Understanding the T56

[High Plains Mopars]

I'm thinking about jumping into the T56 playground and have seen a lot of differing info that leaves me a bit shell shocked. Since the sticky above has lost some of its links and I'm somewhat late model illerate, I'm not quite sure what some of the differences are. I've seen T56s called out as Viper trans, LT trans, LS trans, Mustangs trans, etc. I'd imagine shifter locations vary and maybe bolt patterns, but I'd suspect the transmisssion its self are all the same, or are they? I notice Quick time sells adapters for my engines, but they also specify different trans such as LT, LS, Magnum, etc.



Does anyone have a primer on the differences, break down of styles, donor cars, etc and/or can you point me to a publication that may have that info. I would sure appreciate it.

[SSninja]

Really good thread on the T56:

http://www.camaros.net/forums/showthread.php?t=98387

Hope that's useful!

In case that link ever dies:

There are so many questions from folks about how to do this swap, I thought I'd
post up a little "primer" I did. The post will be in two parts. All
recommendations are solely my own. Any corrections or comments are welcome

The Principal Choices of Swappable
T56’s

There are
three T56’s that are generally used in first generation Camaros.
T56’s that were in an LS1 equipped GM car (Camaro
or Firebird – not a Corvette) these are
referred to as “LS1 T56’s”; T56’s that were in LT1 equipped GM cars (Camaros and
Firebirds) these are referred to as “LT1 T56’s”; and so-called Aftermarket T56’s
that were intended by Tremec and GM as service replacements for T5’s that broke
behind (I think) TPI SBC’s, these are referred to as “Aftermarket T56’s.” The
Aftermarket T56’s came with an adapter plate very much like the McLeod 8207 kit
referred to below, except that the
adapter plate was drilled to correct for the 17 degree tilt built in to the T5
bellhousings. If you get a new Aftermarket T56,
you’ll have to have the plate redrilled, or get yourself a T5 bellhousing.

The LS1 T56's generally and many LT1 T56’s have a 0.5:1
overdrive sixth gear and a 2.66:1 first gear with an overall gear spread of
2.66-1st,
1.78-2nd, 1.30-3rd, 1.00-4th, 0.74-5th and 0.50-6th,. Some of the very early LT1 T56's, the Aftermarket T56 and a
few other more exotic T56's have a 0.62:1 sixth gear and a 2.97:1 first gear
with an overall gear spread of 2.97-1st, 2.07-2nd, 1.43- 3rd, 1.00-4th, 0.80-5th and
0.62-6th. The splits between the gears
for the LS1 T56 are: 0.67 1-2, 0.73 2-3, 0.77
3-4, 0.74 4-6, 0.68 5-6. The splits between the gears for a 2.97 first gear T56
are: 0.70 1-2, 0.69 2-3, 0.70 3-4, 0.80 4-6, 0.78 5-6.

Because of the steep overdrive 6th gear
in an LS1 T56, a car with a radical cam will
need a rear gear at the higher end of the range. By way of example, given a
26.6” tall rear tire and an LS1 T56, a car with 4.11 gears will be
turning about 1560 RPM at 60mph, and will go about 77 mph at 2,000 RPM. A
similar car with 3.55 gears will be turning about 1350 RPM at 60mph, and will go
about 89mph at 2,000 RPM. Yet another similar car with 3.08 gears will be
turning about 1170 RPM at 60mph, and will go about 103 mph at 2,000 RPM (if the
engine makes enough torque).

The equivalent numbers for a similar car equipped with a T56
with a 0.62:1 6th gear are: 4.11 gears will be turning about 1930 RPM at 60mph,
and will go about 62 mph at 2,000 RPM; 3.55 gears will be turning about 1670 RPM
at 60mph, and will go about 72mph at 2,000 RPM; and 3.08 gears will be turning
about 1450 RPM at 60mph, and will go about 82 mph at 2,000
RPM.


Finally, the 2.97:1 first gear T56’s are generally rated by
Tremec for 400Ft-Lbs of torque. The 2.66:1 first gear T56’s are generally rated
by Tremec for 450Ft-Lbs of torque or more. Both are, based on abuse stories,
pretty conservative ratings.

You can tell the difference between an LS1 T56 and an LT1 T56 three ways:


(1) The LT1 T56 has the slave cylinder mounted
on the bellhousing
and the cylinder pushes the outside end of the clutch fork toward the front of
the car. The LS1 T56 has a hydraulic throwout bearing that bolts to the front of
the transmission and is concentric with the input shaft.

(2) The LT1 T56 has a clutch fork
pivot ball on the front of the transmission. The LS1 T56 has no provision for a
clutch fork pivot ball.

(3) The LT1 T56 input shaft is about 5" long from the face of
the transmission (where it's bolted to the bellhousing) to the end of the input shaft. The LS1
T56 input shaft (measured the same way) is about 6.5"
long.

The best way to determine the gear set in an LT1 T56 is to put
it in first gear and count number of input shaft revolutions required for one
full revolution of the output shaft.


(The
Aftermarket T56 has an input shaft that is 7” from the face of the transmission to the end of the input
shaft and doesn’t come with a bellhousing; the Viper T56 has an input
shaft that is also about 7” from the face of the transmission to the end of the input
shaft and has no provision for a clutch fork pivot ball.)

Swapping
an LS1 T56

If you’re starting from scratch and already have a 3 or 4
speed manual transmission in the car, the easiest and cleanest way to swap a T56
into a first generation Camaro behind a traditional BBC/SBC is as follows: You
will need an LS1 T56, the McLeod adapter kit (1/2” thick adapter
plate that goes between the transmission and the bellhousing, extended pilot
bushing, and “collar” on which the throwout bearing rides – McLeod Part No.
8-207 available, for example, at http://store.summitracing.com/partdetail.asp?part=MCL%2D8%2D207&N=700+400374+429
4812239+4294856873+115&autoview=sku), a transmission cross
member (I like the ATS adjustable crossmember available at http://www.t56kit.com/main.html), a
shortened balanced driveshaft (which
you can have made up locally), and an electronic speedometer or an electronic to
mechanical converter such as Cable X (available at http://www.gaugeguys.com/cablex.htm, among others).


Using these parts you reuse your current
bellhousing, clutch setup (swapping in a 26 spline disk if required), throwout
fork, throwout bearing and mechanical clutch linkage. I also prefer an all heim
joint linkage such as the one available from http://www.speeddirect.com/index.aspx?nodeID=34.


If you are converting from an automatic, you
will also need a bellhousing or scattershield for a SBC/BBC, a flywheel, clutch and 26 spline
clutch disk for a traditional SBC/BBC, clutch pedal, clutch linkage (upper rod,
Z bar, and lower linkage (or just buy the Z bar and purchase the heim joint kit
referred to above), throwout fork, throwout fork pivot ball and throwout
bearing. All of these factory style linkage parts should be available from your
preferred restoration part vendor.

I prefer
a mechanical clutch linkage, particularly for an LS1 T56, because
troubleshooting and correcting clutch engagement/disengagement problems with the
factory hydraulic linkage generally requires that you uninstall the roughly 130
pound LS1 T56 to get to the concentric throwout bearing, make whatever
correction you think is needed, reinstall the transmission, test again and then
go through the uninstall/correction/reinstall sequence until the problem is
solved. Call me lazy, but that doesn’t sound like fun.

If you want to use the factory hydraulic linkage with either
the LS1 or LT1 T56, I suggest you simply use the
ATS kit available at http://www.t56kit.com/main.html. The ATS kits use
the factory hydraulic linkages and the factory bellhousings.

Weir Hot
Rod Products also makes conversion kits for LS1 or LT1 T56’s (http://www.weirhotrodproducts.com/index.html) which
use Weir’s cast aluminum bellhousing and hydraulic linkages (which use a
concentric hydraulic throwout bearing for both transmissions), but which, in my
opinion, aren’t as polished as the ATS kits. (Compare the Weir cross member to
the ATS piece.)

Finally McLeod (whose adapter
kit is mentioned above) also makes a “modular” bellhousing which is a
hydroformed steel bellhousing that uses spacer rings of various thicknesses and
transmission mounting plates to adapt a variety of transmissions to a variety of
engines. (If you’re doing anything other than a T56 behind a GM engine, talk to
McLeod.) In addition, McLeod makes front “intermediate” plates for T56’s that
incorporate a clutch fork pivot for adapting an LS1/Viper T56 to a mechanical
clutch setup without the use of the adapter plate kit. A modular bellhousing and
McLeod front “intermediate” plate locates the transmission roughly 0.75” closer
to the engine, increases the effective amount of space in the transmission
tunnel (because the transmission is farther forward) and makes the installation
cleaner, simpler but more expensive.

Swapping an LT1 T56

If you
already have an LT1 T56, your swap is a bit more involved (and likely costly).
As described above, the LT1 T56 has a fairly short input shaft which, because of
limited space between the transmission and the engine block, requires the use of a special “pull” style
clutch and a special flywheel designed to accept the
“pull” style clutch. (Here’s a picture of the clutch just by way of example http://www.clutchcityonline.com/images/04-134.JPG)
You can’t use any "standard" Chevy flywheel and, unless you have a
one piece rear main seal crankshaft, you also can't use the factory LT1
flywheel. In addition, the LT1 T6 uses a hydraulic linkage with a slave cylinder
external to the bellhousing, which is also “one-off” for the LT1. So if you’re
going to install an LT1 T56, make sure you get the bellhousing, the clutch (if
it’s in good shape) and the hydraulic linkage.

Once you
have the basic parts you have four choices: (1) You can use the ATS kit, (2) you
can use the Weir kit, (3) you can contact McLeod’s tech line to see if either
the adapter kit mentioned above with a more extended pilot bushing or one of
their modular bellhousings will work, or (4) if you have a 2.66:1 first gear LT1 T56, you can swap out the input
shaft for an LS1 T56 input shaft and go to the section above. (You can also swap
the Viper T56 input shaft for an LS1 T56
input shaft to simplify installation of a Viper T56 behind a SBC/BBC LSx engine.)
If you swap input shafts, be aware that the input shaft must be correctly
shimmed on a T56, so it would be best to have an experienced transmission
technician do the job.


Interior Details

With any
of the mounting methods used you’ll need to cut a new hole in the transmission
tunnel for the shifter handle and you’ll need a shift boot sealing the floor of
the car to the outside air. The LS1 T56 and LT1 T56’s move the shifter back the
most, the Viper T56 less and the Aftermarket T56 the least. However, all of them
require a new hole for the shift lever at least 4” or so back from the factory
location. (The shifter location itself, however, is fine with any of them.) If
you have a console, it will have to be moved back, or you’ll have to try
something like the McLeod “Slik Stix” shifter, and you’ll need to come up with a
shifter to console boot of some kind.

Finally,
you’ll need to either replace your factory speedometer with an electronic
speedometer (more involved than it sounds because you lose things like turn
signal indicators, etc. when the speedometer is removed – probably best done if
you’re planning on going to replacement instruments), or an electronic to
mechanical adapter like the Cable X.

Other
T56s

The Viper T56 has the same gear ratios as
the LS1 T56, but is supposed to have a higher torque
rating. The Viper has an 8.25” input shaft, which would make swapping it into a
first generation Camaro a bit tighter, as the farther back in the transmission
tunnel you go, the narrower it gets. As mentioned above, you can swap input
shafts with one from an LS1 T56, and solve the input shaft issue. Viper T56’s
have a different speedometer connection than an LS1 T56 and a different shifter
configuration, although a shifter meant for a 2003-2004 Ford Cobra T56 will work on the Viper T56.

The gear ratios for the T56s used in the GTO and Cadillac CT-V
are - 2.97-1st, 2.07-2nd, 1.43- 3rd, 1.00-4th, 0.84-5th and 0.57-6th. The gear ratios for the T56’s used in the
2005 SSR were 3.01-1 st,2.07-2nd, 1.43- 3rd, 1.00-4th, 0.84-5th and
0.57-6th. I would expect (but have not
personally confirmed) they both have the same input shaft length as the LS1
T56.

[High Plains Mopars]

Thats a good start for me

THanks!

[72BBSwinger]

Whats up Tony? I can tell you that a Viper T56 has a 28" from the block shifter location. That is whats in my Dart and it works lovely since stock is 27".

[High Plains Mopars]

Hey man. Good to know, but it may not help me out.

I recently picked up a Quicktime bellhousing for small block mopar to LS T56. Since I haven't played with GM parts for nearly 20 years, I'm a bit out of the loop on their later model stuff, so I'm trying to understand options.

[72BBSwinger]

http://www.ls1tech.com/forums/attach...ms-968x638.jpg