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Have you ever wanted a more positive shift from your
Corvette’s automatic transmission? How
about being able to shift it to a lower gear and have it shift instantly? Maybe you just want more performance. all of these can be achieved by installing a
Shift Kit. A few years ago you had to
remove the transmission and have the Kit installed by a transmission
specialist, but not any longer. Now,
thanks to TransGo, 2621 Merced
Avenue, Dept. CF, El Monte, CA 91733 (818) 443-4953, you can have a
kit that you can install yourself without ever removing the transmission from
the car. The 73 Corvette we were working
on had a turbo 400 transmission in it which shifted good but not as positive as
it should. The answer was to install a
Shift Kit. One that would make the shift
more positive and also allow the driver to have more control. The TransGo 400 Kit was the answer. We took the transmission out of the car for
photo purposes but all of the changes can be done without ever removing
it. As you will see, the installation is
not complicated and the results are well worth the effort.
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01: Here is the complete TransGo Turbo 400 Shift Kit. The only other items you will need are some
hand tools, a drill, a drain pan, jack, jack stands and a little time. |
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02: Since our transmission was out of the car, a thorough
cleaning was in order. When cleaning the
transmission, remember to plug off all the cooling line fittings and dipstick
tube openings.
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03: After cleaning, we decided to do a little
detailing. We refinished the pan with
Eastwood’s Detail Gray and the dipstick tube with Eastwood’s Under Hood Black. |
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04: Before starting on any transmission repair, make sure
that you have the right kit for your transmission. An easy way to check is to line the pan
gasket up with the transmission pan. A
Turbo 400 pan is different than a Turbo 350.
Here you can see the pan gasket matches the detailed transmission pan.
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05: Start by draining the transmission into an appropriate
container. Next remove the pan and
transmission filter. The filter is not
enclosed with the Shift Kit so this will have to be purchased separately. You will want to install a new filter when
you re-assemble the transmission.
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06: Now remove the detent solenoid, valve body and
governor tubes. Keep track of the
mounting bolt arrangement. |
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07: Place the valve body on a bench with the 2-3
accumulator piston hanging over the edge.
With a 3/16” punch drive the 2-3 pin straight down and out of the valve
body. Place your hand under the piston
to catch it when it is driven out. |
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08: You will now assemble the new accumulator piston. Install the “E” clip onto the new threaded
pin. Install the pin through the new piston. Then install the seal onto the new
piston. This new accumulator piston
setup will give an easy 2-3 shift under normal throttle. The more throttle, the shorter and firmer the
shift. |
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09: Install the new piston and thread into the valve body
and tighten the nut. Turn the nut until
you feel the thread bottom in the bore.
This will leave 14 to 15 threads exposed out of the nut. With the nut tightened, leave two or three
threads sticking out beyond the nut and cut off the rest. Take a hammer and flatten the end of the
thread to keep the nut from becoming loose and falling off. NOTE:
This Kit also supplies a new shift valve that allows you to change the
shift pattern to give you total control of 1st gear. If the “shift command” feature is installed,
the transmission will not upshift in 1st gear and will shift back to 1st gear
at any speed. All of the necessary parts
and instructions are included with the Turbo 400 Kit. We did not install this feature in the 73
Corvette because the owner felt he did not want it. |
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10: The next procedure is to select the shift
firmness. This is done by enlarging
holes in the supplied separator plate.
It is important to be conservative here.
Always start by drilling the smallest holes. You can always make it bigger, but you cannot
make is smaller. TransGo supplies you
with a template, drills and full instructions for drilling. You will drill two or three different holes
depending on the type of shift that you want.
The shift firmness ranges from normal to full competition and everything
in between. We had to drill two holes
for the type of firmness we wanted.
Again, start with the smallest holes.
If after the road test you find you need a firmer shift, the plate can
be removed, re-drilled and then re-installed.
Extra gaskets are supplied so this can be done.
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11: The second accumulator and case are now modified. Remove the cover, gasket, low/reverse piston,
second accumulator piston and spring.
Install the new blue spring, re-assemble and re-install. |
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12: If the transmission is on a bench, install the five
steel balls as per the instruction sheet.
Then install the gasket marked “C”. |
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13. If the transmission is in the car, install the five
steel balls on the plate by applying Vaseline to each ball and sticking them to
the plate at the instructed holes in the separator plate. Then place the gasket marked “C” onto the
same side of the plate. This gasket
should seal between the case and the separator plate.
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14: The gasket marked “VB” (Valve Body) is installed now. |
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15:
Next the valve body is
re-installed and these two bolts are started first. Also remember to align the shift detent with
the manual valve.
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16: Now re-install the detent solenoid and the governor
tubes. Remember to install the detent
solenoid metal gasket. |
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17:
A new filter should also be
installed. This is just good
maintenance.
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18: Re-install the pan and pan gasket. If you removed the dipstick tube, remember to
put a new o-ring on the tube before you re-install it. |
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19: We also decided to put on a new transmission mount
which was supplied by Zip
Products, Inc. The
old mount looked OK but installing a new mount is cheap insurance. We also re-installed the exhaust mounts. |
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20: Here is our transmission ready for installation and a
road test. This Kit also allows for
adjustments after it is installed. The
firmness can be altered by changing the springs in the valve body accumulator
valve and enlarging the holes in the he separator plate. Additional gaskets are supplied just for this
purpose. The Kit allows you to adjust
the shifts to suit your driving style.
The perfect Kit for Shifty Business. |
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SHIFTY BUSINESS:
INSTALLING A TRANSGO TURBO 400 SHIFT KIT
SOURCE:
Zip Products, Inc.
8067 Fast Lane
Mechanicsville, VA 23111
(800) 962-9632
PARTS LIST:
The Author would like to thank Richard Gaudio of Greg Donahue Collector Car Restorations, Inc. for his
assistance with this article.
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