By David Kennedy
Photography: David Kennedy and Jerrod Jones

The Ford Power Stroke is an awesome Engine, with the stock turbo and intercooler, these diesels make great power that should be more then enough for any 4x4. “Should be” are the keywords. For many of you, too much power is just enough, but unfortunately your Super Duty’s automatic transmission doesn’t see things the same way.

After we added a larger turbo, propane injections, and high-performance computer tuning, and mounted the 46’s on our F-250, the tranny was having hard time keeping up. If was as if the engine had all the power in the world to give, but only about two thirds of it was getting to the tires. We needed a solutions, and as we searched and researched all the rigs out there with built Power Strokes, we kept hearing about Brian’s Truck Shop in Lead hill, Arkansas. It turns out Brian’s upgrades for the Ford E4OD and 4R100 transmissions are legendary, and when we told owner Brian Thompson about our truck he said, “No Problem.”

“But what if we want to run 46-inch tires?” we asked. He simply said, “With this transmission goes to shift there is so much more clutch material compared to the stock setup that the transmission can’t slip.” At $3200, this kind of heavy-duty upgrade is not for the light-wallet wheelers out there, but it is the ultimate transmission for any Power Stroke Truck.
We thought about swapping the Brian's Truck Shop 4R1 00 into our 46-inch-tire-equipped Super Duty ourselves in the driveway, but pewe's got this "No dying till the magazine's written" rule that we can't break. Luckily for us, Frank Gilliland, owner of South Bay Truck & 4x4, is less than 20 minutes away and is well equipped for any type of 4x4 repair- including transmission swaps. To make the - exchange as easy as possible, Gilliland removed the transfer case first and then lowered the transmission with a jack. While the transmission was out he flushed the cooler
lines with carb cleaner and a compressed air chaser to remove any contaminants.
Plugging in the upgraded 4R100 was a simple remove-and-replace deal for South Bay Truck & 4x4. The original factory wiring plugged right into the new unit, and the transfer case was heaved into position and bolted back on. Notice how Gilliland modified his tranny jack with scraps of welded-on steel to secure the monster automatic-you don't want to drop one of these things!
Any time you replace an automatic transmission you're doing so because you smoked the last one. Usually it's because you over- heated the fluid from towing, engine upgrades, or running large tires. In our case it was all three. To protect our new transmission from fluid failure, we ordered the largest ATF cooler we could get from Flex-a-lite. This 32,OOO-pound-GVW unit (PN 45321) measures 1 O~x21 x1 ~ inches. We plan to fit it where the factory auxiliary cooler mounted and adapt the original Ford cooler lines to work with its female NPT fittings.

What's inside these trannies that makes them so strong? Well, unfortunately, it's proprietary information that Thompson isn't comfortable with us publishing. But it sounds like additional clutches are added to manage the torque without the need for increasing transmission line pressure above stock. Thompson did assure us that every one of the upgrades developed for his 4R100 and E40D comes from tearing down smoked trannies and strengthening whatever failed. Every transmission he builds is stronger than the last one because people are pushing the Power Stroke engine further (now well over 1,000 Ib-ft!) every day. We'll take his word for it because he backs these babies up with a two-year warranty-even in trucks like ours.

Muttidisc torque conver1ers are all the rage now. They increase the torque conver1er's clutch holding power by tripling the friction surface to almost 130 square inches. To prevent converter deformation and tearing the flexplate mounting bolts off the converter face, Brian's Truck Shop also sells a new (billet) converter with a shell that is machined from steel and welded onto the converter.