Deciding to tackle a 47re transmission rebuild is a big commitment, but for anyone running an older Dodge Ram, it's often the best way to keep that Cummins pulling. Let's be honest: these transmissions have a bit of a reputation. While the engine in front of them might last forever, the 47RE usually needs some serious attention somewhere between the 150,000 and 200,000-mile mark—or much sooner if you've turned up the power.
If you're reading this, you're likely at a crossroads. Maybe your truck is hunting for gears, the fluid smells like a burnt campfire, or you've lost overdrive entirely. Whatever the reason, doing the rebuild yourself or prepping for a shop to do it requires a bit of a "plan of attack." It's not just about swapping old parts for new ones; it's about fixing the factory flaws that caused the failure in the first place.
Why the 47RE Usually Fails
Before you start tearing things apart, it helps to know what you're looking for. The 47RE is an electronically controlled four-speed automatic, and while it's heavy-duty, it has some specific Achilles' heels. Heat is the number one killer. If you've been towing heavy loads without an upgraded cooler, the internal seals probably got brittle and started leaking pressure.
Another common culprit is the governor pressure solenoid. When this little guy gets gummed up with debris, your shifts start getting weird—or stop happening altogether. Then there's the issue of the factory torque converter. They weren't exactly built to handle the massive torque of a modified 5.9L diesel, and once they start slipping, they send metal shavings through the rest of the system. That's why a proper 47re transmission rebuild isn't just a "freshen up"; it's a rescue mission.
Setting Up Your Workspace
I can't stress this enough: don't try to do this on a cluttered workbench in the dark. A transmission has hundreds of tiny parts, and if you lose a single check ball or a small spring, you're in for a headache. You'll need a big, clean surface—preferably one with a lip so that fluid doesn't run off onto your shoes.
You're also going to need a decent transmission jack. These units are surprisingly heavy, especially with the transfer case attached if you have a 4x4. Trying to manhandle one of these onto a regular floor jack is a recipe for a trip to the emergency room. Get the right tools, clear your schedule, and maybe grab a box of nitrile gloves because you're about to get very familiar with some smelly, red oil.
Choosing Your Rebuild Kit
When you go shopping for parts, you'll see everything from "basic" kits to "extreme performance" packages. For most people, something in the middle is the sweet spot. A standard 47re transmission rebuild kit usually includes new frictions, steels, seals, and gaskets. But if you're actually using your truck as a truck, you should look into a few "while you're in there" upgrades.
I always recommend upgrading to a better band. The stock front band is a bit flimsy, and a heavy-duty replacement doesn't cost much more. You should also look at replacing the plastic accumulator piston with a billet aluminum one. The plastic ones tend to crack or wear out the bore, leading to lazy shifts. It's these small, inexpensive parts that make the difference between a transmission that lasts five years and one that lasts fifteen.
The Teardown Phase
Taking it apart is the fun part, but it's also where people make the most mistakes. As you pull the internals out, lay them out in the order they came out. I like to take pictures of every single step. "I'll remember where that snap ring goes" is a lie we all tell ourselves. You won't remember.
One of the trickiest parts of the 47re transmission rebuild is the overdrive unit. There is a massive 800-pound spring inside that housing. If you don't have the proper press or a way to safely contain that spring, do not—I repeat, do not—try to take it apart. It can be dangerous if it flies out. Many people choose to take the overdrive section to a local shop to have the internals swapped just to avoid the risk.
Addressing the Valve Body
The valve body is the "brain" of your transmission. During a rebuild, you can't just spray it with brake cleaner and call it a day. You need to take it apart, check the valves for sticking, and ideally, install a shift kit. A good shift kit does more than just give you a "firm" shift; it improves oil flow and increases the pressure held on the clutches.
Increased pressure is your friend. It keeps the clutches from slipping, which reduces heat. If you're feeling adventurous, you can even do some of the manual drilling and spring swaps that come with performance kits, but if you're nervous about it, there are plenty of pre-built "drop-in" valve bodies available that take the guesswork out of the equation.
The Importance of the Torque Converter
If you're doing a 47re transmission rebuild and you put the old torque converter back in, you're essentially wasting your time. All the junk from your old, failing transmission is stuck inside that converter, and it will immediately contaminate your fresh build.
Invest in a quality multi-disk converter if you can afford it. It's probably the single biggest improvement you can make to how the truck drives. It'll feel more "connected" to the road, and you'll notice that more power is actually getting to the ground rather than just turning into heat inside the bellhousing.
Putting It Back Together
Reassembly is all about cleanliness and clearances. Use plenty of assembly lube (or even just clean ATF) so that nothing is dry when you first start the truck. You'll need a set of feeler gauges to check the clutch pack clearances. If they're too tight, they'll drag and burn up; if they're too loose, the shifts will feel like they're taking an eternity.
Don't rush the snap rings. Make sure they are fully seated in their grooves. I've seen more than one "fresh" rebuild fail within ten miles because a snap ring popped out and let a drum travel too far. Double-check everything. Then triple-check it.
The First Start and Break-In
Once the transmission is back in the truck, don't just dump in some fluid and go for a rip. You'll need a lot of ATF+4—usually around 14 to 16 quarts depending on your pan and converter size. Fill it up, start the truck in neutral (Dodge transmissions don't pump fluid in park), and let it get up to temp while you check the levels.
For the first few miles, drive it easy. Let the clutches seat and the air work its way out of the valve body. You might hear some weird noises or feel a strange shift at first, which is usually just air bubbles. Once everything is settled, check your fluid one last time.
Doing a 47re transmission rebuild is a hell of a project, but there's a massive sense of satisfaction in knowing exactly what's inside your gearbox. Plus, your wallet will thank you for not spending $5,000 at a transmission franchise. Take your time, stay clean, and your old Ram will be back on the road in no time.