 26-spline input shaft is one of the first performance modifications people make.
Splines (the ridges on the end of the input and output shaft) are what create grip and a point of contact. More splines creates a tighter and more stable connection. This means it’ll be harder for any individual point of stress to have much impact.
The Magnums have a 26-spline input shaft. This is part of why they’re more durable than the Cobra’s original T-56 Transmission.
Higher Torque Capacity
A transmission’s torque capacity relies on several factors. Though every transmission has a stated torque capacity, that shouldn’t be read as an absolute. If a transmission has a torque capacity of 200 lb-ft, it won’t necessarily break immediately if attached to a torquier engine. It does mean that over time, the transmission’s usable lifespan will be reduced.
If you’ll frequently be driving at peak, you want a torque capacity that is suited to your engine. While the T-56 used in the Cobras peaked at 450 lb-ft, the Magnum can handle 700 lb-ft.
That’s more than enough to handle an SN95 Coyote Swap.
Built for Flexibility
Tremec’s Magnum is very much like a T-56 but with a few differences. In addition to integrating all of the improvements made for the TR-6060, the Magnum has some features designed for the aftermarket.
The Magnum is designed with transmission swaps in mind, so it’s based around flexibility.
There are pickups for mechanical or electronic speedometers, dual-patterned crossmember mount area, and multiple shifter locations.
Is a T-56 Right for Your Mustang?
When compared to modern transmissions, the T-56 has advantages that make it a perfect fit for many. It has a lot of aftermarket support. If it’s being installed in an SN95, it requires very little modification.
It may be challenging to find a used T-56 in good condition. That’s not the only reason to consider a Magnum instead though. The T-56 Magnum has a better torque capacity. It also has substantially more features.
The Magnum comes with a first gear of either 2.66 first or a 2.95. Both have a 26-spline input shaft.
Though a T-56 Magnum is designed to fit into an SN95, it does require some additional parts. It will still need the Cobra bellhousing, the proper crossmember, a clutch fork, and a 31-spline driveshaft yoke. It’s also probable that you’ll need to shorten your driveshaft.
If you don’t already have a 26-spline clutch, you’ll need to change that as well.
Refreshing a T-56 Transmission
There are ways to make an existing T-56 better. In addition to basic maintenance, a few additional modifications can keep your T-56’s throws short and crisp.
If you’ve noticed any of the common symptoms associated with clutch problems, then it may be time to replace it. Some of these symptoms include mushier shifting or unusual sounds when between gears.
Driving correctly can help extend a clutch’s life, but eventually they’ll always need to be replaced. Depending on whether or not you’ve upgraded your input shaft, there are a variety of clutch packs to pick from. Many of the heavy-duty ones do need a 26-spline upgrade before they can be added.
There are a lot of factors that will determine what the right clutch is for you.
Short Throw Shifters
If short, crisp throws are what drew you to the T-56, then a short throw shifter might be the perfect modification for you. Just like it sounds, a short throw shifter reduces the lengths of your throws. Far from just cutting down your shift rod, this mod changes the pivot point.
The result? Short, fast throws.
The T-56 Transmission’s Place in History
The T-56 transmission is over twenty years old, but it’s still considered a great transmission for swaps. The T-56 pairs well with a GM LS engine for a lightweight build. Thanks to the Tremec Magnum in particular, it’s not uncommon to hear enthusiasts talk about a T-56 swap. The Tremec Magnum and Tremec Magnum XL are especially valued for the flexibility they provide.
While Ford reserved the T-56 and its younger sibling, the TR-6060 for Cobras and Shelbys, they’ve been installed on many performance Mustangs since then. The lightweight transmission is surprisingly durable, and its appeal has been equally enduring.
This article was researched, written, edited, and reviewed following the steps outlined in our editorial process. Learn more about CJ's editorial standards and guidelines.