AOD to T-5 Conversion
Thanks 173speed for this write up!
AOD to T-5 conversion
Automatics are boring. Let's face it, stabbing the clutch and shifting the gears is the essence of performance driving. Automatic transmissions certainly have their benefits, and we enjoyed ours thoroughly, and were impressed with how it responded to minor modifications such as a shift kit and higher stall converter. However, as we had always planned from the moment we bought the '88 LX, the time has come for the AOD tobe replaced with a T5 manual.
We performed the swap for several reasons including the fun factor. We wanted a performance gain, not only from better gearing in the T5, but also due to the less parasitic loss, not to mention the weight loss. An AOD is roughly 40lbs heavier than the T5. Furthermore we hope the T5 will result in better fuel economy, due to the lower overdrive rpms as a result of the lower gear ratio and by eliminating the slippage of the non-lockup converter.
Performing a T5 swap in a late-model Mustang is very easy. In order to reduce assembly line costs, Ford setup the FOX platform to accept either the AOD or the T5 with minimal parts differences or chassis modifications. The starter, driveshaft, crossmember, transmission mount and speedo-cable are all interchangeable.
Other than acquiring the T5 itself, the pedal assembly, the clutch parts, and the console plate and boot, there is not much else that is needed, other than a spare weekend to perform the job. It is important to mention that T5 cars used a different EEC-IV processor than AOD cars. It is not necessary to change to a manual processor. In fact, it is recommended that you don't because the manual processor requires a wiring harness that is not found in the automatic cars. Without this harness the manual computer cannot complete the self-tests, meaning you can't "pull" diagnostic trouble codes. If you simply leave the automatic processor in place, the self-tests and codes will function properly.
The actual swap is fairly simple to perform, and will take anywhere from 10-16 hours, depending on your experience and how many friends show up to give you a hand. We actually installed the pedal assembly months before we installed the T5, just to get a head start. Believe it or not, the pedal assembly is probably the most difficult part of the entire swap! It took about three hours to complete, including rerouting the speedo cable, which on automatic cars is routed through the clutch cable hole. The rest of the swap consists of removing the AOD and associated parts, and then essentially performing a clutch job and installing the T5.
Finding all the parts is not all that tough either. We got lucky and found someone parting out a low-mileage 1992 Mustang in the local classified. We struck a deal on all the T5 parts, including the transmission for $500.
Perhaps the most sought-after parts are the console cover, rubber insulator, and leather boot. We were fortunate that the donor car had these intact and in great shape. When taking the pedal assembly, be sure to get all the switches mounted on it. Take every little piece of hardware you can, since many of the small parts are Ford pieces that are not sold anymore, or are very expensive.
Removing the AOD pedal assembly and installing the T5 pedal assembly is trial of your patience. Not only are you working in a dark and confined space, but the pedal bracket is wedged up in under the dash. We found the easiest way is to create as much working space as possible. Remove the drivers seat, unless you like being a contortionist. Secondly, take our advice and drop the steering column down. We know it sounds like a lot of work, but the ten minutes it takes to drop the column will save over an hour of wrestling with the pedal assembly.Finally, if you haven't done so yet, purchase a aftermarket clutch cable quadrant, the stock plastic one is junk. We highly recommend the Fortes unit as shown here. The billet aluminum construction will last forever, and the large firewall adjuster makes adjusting the cable tension a breeze.Fortes Quadrant with Firewall Adjuster
1. Here is the T5 pedal assembly we pulled from the donor car. You cannot install the clutch pedal on the automatic pedal assembly. 2. On the lefthand side of pedal assembly are the neutral saftey and clutch interlock switches. Make sure you get these when pulling pedals from a donor car. 3. On the right side of the pedal assembly is the cruise control switch, which disengages the cruise when the clutch is pressed. Also notice the stock plastic clutch cable quadrant.
4. Now is a good time to install the new quadrant on the pedal assembly. Remove the two hair-pin clips and slide off the stock plastic quadrant, adjuster and spring. 5. The supplied white bushing goes on first, then the quadrant. Secure it with the stock hairpin clip. The front of the quadrant should rest on the stop as shown. 6. On AOD Mustangs, the factory routes the speedo cable through the clutch cable hole. The highlighted area is where the speedo needs to be relocated to.
7. To re-route the speedo cable, the gauge cluster needs to be removed. Remove the dash cover and disconnect the switch plugs to access the half-dozen torx screws that secure the gauge. 8. Squeeze the white clip on the speedo cable and pull the cable off the gauge. Now the cable can be pulled through the firewall and rerouted through hole shown in pic.6. Reattach the cable and reassemble the dash 9. Remove the two nuts that hold the steering column bracket, and let the steering column hang down as low as possible. You'll want to remove the harnesses that plug into the column to avoid straining the wires. Remove the upper pedal bracket bolt shown in the highlighted region in the photo.
10. Four 9/16" nuts hold the pedal bracket to the firewall, you can access all but one with a ratchet. Be sure to disconnect the master cylinder push rod from the brake pedal, it's held in place with a hair-pin clip. 11. The top left pedal bracket nut cannot be reached from underneath. Take our word for it, otherwise you'll spend an hour swearing and cussing. The way to get to it is with a super long 3/8" extension, reaching through the dash as shown. 12. If you're lucky the pedal will come out without any of your blood on it. Otherwise, expect to wrestle with it for a while, eventually it will work its way out from the tangle of wires and brackets under the dash. Take a breather, because the new clutch pedal assembly goes in the same way
13. With the pedals in place, the hardest part of the swap is behind you!Before you climb out from under the dash, find the two plugs shown in the highlighted region in the photo. On AOD cars they are jumpered and taped up as part of the large bundle of wires near the drivers side vent. 14. Remove the jumpers and attach the plugs into the switch on the clutch pedal. Note, the two plugs look similar, but they are not, each one will fit a unique position on the switch as shown. Once they are plugged in, grab the white serrated plastic rod and pull the square adjuster (arrow) as far up as it will go, you'll feel it ratchet up. You can see this rod better in pic.2. 15. On AOD cars, behind the stereo and console you'll find a plug with a green jumper wire. This is the cruise control disengage circuit. If you have cruise, you'll want it to disengage when the clutch pedal is pressed. Remove the jumper and attach to the switch shown in pic.3.
16. Remove the rubber bushing that is included with the stock cable, and use a razor blade to cut off the four plastic tabs at the end of the firewall bushing. 17. Place bead of RTV around the lip of the adjuster and place it through the firewall until the lip seats squarely. Then feed the cable through and seat the plastic cable bushing into the aluminum adjuster. From under the dash, attach the cable to the hook on the quadrant. 18. The new replacement cable comes with a bracket which attaches to the factory mounting point above the motor mount and k-member. We had to bend our mount slightly to keep the cable from touching the headers.
Removing the AOD and installing the T5 is very straight forward. If you are not working on a lift, you'll want the car jacked up as high as possible on jackstands at all corners. This should allow enough room for AOD to be pulled out from under the car. We recommend you drain the AOD before taking it down, otherwise you'll be in for a huge mess when you remove the converter.Of course you'll need to remove the driveshaft and starter, both of which will be reused with the T5. Disconnect the cooler lines, after the case is drained! (The lines have to be cut to remove them completely from the car.) Finally remove the speedometer cable and gear, the throttle and TV cables, and the electrical connector. The bellhousing bolts are hard to get to, we found that using a long (24") 3/8" extension and a wobbler socket attachment made it a breeze, especially reaching the two bolts at the top of the bellhousing. The T5 goes in just as if you were doing a clutch job. We used a stock flywheel and had it resurfaced to ensure trouble free operation with our SPEC clutch. Be sure to connect the electrical connectors outlined below and don't be alarmed if your car doesn't start after the swap, you probably did not connect the neutral saftey switch connections correctly. Double check the connections at the pedal and at the transmission. Many times the plastic rod on the pedal switch is not adjusted properly, so double check it and adjust as outlined below. If the engine still does not start, remove the two connectors at the pedal and re-install the jumper wires. This will bypass the saftey mechanisms and the engine should start. (Be sure the shifter is in neutral and your foot is on the brake before you turn the key!) It is possible your pedal switch is bad, you can purchase a new one from Ford. Make sure you've got fluid in the T5 case before you take the car for a test drive. Check for any unusual vibration or poor clutch operation. Our clutch engagement was a bit low at first, but using the Fortes firewall adjuster we easily adjusted the cable tension until the clutch engaged about half-way up off the floor. After a couple weeks of driving the T5 car, we're absolutely thrilled with the conversion. The SPEC clutch is incredibly smooth. You can lug the car at idle with your foot off the throttle, in first or second gear, and the clutch will not chatter or stall the engine out. The car is a blast to drive and acceleration had improved dramatically. G-Tech numbers show a increase in the 1/4-mile trap speed from 107 mph (AOD) to 111 mph after! (Keep in mind the G-Tech measures true mph at the end of the 1/4-mile, whereas at the dragstrip the speed is an average over a distance at the end of the track.) We'll take the car to the strip in the next couple weeks to see how much we improve over the best of 13.59 @ 102 with the AOD. F/M
1. Removing the AOD is simply a matter of disconnecting everything that's attached to it. Be sure to remove the four converter bolts or nuts. Wedge a screwdriver between one of the slots in the flywheel and the block plate to keep the converter from turning as you loosen the bolts. 2. When all the cables and fluid lines are disconnected and the bellhousing bolts are removed, the AOD can be lowered down. It's heavy, so keep it level! 3. With the AOD out of the way, remove the flexplate and blockplate. We'll reuse the flexplate bolts for the manual flywheel.
4. No job is complete without using the trusty 4" grinder at least once!We found that the lower AOD shift plate would not fit through the shifter opening. Since we weren't in the mood to spend and hour removing entire console, we simply cut the bracket so it could be bent and pulled out. 5. Here is the AOD shifter assembly that gave us trouble. The two halves were actually riveted together, so we had to drill the rivets out. The top half came right out, but the throttle cable bracket on the lower half made it impossible to remove. We cut the plate (arrow), which allowed us to bend it an yank it out. The plate can still be used with a little tack welding. 6. Be sure to install the pilot bearing! A little moly on the outside and a socket and hammer is all that is needed to tap it into place. Now is also a good time to replace the rear main seal for good measure.
7. The T5 dustplate goes on followed by the flywheel. We had the stock flywheel machined beforehand. Be sure to install the pressure plate locating dowels! We reused the AOD flywheel bolts. Use a dab of RTV on each and torque to 90 lb.ft. The clutch goes on next . Torque the pressure plate bolts to 25 lb.ft. 8. Install the new throwout bearing on the clutch fork, then bolt the bellhousing to the block. You'll need a few new bellhousing bolts, as some of the AOD bolts are too long and bottom out in the block. Take an AOD bolt to the hardware store and get four new grade 5 or 8 bolts, one-inch shorter. 9. The T5 is finally bolted to the bellhousing.( Be sure to have the correct metric T5 to bellhousing bolts beforehand! ) Your existing AOD crossmember and mount will work.
10. The T5 uses a shorter speedometer gear, available from Ford. Don't order the same tooth count however! Use this site to determine which gear you need. 11. There are two electrical connection to make on the T5. This harness contains the reverse lights and the neutral safety switch. The left end connects to the terminals on the T5 case, the other end connects to the harness hanging under the car -the same one the AOD connected too. 12. This harness that hangs off all T5 cases won't be used. On factory T5 cars it connects to a harness exiting under the floor pan, however this entire harness and circuit is not found on AOD cars. As we mentioned earlier, without this harness in place you cannot use the self test features when using a T5 processor.
13. Reinstall the driveshaft. Use Loctite red on the driveshaft bolts and torque to 90 lb.ft. Reinstall the starter, and fill the case with 2.5 quarts ATF. 14. We recommend using the stock rubber insulator, as it keeps noise and fumes out of the car.Only the two of the four holes line up, which was fine with us. You could drill the tunnel to attach the other two screws.Note the AOD shift position light harness - disconnect it. 15. Last but not least, attach the end of the cable to the clutch fork. Don't forget the retaining clip (arrow). There is also a cover (not shown) that seals up the fork and opening from moisture and dirt, you can see the black RTV outline for where it goes. Both are available from Ford if you don't find them used