Aisin Seiki AS69RC Transmission • Problems & Solutions

Aisin Seiki AS69RC Transmission • Problems & Solutions

Next Gen Drivetrain Research & DevelopmentFebruary 27, 2022

Introduction:

     As popularly demanded by our valuable clients, we have decided to create a Drivetrain 101 installment on the prolific and often unpredictable Aisin Seiki AS69RC transmission found in many diesel trucks on the road today; a spin-off of the later 80’s Toyota Land Cruiser unit.

     Many know Next Gen as the prevailing authority in engineering and development for the Aisin Seiki community. Now, we will be sharing much of our knowledge in the interest of educating the public on the probable failure points of this complicated transmission and how to properly correct them based on application.

Aisin Seiki AS69RC Product Resources:

- AS69RC Transmissions
- AS69RC Torque Converters
- AS69RC Rebuild Kits
- AS69RC Valve Bodies
- AS69RC Parts

In this Drivetrain 101, we will be addressing:

- The most popular failures we witness on the AS69RC transmission

- Its capabilities (or lack there of) in reference to TCM tuning and shift/lockup protocol modification

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

- Footnotes for Ram AND Nissan owners

And much, much more!

A Brief History of the AS69RC Transmission:

     This transmission is the successor to the not-so-missed Aisin Seiki AS68RC Transmission. The AS68RC transmission maintained its tenure until 2012 in Ram trucks and was never used in Nissan trucks. For the Ram community, it was replaced for the 2013 model year with the AS69RC transmission.

     Part of the reason for the change was the incredibly high warranty rate of the AS68RC Transmission from the OEM, but, the main reason was the increase in power from 2012 to 2013. This same year change brought a host of engine modifications including a different and more capable turbo.

     With this newfound power came the need for stronger transmission. Resolutely, Mopar converted to use of the AS69RC transmission in all Cab & Chassis vehicles and some bedded trucks. As for the Nissan Titan, the transmission was released in 2016 along with the 5.0 Liter Cummins diesel motor.

     Historically, Nissan has not offered a diesel truck in this category and hence this was a bit of an “educated guess” for the Nissan world. Fortunately, the transmission is slightly better suited for the Titan than the Ram, due to its lower GVWR and output torque.

     Both of these transmissions are still in use today, however the AS69RC appears to be disappearing in 2023 for a ZF developed 8 Speed, and the 5.0 Titan seems to be simply disappearing as a whole with 2020 being the last slated production model year. Due to extremely poor sales figures, there is no known date of return.

How the AS69RC clutch packs work:

     The AS69RC transmission is 100% TCM controlled. Due to it’s incredibly complex security encryption, the TCM protocol is almost impossible to modify. This is why you see no TCM tuning in the Aisin Seiki community.

     Fortunately, the AS69RC factory shift and lockup protocol is quite favorable and all improvements to it’s drivability and behavior are to be made inside the units mechanisms rather than through TCM Tuning. 

     To recognize some basic operating facts about this transmission, the Aisin Seiki AS69RC transmission is a 6 Speed Automatic computer controlled transmission, with lockup capable torque converter. In the drive position you will have 6 forward speeds.

     When pressing the “tow haul” switch or “O/D off” switch on the end of the shifter handle once you will omit 6th gear and have later upshifts into all other gears. Press the switch a 2nd time and you will omit both 5th and 6th gears. Pressing 3rd time will give you full upshifts of all 6 gears again.

     Below, you will see a comparison of the AS69RC transmission final drive ratios as compared to other transmissions used across the same period of time. You can see that the AS69RC transmission final drive ratios are almost identical to that of the AS68RC.

      These shifts, like most 6 speed transmissions, are controlled purely by the energization and de-energization of an array of pressure solenoids about the valve body. This unit also uses one singular pressure switch. Below, you can see the how solenoid application correlates to the activation of each gear within the transmission.

     As you can see, the AS69RC transmission is immensely complex. No attempt was made to simplify this transmission, especially electronically. The end result was a transmission that has tremendous operational capabilities, but simply suffers from it's own inherent complexity. Fortunately, Next Gen welcomes highly complicated drivetrain challenges. Now, we will observe the most prolific failure points in the Aisin Seiki AS69RC Transmission and how we permanently resolve them!

Problem #1 - The Torque Converter

     Much like the former AS68RC, the AS69RC transmission uses a 3 steel/3 friction lockup assembly from the OEM. This allows for above average torque capacity, despite their small size. Unfortunately, the 3 disks are so small that the torque capacity is roughly the same as a 68RFE torque converter.

     In fact, it has LESS friction area than the 68RFE transmission torque converter clutch, but the massive line pressure capabilities of the AS69RC transmission compensates for this just slightly. We have not found an accurate way to measure this to provide further data, but this much we can confirm.

     Further, the converter cover can be aggressively eaten up by the steels synchronizing against the friction elements of the converter clutch at rapid speeds, contributing to converter cover failure. The cover is the component on the front side of the converter that bolts to the flexplate.

     There beyond, the stator assembly (the component that controls stall speed) is made of cast aluminum and doesn’t “break” but does suffer from other issues. It is grossly inefficient, robbing the truck of a considerable amount of power.

     Clients who purchase only a torque converter report massive differences in drivability and perceived power for this reason. It should be noted that this modification does not “add” power, but does restore lost power in lower gears where the TCC is not engaged and the stator is largely responsible for how much power reaches the ground.

     Luckily, our AS69RC torque converters all come with an upgraded torque converter clutch assembly, stator, impeller hub, piston and more. We offer full-billet options for more audacious applications, but it is important to have this basic host of modifications in your AS69RC to support virtually any goals. This is because power is not the only thing that breaks this transmission.

Problem #2 - The High Pressure Oil Pump

     Much like the preceding AS68RC transmission, the pump is one of the most common failure points in this transmission. It’s poor longevity is attributed to its basic design, a single stage dual-gear pressure pump. It functions largely the same as an LS motor oil pump, pressing the pump gears against one side of the pump at all times.

     Over time, the gears will attempt to “push” to the side opposing the oil galley that feeds the valve body. When this happens, the pump gear galley will become oblong in shape, beginning to resemble an egg. When this happens, two things are effected.

     One is the ramp rate of oil pressure being produced due to its lack of vacuum inside the pump assembly. The other is a lack of peak pressure, again for the same reason. Customers whose pumps are beginning to wear often report less concise shift quality than date of purchase, or “wonky” shift behavior.

     A proper oil pump consists of coated pump gears that do not pierce the surface of the pump’s metal, negating this longevity-inhibiting problem. It is for this that any pump that arrives here unserviceable is replaced with a new OEM before the remanufacturing and upgrading process begins.

Problem #3 - The Valve Body

     One should be able to start seeing a trend that this transmission suffers from most of the same failure points as it’s predecessor, and hence one could logically see how the valve body is also a tremendous failure point. Fortunately, the AS69RC valve body is modular in design and easy to replace.

     Unfortunately, AS69RC valve bodies are designed to be proactive upgrades, not reactive repairs. If you’re experiencing codes or ill behavior of the AS69RC, a valve body may have been the route cause, but will not fix the problem. This is because valve body issues almost all produce a lack of oil pressure.

     To further complicate things, this symptom often only becomes detectable by the driver once it damages the clutch elements inside the transmission beyond their ability to properly engage, causing the symptoms many people report. In fact, much of the AS69RC transmissions poor drivability comes from the OEM accumulator and dampener set inside the valve body.

     From the OEM, this transmission comes with 5 main accumulators and one main dampener. There are tiny secondary accumulators that are seldom problematic. At Next Gen, we have invented the only full billet accumulator and dampener set available, featuring 2 O-Rings per piston as opposed to the factory zero. Further, they come with an entirely recalibrated accumulator spring set.

     This allows us to say we have the only air-tight AS69RC accumulator set in existence, yielding crisp, welcoming and concise shifts. This is a must for everything from stock trucks looking for preventative measures all the way to highly technical performance applications.

     It is for this that our coveted BulletproofAS69 kit is standard in all valve bodies, rebuild kits and transmissions we offer for the AS69 community. You can learn more about our 100% engineered and machined in-house BulletproofAS69 Kit here.

Problem #4 - The K1 Clutch Assembly

     K1 is known as the “underdrive” clutch assembly, being used in all underdriven gears. It features 7 low quality clutches that engage the moment the truck enters drive and uses a massive dampener in the valve body. As mentioned previously, we offer a billet dampener unlike anything in existence, but that only gets us so far.

     From the OEM, this clutch pack comes with a set of low quality stamped steels and a set of cheap papers designed for smooth engagement. In fact, the pattern of the clutches matches most heavy passenger vehicles such as a city bus. It is designed to synchronize slowly and be ultra-smooth.

     Ultra-smooth, although nice for many communities, is not nice for the Ram and Nissan AS69RC community because it lacks the confidence necessary to capacítate added power or heavy towing. The goal here is not “aggressive” shifts, but rather simply refined shifts that are a bit crisper than the OEM.

     Because of this, we see many K1 failures associated with higher mileage, deleted trucks and frequent towing. Our most basic complete transmissions will still offer a higher quality clutch material in this portion of the unit as well as our popular laser cut and hand finished steels. 

     An upgrade in clutch material and steel quality can yield as much as 25% more torque capacity without increasing the capacity of the assembly, a massive gain. However, we can always increase the quantity of friction elements inside this drum for ultra-high power applications. This is standard in units such as our Formula One AS69RC Transmission.

Problem #5 - The K2 Clutch Assembly

     More problematic than K1 is K2, also known as the “overdrive” clutch assembly. This system is engaged during the 3-4 upshift and stays engaged in all forward gears above that, making it critical for gears 4, 5 and 6. As in all transmissions, the upper gears have the highest Torque Multiplication Factor, causing them to often be the first to fail; especially with a measly 6 low quality frictions.

     Beyond even this, the hub that these clutches spline onto is made of flexible and thin stamped steel; quite scary for most applications. Every time the transmission enters 4th gear, this hub is forced to synchronize in speed with the input shaft. The more weight the truck is carrying behind it, or on it, the more stress this component experiences.

     For these facts together, almost every application can justify a Billet K2 Hub assembly. However, that is not all that’s necessary. A billet piston and backing plate are necessary to adjust the capacity of this drum, and upgraded clutch materials and steels are critical for success.

     Unfortunately, the OEM does not see it this way, offering an overdrive assembly almost congruent with the Toyota Land Cruisers of decades past. It works for most things, so it should work for a large diesel truck, right? Wrong.

Problem #6 - The K3 Clutch Assembly

     Less frequently damaged, but still worth discussing, is the K3 clutch assembly and drum. These clutches are used in third and fifth gear, giving them a slight break from the aggressive 4-5-6 clutch pattern of K2. For this, we usually see failures of K3 drum associated with sizable power increases in excess of 700HP.

     But, just because you are under 700HP doesn’t mean you’re safe. Perhaps flexion and cracking of the drum is not so probable at low power, but incinerating the factory paper on the OE clutches is. This is because the unit does not offer a high capacity of clutches in this part of the transmission and just rely on the same 6 frictions used in K2. 

     Because of the AS69RC’s factory use of a cheaper high energy material, a material favoring smooth engagement over durability, the minimum to capacitate even a stock truck for any extended period of time consistently is an upgraded clutch and steel material.

     Logically, we prefer a heavy duty organic friction and our standard laser cut steels as a bare minimum. For more audacious applications, we convert to a high capacity steel drum assembly to dramatically increase overall torque capacity.

Problem #7 - The Internal Wiring Harness

     This is a rather simple problem, a welcomed change to the usual. The OEM internal wiring harness is oriented in a very complex and convoluted shape that makes internal cracking of wires a very very high risk. It’s much like bending a paper clip back and forth until it simply snaps.

     The OEM later updated this with a new OEM wiring harness offering slightly thicker gauge wiring inside that negates this concern and is far more befitting the application. As always, Next Gen has a solution. We are the only transmission company direct with Aisin Seiki corporate, allowing us to offer these updated products far faster and more accessibly than the dealership who simply waits for Mopar or Nissan corporate to use their current supply before carrying updated part numbers.

Problem #8 - The OEM Solenoids

     OEM solenoids are usually the most reliable option for any rebuild, and frankly, the Aisin Seiki lineage is no different. That being said, why are solenoid codes such a popular problem on this transmission? Let’s learn something.

     We have said over and over again for years that the AS69RC transmission, despite its many issues, is not a “dumb” transmission. In fact, the TCM protocol of this unit is among the most complicated from its generation and even rivals current 8 and 10 speeds in complexity.

     Hence, both Nissan and Ram will often throw codes when a pressure solenoid is pushed on by oil pressure at the wrong time or does not turn on when the TCM energized it with control voltage, expecting it to turn on.

     This generally happens not because of the solenoids, but because of internal oil crossleakage of the valve body forcing solenoids open when they should be closed and otherwise. When this happens, the truck does not understand the problem but does understand the solenoid is acting irrationally.

     As a result, the truck will throw a solenoid code denoting voltage being high or low, or a more generic “Friction Element Apply” fault code. Generally when these codes present, the solenoid is suffering from the valve body doing what it wants to do rather than the solenoid itself being an inferior design.

     This is why OEM solenoids last incredibly long (sometimes upwards of 500,000 miles!) so long as the transmission stays otherwise together. This further explains why we witness an extraordinarily low and virtually nonexistent failure rate of OEM solenoids on our built transmissions as well as our Formula One AS69RC Valve Body, but yet it appears so common on factory transmissions.

Problem #9 - The OEM Bushings

     Much like many transmissions on the road, the Aisin Seiki lineage uses a low quality babbitt material to manufacture bushings. The concern here is that babbitt bushings in any transmission usually have a 150,000 to 200,000 mile terminal life span. 

     This does not mean that the transmission cannot exceed these miles under very fortunate and unlikely conditions, but what it does mean is that there is a noticeable drop-off in smoothness during this time frame. Most units will experience issues before this that have been paired to deleted or tuned trucks, as well as those with intense applications.

     A more quality solution would be bronze bushings, a standard on nearly all Next Gen transmissions. The intent is to produce far greater longevity as bronze bushings have no determinate life span.

     Although they feel the same as babbitt bushings on day one, they will feel new at virtually any mileage while babbitt bushings quickly begin to degrade and are noticeably less confident as mileage increases.

Conclusion:

     If you own an AS69RC transmission, do not fret. This transmission has the capacity for excellent longevity, frankly in excess of almost any other direct competitor. They also capacitate massive power levels once appropriately built for the application. They may be an underdog from the factory, but can be easily upgraded to endorse crisp shifts, cool operating temperatures, incredible reliability and low cost of lifetime maintenance. Still have questions? Call in and speak to one of our experts today!

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