T56 Information - First Generation Camaro Swap
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.)
Mike - '68 Camaro with lots of stuff done to it.
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Last edited by DjD; Jul 29th, 10 at 05:55 PM.