By Chirag Asaravala. Assembly performed by Bruce Couture,
For small block Ford enthusiasts the T5 manual transmission
may be the greatest thing since sliced bread. With five fully
synchronized forward gears, overdrive, an internal shift-rail
mechanism and the ability to handle over 300 lb-ft of torque,
the T5 is easily the number one choice of anyone considering
an auto to manual transmission conversion. The compact dimensions
and feather-like weight (75 lbs.) also makes it well suited
for competition oriented Mustangs to restomoded Falcons and
Comets looking for a modernized drivetrain.
Subsequent to the T5 the only worthwhile manual gear box to
put behind a modified, yet street driven, small block Ford
was the tremendously popular Ford four speed "Top-Loader".
Other manual transmissions were certainly available to put
behind a 302 engine, such as the Borg Warner T10, the English
sourced Dagenham four-speed (factory option in most 60's Mustangs
and Falcons). However none of these transmissions offered
overdrive, perhaps the single biggest reason that enthusiasts
seek out a T5 transmission swaps. The four-speed SROD's boxes
had overdrive, but not suitable behind any significant power
Borg Warner/Tremec World
Ford began using the Borg-Warner designed T5 in small passenger
cars in the early 80's. However these early non-World class
(NWC) models weren't suited to handle the power of modified
V8 engines, and it wasn't until the availability of the World-Class
(WC) T5 gearboxes designed for the new fuel injected 5.0L
Mustangs that the popularity of the transmission took off.
Compared to NWC T5's the WC's benefit from needle bearings
under the gears and tapered roller countershaft bearings for
reduced friction. This change also allows the later to run
considerable less viscous ATF fluid rather than heavy gear
oil. The blocking rings are upgraded from brass to fiber lined
steel for smoother gear synchronization. The early WC T5 versions
were rated to handle 265 lb-ft of torque, while subsequent
changes to gear material and size in 1990 bumped the torque
rating to 300 lb-ft. The 1993 Cobra T5 was rated to handle
310 lb-ft, while Ford Racing's aftermarket "T5-Z"
could handle 335 lb-ft as a result of a smaller first gear
(2.95:1 compared to 3.35:1) and stronger steel.
Making the T5 Stronger
While it may seem a 300 lb-ft rating is easily surpassed with
today's cylinder heads and camshafts, in reality most T5's
can easily endure well over that figure when used in street
driven applications. In fact our experience has been that
shifting style, and not torque rating alone, is the biggest
factor is the life of a T5. We've seen power shifted T5's
snap behind stock 5.0L engines, while on the other T5 hold
up mile after mile behind stroked Windsor's. In fact, our
own Project '67 has been
running a stock 1990 T5 for nearly five years. We've made
over several hundred 11 and 12 second passes launching at
5000 rpm on slicks. Admittedly we are biding our time with
this T5, and with the recent addition of a supercharger, we're
not pressing our luck any longer.
It used to be that once you got in to the 500 horsepower range
you were well beyond the capabilities of any T5, and it was
time to think Tremec TKO (incidentally, TTC, the company which
owns the Tremec brand, bought the T5 design and tooling from
Borg Warner in 1997.) However no longer is this the only option.
G-Force Transmissions, the maker of some pretty stout competition
gear boxes, also manufacturers high strength gears, shafts
and other internals for the T5 transmissions. When properly
assembled the G-Force T5 can handle 500 lb-ft of torque. While
there are still strength limitations of the stock T5 case
(G-Force does offer their own T5 case) the stronger internals
are the key to keeping a T5 together behind a stout small
block. G-Force offers their T5 gear sets in synchronized and
versions. Dog-ring refers to the modification of blocking
rings for synchro-less engagement. This make shifting easy
at high rpms but at the expense of tougher gear engagement
at lower rpms. We selected the fully synchronized kit for
While the G-Force components are built to be bullet proof,
that is only half of the recipe for an indestructible T5.
The other half is in the proper rebuilding of the T5. In fact,
most of the nations major T5 rebuild shops offer their own
"G-Force T5" versions, which include their own personal,
and often closely guarded, secrets for success. We spent the
day with Bruce Couture of Modern Driveline (see side bar)
to document the steps involved in how he builds the Modern
Driveline G-Force T5.
While disassembly can be achieved with basic tools you'll
also need external snap ring pliers, retaining ring
pliers, T40 Torx bit, a drift punch and cold chisel.
For reassembly however you'll need access to a press,
bushing driver, calipers and a dial indicator. The most
important tool is the T5
manual (PDF 4MB).
If you have aren't sure whether or not you have a World
Class T5, the quickest external check is to look at the
counter-shaft bearing cup, just below the bearing retainer.
It it is of the roller bearing type, with Timken engravings
(left) you have a WC T5.
The disassembly process begins with removing the shifter.
Using a drift punch drive the roll pin through the offset
lever. The pin will bottom out but not be retrievable
at this point.
Remove the eight 15mm tailhousing bolts.
While holding the offset lever back as shown, tap the
case with a hammer to break the tailshaft housing free
of the case. Do not attempt to pry between the mating
The tailshaft housing can now be removed buy sliding it
straight back until it is off the shifter shaft and main
At this point the speedometer drive gear can be removed
from the main shaft. Depress the retaining clip and slide
the gear off, then remove the clip from the shaft.
T5 Speedometer drive gears come in three tooth counts;
6 (black), 7 (yellow) and 8 (green). By changing to the
lower count gear (6 or 7) you can compensate for steep
axle ratios and have accurate speedometer readings. With
a 6 tooth gear, for instance, you can use an 18, 20, and
21 tooth driven gear (on the end of the speedo cable)
for accurate reading with 3.73, 4.10, or 4.30 gears respectively.
With the yellow drive gear you can use 21 tooth speedo
gear for 3.73's and 23 for 4.10.