For Part 3 of our Serious 7.3L Upgrades series, we found ourselves beefing up our ’97 F-350’s automatic transmission. How long your E4OD (’94½ to ’97) or 4R100 (’99 to ’03) transmission lasts behind your modified 7.3L Power Stroke can vary depending on how hard you run the truck, which performance parts you’ve added, and the overall health of the unit to begin with. You might get by with Stage 1 or Stage 2 injectors and a slightly modified transmission (torque converter, valvebody) or even a stock transmission for a while if you’re easy on it. But sooner or later, you’ll be upgrading your ticking time bomb to a fully built, performance version capable of absorbing all the torque and horsepower you can throw at it.
| serious 7 3l Upgrades Part 3 e40d Transmission
Since we plan to make 450 rwhp with our Power Stroke’s Stage 3 hybrid injectors (“Hybrid Injectors, Head Studs, and Custom-Tailored Tuning,” May ’11), a transmission upgrade was in order for us. And while Flynn’s Shop performed our up-pipe replacement (“Power Stroke Up-Pipe Replacement,” June, ’11), we shipped our E4OD down to John Wood Automotive in Holtville, California, for a bulletproof transformation.
As a reputable transmission builder, Wood knows to add a little built-in insurance to his product. If the customer’s eventual goal is to make 500 hp, the unit should be good for 600 hp. This is done for two reasons: 1) so the transmission will last (and overbuilding is a great way to increase the lifespan of a transmission), and 2) a good builder knows all too well that the thirst for more horsepower never ends. Let’s face it, you may only want to make 500 hp right now, but what happens once you reach your goal? The thought of 550 hp enters your mind, and before you know it, you’re knocking on the door of 600 hp.
| Because the centersection on stock flexplates can crack due to torque, we replaced it with a 4340 billet-steel unit from Elite Diesel Engineering. Its flexplate is 29.3 SFI-approved, and since 7.3Ls are externally balanced, it has a counterbalance built into it. Elite’s flexplate retails for $650.
Here, we’ve laid out the key ingredients for one of Wood’s street performance transmissions with a 500hp long-term goal in mind, as well as what Wood does to ensure longevity and get maximum power to the ground. With a fortified E4OD now under the truck, we’ll be heading back to the dyno to see what kind of power the hybrids added to our equation. So stay tuned for Part 4 of our build, coming next month.
Street Performance Transmission Ingredients:
- TCS Performance triple-disc, 6.0L-based, billet torque converter
- 300M billet-steel input shaft
- Cryogenically treated intermediate shaft
- Cryogenically treated output shaft
- 4340 billet-steel Overdrive planetary
- Factory-specification BorgWarner clutch plates
- Custom-machined pressure plates
- Machined, re-surfaced pump with hardened pump gears, and a new boost valve sleeve (for torque converter lockup)
- Machined center support with tighter tolerances
- Hand-surfaced transmission case
- Reinforced factory Reverse hub (CNC-machined ring that’s TIG-welded to the bottom of the hub)
- Machined factory coast clutch drum for larger, retaining snap-ring
- Locking snap-ring outfitted on Overdrive piston during Overdrive and coast clutch assembly
- Forward drum plug replaced with a set screw
- Custom valvebody, using TransGo and Sonnax components
Price: $4,800
Warranty: Lifetime Labor Warranty; after initial, 3-year/50,000-mile warranty all internal labor is free
Billet Torque Converter
The billet torque converter found in John Wood Automotive’s street performance transmission is based on the triple-disc unit found behind the 6.0L Power Stroke. Designed by John Wood and built by TCS Performance, the entire converter is re-engineered using a large custom lock-up clutch and more damping springs, and all internals are furnace-brazed for utmost strength. It’s also a tighter converter than most transmission shops offer for the 7.3L; with a stall speed 200 rpm lower than the competition. The tighter converter helps get more power to the ground without locking the converter.
| serious 7 3l Upgrades Part 3 billet Torque Convertor
Valvebody Tuning
As mentioned in Part 1 of our series (“Hybrid Injectors, Head Studs, and Custom-Tailored Tuning” May ’11), Gearhead Automotive Performance handled our computer tuning. This means it not only dialed in our engine and injection system but also helped fine-tune the transmission. It’s extremely important that your transmission builder be in touch with your tuner. By knowing how much your tuner plans to ramp up line pressure electronically and how you want the transmission to shift, your builder will know how to set up the valvebody. For us, we prefer the smoothest shift possible, so Wood (shown) wasn’t as aggressive in building our valvebody as he could’ve been. This left the option of firming up our shift points up to our tuner. Instead of pulling the valvebody to firm up shifts, a simple chip re-burn makes the process easier should something need to be tweaked.
| serious 7 3l Upgrades Part 3 valvebody Tuning
