Automatic Transmission Factory (ATF) customer Steve Hines wanted more from his 2004 GT.  There was a lot of performance waiting to be unlocked from within the transmission and torque converter.  ATF has the keys.  Steve's Mustang pulled into ATF's shop with 60K miles on the clock and the engine and transmission were in good working condition.  On the power side of the pony, Steve's '04 GT has a JLT cold air intake, an Accufab plenum and throttle body, a UPR x-pipe, a Flowmaster catback exhaust and a set of 3.90:1 gears that deliver the final drive to Nitto 555 tires.  The suspension mods include Tokico Illumina adjustable struts and shocks, lowering springs from Ford Racing, and a set of UPR upper and lower control arms.  Steve's 4R70W transmission was in good condition and did not require a full rebuild.  This was the perfect time to add some eye opening upgrades to wake up the 4R70W's lazy factory set shifting and the lack luster stock torque converter.  Steve opted for a custom triple disc, 2,800 RPM stall torque converter and a custom ATF performance 4R70W valve body.  The one-two punch of the new high performance torque converter and the ATF performance valve body will surely give Steve's pony a lot more giddy-up! 

2004 Mustang GT / 4R70W automatic transmission.

Torque converter.

The torque converter of choice is this custom ATF spec unit from Precision Industries.  There's a lot of performance under that purple paint.  This bullet proof torque converter features a billet front cover, 3 internal clutch discs ("triple disc") and a 2,800 RPM stall speed.  It's capable of harnessing 1,000+ horsepower and Steve's 2004 GT will "grow into it" even more as he continues to push the performance of his Mustang with future engine upgrades and a power adder. 

The transmission side...

The engine side...

Transmission removal.

Steve's 2004 GT before ATF began the upgrades.

Note the position of the driveshaft prior to removal.  The yellow paint markings indicate the proper location of the driveshaft in relation to the pinion gear. This must be reassembled in the same position to avoid potential drivetrain vibrations.

After removing the exhaust, driveshaft, transmission crossmember and the starter, ATF removed the transmission pan and drained the fluid.

The pan was put back on to contain the dripping fluid while the transmission was removed.

The 4R70W is an electronically controlled transmission with multiple sensors that are connected to the vehicle with a wiring harness.  The shifter cable and electrical harness were carefully unplugged and removed from the transmission.  

The left side of the 4R70W houses the shift lever and various sensors that operate the transmission.

The right side of the 4R70W transmission is where the transmission cooler lines and dip stick tube are attached.

From the front we can see the stock torque converter and it's four welded studs.  These four studs attach the torque converter to the engine's flexplate.

Here's a view of the flexplate, the shifter, etc...

Disassembly.

With the transmission out of the Mustang, it was moved to the tear down bench for disassembly.

The stock torque converter was removed and set aside.

Then the transmission was repositioned for access to the pan which was removed and thoroughly cleaned.

ATF removed the internal electrical harness and other components to get to the valve body.

All of the internal parts that ATF removed were carefully cleaned, inspected and set aside for reassembly.

The valve body was removed...

Here's a fast forwarded clip of Dave removing the 4R70W valve body...

The stock 2-3 accumulator piston is on the left. The ATF 2-3 accumulator piston, on the right, is superior in form and function. This upgrade makes the 2-3 shift faster and firmer.

The valve body.

The valve body controls when and how the transmission shifts.  The transmission's critical "line pressure" is also set within the valve body.  As you can see, the fluid circuits are a complex maze that force transmission fluid to and from solenoids, valves, pistons, check balls and metered openings to make the transmission function.  This vital component can "make or brake" the performance of your vehicle.  ATF highly recommends our qualified and experienced professional services for modifying, servicing and testing valve bodies and their related parts. 

Jason Gatlin, the owner of ATF, prepared the valve body for it's new upgrades by placing it into the hot parts washer...

...after the cleaning cycle was completed, Jason thoroughly dried and inspected the valve body.

ATF modifies and upgrades valve bodies to our proprietary specifications.  They are professionally adjusted and assembled using the best parts, the best tools and the knowledge of over 20 years of experience.  Then ATF bench tests them in our VBT 4000 valve body dyno to ensure perfect performance.

Here we can see the valve body being assembled after receiving custom upgrades based on a combination of the vehicle's intended use and the vehicle owner's desired performance.  Every detail of ATF's valve bodies are gone through to ensure many years of trouble free performance.

All fasteners are final torqued to spec.

The valve body dyno.

ATF's state-of-the-art valve body dyno tests all of the functions, pressures and shifts of the valve body and valve body's electronic solenoids. 

Here Jason is installing the freshly modified valve body on the valve body dyno's test plate.  This is a specially customized valve body dyno test plate that Jason made by cutting a donor 4R70W transmission into pieces.  

Then Jason put the assembly into the valve body dyno and attached the fluid lines and the electrical test leads.

Transmission fluid shoots out of the valve body under high pressure as the valve body dyno thoroughly tests it.  Jason monitors all functions of the valve body making certain that it performs properly on the dyno. 

Here we can observe the valve body as it is being put through it's paces inside the valve body dyno.

The valve body dyno results were in... all pressures and functions tested perfectly.  Jason then removed the valve body from the testing plate.

The ATF performance 4R70W valve body is ready to be installed!

At this point, ATF replaced the front seal and output shaft seal.  Additional sealer was applied to the front seal and the output shaft seal to ensure leak free operation. 

New front seal...

New output shaft seal...

Installing the new torque converter.

ATF carefully installs the new torque converter to avoid damaging the front seal.  Proper engagement of the converter to the splines on the input shaft is very important.  ATF double checks that the converter is properly installed by rotating it and feeling it line up into the transmission.

The new torque converter (installed, right) next to the stock converter.  Notice that the new converter bolts to the engine's flexplate.  This method of fastening the converter to the flexplate gives the front cover more strength and reliability.  The stock converter's studs can cause cracks where they are welded onto the front cover causing leaks and failure.

Strength is actually a side benefit of the new converter.  The real trick part about this converter is that it helps to multiply the engine's torque output.  Also, the higher stall speed allows the engine to rev up into it's powerband. For example, on a five speed manual equipped vehicle, it's the equivalent of holding the clutch pedal to the floor while applying the accelerator pedal to get the RPM's up, then releasing the clutch pedal.  A properly spec'd and built torque converter makes all the difference in the world for an automatic transmission equipped vehicle.  Call the pro's at ATF to get the the proper torque converter for your application.

Transmission installation.

While Jason was modifying the valve body, his ATF technicians were busy installing the transmission.

The transmission pan was then removed to install the ATF performance 4R70W valve body.

The valve body was installed...

...followed by a new transmission filter...

...and the transmission pan.

The Mustang was lowered to the ground, filled with fresh automatic transmission fluid and fired up.  After the transmission fluid was properly topped off, we took the Mustang out for a test drive.  We know that Steve will be happy with the results!  ...and the improved performance will surely speak for itself at the drag strip.

Conclusion.

In it's stock form, the 4R70W isn't set up for firm, positive shifting.  Likewise, the stock torque converter holds back a lot of the engine's performance capability.  After the installation was completed, we noticed an immediate improvement in up and down shifting, shift firmness and "seat of the pants" power.  The ATF triple disc converter and performance valve body were just what the doctor ordered for this Mustang.  They worked together to get the RPM's up into the engine's powerband giving the Mustang much better responsiveness.  The instant down shifts at wide open throttle are also a welcomed advantage.  All of this was achieved while maintaining acceptable street manners, relatively smooth part throttle shifting and good around town performance. Additional tuning of the 4R70W's electronic controls will bring more performance benefit aswell.

This Mustang has clocked a best quarter mile time of 13.59 @ 102 MPH on regular street tires before the transmission modifications by ATF.  Steve will revisit the drag strip soon to update us with his Mustang's new performance numbers. ATF looks forward to updating this article with Steve's new best times at the drag strip. (Note that this article is intended for informative purposes only.  ATF specifically omitted some steps of this installation to protect proprietary parts and techniques.  ATF assumes no responsibility for the completeness of this article or its contents.  Do not try this at home.  Obey all traffic laws and posted speed limits.  And of course, bring your vechicle to ATF and have it done right!)

ATF provides these services and more for any domestic or foreign car, truck, van or SUV.  From street to all out race, all automatic and manual transmissions are welcome!

Automatic Transmission Factory: Make The Shift, You'll Be Converted!