Chrysler 68RFE Transmission • Problems and Solutions (2023)

Introduction to 68RFE Transmission:

As the leading choice for high quality, proprietary 68RFE transmissions, conversion kits and parts, we are often bombarded with questions about their myriad problems and how to avoid them. As a result, it became clear that this popular and often problematic transmission needed its own installation in our Drivetrain 101 Education Section.

Are you ready to become an expert on the "infamous" 68RFE transmission? The Chrysler 68RFE transmission has been a step forward and a bane for the Cummins 6.7L community since 2007.5 when it became the successor to the heavily supported system48RE transmission.

The 48RE was based on the 727 TorqueFlite from the '60s and '70s, making it a reliable commodity; despite its unique imperfections. To become an expert on 47RE or 48RE,Check out our 101 shows on 47RE and 48RE here.

- The most popular crashes we've seen on 68RFE broadcast

- Its functions related to TCM tuning and shift/lock protocol modification

- The strengths (believe it or not, there are quite a few!) of this stream

-Resources for relevant updates and upgrades

Popular sources of information about shipments:-Top 5 benefits of an upgraded or built gearbox
-Why is the torque multiplication factor calculation so important?
-Top 5 ways to extend the life of a factory transmission

A brief history of the 68RFE transmission:

The 68RFE transmission came out at a time when the Ford 5R110 was in the midst of turning and the 6R140 was just an idea gaining momentum. At the General Motors end, the 6-speed Allison was in service and the LMM DuraMax had just emerged as the more emission-friendly LBZ. This meant Dodge played as usual to catch up with its outdated and inferior powertrain technology.

Roughly speaking, the 68RFE transmission arrived in 2007.5, controlled by a standalone TCM mounted on the passenger side of the truck's firewall. This lasted until model year 2010, when not only the body style of the "4. Generation”, but also an all-in-one PCM system that obviated the need for a standalone control module for the transmission. The following year, 2011, it became apparent that the material used to manufacture the pumps and valve bodies (an extremely soft aluminum) was deteriorating rapidly, contributing to an excess of warranty claims for Mopar.

Of course, Mopar heard the news of warranty calls and took action to make a product that was marginally cheaper (let's be honest here) and anodized the casting itself to avoid the complications of bore wear over time. In fact, we have an entire Transmissions 101 dedicated to this particular topic. It can be seen here:

This had an advantage, it partially minimized cross leakage. That's all. We've tried and tested anodized and non-anodized valve bodies and the conclusion is consistent and simple.In the factory configuration, anodized valve bodies appear to have the same problems as non-anodized valve bodies. They just seem to wear out more slowly.

Luckily, they tried to address the complications that plagued the 68RFE transmission in 2019. Unfortunately, they didn't properly address the issue. They have completely redesigned the pump and valve body to provide the torque converter lock-up clutch with reliable construction and precise control. All of this in good faith, but it doesn't address the most productive issues in this show, as we'll discuss below.

How the 68RFE Transmission Clutch Packs Work:

Each transmission has unique qualities in how it calculates shifting behavior, how it responds to solenoid inputs, and more. The 68RFE transmission is no different. Something that is critical to understanding the 68RFE transmission is understanding the clutch application chart. To do this we need to analyze the following information:

Reverse - Down/Reverse + Reverse

1st gear - slow/reverse + underdrive

2nd gear - 2nd clutch + underdrive

3rd gear - 4th clutch + underdrive

4ª Marcha - Overdrive + Underdrive

5. Gang - Overdrive + 4. Kupplung

6. Gang - Overdrive + 2. Kupplung

This is a very common configuration for a 6 speed automatic transmission with dual overdrive torque converter. As you can see each gear consists of 2 clutch packs. This is because clutch packs are not assigned to specific gears (1, 2, 3, etc.), but to different transmission functions; often including hubs, baskets and the like. In most transmissions, a combination of planetary assemblies/clutch packs must be activated together to produce the desired input shaft to output shaft speed ratio.

To generate an arbitrary example that might make this more understandable, imagine losing 4th, 5th, and 6th gear. Based on the above data, it is clear that the overdrive clutch pack is the designated clutch pack based on the gears being driven and the clutch packs engaged in those different gears. If overdrive is only used on 3 gears and all 3 gears are not accessible then the likelihood is overdrive failure.

This diagnostic logic can be applied to virtually any transmission. The overdrive clutch pack is an exceptionally large failure point on these transmissions and that's why we pioneered our innovation68RFE Cherry Bomb.This would include the overdrive, underdrive and reverse sections of the input clutch drum to correct said error.

68RFE Transmission TCM Tuning and Adaptability Protocol:

As previously mentioned, the 68RFE transmission attempted to make a direct (and miscalculated) turn in the Allison/TorqShift market. This transmission had to be electronically advanced and able to think for itself. Compare this to Tesla cars being able to drive themselves and other automakers trying to keep up with the technology. Allison has been at the forefront of adaptive shift technology from the start, and it was Mopar that eventually came on board.

The point is simple, the 68RFE transmission wasn't advanced enough in its logic to make really good decisions about shift timing and driving dynamics. As a result, the show suffers from constant confusion. Does he want to lock or unlock the torque converter? Which gear does he want? How much line pressure does he want now? The only solution to these extremely sporadic variables is TCM tuning.

There are numerous aftermarket products that act as "plug and play boxes" and artificially increase the line pressure. We have gone to great lengths to understand how all of these products work and we have found that they all work very similarly. They are assemblies of resistors and logic gates used to "fake" transmission into certain behavior patterns.

*Pro-Dica*- Are you looking for a safe way to plug internal leaks and allow higher line pressure in clutch packs? One of the smartest and easiest transmission upgrades for the 66RFE transmission is a valve body. Consider airtight, ultra-fast shiftingNext generation valve bodies here🇧🇷 a very significant improvement.

These devices arenoa safe method of increasing line pressure and should be avoided. The best tuning rigs (and we don't get a dime to say so) in our opinion are EFI Live and EZ Lynk for the 6.7-liter Cummins. Both prove to be excellent systems for implementing high-quality TCM tuning under the guidance of a qualified tuning professional.

-Yrepresents the commanded line pressure based on the calculations to the right of the equals sign.

-Mrepresents gain, a variable used to correlate engine load to rail pressure requirements. Tuners adjust this value to increase line pressure.

-xrepresents engine load, a factor used by on-board computers to process and understand the resistance exerted on engine torque.

-Brepresents a baseline of minimum line pressures that must be commanded in each forward gear.

When we talk about the TCM fit and adjustability protocol, it's important that we talk about clutch volume indices, also known colloquially as “CVIs”. CVIs are a rational time metric for applying piston travel distance. This unit of information is used to understand the remaining three-dimensional volume of the clutch based on the engagement times of the clutches at the moment their respective solenoid was energized and the circuit was closed; returns an electrical continuity signal to the onboard TCM.

The TCM then uses both binary and Boolean logic to evaluate which solenoids are on and off and what logical decisions the onboard computers controlling the transmission will make. In simpler terms, the longer the clutches take to engage, the less friction there is left in the clutches themselves, according to the 68RFE transmission control module. Based on this information, the transmission will retard or advance the solenoid timing accordingly to improve shift response. Below is a list of the average CVI ranges as mandated by the Automatic Transmission Rebuilder's Association:

Putting all this information together should give you a much better idea of ​​how the 68RFE transmission brain works. It's all too common for transmission specialists to sue the mechanical and hydraulic side of the trade and pay little attention to the electronics that turn them fully on. We will now continuously, in no particular order, cover the critical components of the 68RFE transmission and their problems, fixes, and upgrades. As we provide additional reading on each of these components, we will answer these 3 questions for each critical component:

- WHY does it break?

- HOW do I prevent it from breaking?

- WHAT can I use to make it stronger?

Problem #1 - The torque converter

The torque converter of the 68RFE transmission is actually very efficient in some respects. It has a huge stator (the most powerful of the Big 3, believe it or not!) and a double-sided friction element, shaft. This makes it a viable factory-form competitor in head-to-head competition.

Unfortunately, it has numerous diseases. It can't handle the power of a tuned truck, even at its smoothest tune. It might survive, but it's temporary and the physics are against you. The stator spring itself is prone to failure, as is common on some Dodge converters. This is caused by your lower oil seal which can be upgraded to an aftermarket torque converter like ours.68RFE Project Carbon™ triple disc torque converter.

These torque converters also have unnecessarily high stall speeds. This is evidence of Mopar's emissions compliance and is not based on any practical or functional reason. The solution here is to minimize friction within the torque converter by opening up the ribs on the stator itself. This slows the stall speed, allowing the torque to reach the ground safely and efficiently. Many people describe this as a feeling of "empowerment," but it's actually an illusion. The truck simply replaces lost torque that didn't make it to the bottom in the factory torque converter, which is plentiful and parasitic.

Problem #2 - The high pressure oil pump

The 68RFE transmission has a very unique pump design with 3 pump gears instead of the standard 2. This should help the 68RFE generate line pressure quickly, reliably and efficiently. The good thing about this design is that it's really fast and efficient!

However, the problem is reliability. This pump empties its bores very quickly and starts to leak just like the valve body. There are many reasons for a pump failure, but we will cover the bigger points as follows:

- The center pump gear wears out badly and causes oil reversal problems.

- There is a little known pump drain circuit that needs to be closed to permanently eliminate this issue.

- The pump's internal valve train needs a complete overhaul for longevity. The valves are heavily made of magnesium (Mg) and nickel (Ni), two elements that are fierce when held in an aluminum (Al) port.

- The accumulator piston for the TCC has a tendency to fall against its support during converter clutch actuation. This can be fixed by recalibrating the pump accumulation system with different hardware.

Another understandable data point is that the 68RFE transmission oil pump acts as the torque converter valve body. They go hand in hand, and when one fails, the other usually fails. Our68RFEProject Carbon™ High Pressure Oil PumpIt combines all of these critical modifications into one and is a good platform for gear designs where there are doubts about the integrity or performance of an OEM pump.

Problem #3 - The input shaft

The input shaft of the 68RFE transmission is a very simple part of the equation. It is responsible for collecting and delivering all the power that comes out of the torque converter68RFE input clutch hub.The point here is pretty easy to guess, the factory input shaft was never made for aggressive use. In fact, it was hardly made for factory use. The 68RFE transmission input shaft is an inflated version of the 545RFE input shaft. In fact, we've attached a photo of a billet 545RFE input shaft below, does it look familiar?

The 68RFE transmission's input shaft is instantly undermined in power and performance, just as it is undermined by drag and the powerful locking action of a billet three-plate torque converter. It is made of alloy mild steel with low stress and huge yield. The OEM input shaft is not necessarily lossless, it is very safe to use at modest power levels. It's even standard on some of our simplest transmissions, like oursXtreme Tow™68RFE Transmission🇧🇷 Thing is, once you start raising high expectations, the factory axle just isn't good enough.

The next logical step is a300M billet 68RFE transmission input shaft.This becomes necessary for anyone planning to increase launch, heavy tow, add significant amounts of power, or simply invest in safety and longevity. We see these input shafts reliably surviving up to around 900hp, but we've seen several success stories at higher numbers. For everyone over 850hp we recommend theMaraging steel 68RFE input shaft.

Problem #4 - The input clutch drum

The input clutch drum on 68RFE transmissions is a complex composite component with many different purposes. In fact, all gears use at least one of the clutches in the drum. The input drum of the 68RFE transmission consists of (front to back) reverse, overdrive and underdrive. It is basically built around a large reluctance wheel that communicates with the input shaft speed sensor. This reluctance wheel is known as the "input clutch hub" and is often replaced with a spline in heavy-duty applications. Below is a photo of a 68RFE billet inlet clutch hub.

This drum has several diseases. The first is that it flexes outward due to a physical force known as "centrifugal inertia". This is the same force that allows you to spin in circles while swinging a bucket full of water, and the water will stay in the bucket as long as you spin fast enough. This is solved in a number of ways, but the most popular is the patented Overdrive/Reverse PistonTambor Sonnax 68RFE Smart-Tech.

It also lacks the clutch volume needed to securely engage the overdrive clutch pack. The 68RFE transmission's overdrive clutch pack consists of .051 inch thick clutches (no kidding, they really are that thin) stuck in a hot, malfunctioning, severely restricting drum. While there is too much data to reasonably include in this article, it is safe to say that every 68RFE transmission we make has a completely redesigned overdrive section. This is widely considered to be this transmission's biggest Achilles' heel and we do not offer a stock overdrive stack on any of our transmissionsbuilt 68RFE transmission.

A final and equally valid affliction for the 68RFE transmission's input clutch drum is the overdrive hub. The overdrive hub (pictured above) is the splined part that the overdrive clutches sit on. During 3-4 upshifts, this hub is speed synchronized to the input shaft against the truck's ground. The problem with this is that just like an input shaft, it will microfracture and fail. If you're doing the 3-4 gear change with the torque converter lock-up assembly engaged (as tuners often do), you're putting incredible stress on that particular component. As a result one68RFE overdrive hub for extreme useshould always be used for proper applications.

Problem #5 – The Support Center

 The center support of the 68RFE transmission is unique. Each gear (except low gears) with overdrive OR underdrive must use at least one of the two clutch packs in the center bracket. The center bracket houses the 2nd and 4th clutches and is located just behind the input clutch drum assembly. It should be noted that these 2 clutches correspond directly to planetary arrangements that conflict with each other in the final gear ratio. As a result, these claws cannot be applied without forcing the person to "win". These clutches should never attempt to engage simultaneously.

These clutches rarely fail, but when they do, it's usually the cause of a valve body leak (as discussed later in this post) or the culprit of the huge power increase. Luckily we have both covered in ours68RFE Transmission Conversion Kitsand other complete transfers. While there are many ways to solve this problem, adding clutches to the center member assembly is a surefire way to increase torque capacity.

These center brackets are also prone to failing or excessive wear on the inside, sometimes necessitating a complete replacement. For more information about our center's support, visit our68RFE Project Carbon™ Center Support Kit.Steel billet options are available for customers looking for extra high performance alternatives.

Problem #6 – The low/reverse drum

 Fortunately, the 68RFE Transmission Low/Reverse Drum is a generally powerful and durable system. However, there is one major flaw in this component that is worth understanding. This point of failure is known as "low/reverse sprag".

The Low/Reverse Sprag is a “roller clutch” style component that tends to physically snap or break at the rear end of the transmission due to impact. The reel seats inside the clamp body are plastic (seriously) and can withstand pretty much ANY impact. The impulse start is the number one cause of error here. A general rule of thumb here is simple: if you plan to unleash the momentum, plan to68RFEProject Carbon™ Reverse/Low Reamer.

Spreaders are nothing new. In fact, they date back over half a century in the world of automatic transmissions. In the past, sprag solutions have included, but are not limited to: soldering the spragin position, bolting to the box, and more. All of this is implausible due to the location of the spring within the 68RFE gearbox; placed between two critical oil kitchens. Our only option is to deploy a stronger alternative.

Problem #7 - The valve body

The 68RFE broadcast community talks no more thanas hellvalve body. In fact, it was such a hot topic of discussion that we individually created our own Transmissions 101 post on the subject, seehere!However, we will cover wave peaks here.

As with the 68RFE transmission's high-pressure oil pump, the valve train is machined from aggressive, low-grade metals that are undesirable in their intended applications. The valve body is just no different.

In fact, it's worse on every applicable metric. We simply tested the new 68RFE transmission valve bodies on data in the past and found that theyathas a noticeable cross-leakagestraight from the factory!The amount of cross leakage generally approached 2-3 inches of vacuum pressure. That's not enough to defeat the function of the valve body, but it's certainly not perfect.

With our thorough understanding of the 68RFE transmission's valve body, its leaking valves, accumulator system, separator plate and other immense imperfections, we can go back to the drawing board and use that knowledge to develop a truly superior product. That's why we're so proud of oursSeries of 68RFE valve bodies!Alternatively, our bestsellerProject Carbon™ 68RFE-Ventilkörper-Upgrade-KitIt's an amazing way to fix all of these problems at a fraction of the cost.

Tip: To avoid premature bore wear, regularly service the gearbox with our

Problem #8 – The electronics

Automatic transmission electronics is always a risky business. This is actually not about the factory, but about the opposite. The aftermarket is notorious for trying to save money by making cheaper electronics overseas or sourcing them from third-party manufacturers. The problem here is that most manufacturers are smart enough to patent their own electronics, preventing the aftermarket from properly reproducing their quality.

While not necessarily an industry standard, Next Gen Diesel includes in-box electronics with our 2-year unlimited mileage warranty. As a result, we need to compile data on the most likely failures as well as the most successful solutions available for this transfer.

What we've found time and time again is that true OEM electronics like the68RFE Mopar OEM Upgrade Solenoid Packare the only viable options for a successful transmission rebuild.

Problem #9 - The jacks (seriously!)

It's not common for bushings to be on a list, but we didn't make that list 'easy' for the 68RFE gearbox. Therefore, we must assert the lower factory bushings. The OEM bushing design is a very cheap and outdated Babbitt material, common in the diesel world but long forgotten in other parts of the transmission engineering industry.

The reason for this is that Babbitt bushings, by design, don't last very long. They typically have a lifespan of around 150,000 to 200,000 miles in average "peak bell curve" applications. At about twice the cost, upgrading to bronze bushings can become questionable. However, if we look at some basic scientific facts, we will see that the solution is right in front of us.

The bushings in an automatic transmission have two enemies; One is heat, the other is oil pollution. Bronze is virtually impervious to both. Bronze is strong enough to withstand the effects of oil failures with minimal impact. In terms of heat, bronze is saturated (begins the process of transitioning from the solid to the liquid state of matter) at 1,742 degrees Fahrenheit at 14.7 PSI barometric pressure (sea level). The long and short is easy, you don't hurt the brass bushings, spend the extra $40. You will thank us in the future.

Problem #10 - The oil pan

The factory transmission oil pan was designed to achieve one thing only, and that is to save money. This pan is stamped from heated sheet steel that is not strong enough to withstand shock or abuse. The pans are also incredibly shallow, making the factory filters barely work properly.

This is an objectively terrible decision and does not contribute to the longevity, health or function of the transmission. One thing to consider when considering a deep transmission failure is the additional time between transmission maintenance intervals. Adding 20 to 30% more oil extends the time between transmission services by about the same amount. The same logic applies to heat as well.

Other benefits of an aftermarket pan include the implementation of a drain plug. This makes servicing your transmission extremely quick, easy and clean. The works pan offers none of these benefits, making it the least qualified option of them all. ONE68RFE Transmission Deep Transmission Panoramashould be among your first considerations when updating this problematic transfer.

Problem No. 11 - That Flexplate

Flexplates are a very misunderstood part of the powertrain equation. It seems the only discussion in the flexible board market is how to ensure they don't break. While it's important to have a strong, well-balanced flexplate, the flexplate serves a higher purpose.

Think of the flexplate as a giant shock absorber for the torque converter. There is enormous pressure inside the torque converter, which can only escape between the outside diameter of the input shaft and the inside diameter of the oil pump stator bracket. If you're using an OEM pump, you're already at a huge disadvantage.

The solution is a balanced flexible board that meets SFI approval standards. However, it should also be a flexible board that is not unnecessarily bulky or thick. This is a Pyrrhic victory (a greater loss than a victory in the Force) because overly large flexplates don't have the versatility or flexibility to truly serve their intended purpose. As a result, the moderate stiffness of our SFI-approved flexplates, as well as their overwhelming strength, make them credible advocates of healthy, successful gear design.

Conclusion:

The 68RFE transmission has been talked about endlessly since 2007.5. It was an endless conversation about what works, what doesn't, and why. No two trucks are identical, nor should there be two 68RFE transmissions. However, with the data compiled above, you should be well on your way to making an informed decision as to which 68RFE gearbox or parts are right for your application. To learn more, clickhereor call and speak to one of our experts!