When the late-model Cummins rolled out to the public, it was the first time in the history of Cummins-Dodge partnership that the trucks had specifically-designed transmissions to deal with diesel powerplants. The transmission was called the 68RFE, with the RFE denoting a Rear-wheel-drive design and Full Electronic control system. It was mated to the then-new 6.7-liter Cummins, which debuted in midyear 2007.
Initially, many were impressed with the gearbox – gone were most of the problems that affected transmissions like the 47RE and Torqueflite four-speeds of earlier generations. However, if owners wanted to bump up the output of their trucks, the 68RFE became finicky and problematic.
This is where BD Diesel has stepped in to offer a few products – the Protect68 kits – that can help these transmissions deal with the added demand. Currently, BD offers three overhaul kits for customers to choose from, ranging in price from $149.99 to $1,575.00 (there are also complete exchange transmissions, of course).
The overhaul kits get progressively more involved as price increases, so we’re giving our audience the lowdown on each of them and what they’re meant for. We spoke with BD’s Matt Priest to get a better understanding of these kits, but first, we wanted to get a firm grasp on the 68RFE and its traits.
Background of the 68RFE
68RFE Specs and Features
- Six-speed automatic transmission, double overdrive
- Succeeded the Chrysler 48RE
- Weighs 263 pounds
- Dual transmission fluid filters
- Dual-face torque converter lockup clutch
- Torque converter lockup capable in forward gears 2 through 6
- Integrated tow-haul mode provides alternative shift schedule for towing
- Band-less design reduces maintenance requirements
What was special about the 68RFE was that it was the first diesel-specific transmission offered by Chrysler; up to that point, Chrysler had tried to adapt gas-vehicle-oriented gearboxes to fit the Cummins, with varying success. The disappointing thing was that competitors Ford and GM had been building competent five- and six-speed transmissions for years, while Chrysler had lagged behind.
For example, Ford had the 5R110W Torqshift, a five-speed automatic overdrive transmission, since 2003. GM had partnered with Allison from the beginning to offer the Allison 1000 in both five-speed automatic (2001-05) and six-speed automatic (2005-present).
Nevertheless, when the 68RFE came out, owners were quick to pick up on the fact that it was sturdy – at least in stock form. As we mentioned before, modifications were usually what caused the 68RFE to malfunction.
68RFE Issues And BD’s Solutions
To hear it from BD’s Matt Priest, some of the big problems with the 68RFE are its overdrive clutches. “We’ve seen several overdrive clutches burn up,” he commented. “They are the most common failure points in the 68RFE.”
What causes this is a lack of line/clutch apply pressure. BD has worked on increasing line pressure, as well as the amount of clutch surface. The solution to reducing clutch slippage, however, was in being able to maintain the high pressure, and that’s what the Protect68 kits achieve – a new valve body separator plate and gasket seals in the higher pressures, which increase the clamping power of the clutch packs.
BD’s Protect68 Kits
The first one is the Gasket Plate kit (PN 1030373). It’s comprised of a few parts, namely a separator plate, valve body gaskets, pan gasket, three doughnut seals, and a check ball.
Comparing Cross Leakage
BD’s exclusive separator plate gaskets eliminate cross leaks and P0871 codes. “Our design stands up to the abuse,” said Priest. You can see it in our diagram, where stock can do 160 psi and suffer 5 psi of leakage. The competition does 225 psi and suffers 11 psi of leakage. Ours, however, can withstand 260 psi and only endure 3 psi of leakage.” These separator plate gaskets are offered in all three of the Protect68 kits.
BD found that by just increasing line pressure on a stock unit, the cross leakage between the case and valve body can result in multiple clutches being partially engaged at the same time. Lots of heat and premature clutch wear results from just increasing line pressure. By installing BD’s separator plate and gasket, this cross leakage is eliminated.
You can see on the diagram to the left just what happens between different valve body setups. What’s worth noting is that the BD version could withstand up to 250 psi of line pressure with 3 psi of cross leakage, where the others had much lower line pressures, yet noticeably higher cross leakage.
The next kit up is the Protect68 Pressure Control Kit (PN 1030362). This one contains all of the same pieces as in the Gasket Plate kit, but differs in that it also comes with BD’s 68RFE Pressure Controller.
The pressure controller essentially takes the same role that the aforementioned aftermarket programmer would. As Priest explained, “Our pressure controller plugs into the pressure sensors on the 68RFE, as well as the MAP sensor. It uses boost to dynamically drive up line pressure.”
What this means is that clutch apply pressure in the 68RFE will match well with increasing demand from the engine as more and more throttle is added. This strategy increases fuel economy and reduces load on the transmission pump. “With little boost pressure, the driver will get nice, smooth shifts,” said Priest. “At full throttle, the driver will get really fast, firm shifts. This helps improve driveability of the vehicle, and gives drivers satisfaction no matter how hard or easy they’re going.”
Rounding out the kits for the 68RFE is the Build-It Trans Kit, available in Stage 3 (PN 1062023) and Stage 4 (PN 1062025) versions. The Stage 4 kit includes all of the parts included in the Gasket Plate and Pressure Control kits, but also contains things like a new transmission filter, clutch plates, an overhaul kit, and more.
“This kit gives customers the plate, the gaskets, the module, as well as our ‘other half’ of the shifting equation for performance transmissions,” commented Priest. “This includes added friction material on the shifting clutches, as well as a new and improved Low/Reverse sprag with no core charge.”
The Low/Reverse sprag, originally a dogbone design, is now a cam-and-roller design through BD’s kit, making it stronger than stock. “Basically, our sprag can’t flip and go both ways,” said Priest. “It would have to break the case or sprag race in order to slip. This means our sprag design gets a lot more positive engagement than stock.”
In the input drum (underdrive/overdrive/reverse clutch assembly), BD has installed its own billet QT100 pressure plates. “QT100 is a very durable steel, and is the same type of steel used in digger buckets,” explained Priest. “This helps stop any deflection or distortion in the drums.”
The billet accumulator plate is another cool feature of the Build-It kit. “68RFEs have problems with the accumulator plate popping off of the side of the valve body,” said Priest.
The BD Diesel Way
We’ve just explored the Protect68 kits and what they can offer current-generation Ram owners. Even on stock applications, BD has recommended that Ram owners consider one of these kits to supplement their vehicle, if not for performance, then for peace of mind and longevity.
“Whether they’re going mild on their truck or they want to go to the next level, our kits were made with the customer in mind,” said Priest. “Even the average guy is going to want to get one of these kits.”
So before you try your hand at upgrading your Cummins, be sure your transmission is ready for it by checking out a Protect68 kit that’s right for your application. Head over to BD Diesel’s website, and follow the company on Facebook, too.