Articles
Muscle Mustangs & Fast Fords Holy Shift (Transgo shift kit)

by John Hunkins
photography by the author

HOLY SHIFT! Drop two-tenths off your AODE Mustang with a TransGo shift kit and you'll have to watch what you say

When it comes to beefing up Project cars, we pretty much shoot from the hip and hope for the best. if it doesn't work the way we want it to, we go back to the drawing board and chalk it up to experience. But when the boss hands you the keys to his '95 GT convertible and says, "Punch up the performance a bit. Oh, and by the way, screw this up and there's a nice spot for you in the mail room," then you resort to tried-and-true no-brainers.

One of these no-brainers is the AODE valve body shift kit from TransGo. Ford's AOD and AODE transmissions have not had the best performance reputation over the years. Sloppy shifts, poor durability and barely adequate, torque capacity have hindered the performance and reliability of Ford performance vehicles equipped with the AOD family.

Are the AOD and AODE transmissions inherently weak? Absolutely not. Virtually all of the problems associated with them stem from not having enough line pressure to hold the bands and clutches and from compromising gear overlap. Both of these problems can be partly or mostly cured with relatively simple valve body modifications. Let's talk about each one individually.

The labyrinth incorporated into valve body design is ostensibly to provide a fluid circuit to hold the trans in gear. The pressure in an active circuit provides the holding force for both clutches and bands. Not enough pressure and there is slippage, too much and there are leaks. Since the AOD and AODE transmissions have been calibrated on the low-pressure end of the spectrum for such things as smooth shift quality, the tendency in even mild performance applications is to slip, causing burnt clutches and bands. The TransGo kit increases line pressure without major transmission repairs, improving performance and longevity.

The AOD and AODE transmissions are unusual compared with their GM counterparts in that they are non-synchronous units. Specifically, gear changes must be orchestrated to reduce clutch or band apply pressure to the gear being disengaged, while pressure must be increased to the gear being engaged. This complex dance of rising and falling pressures occurs within the valve body fluid circuits and influences performance and shift quality to a tremendous degree.

To understand the importance of this concept, imagine this: You're accelerating briskly and approaching the point where the transmission will shift from Second to Third. As the threshold of the shift approaches, the transmission is reducing the pressure to disengage the intermediate clutch pack. At the same time the valve body is applying pressure gradually to the direct clutch. In effect, these two clutches are overlapping. This gradual cross-gear slippage ensures that no little old ladies will spill them Geritol and that no back seat diamond cutters will miss their mark on that five-carat Marquis.

But this smooth shift is silently killing the clutches in your AOD or AODE, not to mention throwing performance out the window needlessly (When the clutches are engaged simultaneously the difference in speed generates tremendous heat as the two fight each other) The TransGo kit however makes gear changes effortlessly like passing the baton in the 1,000-meter relay.

The TransGo shift occurs quickly as the overlap time between gears is reduced dramatically. This quarter-mile performance improves while clutch life is lengthened.

But there is yet a third reason for buying a TransGo Shift kit, and that's the unique Gear Command feature. Unlike the factory valve body calibration, the TransGo kit allows the user to hold the trans in any gear for as long as needed, and it won't result in smoked clutches. Usually, when manual shifts are performed, the default line pressure for manual shift operation is way too low for holding the clutches and bands. The TransGo kit increases line pressure when manually shifted to save those friction surfaces. Now you can shift in confidence!

Before installing our TransGo AODE kit in the boss's car, we took his steed down to Raceway Park in Englishtown, N.J., to baseline it stock. We made two passes with the selector lever in 'D' and the ignition was a stock 10 degrees. Next, we bumped the timing up to 14 degrees, cooled the engine down and ran two more passes. The results were as follows:

ET MPH Notes

15.97 88.42 lever in "D"
15.94 88.50 same
15.74 89.56 timing at 14 degree, lever in "D"
15.74 89.53 same

Next we brought the car to Level 10 Performance in Hamburg, N.J., to install the TransGo Shift Kit. The installation took about six hours but also included lots of time-outs for photographs and note-taking. In real-world terms, the installation should take about four hours, including ample time for road testing.

At this point we should mention that the TransGo AODE kit comes with an indispensable 40-minute videotape that details every step of the kit's installation, from how to test the car before and after, to tool requirements and time-saving tricks. We've seen a lot of good shift kits, but what really sets this one apart from the rest is the video tape. For the first-time installer, the video tape will make the difference between frustrated rage and laying rubber before dinner.

Installation first consisted of removing the trans pan and filter (with fluid). The valve body was removed after disconnecting several solenoids and switches attached to the valve body. On the repair bench the separator plate was removed, and several holes were drilled with the bits provided in the kit. The valve body was modified next by drilling two holes in the electronic pressure control circuit (EPC) and installing an external EPC relief valve. Next a new 1-2 valve, spacer ball and spring were installed in the 1-2 circuit. The pressure regulator valve received an upgraded spring, and the 3-4 capacity valve received new springs as well. The final valve body mod was a new manual control valve. Note that the factory Duratech valve body gasket is .040 inch thick and is very compressible. When disassembling the valve body, make sure that you do not tear this thick gasket. If you do, you will have to install a new one, which will require the valve body bolts be retorqued within two weeks (or severe damage could result as the bolts lose torque).


When you remove your metric AODE pan the first time, you'll find this little thingy floating around inside. (The video doesn't mention anything about it) Don't worry; it's a plug used during factory assembly that pops into the pan the first time the dipstick is inserted. Remove it from the pan and continue.

The video recommends deburring each hole by hand with a large drill bit. We opted for a light honing stone on each side. Either way is acceptable as long as there are no burrs.
We removed the pan and filter; disconnected the EPC solenoid and thermistor, and modulated computer converter control prior to removing the valve body.
Once the valve body is removed from the trans, the separator plate must be removed from the valve body (shown). Holes must be drilled in certain locations with the supplied drill bits. Note: Some holes will be drilled different sizes depending on the firmness of shifts desired. Make sure you know exactly what you want before drilling because you won't get a chance to do it over. (The level of shift firmness is one area the video isn't too specific about.)
We circled each hole to be drilled so that we wouldn't mistakenly drill the wrong one. We highly recommend this procedure.
Two holes need to be drilled in the valve body partition for EPC relief. Make sure all shavings are cleaned out afterward. (The video will remind you to keep everything clean throughout the tape.)
The valve body was reassembled at this point and set aside. A new set of second gear accumulator springs and a spacer were installed in the trans, as well as a new set of third gear accumulator springs. Both were swapped just prior to reinstalling the valve body. After installing the accumulator springs and valve body, the pan was bolted back on, and the trans was filled with fresh fluid. A quick road test afterward revealed much crisper shifts, but was there any real improvement in performance? For that we would have to go back to E-Town to find out.

The 80-mile drive to the track was informative. Our test drive at Level 10 clued us to the fact that the TransGo kit had fangs, but we were concerned that the boss might object to any perceived harshness. Since we had carefully chosen to drill the separator plate holes for the "street showoff" calibration and not for "full race," shifting in normal traffic at modest throttle produced smooth but authoritative shifts, just perfect for our needs (and the boss', too).

At the track, we cooled the engine and left the timing at the same 14 degrees. We left the selector lever in "D" and made three runs as follows:

ET MPH
15.56 90.37
15.66 90.02
15.51 90.54

If we compare the best result from each test session, we get a twenty-three-hundredths improvement, or almost a quarter-second (not to mention a full mph). If the engine had been modified for better breathing, we might have gained even more by using the manual shift Gear Command. As it was, the stock engine was running out of steam at the 5100-rpm shift point so nothing would have been gained by shifting manually.

This photo outlines the rest of the modifications performed on the valve body:

  1. replace the pressure regulator spring with the white one provided;
  2. replace the 1-2 shift valve with the new one & add a small red spring & ball bearing;
  3. replace the manual valve with the new unit;
  4. replace the stock 3-4 capacity valve springs with the new white and blue pieces;
  5. when reinstalling the check balls in the valve body, leave this one out.
When reattaching these three plates on the separator plate, make sure that the notches face up in the same direction as they did originally. The video recommends etching a reference groove in the plate before removing them.
Install the new second gear accumulator springs like this. Don't forget that the spacer goes on the end with the deepest cavity (which could be either end depending on the transmission). Note: A snap ring tool is required to complete this operation. The third gear accumulator springs are last and will have to be completely pushed into the tranny by snugging the valve body up. Go slow when mounting the valve body. You'll have to check that the accumulator valve and springs are not binding between the tranny and the valve body. The video outlines a really easy way to do this, using a long bolt first and then installing two shorter bolts on either side.

We wanted to install the EPC relief valve until after the valve body was installed in the tranny. (The video and instruction manual recommended doing it with the valve body off, but we felt the possibility of damage to it would be reduced if we waited.) Don't forget to pull the cotter pin out after the bracket is attached. Install the filter and pan, and fill the tranny with fluid (5 to 8 quarts is about right for a tranny/converter-in-car installation.)
So is it worth it for the average '94-95 AODE Mustang owners We'll let you decide, but consider this: The AODE kit costs only $138.78 and increases performance by almost a quarter-second. The fact that it is probably the only shift kit on the market that stands a reasonable chance of being installed correctly at home by a first timer (remember the video?) makes it an outstanding value. But the most indisputable proof of the TransGo kit's performance is that this author has yet to be assigned to the mail room.

SOURCES

Level 10 Performance
188 Rt. 94
Hamburg, NJ 07419
201/827-0900

TransGo Performance
2621 Merced Ave.
El Monte, CA 91733-1997
(818) 443-4953
AOD and AODE Shift Kits