The T5 Transmission
The T-5 is one of the most respected, and long-lived, manual transmissions. Mustangs were first equipped with T-5 Transmissions in 1983 and continued using them for all V8 applications until the 1998 Mustang. The T-5 continued to be in use though, as the manual transmission of choice for V6 Mustangs until 2010. This durable transmission lasted through the Fox Body, SN95, and S197 Mustang generations, longer than any other transmission, though by the end significant changes had been made to the T-5.
Though the T-5 was initially manufactured by Borg-Warner, production has since shifted to Tremec. Tremec still manufactures and sells T-5s, which are immensely popular for particular applications like hot rodding. Due to its popularity, there is significant aftermarket support available for these transmissions.
Part of the reason for this popularity is the T-5 transmission’s lightweight all-aluminum design which makes it an ideal choice for racing. Eliminating transmission weight is an exceptionally effective way to make serious gains since it’s dropping rotational weight rather than static. Another reason people tend to go to the T-5 transmission rather than earlier manual transmissions is that it was the first manual transmission for the Mustang that offered an overdrive gear.
Overdrive gears exist to reduce fuel consumption and engine noise when you’re at a cruising speed. Essentially it’s a gear where the output shaft speed is greater than the input gear speed. This multiplies the torque of an engine. Though in older transmissions the gear ratio typically topped out at a 1:1, an overdrive gear is less than one.
This may all sound ridiculous in an era where six-gear transmissions are a given, but at the time it was a big development for Mustang.
There are two primary distinctions of T-5 transmission: World Class and Non-World Class. Ford only used the Non-World Class transmission in 1983 and 1984, but by 1985 had made the switch to the World Class T-5.
World Class vs Non-World Class T-5 Transmissions
There are several differences between the non-world class (NWC) and world-class (WC) T-5s. The first of which was a wider gearset ratio. This alone would make them improved over the NWCs, but they also improved the synchro rings from bronze to ones with fiber linings, increasing their resiliency.
The biggest change of all though was that the world-class T-5 transmissions moved first, second, and third gears onto roller bearings (sometimes called needle bearings). This allowed for reduced friction within the transmission, increasing its longevity and improving performance. The result felt “snappier” to users. These seemingly small changes are what Borg-Warners estimated were needed to take the transmission “world-wide” which is why it’s named accordingly.
Even within the world-class T-5 transmissions, there are a few key differences from year to year, and not all WCs are equivalent.
Changes and Improvements to the T-5 Transmission
Starting in 1990, The T-5 was upgraded to a stronger gear set. This was accomplished by increasing the nickel content of the gears. Later, in ‘92, the synchro rings for the third and fourth gear were further improved by adding a carbon fiber lining. These improvements paid off quickly and by ‘93 the torque rating for the T5 transmission had jumped up to 300 lb-ft, a huge improvement from its previous 265 lb-ft rating.
For the 1994 and 1995 Mustang years, Ford added deeper bellhousings to the T-5 transmission, which helped to make the input shaft longer. These improvements may sound major, and in some ways they were, but most of them are impossible to observe without dismantling the transmission. An easier to spot indicator is that the earlier T-5 transmissions were equipped with a yellow tooth speedometer drive. The 1990-1995 T-5s were equipped with a light green speedometer drive, and finally, all of the post ‘95 T-5 transmissions were manufactured by Tremec after Borg-Warner sold their manual transmission department.
1995 Mustang GTs were the last V8s to have a T-5 transmission, but they continued to be made with mostly minor improvements and changes. The largest changes were the ones necessary to squeeze the T-5 transmission into the S197 Mustang. This means that if you’re looking to upgrade or replace a transmission on an S197 Mustang, you’ll need to make sure that you pay attention to how the transmission is bolted onto the body and the shifter set up.
T-5 Transmission Gear Ratios
The T-5 Z Transmission
The 1993 Cobra’s particular T-5 transmission was modified in several key ways that allowed it to outperform similar transmissions. In particular, the gearing for the first through third gears was reduced, and all five gears were hardened. The clutch was also improved. These changes made the Cobra’s T-5 more suited to high horsepower applications. This model is sometimes referred to as the “Z” version.
The Z version not only had hardened gears and an improved first gear ratio, but it also had a short throw shifter, a steel fronted bearing retainer, and a soft locking clutch. In short, it had absolutely the best of everything.
Thankfully, Tremec still manufactures this transmission. Tremec also produces additional T-5s that offer new power and performance.
New T-5 Transmissions
Tremec manufactures a TKO 500 and 600 which are easy upgrades from a standard T-5 but have a much higher max torque capacity. The 500 has a 500 lb-ft capacity and the 600 has a 600 lb-ft, which makes them very easy to remember. Typically this transmission upgrade requires a new bellhousing and yoke, but depending on your individual model this may vary. There are even conversion kits to allow first and second-generation Mustangs to accommodate a T5 transmission.
New T-5 Gear Ratios
|T-5 “Z” Model
Maintaining and Fixing your T-5 Transmission
Though upgrading your transmission may seem challenging, and it definitely can be, this is one of the easier conversions. In this CJ’s video, Bill walks us through the process of converting a 1967 Mustang convertible to the T-5 Transmission.
The T5 is a transmission from an era where people anticipated doing a lot of their own transmission work. This is great news for people who are happy with their T-5 transmission but have noticed a couple of issues they’d like to address since Tremec works hard to make it as easy as possible to address problems at home.
This helpful guide from Tremec will tell you what to do if your T-5 transmission suddenly won’t shift or, conversely, is stuck in one gear. Whether you’re troubleshooting a faulty transmission or just trying to figure out how to swap out your synchronizer rings, this guide will walk you through it.
Of course, one of the most important things you can do for your T-5 is ensure that you’re paying close attention to the max torque rating. Though it’s a durable transmission and can withstand a lot of abuse, the one thing it cannot endure is substantial torque. If you are doing major performance upgrades, it may be worth it to either consider upgrading to a newer version of the T-5 or else perhaps purchasing a less strong clutch.
While it may sound counterintuitive to get a weaker clutch in order to protect your transmission, it makes sense when you think about it. When a clutch really grabs onto a transmission is when the majority of the torque is transferred to the transmission. So, a clutch that can’t grab as hard can’t transmit a hundred percent of the torque and leaves the clutch to take the hit before the transmission. Of course, that means that you can’t actually use a hundred percent of your torque, so upgrading is strongly recommended.
T-5 Transmission Pros and Cons
Though there are certainly more advanced transmissions, T5s remain popular due to their durability and reliability. Many car enthusiasts love how easy it is to work on the T5s. The one major downside to these older transmissions is that they have a pretty low torque rating, but fortunately Tremec now makes upgraded T-5 transmissions with improved torque ratings. The TKO 600 has a torque rating of 600 lb-ft, more than enough for most Mustangs. Even classic Mustangs can be upgraded to the T-5.
Sources: Saturation Dive: Manual Transmission Gear Design, The Truth About Cars | T-5 5-Speed Rear-Wheel Drive Manual Transmission, Tremec | How to Rebuild and Modify High-Performance Manual Transmissions, CarTech | Image Credit: MotorTrend | Mustangs and Fords | FoxStang