Thread: Transmissions for a LS motor - 5 spd vs. auto

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"Newer" transmissions include the 4L60E, 4L65E, 4L70E and 4L80E. The shifting is electronically controlled, once you're in overdrive (4th), but you need a mechanical shifter to shift from park to reverse and OD. The mechanical shifter can also be used to manually shift down to 3rd, 2nd, or 1st. You can get a floor mounted or column mounted shifter, but the column version would be part of a new or used column, made for a 4 speed automatic.

Even more recent auto transmissions are 6 speed. One problem with them is substantially larger exterior dimensions, that may cause problems. All of them (4 & 6 speed) will be longer than your old transmission mount can handle.

You'll also need an electronic controller for the transmission - it won't work without it. Trucks from the factory will have the engine and trans controlled by the same computer. At a salvage yard, you'd need to get everything from a donor that is possible - the engine, column/shifter, computer, trans and wiring harness. There's quite a mess of wires to deal with - around a hundred in a typical engine and trans wiring harness.

I chose to use a GM connect and cruise package for my car. It include the LS engine of your choice (430-556hp), an appropriate 4 speed auto trans and all of the needed electronics to make it run. The engine's computer is separate from the transmission computer (supplied by PCS). It's not a cheap route though (starting around $10K), but there's little to do put hook up a few power-source and ignition switch wires.

LS Trans & Engine Packages

https://www.powertraincontrolsolutio...on_Controller/

I found that the floor shifter that Lokar sells as 4L60E compatible, does not work properly with the newer 4L65E (and probably none of the other higher numbers). I made one work, but it required a change in the lever arm length to better match the travel required by the trans. The shifter had about 10% too much travel.

Another issue you'll have to deal with is a major change to the fuel pump setup. The newer LS engines require 58 psi. I have an in-tank pump from Tanks, plus a special pressure regulating filter, with a return line to the tank.

http://www.tanksinc.com/index.cfm/pa...prod/prd84.htm

http://www.tanksinc.com/index.cfm/pa...rod/prd425.htm