T-5 History
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History of the BorgWarner T-5
by Stan Peace, www.Pro-ForcePerformance.com

This article is a culmination of research begun in 2009; it is 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 document.    T-5 History Article  
Questions, or requests for updates may be made by contacting the author through his website. 

Overview
The BorgWarner T-5 was first introduced in AMC cars, Jeeps, and smaller GM trucks in 1982. Since that time it has appeared in many brands of vehicles, but most notably in Ford Mustangs as well as GM Camaros, Firebirds, and S-10 Trucks.  BorgWarner sold its Light-Duty Transmission Division to Transmission Technologies Corporation (TTC) around 1997.  While the T-5 remained virtually unchanged, T-5 units produced by TTC bear the Tremec name as do all OEM replacement parts. 

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.

Transmission Fluid
BorgWarner allowed each manufacturer to choose the lubricant for its particular application, but it seems that BorgWarner's recommendation was Dexron-II ATF from the very beginning.  GM adopted the Dexron, as proven by the stickers placed on each transmission.  Ford adopted Dexron as their official fluid, as proven by specifying the ATF product in their original 1983 and 1984 Field Service Manual publications.  For some reason, AMC chose to continue specifying gear oil instead of ATF.  The early style of Dexron is no longer available.  Generic ATF such as DEX/MERC is a suitable substitute.  A Ford dealer will recommend their Mercon-V ATF which is also a good substitute.

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 T-5's:
Dexron-III ATF replaced Dexron-II in 1993.  While Dexron-III meets or exceeds the previous specifications, the viscocity of Dexron-III is thinner than the original Dexron-II that was specified for the NON-World Class T-5.  This thinner fluid is fine for the World Class T-5 with the lined synchro rings, but the NON-World Class T-5 with the brass synchro rings needs a thicker fluid to work optimally.  As a result, Tremec has specified 30W MOTOR OIL for the NON-World Class T-5's.  While Tremec has not published an official document about this, it is confirmed by an email dated 1/9/2012 from a Tremec Engineering/Support employee.         

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 term "World Class" was designated for those transmissions designed with an improved bearing structure and "lined" blocker rings for the synchronizers.  While AMC never went to the World Class structure, Ford adopted it in 1985, the Camaros and Firebirds in 1988, and the S-10 truck in 1993.

Bearings
The bearing structure changes included the addition of "needle" bearings under gears 1-3 and the use of tapered bearing sets on each end of the counter gear.

Blocker Rings
While the original blocker rings (synchro rings) were made of brass, the World Class units received steel rings that were lined for gears 1-4.  The blocker rings for gears 1 and 2 became 3-piece sets with an inner and outer cone made of steel. These linings have been called "composite", "paper", and even "fabric."   For simplicity I will use the term "composite."  The blocker ring for fifth gear has remained with the original brass design throughout.    In 1992, the Mustang T-5's received Carbon-Fiber lined rings for third and fourth gears.  This helped with high-RPM shifts.  I don't believe that GM incorporated the carbon-fiber 3-4 linings until their W/C units received a major redesign in 1993.  By that time, GM was no longer offering the T-5 for a V-8 application.
Interestingly enough, in the summer of 2011, after all T-5 production had ceased, except for the aftermarket T5Z units, Tremec released a redesigned 3-piece blocker ring set that was lined with carbon-particles instead of the composite material that was previously used.  This has made a notable improvement in high-RPM shifts for first and second gears as well.  After releasing carbon technology blocker rings, the previous composite type of ring was discontinued.  This means that any time a WC T-5 is rebuilt, it will receive the carbon-technology rings as an automatic upgrade.

Synchronized Reverse Gear
The T-5 was one of the last transmissions used by Ford that did not have a synchronized reverse gear.  In 1992, all of the Ford T-5's received a "Reverse Brake" feature.  This feature was mildly effective and was never adopted by any other auto manufacturer.  To implement it required the use of several redesigned parts making the main case, the tail housing, the fifth gear synchro hub, and almost all of the linkage for fifth gear and reverse gear engagement incompatible between the 1991 and 1992 model years.  Note that the T5Z is the only Mustang transmission that did NOT adopt this change.

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.     

Gear Sets
The gear strengths and various ratios are a bit hard to categorize as there were several different sets of gears produced.  I say SETS of gears because the various input shafts, counter shafts, and gears for first through third must stay together as a set, but sometimes these gear sets crossed product lines.  Generally, it is the counter gear that determines the "set" of gears used, as the other gears must match.  For example, a V-8 Non-World Class T5 for an 83-84 Mustang used the same gears as a Non-World Class V-8 T-5 for an 83-87 Camaro or Firebird.  The cases are quite different, the input and tail shafts are different, but the internal gears are the same except for the small fifth gear that is splined to the specific tail shaft.  These Non-World Class V-8 transmissions all had a 2.95 first gear ratio and were rated at *265 ft/lbs.  (* Let me know if you can confirm this from a reliable source.)

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.

Gear Set ID# - Gear Ratios
#052         3.35 1.93 1.29 1.0
#053         2.95 1.94 1.34 1.0
#065         3.35 1.99 1.33 1.0
#068         3.35 1.99 1.33 1.0
#070         2.95 1.94 1.34 1.0

Fifth Gear Ratios
There are a limited number of fifth gear pairs available for the T-5. There is also some confusion about the ratios because the same fifth gear pair in one transmission will yield a different ratio when used in another. The final drive fifth gear ratio depends on the number of teeth on the input shaft and its mating countershaft gear.

  Fifth Gear Options for a 3.35 T-5:
   
0.68 27t/59t
    0.73 25t/51t 
    0.83 31t/55t
    0.92 33t/53t (no longer available)

  Fifth Gear Options for a 2.95 T-5:
   
0.59 27t/59t
    0.63 25t/51t
    0.72 31t/55t
    0.80 33t/53t (no longer available)

Note: 
While the 33t/53t pair is no longer available there are a couple of aftermarket gear pairs that have a very similar gear ratio and are stronger parts as well.

Better Alloys
The 1990 V-8 Mustangs received a revised "High Alloy" 3.35 gear set #065 that changed the ratios for second and third gears slightly and provided enough additional strength for the gear set to be rated at 300 ft/lbs.  The differences in this gear set and the #052 gear set are the counter gear, second gear and third gear.  All other gears remained the same.

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. 

COBRA Changes
There was one innovation added to the 93 COBRA T-5 that was aimed at increasing reliability.  At issue was the failure of the input shaft bearing and wear on the input gear against the counter gear.  These two gears were phosphate coated to reduce wear and the 15 loose roller bearings in the cup between the input shaft and the main shaft were replaced with a caged, tapered bearing set.  This change eliminated the flat Torrington bearing that was also between those two shafts.  If these 15 roller bearings failed to receive proper lubrication, they would fail and would damage the front tip of the main shaft, causing expensive repairs.  The input shaft and the main shaft were redesigned to accept this tapered bearing set.  Other than this change, the COBRA T-5 was the same as the GT T-5.  This same change was repeated for the 94 and 95 COBRAS except that the 94 and 95 input shafts were longer for the SN-95 body.

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
The input shaft length became longer for the 1994 and newer Mustangs due to the SN-95 body changes that moved the engine a little forward from the Fox-Body Mustangs. Beginning in 1994, a deeper bell housing was used to compensate and place the rear of the transmission back in the same relative position as before.  Saying that the engine was moved forward may sound a little strange, but both the Fox-Body and the SN-95 Mustangs use the same length drive shaft.  The 1994 and newer models no longer had a "Neutral" switch and harness mounted on the top cover.

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)
With the success of the added reliability to the T-5 brought on by the COBRA changes, Motorsport decided to offer the best T-5 ever by combining the COBRA changes with their popular 2.95 aftermarket transmission.   One additional change was that the #053 counter gear was replaced with the #070 counter gear.  This gear is dark in finish like the #068.  Exactly why the change was made is unknown, but presumably the alloy of the #068 and the #070 is stronger.  The resulting T-5 is rated at 330 ft/lbs. Some think the T5Z and the COBRA transmission are the same; others think the T5Z is THE World Class T-5 because it is the best T5 built by Tremec.  No, the T5Z is the T5Z.

Beyond Production
Aftermarket companies have created custom gear sets and shafts that are even stronger than the T-5Z.  

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.   


This article was last updated on 02/09/2012 .        Hit Counter