History of the Borg Warner T-5 Transmission; Mustang, Camaro Firebird, S-10 (2024)

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

This article is a culmination of research begun in 2009;it isperiodically updated with new information and clarifications. The authordoes NOT give permission to copy and re-post this on other websites withoutproviding credit to the author and a functioning link back to thisdocument. T-5History Article
Questions, or requests for updates may be made by contacting the author throughhis website.

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

Today (2019) one version of the T-5 is stilloffered as a new transmission under the Ford Motorsport/Ford Racing name andthrough some auto specialty shops. It is called the T5Z because it wasoriginally tagged M-7003-Z 1352-249. This identical unit, when marketedoutside the Motorsport structure, is tagged 1352-251. Be aware that someresellers market the T5Z as the 1993 COBRA T-5 IT IS NOT THE SAME but it fitsjust fine. The COBRA T-5 transmissions ALL came with the 3.35 ratio gearsand not the 2.95 ratio gears..

Whilethese transmissions are all T-5's, they are generally not interchangeable acrossproduct lines because the input shafts, output shafts, and cases are differentfor the various auto makers. Interestingly enough, due to the design ofthe case, parts are rather interchangeable, and custom versions are oftencreated. The most popular "hybrid" T-5 is the use of an S-10 tail ona Mustang transmission. This combination offers a strongtransmission with a shifter that is located much further forward than with theMustang so that it fits classic cars with bench seats, or older pickuptrucks. Care must be taken to choose compatible parts when attempting tocreate a custom transmission.

The vast popularity of the T-5 and its notedability to shift smoothly have led to many aftermarket modifications to allow itto stand up to high-horsepower applications. The all-aluminum case andover all lightweight design have made it popular in the racingcommunity.

The T-5 first appeared as a 5-speed option for both Mustangs and Camaros in 1983. Fordused 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-10truck series from 1982 through 1992.

Transmission Fluid
BorgWarner allowed each manufacturer to choose the lubricant for itsparticularapplication, but it seems that BorgWarner's recommendation was Dexron-II ATFfrom the very beginning. GM adopted the Dexron, as proven by thestickers placed on each transmission. Ford adopted Dexron as theirofficial fluid, as proven by specifying the ATF product in their original 1983and 1984 Field Service Manual publications.For some reason, AMC chose tocontinue specifying gear oil instead of ATF. The early style of Dexron isno longer available. Generic ATF such as DEX/MERC is a suitablesubstitute. A Ford dealer will recommend their Mercon-V ATF which is alsoa good substitute.

Many Internet sourcesinsist that gear oil should be used in the Non-World Class T-5, but thedocumentation above clearly reveals that both Ford and GM chose to use ATF fromthe start. Using gear oil in a Non-World Class transmission will notsignificantly damage the transmission, but many times, due to Internet confusionas to what is, and is not, a World Class T-5, gear oil has been mistakenly usedin the World Class units.

Update on Dexron VS Gear oil for NON-World ClassT-5's:
Dexron-III ATF replaced Dexron-II in 1993. While Dexron-III meets orexceeds the previous specifications, the viscocity of Dexron-III is thinner thanthe 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 needle bearings and lined synchro rings,but the NON-World Class T-5 with the brass synchro rings needs a thicker fluidto work optimally. As a result, Tremec has specified 30W MOTOR OILfor the NON-World Class T-5's. While Tremec has not published an officialdocument about this, it is confirmed by an email dated 1/9/2012 from a TremecEngineering/Support employee.

I personally support the use of "Pennzoil forSynchromesh Manual Transmissions" as a good fluid for the NWC T-5.

WARNING:Using gear oil or motor oil in a T-5with the composite lined blocker rings found in the World Class T-5's willdestroy the original style blocker ring linings over a period of a few months rendering thosesynchronizers useless.The newer Carbon-Fiber style blocker ringsare not as sensitive as the originals.

World Class Transmissions
The term "World Class" wasdesignated for those transmissions designed with an improved bearing structureand "lined" blocker rings for the synchronizers. While AMC neverwent to the World Class structure, Ford adopted it in 1985, the Camaros andFirebirds 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 setson 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 outercone made of steel. These linings have been called "composite","paper", and even "fabric." For simplicity Iwill use the term "composite." The blocker ring for fifth gearhas remained with the original brass design throughout. In1992, the Mustang T-5's received Carbon-Fiber lined rings for third and fourthgears. This helped with high-RPM shifts. I don't believe that GMincorporated the carbon-fiber 3-4 linings until their W/C units received a majorredesign in 1993. By that time, GM was no longer offering the T-5 for aV-8 application.
Interestingly enough, in the summer of 2011, after all T-5 production hadceased, except for the aftermarket T5Z units, Tremec released a redesigned3-piece blocker ring set that was lined with carbon-particles instead of thecomposite material that was previously used for First and Second gears. This has made a notableimprovement in high-RPM shifts for first and second gears as well. Afterreleasing carbon technology blocker rings, the previous composite type of ringwas discontinued. This means that any time a WC T-5 is rebuilt, it willreceive the carbon-technology rings as an automatic upgrade.

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

The functionality of this reverse brake is that theredesigned linkage engages a second blocker ring against a stationary cone thatis mounted on the rear of the fifth gear synchro hub. This cone isanchored by a tab to a notch in the tail housing. Engaging reverse willactivate the "brake" and stop the counter gear from spinning. Ifthe car has been brought to a full stop, nothing inside the transmission will beturning and the engagement of the reverse gear cannot scrape. Some willargue that because this feature includes the use of a blocker ring to apply thebrake, then, it is synchronized. No, with a synchronized gear, the car canbe moving and obtain a smooth shift, but with Ford's reverse brakeimplementationreverse will scrape if the car is moving.

It is apparent that GM consideredimplementing this reverse brake in its 93 redesign of the S-10 T-5 becausethey implemented the "notch" in the tail housing that anchors the Fordbrake cone and they adopted the redesigned shift fork, but not the actuallinkage, nor the main case modification. Use of these few parts in thetail 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. Inthis transmission, GM implemented ALL of the reverse brake linkage, but did notinclude the anchor notch in the tail housing and did not use the synchronizerhub and ring needed to actually activate this brake. Instead, theymachined a groove in the rear of the fifth gear bore and inserted a damper ringwith a rubber outer friction lining into that recess. This damper has atine that fits into a notch that was machined into the rear part of the countershaft. Had GM's implementation really worked, it would have been brilliant becauseit did not require the car to be stationary in order to shift smoothly intoreverse. First, the damper did not provide enough friction to reallymatch the speeds of the two rotating masses; secondly, the little tine thatanchored the damper to the countershaft would break off, rendering the entiredevice inoperative. To make matters worse, they reverted to the previousstyle fifth gear synchro hub assembly, but left the linkage that provides theextra reverse-throw of that synchro assembly. This extra motion was notcompatible with the stamped steel retainer plate that goes with the oldersynchro hub. The 3 tines on that retainer would intermittently catch onthe synchro slider when shifting into reverse. This would bend theretainer 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 tochange all of the reverse gear selector linkage back to the style previouslyused. It seems that Ford was very wise to retain the older style linkagein their T5Z.

Gear Sets
The gearstrengths and various ratios are a bit hard to categorize as there were severaldifferent sets of gears produced. I say SETS of gears because the variousinput shafts, counter shafts, and gears for first through third must staytogether as a set, but sometimes these gear sets crossed product lines.Generally, it is the counter gear that determines the "set" of gearsused, as the other gears must match. For example, a V-8 Non-World Class T5for an 83-84 Mustang used the same gears as a Non-World Class V-8 T-5 for an83-87 Camaro or Firebird. The cases are quite different, the input andtail shafts are different, but the internal gears are the same except for thesmall fifth gear that is splined to the specific tail shaft. TheseNon-World Class V-8 transmissions all had a 2.95 first gear ratio and were ratedat *265 ft/lbs. (* Let me know if you can confirm this froma reliable source.)

When Ford implemented the World Class T-5, theoriginal 2.95V-8 first gear ratio was dropped in favor of the 3.35 first gear set that wasused for the remainder of production. This 3.35 gear set would be known asthe "#052" set which was rated at 265 ft/lbs and was used in the1985-1989 V-8's as well as in the 94-98 V-6 cars. The gear sets arecommonly identified by the last three digits of the part number of the countergear. While the number of teeth on the input shaft gear must match thegear set, the length of the input shaft and the selection of a fifth gear pairis NOT tied to a specific gear set. For example, the #052 gear sets usedin the V-6 Mustangs have a longer input shaft and a different fifth gear ratiothan those used in the V-8 Mustangs. There is more information about thedifferent input shaft lengths below under "1994/1995 Mustang Changes."

There was never a 2.95factory World Class T-5 offered in a production Mustang, but Ford Motorsportimmediately revived the popular 2.95 gear set by offering a World Classaftermarket 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 adventof the T5Z. This #053 gear set was also used in the 1988-1992 Camaro V-8World Class Transmissions. There was never a production input shaftoffered that was the correct length for a 94 or newer Mustang application, but acompatible shaft has appeared in the aftermarket parts world..

GearSet 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

In about 1992, the #065 counter gear was replaced by another"High Alloy" #068 counter gear that is phosphate coated. Theinput 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 ratingremained 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-6engines. Of course, beginning with the 1994 models the input shaft islonger to match the deeper bell housings.

COBRA Changes
Therewas one innovation added to the 93 COBRA T-5 that was aimed at increasingreliability. At issue was the failure of the input shaft bearing and wearon the input gear against the counter gear. These two gears were phosphatecoated to reduce wear and the 15 loose roller bearings inthe cup between the input shaft and the main shaft were replaced with a caged, tapered bearingset. This change eliminated the flat Torrington bearing that was alsobetween those two shafts. If these 15 roller bearings failed to receiveproper lubrication, they would fail and would damage the front tip of the mainshaft, causing expensive repairs. The input shaft and the main shaft wereredesigned 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 wasrepeated for the 94 and 95 COBRAS except that the 94 and 95 inputshafts were longer for the SN-95 body.

The 1993 aftermarket Mustang COBRA T-5(1352-239) received a steel input shaft bearing retainersleeve (for the throwout bearing) to rectify issues with wear that occurred onthe aluminum retainers. This wear was causing the clutch to bind for allFord T-5s prior to mid-year 1994.

1994/1995 Mustang Changes
The input shaft lengthbecame longer for the 1994 and newer Mustangs due to the SN-95 body changes thatmoved 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 thetransmission back in the same relative position as before. Saying that theengine was moved forward may sound a little strange, but both the Fox-Body andthe SN-95 Mustangs use the same length drive shaft. The 1994 and newermodels no longer had a "Neutral" switch and harness mounted on the topcover.

A mid-year change in the 1994 models was the use of a steel sleeve onthe input bearing retainer for the throwout bearing to slide on. All ofthe previous Mustang T-5s had used an all-aluminum retainer which would wear andcause the clutch to bind. The only 93 model Mustang T-5 to receive thissteel-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 COBRAchanges, Motorsport decided to offer the best T-5 ever by combining the COBRAchanges with their popular 2.95 aftermarket transmission. Oneadditional change was that the #053 counter gear was replaced with the #070counter gear. This gear is dark in finish like the #068. Exactly whythe change was made is unknown, but presumably the alloy of the #068 and the#070 is stronger. The resulting T5Z is rated at 330 ft/lbs. Some think the T5Z and the COBRA transmission are thesame;others think the T5Z is THE World Class T-5 because it is the best T5 built byTremec. No, the T5Z is the T5Z.

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

Solid Keys for the 3-4 Synchro hub keep the keys frompopping out and causing a jam that breaks the shift fork.

A Billet CounterGear Support Plate holds the rear counter gear bearing race firmly in place sothat it does not wallow out the main case where that bearing race isanchored.

Steel Input shaft bearing retainers are available from varioussuppliers including Tremec. Unfortunately, no aftermarket steel retainers havebeen produced for the 4-cylinder Mustang T-5s.

Several vendors offeraftermarket shifters that have a firmer feel and provide betterguiding through the linkage to avoid missing that quick shift to third gear.

Someof the production gears and parts for the T-5 are being produced overseas andare readily available to provide less expensive replacement parts for theT-5. While it is necessary to sometimes use these parts because some areno longer available from Tremec, one should be careful of thequality.

This article was last updated on 01/28/2024.