I will come right out and say it — when kept in stock form, it is no secret that the 68RFE transmission needs help. Sure, it can be a “decent” transmission when used in a stock application. However, there are several known issues with the construction of the internal parts, so adding any increase in horsepower will cause these problems to really wreak havoc on a truck owner. In fact, Ram even had a recent recall on one of the issues, the valve body. You can check out any truck forum and the most frequently asked question is about the best upgrades for this transmission. The first answer to that question is usually, “a 68RFE valve body swap”.
Since Project WorkHorse has one of these problem-prone transmissions behind the Cummins, I knew right out of the gate that the transmission was going to need some simple, durability-enhancing upgrades. Some of the first steps to making a 68RFE last a long time are a valve body swap, torque converter upgrade, and aftermarket tuning. Sure, there are other upgrades available, but those are not as needed until your horsepower ratings climb above the 500-horsepower number. For WorkHorse, I decided to start by changing out the valve body.
But, with so many companies offering upgraded valve bodies, which one to use was the next question. I did a lot of research and finally landed on Next Gen Drivetrain. After checking out the website, it was immediately clear that Nate at Next Gen knows what he is doing when it comes to transmissions.
According to Nate, “our Project Carbon valve body for the 68RFE is the fastest shifting, only air-tight valve body in existence for the 68RFE, and is 100-percent designed in-house. This valve body is designed to be the perfect dichotomy between practicality and performance; maximizing both without sacrificing the other. ” But before I get into the swap, let’s talk about why a 68RFE valve body swap is a requirement.
It’s All Down Hill From Here
All automatic transmissions work off hydraulics. Fluid is pumped through the transmission which actuates various valves and solenoids that apply pressure to the clutches to activate gear changes. This fluid is directed through various channels within the valve body. If this fluid is allowed to leak out of the channel it is supposed to flow, reduced clutch-clamping pressure is a result that will inevitably cause slippage and burned clutches. Add a custom tune that increases this pressure, and the problem is exacerbated.
The valve body is the brain, or control center of the transmission. If you take it apart, you will see a maze filled with valves, passages, and solenoids that direct transmission fluid to where it’s needed. The transmission valve body isn’t known to actually fail all that often, which is a good thing. Even though the failure rate is not high, the valve body in a 68RFE does feature some lacking quality when it comes to the parts that make up the whole.
Let’s start with the accumulator pistons. These small plastic parts are designed to absorb the shock of each shift. If the accumulator pistons were not in the valve body, that shock would be deployed directly to the clutch pack. That means very harsh gear changes and the application of the clutches would be ill-timed.
The accumulator pistons in a stock 68RFE have two seals around their diameter that do not fit very well in the cylinder and allow an overabundance of venting. While a properly functioning accumulator piston is supposed to have a controlled leak (vent), the excessive venting in the 68RFE forces the clutches to suffer from insufficient application pressure.
Keeping the spring-loaded accumulator pistons in their bores is a backing plate. The 68RFE valve body accumulator backing plate is, unfortunately, made of a “soft” metal that bends easily. Add a transmission tune to your 68 that delivers increased transmission line pressure, and this plate doesn’t stand a chance.
Switching It Up
Next up, we’ll talk about the Solenoid Switch Valve (SSV). The SSV is actually the largest cross-leak found in the 68RFE transmission. Problems with the SSV are what usually cause overdrive failures and the appearance of trouble code P0871. The SSV is made of a very coarse/porous metal that can cause the bore to wear very quickly.
When that happens, transmission fluid will leak past the valve and cause a decrease in clamping pressure to the overdrive clutches. The decreased clamping pressure allows things to slip and those things get hot. Heat causes bad things to happen inside a transmission. But wait, there’s more…
Between the two valve body “halves” is a separator plate. This plate functions as a gasket for the upper and lower halves of the valve body assembly. It is a steel plate with holes for oil flow within the circuitry in the valve body. The OE separator plate is made of a very thin metal that can distort under pressure, causing cross leaks. Also, the oil circuitry utilized is not very efficient and an updated design is the perfect opportunity to enhance how this transmission behaves. Now that we know some of the more simple issues that plague the 68RFE transmission, we need to explore the fixes.
Billet Makes Things Better
To alleviate all of the known issues with the valve body, Next Gen Drivetrain developed the Project Carbon Valve Body. This upgraded unit starts with a 1-inch-thick billet aluminum channel plate (bottom half) which is stronger than the OE piece. Also, the billet aluminum used is not porous like the OE piece. The plastic accumulator pistons are eliminated, and billet aluminum pistons with custom relief circuits now reside in the bores. “The pistons have five seals, which is the most of any on the market,” Nate states. “Also, the thickest-in-the-market steel piston-retaining plate is also incorporated to keep the pistons in their respective bores.”
The problematic OE SSV is also replaced with a valve constructed of billet aluminum and the SSV bore is anodized to resist wear. Finally, a crush-style separator plate and modified oil circuitry control how well the transmission shifts. When talking about the separator plate, Nate informs me this is a crush-style plate that completely seals all channels to eliminate any cross leaks. Combine all these upgrades and it’s easy to see why I chose the Project Carbon Valve Body.
Time To Get Messy With Our 68RFE Valve Body Swap
I’m not going to lie, changing the valve body can get messy. You need to drain the transmission, remove the transmission pan, and then unbolt the valve body from the transmission. Inevitably, you will get oil on you and your driveway — or garage floor. I am not going to spend a lot of time thoroughly explaining how to complete this swap, you can watch the video at the top of this article to see how I did it. However, I will let you know that this might seem like a very in-depth swap, and it is. However, if you have a mechanical ability and the appropriate tools, you can do this.
But, once you have the swap done, the change in how your transmission shifts is immediately noticeable. The transmission no longer “lazily” makes the change between gears. The gear changes are crisp, but not harsh. Remember, the valve body will not increase line pressure to firm up the shifts, but the stoppage of any cross leaks is what I feel made the improvement.
Learning To Live Again With A 68RFE Valve Body Swap
If you research a 68RFE valve body swap like this on the internet, you will surely read about how you must do a quick relearn for the transmission before you drive your truck. I asked Nate about this, and he said that is not the case. He did tell me that the truck needs to be “gently” driven for approximately 100 miles. Those 100 miles should not be on the interstate. “Drive your truck around town,” he says. “The more the transmission shifts during this learning period, the better.”
Since I do not have a scan tool to complete a quick learn, I followed his advice and for the next several days after the swap, I drove WorkHorse around town for errands and let it do its thing. I know the timing surrounding this swap was risky, but I completed the upgrade just two weeks before a planned trip to Pennsylvania in late June. The trip was to attend the Northeast Diesel Nationals and the Bloomsburg 4-Wheel Jamboree. I also planned to haul the gooseneck trailer on this trip and hopefully pick up a few loads to offset the cost of fuel.
Although I do not have a transmission tune installed in the truck — yet — it worked flawlessly for the entire trip. While the shift quality is already better, I know transmission tuning will definitely help even more. The Project Carbon valve body is a definite improvement.
In fact, over the 4,800-mile trip to Pennsylvania, I logged 15.4 miles per gallon with the trailer connected. I didn’t check mileage while not hooked to the trailer. I feel more than confident that adding the tune in the near future will only improve how the transmission works. If you are on the fence about a 68RFE valve body swap for your Ram’s transmission, get off the fence. The peace of mind you get with the upgrade is definitely worth the price of admission.