History of the BorgWarner T-5
This article is a culmination of research begun in 2009;
periodically updated with new information and clarifications. The author
does NOT give permission to copy and re-post this on other websites without
providing credit to the author and a functioning link back to this
Today (2011) one version of the T-5 is still offered as a new transmission under the Ford Motorsport/Ford Racing name and through some auto specialty shops. It is called the T5Z because it was originally tagged M-7003-Z 1352-249. This identical unit, when marketed outside the Motorsport structure, is tagged 1352-251.
While these transmissions are all T-5's, they are generally not interchangeable across product lines because the input shafts, output shafts, and cases are different for the various auto makers. Interestingly enough, due to the design of the case, parts are rather interchangeable, and custom versions are often created. The most popular "hybrid" T-5 is the use of an S-10 tail on a Mustang transmission. This combination offers a strong transmission with a shifter that is located much further forward than with the Mustang so that it fits classic cars with bench seats, or older pickup trucks. Care must be taken to choose compatible parts when attempting to create a custom transmission.
The vast popularity of the T-5 and its noted ability to shift smoothly have led to many aftermarket modifications to allow it to stand up to high-horsepower applications. The all-aluminum case and over all lightweight design have made it popular in the racing community.
The T-5 first appeared as a 5-speed option for both Mustangs and Camaros in 1983. Ford used this initial design, commonly called the Non-World Class T-5, only in 1983 and 1984. GM, however, continued using this initial design in the Camaros from 1983 through 1987 and in the S-10 truck series from 1982 through 1992.
Many Internet sources insist that gear oil should be used in the Non-World Class T-5, but the documentation above clearly reveals that both Ford and GM chose to use ATF from the start. Using gear oil in a Non-World Class transmission will not significantly damage the transmission, but many times, due to Internet confusion as to what is, and is not, a World Class T-5, gear oil has been mistakenly used in the World Class units.
Update on Dexron VS Gear oil for NON-World Class
WARNING: Using gear oil or motor oil in a T-5 with the composite lined blocker rings found in the World Class T-5's will destroy the blocker ring linings over a period of a few months rendering those synchronizers useless.
World Class Transmissions
The functionality of this reverse brake is that the redesigned linkage engages a second blocker ring against a stationary cone that is mounted on the rear of the fifth gear synchro hub. This cone is anchored by a tab to a notch in the tail housing. Engaging reverse will activate the "brake" and stop the counter gear from spinning. If the car has been brought to a full stop, nothing inside the transmission will be turning and the engagement of the reverse gear cannot scrape. Some will argue that because this feature includes the use of a blocker ring to apply the brake, then, it is synchronized. No, with a synchronized gear, the car can be moving and obtain a smooth shift, but with Ford's reverse brake implementation reverse will scrape if the car is moving.
It is apparent that GM considered implementing this reverse brake in its 93 redesign of the S-10 T-5 because they implemented the "notch" in the tail housing that anchors the Ford brake cone and they adopted the redesigned shift fork, but not the actual linkage, nor the main case modification. Use of these few parts in the tail housing caused no problem.
GM did implement a reverse brake DAMPER on its last model (1996+) V-6 Camaro T-5. These are tagged 1352-247. In this transmission, GM implemented ALL of the reverse brake linkage, but did not include the anchor notch in the tail housing and did not use the synchronizer hub and ring needed to actually activate this brake. Instead, they machined a groove in the rear of the fifth gear bore and inserted a damper ring with a rubber outer friction lining into that recess. This damper has a tine that fits into a notch that was machined into the rear part of the counter shaft. Had GM's implementation really worked, it would have been brilliant because it did not require the car to be stationary in order to shift smoothly into reverse. First, the damper did not provide enough friction to really match the speeds of the two rotating masses; secondly, the little tine that anchored the damper to the countershaft would break off, rendering the entire device inoperative. To make matters worse, they reverted to the previous style fifth gear synchro hub assembly, but left the linkage that provides the extra reverse-throw of that synchro assembly. This extra motion was not compatible with the stamped steel retainer plate that goes with the older synchro hub. The 3 tines on that retainer would intermittently catch on the synchro slider when shifting into reverse. This would bend the retainer tabs and allow the fifth gear synchro keys to dislocate and fail. I have not seen a service bulletin on this issue, but the fix would be to change all of the reverse gear selector linkage back to the style previously used. It seems that Ford was very wise to retain the older style linkage in their T5Z.
When Ford implemented the World Class T-5, the 2.95 V-8 first gear ratio was dropped in favor of the 3.35 first gear set that was used for the remainder of production. This 3.35 gear set would be known as the "#052" set which was rated at 265 ft/lbs and was used in the 1985-1989 V-8's as well as in the 94-98 V-6 cars. The gear sets are commonly identified by the last three digits of the part number of the counter gear. While the number of teeth on the input shaft gear must match the gear set, the length of the input shaft and the selection of a fifth gear pair is NOT tied to a specific gear set. For example, the #052 gear sets used in the V-6 Mustangs have a longer input shaft and a different fifth gear ratio than those used in the V-8 Mustangs. There is more information about the different input shaft lengths below under "1994/1995 Mustang Changes."
There was never a 2.95 factory World Class T-5 offered in a production Mustang, but Ford Motorsport immediately revived the popular 2.95 gear set by offering a World Class aftermarket transmission that was built with a new 2.95 gear set #053. This gear set was used in all 2.95 World Class transmissions prior to the advent of the T5Z. This #053 gear set was also used in the 1988-1992 Camaro V-8 World Class Transmissions. There was never a production input shaft offered that was the correct length for a 94 or newer Mustang application.
Set ID# - Gear Ratios
Fifth Gear Ratios
In about 1992, the #065 counter gear was replaced by another "High Alloy" #068 counter gear that is phosphate coated. The input shafts began receiving phosphate coating at this time as well. All of the other gears in the #065 gear set were retained with the #068 gear set. The ft/lb rating remained the same, as phosphate coating only affects wear. This gear set was used from 1992-95 in the V-8 Mustangs and again, from 1999-2004 behind the V-6 engines. Of course, beginning with the 1994 models the input shaft is longer to match the deeper bell housings.
The 1993 aftermarket Mustang COBRA T-5 (1352-239) received a steel input shaft bearing retainer sleeve (for the throwout bearing) to rectify issues with wear that occurred on the aluminum retainers. This wear was causing the clutch to bind for all Ford T-5s prior to mid-year 1994.
1994/1995 Mustang Changes
A mid-year change in the 1994 models was the use of a steel sleeve on the input bearing retainer for the throwout bearing to slide on. All of the previous Mustang T-5s had used an all-aluminum retainer which would wear and cause the clutch to bind. The only 93 model Mustang T-5 to receive this steel-sleeved retainer was those retrofitted with the aftermarket COBRA T-5 (1352-239) and the aftermarket Super-Duty T5Z (1352-249 & 1352-251)
M-7003-Z (The T5Z)
Billet Keys for the 3-4 Synchro hub keep the keys from popping out and causing a jam that breaks the shift fork.
A Billet Counter Gear Support Plate holds the rear counter gear bearing race firmly in place so that it does not wallow out the main case where that bearing race is anchored.
Steel Input shaft bearing retainers are available from various suppliers including Tremec. Unfortunately, no aftermarket steel retainers have been produced for the 4-cylinder Mustang T-5s.
Several vendors offer aftermarket shifters that have a firmer feel and provide better guiding through the linkage to avoid missing that quick shift to third gear.
Some of the production gears and parts for the T-5 are being produced overseas and are readily available to provide less expensive replacement parts for the T-5. While it is necessary to sometimes use these parts because some are no longer available from Tremec, one should be careful of the quality.