T5 Transmission Limits

Ford introduced the Borg-Warner made T5 transmission into the Mustang line up for 1983. Replacing the SROD, the T5 is a lightweight 5-speed transmission intended to increase performance and gas mileage during the Fox era. Since its inaugural debut in 1983, Ford has made many revisions to the T5 over the years, leaving some quite different than others. The most well known difference is the Non World Class T5 (NWC) and World Class (WC) T5. Is one specifically better than the other? Use the links below to learn more about the T5 manual transmission and how it changed throughout the years. The T5, overall, is a good transmission for how it is built. The problem with it, as many owners already have witnessed, is that the T5 is pretty much at its limit on a stock Mustang. It is a well designed, well functioning transmission, but it is not well applied in the Mustang. The T5 is a light-weight transmission, and does not fare well at anything above stock Foxbody power levels (225 HP, 300ft-lbs)

Non World Class T5 Breakdown
World Class T5 Breakdown
What is the difference between a NWC and a WC?
Are they interchangeable?
Is one better than the other?
What are the limits of the T5?

T5 Quick Sheet

TypeYearTorque RatingRecommended Gear Oil
Non World Class1983-1984265 ft-lbsDextron III, Mercon, Mercon V ATF
World Class1985-1989265 ft-lbsDextron III, Mercon, Mercon V ATF
World Class1990-1993300 ft-lbsDextron III, Mercon, Mercon V ATF

Non World Class (NWC) Breakdown

As mentioned, Ford began equipping Mustangs with the T5 manual transmission in 1983. The first version of this Borg-Warner transmission used a 2.95 ratio first gear and a 0.63 ratio overdrive for V8 Mustangs. First (1st), second (2nd) and third gear (3rd) ride on a solid output shaft. The counter gears ride on straight cylindrical bearings with a thrust washer at the front of each bearing (for load support). Synchros are made of solid bronze. Dextron II was originally used, but as it is not available any more, Tremec now recommends 50W straight gear oil in its place. Everything said and done, the 1983-1984 NWC T5 is rated at 265 ft-lbs of torque.

The T5 was also used in the 2.3L four-cylinder Mustang, this model featuring a 3.97:1 first gear and a smaller pilot bearing, which resulted in a decreased torque capacity rated at 245 ft-lbs. The 4-cylinder transmissions are NOT a direct swap for 5.0L versions. However, they can be converted to work with a V8. This will be covered in more detail in a separate article.

World Class (WC) T5 Breakdown

In 1985, Ford adopted the World Class version of the T5. Initially, it was not any stronger than the initial Non World Class version. Rather, Borg Warner made several changes to the bearings and synchros such that the transmission could be marketed worldwide (thus the name World Class).

With the World Class transmission, Ford selected a 3.35 gear set and a 0.68 over drive. Needle bearings were installed under the first 3 gears to reduce drag, whilst tapered bearings replaced the bronze thrust washers. Main shaft synchros were changed to fiber-lined steel plates (fifth gear remained bronze). These synchros provided added friction to further slow the gears for a smooth shift (particularly at high RPM). Despite these changes, the torque rating of the transmission did not change, and is still rated by Borg-Warner at 265 ft-lbs.

1990 to 1993 Mustangs continued to use the World Class T5 transmission, but with a few more changes. Ford upgraded the gear set by increasing the nickel content, thereby strengthening the gears. Third and fourth gear synchro linings were changed to carbon fiber. Because of the gear set improvement, torque rating was increased to 300 ft-lbs, making the 1990-93 T5 the strongest production transmission to be found in the Fox platform.

Non World Class and World Class T5 Differences

To clarify, back in 1983 when the T5 was introduced into the Mustang lineup, Borg-Warner did not call the T5 transmission non world class. Rather, the term "Non World Class" came about only when in 1985, Borg-Warner released the T5 globally, under the name World Class. From that point on, there needed to be a way to distinguish between the early model and late model (World Class) T5 transmissions. Therfore, the early models began being referred to as the Non World Class transmission. (Just like there is a HO 5.0L V8, and a non-HO 5.0L V8)

Internally, there are some differences. First off, as mentioned above in the breakdown sections, NWC T5's used a 2.95:1 first gear and a 0.63 ratio overdrive, whereas World Class versions used a 3.35 first gear and a higher 0.68 ratio overdrive. Synchros changed from solid bronze to fiber-lined steel, needle bearings were installed on the mainshaft cluster as opposed to the solid shaft design of the Non World Class T5, and finally, in 1990, nickel content was increased making the gear set in the 1990-1993 Mustangs the strongest ever. In a nutshell, T5's produced from 1983-1989 were rated at 265 ft-lbs of torque, and 300 ft-lbs from 1990-1993.

Are the NWC and WC transmission interchangeable?

Yes, both transmissions are interchangeable. There are no mounting differences or changes in the case that would prevent one being swapped for the other.

Which is better, the NWC or WC T5?

Purely from a power aspect, the World Class transmission from 1990-1993 is the best, as it is rated at a capacity of 300 ft-lbs. However, some owners who have used both versions of the transmission reported the NWC version as shifting smoother in stock form.

The limits of the T5 transmission

The T5 is a light-weight, light-duty transmission. For what it is (roughly 80 lbs and pretty compact), it is a pretty good transmission. However, throw one of these T5's in a Mustang, and it is an entirely different story. Essentially, any T5 transmission is already at its limit - even on a stock Mustang. Real world applications have shown that the T5 transmission is pretty easy to break if any amount of power (the like of which a Mustang is capable) is put through it. For example, I blew my own T5 transmission on a stock Fox running BFGoodrich radial T/A tires. On the other hand, others claim to be running around the streets with 400-500 horsepower and report no issue (rather, they report it hasn't broken yet!).

Realistically, if you drive carefully and don't abuse it (meaning no power launches, redline full throttle shifts, or hook hard), the T5 can last. But, this could be said about anything, really. If you baby any type of object, chances are it will last a while.

For stock Mustangs that aren't going to be launched hard, the stock T5 will work very well and should continue to work well on mildly modified Mustangs. Start taking the Mustang to the track, however, and it is only a matter of when, not if, the T5 will break.

Upgrading a T5 transmission

Do I need to upgrade my T5 transmission? Well, it depends. If you're driving around in a stock Foxbody Mustang, the factory T5 should be adequate. If you are planning on building the engine, then it is at this point that you will want to consider upgrading the T5. Personally, however, I would run the stock T5 until it blows, and only once it blows, upgrade it or swap it out. Who knows, maybe you'll be one of those lucky guys that are somehow running around with 400+ horsepower and their T5 has never worked better - or so they claim.

On a more serious note, when you decide it is time to upgrade, it is still possible to do so. Presently, in 2016, it seems that T5 parts are slowly dwindling and there are less options available on the market. G-Force, Astro Performance and Promotion Powertrain seem to be the only three companies still offering parts and upgrades for the T5 transmission. All three companies offer to sell the upgrade kit (internals) separately or pre-installed (if you pick the latter, you must send in your original T5 as a core). It's possible to get stock rebuild kits (yuck) or upgraded versions that will support as much as 575 ft-lbs.

Alternatively, you could do away with the T5 altogether and throw in a TKO-500/TKO-600 or even a Tremec T56 (6-speed transmission, woooo!). While not a direct bolt-on, both are "relatively" easy to get in there as the aftermarket has come up with all the necessary pieces to make the conversion pretty simple (bellhousing, cross-member, shift fork etc). Keep in mind these transmissions use a 26-spline input shaft, so you will have to change the clutch too (stock clutch is 10-spline). For more information on transmission swaps, check out the TKO-500 TKO-600 swap guide.