Your transmission and valvebody may look like a complex maze of fluid passages and little metal balls, but installing a shift improver kit is easier than you think.
In our November issue we rebuilt our TorqueFlite for severe street duty, and outlined the performance modifications required to make your transmission bulletproof. We ran out of pages, so we'll take you through the valvebody and servos to show what it takes to firm up the shifts for tire chirping results here on our Web site.
For our project, we chose the Trans-Scat performance modification kit from TCI Automotive. This kit will give us the shift quality we desire, while retaining the automatic shift features when selected in the drive position.
TCI Automotive has been in the transmission business since 1968 and has a reputation for providing quality products. TCI can provide the parts you need to modify or rebuild your transmission, or they have transmissions and components in stock and ready to install. We chose to install our Trans-Scat kit ourselves to save a few bucks.
Our kit had options for either street/strip or heavy duty/towing. Since our transmission is destined for our '68 GTX clone, we chose to install it using the street/strip instructions. We found the instructions provided with the kit complete and easy to follow. Since our transmission was being overhauled, we installed the kit during the process. The kit can also be installed with the transmission still in the vehicle without much trouble, so don't be afraid to tackle the job in your garage, or driveway for that matter. Remember this kit is designed to improve shift quality and will not fix internal problems with your transmission. If you question the integrity of your transmission's internal workings, our advice is to pull it for an overhaul before installing the Trans-Scat kit. Also remember these pictures and instructions are a good reference, but are not a substitute for the instructions provided in the kit. Always read and understand the instructions before beginning the project.
The first step is to drain the transmission and remove the pan. If the transmission is still in the vehicle, it's wise to let it cool a little before beginning the work. If you're impatient, be sure to have a first aid kit handy so you can treat the burns that the 250-degree fluid causes as it pours over your hands. After removing the pan and treating your burns, you can remove the valvebody by removing the 10 retaining bolts. Also, you will need to remove the shifter and kick down arms before removing the valvebody. Remove the last bolt slowly as there is a servo spring between the valvebody and the case. As you remove the valvebody, you'll need to pull it down and forward to disconnect the park rod. Your car should be on jackstands with the wheels chocked for this operation. If the car is parked on a hill, try to move out of the way, so it doesn't roll onto you and crush you when you disengage the park rod. The filter can now be removed from the valvebody by removing the three retaining screws. | 
With the valvebody removed, the front band adjusting screw on the outside of the case can be loosened enough to remove the band apply-linkage. The front-band lever can now be moved so that the front servo cover can be removed. This is done by removing the snap ring. Use a C-clamp to compress the servo slightly to aid in the snap ring removal. This will expose the servo and return springs. If your transmission has two servo return springs, remove the outer spring and reassemble the servo. If only one spring is present, reassemble the servo as it was removed. The band adjusting linkage can now be reinstalled and adjusted by tightening to 72 inch pounds, then backing off two full turns before tightening the lock nut. | 
The rear servo is now accessed by fully backing out the rear band adjustor and pushing in on the band so that the band strut can be removed. Now rotate the band-apply lever so the rear servo retaining snap ring can be removed. Be sure to apply pressure to the retainer as you remove the snap ring so the spring doesn't jump out and get lost or cause injury. Our transmission is the '67-and-later design, so we compress the servo spring slightly and replace the snap ring with the one provided in the kit. The servo is now reinstalled with the servo return spring supplied in the Trans-Scat kit. The band apply linkage can now be reinstalled in reverse of the way it was removed. Adjust the rear band by tightening to 72 inch pounds and backing off two-and-a-half turns before tightening the lock nut. |
Now the accumulator (center) piston can be removed by pulling straight down. If you find a spring behind the piston, you can discard it. For street/strip applications such as ours, the piston is reinstalled without the spring. For the heavy-duty/towing setup, install the kit's blocker rod into the back of the piston before installation. Using a punch and hammer, we tap the cupped orifice plug into the direct clutch oil passage in the case, making sure it is completely below the surface of the case. The modifications to the case and servos are now complete, so we can move on to our valvebody. | 
Set the valvebody on a clean workbench to begin disassembly. Begin by removing the pressure regulator spring retainer (located next to the selector lever), then the adjustment plate, regulator spring, converter valve spring, regulator valve, and converter valve and lay them on the bench. | 
Now the 14 screws that sandwich the separator plate between the valvebody casting and the transfer plate (looks like a maze) can be removed, and the three parts separated. Take care not to loose the metal check balls from the transfer plate. |
After removing the shift valve end plate, Shift Valve, and spring, as well as the governor plug end plate, both shift valve governor plugs, shuttle valve throttle plug, and springs, the main casting is drilled using the drill guide and bit supplied in the kit. When removing valves, plugs, and springs, be sure to keep the valves separate and keep the springs with their respective valves to avoid confusion later. If you do confuse some of the valves or springs, the instructions contain a nice exploded-view diagram to aid in reassembly. | 
The main casting is now drilled by installing the drill guide onto the casting as shown in the instructions, and drilling out the portion of the casting under the center hole with a 3/16-inch drill. Be careful to drill out the casting wall only to the floor of the casting. Do not drill completely through the casting. The idea is to remove the wall, allowing fluid to travel between the two open areas. You can make a drill stop by wrapping tape around your bit 3/8-inch from the end of the tip to prevent drilling too far. | 
After drilling the main casting, we cleaned all of our valvebody parts in solvent and dried with compressed air. The shift valves can now be assembled in the reverse order of removal. The governor plug valves are also reinstalled. The Trans-Scat kit offers the option of a special 1-2 shift valve governor plug that allows you to downshift to low gear at any speed. We chose not to install this feature since our car is destined for family use. The throttle pressure-valve, kickdown valve, pressure regulator-valve, and converter valves are now installed in the casting, and the casting is set aside. |