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T5 to 4R70W swap

Ouch! 130k miles and a bunch of 11 second passes

My car was originally equipped with a T5 manual transmission. It was fine for 130,000 miles, but after one too many runs with 450# of rear wheel torque, it finally destroyed third gear while I was making a pass.

My Choices
I decided to go with an automatic transmission. I had a few choices: a C4, a built AOD and a 4R70W. With the C4, I would give up overdrive and would have to use a non-lockup converter (a C5 would have a lockup, but no OD). A built AOD is expensive, to get one that would take all the power I was delivering, it would be a bit more than I wanted to spend. I decided to go with a 4R70W.

The latest Ford 4R70Ws can take 700 RWHP with a few basic mods. The 4R70Ws originally came on a lot of vehicles, but the best were the '99 and up Mustangs. The 4.6 Mustang tranny won't bolt up to a 5.0. However a V6 automatic transmission will bolt right up. The '99 and up V6 Mustang trannies are very strong and with a few simple valve body mods would be up to the task.

CCS Solenoid

Using a '99 V6 4R70W

To use a '99 and up V6 Mustang 4R70W, you have to change a few things. First you need to swap out the tailhousing and substitute a '94-95 Mustang tailhousing, the '99 tailhousing is a larger diameter. The other thing you have to do is to use a '94-95 Mustang clutch converter solenoid (CCS). The CCS on a '99 is a different impedance and will fry your EEC if you use it. It pops right out with one or two bolts. The problem is a '95 solenoid uses a different style connector, to use a '95 solenoid, you have to cut the plastic skirt from around where the wire connector is located. It's no big deal to do this, and once you do it, you can snap the '99 style connector right on. You also have to move some of the wires around as the wiring arrangement is different on 95's and '99s'. TCCOA has an excellent article on rewiring for later VBs.

99 Style 1 piece solid connector

What I did

I finally decided to get an AODE rebuilt to 4R70W specs with all 4R70W internal parts. Unfortunately, once I got it all back together, I found it was hitting the limiter on the 2-3 shift. I tried a manual valve body, but I did not like it on the street and it fried my OD band. The valve body had the J-mod from http://www.tccoa.com Doing this got the shift points closer, but it still wasn't right. It took an obscure bit of EEC tuning to get it fixed. Apparently, Ford has seen fit to add a bit of code in the computers that causes the transmission to wait 3 seconds after the 1-2 shift before it does the 2-3 shift. Lowering this made it work.

The Valve Body

Valve Body

Initially, my transmission had a '95 Mustang transmission with '99 Mustang 4R70W internals, including a '99 valve body. I modified the valve body according to the instructions provided at TCCOA it's pretty simple, it involves drilling a few holes in the separator plate and gasket.

EPC Solenoid

Internal Wiring

I decided to use a '95 style wire connector, rather than the '99 style all in one connector. I did this because the transmission already had the '95 connector on it and had a '95 style Pressure Solenoid (EPC) on it. I had to obtain a '95 CCS and a TOT sensor.

The TOT sensor is the transmission temperature sensor that just snaps onto a hole in the valve body. On a '99 valve body the TOT sensor is incorporated in the plastic connector-a separate sensor is not used. Remember, you can use either style connector as long as you use a '95 CCS and modify the skirt. Also doing it this way I could keep the stock harness and not have to move the wires around.

Shifter Mounting


Believe it or not, Ford used a different tunnel configuration for manual and automatic cars. The T5 tunnel has a 'cap' welded on it to place the shifter higher. If you use a stock shifter with the automatic, something I was going to do, without modifying the tunnel, the shifter would be way too high. I could have cut away the cap and made a lower one, I could have used an aftermarket shifter-something I didn't want to do, or I could have just left it looking too high. I studied it for a while and decided to mount the shifter from underneath the car.

To do this, I had to cut a small amount of metal from the top of the opening in the interior, so the top of the shifter could be threaded into the interior from underneath. I also had to cut away a small lip from underneath and used a ball peen hammer to dent an area for the shift cable bracket. I then made two rectangular heavy steel sheet metal plates and fastened them from above (in the interior) with rivets to the tunnel. With two people positioning it, I established where the mounting holes should be and drilled them into the plates. I fastened it down with four 3/8" bolts and locknuts.

EEC/Controlling the Transmission

With a 4R70W you need some way to control the transmission electronically or go to a full manual valve body.

Since I obtained an '95 AODE EEC (W4H0) and reburned my chip to control the transmission. Converter lockup and shift points were modified. Getting shift points perfect took some on-road driving, since this cannot be done on the dyno.


With a car producing the kind of power I generate, there is only one converter that will work. It's very expensive, but there is no other choice, plus, it is the best converter available. It is a Precision Industries multi disk lockup converter. I decided on a 3000 RPM stall for it after talking to PI. I got the best price from Houston Performance.

Cooler and fans

Cooler Lines


The death of most transmission results from overheating. I wanted to be sure my transmission would live a long life. Additionally, with the 3000 stall multi disk converter, there would be a lot more heat generated.

Since my car was originally a T5 car and it had a manual Fluidyne radiator, I had to fab up my own custom cooling system. I decided to get a B & M plated style cooler. I opted for the 28,000 GVW 'race' cooler from Jegs (130-70266). I also decided to add a fan to it, so I also got an 8" Perma Cool electric fan (771-19128) from Jegs. You can buy the B & M cooler with a fan already on it, but it's much cheaper this way. I mounted the fan on the cooler with aluminum "L" channel.

The cooler is mounted in front of the radiator. The fan is controlled manually with a lit rocker switch in the ashtray. It is wired with a 30 amp Radio Shack relay and a 30 amp slow blow fuse. The cooler comes with 1/2" NPT female inlets/outlets. I used NPT reducers and 5/16" hose end barb fittings. I used a few brass 1/4" NPT fittings in the transmission, terminating into 5/16" hose end barb fittings. For lines, I planned to use all flexible stainless steel lines, but they would be too expensive. I decided to go with 5/16" fuel line, protected by 3/4" ThermoFlex insulating outer lines (Jegs 893-17075).

Don't use the old flywheel bolts! They are not the same!

Putting it together

After the T5 was out, I pulled the clutch pressure plate and flywheel off. Be sure to remove the pilot bearing too. You'll need a puller to do that - Autozone lends them out for free. I mounted the flexplate, using new ARP bolts - don't use flywheel bolts, they are a different length. Be sure to use teflon thread sealer on these bolts. Using a flywheel holding tool really helps. Torque the flexplate bolts in an 'across' pattern in two stages at a final torque of 75-85#. I got a transmission jack from Harbor Freight - it sure made the job easier. With the tranny on the jack, under the car, we installed the converter after first adding 1/2 quart of Mercon V fluid to it. When you are installing the converter, be sure you hear three distinct 'clunks' when you put it on.

We jacked the transmission up and bolted it to the engine. Again, the bolts are a different length than the T5-we used Grade 8 bolts from Tractor Supply Store. You might want to use an older AOD-E pan to jack it up-because it is flat-the newer pans have a raised area on them-for more capacity. Once it was bolted on, we added the driveshaft-I use a FRPP aluminum shaft which is supposed to be the right length for either a T5 or AODE, but in my opinion, I'd like to see a bit more of the driveshaft engaged in the tranny, so I have added a 5/8" DS spacer from UPR Products.

We also had to modify the crossmember mounting holes. We drilled holes, on a drill press about 1" away from the existing holes and also had to cut off part of a leg of one of the crossmember brackets on the band saw. I later found out, we could have just swapped the crossmember end to end and it would have fit. We also installed the automatic pedals, the shift linkage, the dipstick, the filter and the pan. To fill it, it should take about 8-10 quarts of Mercon V.

We aligned the marks on the shift indicator sensor that mounts on the side of the tranny, with the transmission in neutral. Oh, and be sure to use the supplied bolts to secure the torque converter to the flexplate. You'll also need to override the clutch safety switch.

We had one thing fool us during the install-The OD light would not come on at all. I assumed that the wiring harness is all there and we hooked everything up correctly. We did, except one component was missing - a transmission control switch module (TSCM). It is needed for proper operation of the OD switch and light. It is normally located behind the glove box under the dash. On 5 speed cars, the connector is there for it, but no TSCM. We found out that they were used only on '94-'95 AOD-E cars and the worst part is they are no longer offered by Ford. Maybe a few dealers still have them (F4ZF-7E453-AA), but it's doubtful. We got ours at a junkyard for $10.

Another note: we decided to switch to all steel cooler lines as it turned out the exhaust pipe was too close to the rubber lines-we used steel brake lines and a pipe bender. The fitting that goes into the tranny is 1/2" NPT-you actually use a NPT to flare adapter for that. The steel line gets a DOUBLE flare, not a single flare.

We added about 8-9 quarts of Mercon V to the tranny and started it for the first time going through the gears with the wheels in the air. We then rechecked fluid and kept adding, then going through the gears again until it was full. It took about 10-11 quarts to fill it completely.

The Driveshaft needs a spacer to work correctly

The TCS box that you need


LaSota Racing Takes no responsibility for any damage done to your vehicle by attempting this swap. This article is to simply help you do the conversion, it is expected that you have basic mechanical and electrical skills and understanding of Ford systems.

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