It seems that Dodge had decided to build their transmissions to work with specific motors only. The Aisin transmission works with the high-output 6.7-liter Cummins I6 turbo-diesel. The 68RFE is attached to the standard 6.7 diesel engine.
When it comes to towing, stay away from the 68RFE, the word is that it is not designed to handle heavy towing duties. If you want to heavy tow, go with the truck that has the Aisin transmission in it. You will get to your destination a lot easier and faster.
To learn more about these transmissions, just continue to read our article. It explores these transmissions to give you the best information and let you know their differences. Dodge may be scrapping the AISIN and going with an Allison or ZF model.
The word on both is not encouraging. It seems that these two transmission models could have been built better. The 68RFE is supposed to be great and goes for over 400,000 miles when treated right.
But only when there are no modifications made to your truck. This transmission is only good with standard output motors and if any changes are made, it is said to fall apart.
On the other hand, the Aisin transmission is a little better but people are not filling their posts with praise. This transmission can tow heavier weights but with the recent upgrades to the 68RFE, it can handle some heavy weights as well, just not as much as the Aisin transmission.
Also, one review said the only way to get the 68RFE up to standards is to properly build it. In its current form, it is only good for factory power. But everyone has their own opinion.
Many truck owners who have the 68RFE say it works finer and has pulled their trailers, including their 5th wheels well. They have no complaints about the performance.
We have not heard of any complaints about the Aisin transmission either. Its 6-speeds are said to be rated to tow 31,000. The best thing to do is to test drive both and see how they feel under your driving conditions.
One owner described the Aisin transmission to be the same as the 68RFE except that it is built with tighter tolerances and was made beefier than its competitor.
That may be true as the 68RFE is said t be rated for 800 lb-ft of torque and only 370 HP. The Aisin transmission is supposed to handle 1000 lb-ft of torque and 400 HP.
One complaint that was made about the 68RFE and not the Aisin was that the former had a goofy downshifting attitude that showed up from time to time. It got worse when the owner added some modifications to the engine.
Then the 68RFE transmission seems to have more problems and is in need of repair more often than the Aisin transmission. It is said that these problems are not limited to the mechanical side of the device but extend to the electrical and hydraulic sides as well.
Both transmissions were introduced in 2007 and have performed admirably for most of their owners. Some owners prefer the 68RFE over the Aisin and other owners have the opposite view.
Your opinion will be based on your experience. The Aisin owners say it is a very durable and tough transmission that does not overheat. The downside is that this transmission does not go very fast.
One more vulnerability in the Aisin is its wiring harness. They say Dodge dropped the ball when they made this part connecting the transmission to the computer.
When it comes to this topic, you do not have to be an experienced mechanic to tell which transmission your truck came with. All you have to do is look under the hood to see which model it is.
The 68RFE has its dipstick on the passenger side of the engine, while the Aisin transmission has its dipstick on the driver’s side. That is it. There are no technical or mechanical details involved.
You just have to look and you will know which is which. The Aisin dipstick handle may be colored yellow but we are not sure if both options come with a yellow-colored dipstick.
Or if you want to use your computer, you just copy down the VIN for your truck, go to Dodge’s web page and input the VIN. The website should be able to tell you which transmission you own.
One owner crawled under his truck and looked at the brand name on the transmission. His transmission said Aisin so he has that model. If you want to crawl on the ground that is one way to know which transmission you have.
Most owners have not had any complaints about this transmission. It is a good model as it has been around for a very long time. Dodge and other companies that use the Aisin brand would not do so if it were a lousy transmission.
Here are the specs for the Aisin Seiki Six-Speed AS68RC (Dodge Cab and Chassis):
First gear: 3.74
Second gear: 2.00
Third gear: 1.34
Fourth gear: 1.00
Fifth gear: 0.77
Sixth gear: 0.63
Weight: 348 pounds
Torque Converter: 12.2-inch (diameter) with a four-disc converter
Takes Dexron III transmission fluid
One of the things that make the Aisin transmission good is its high first-gear ratio. In a comparison with the Allison 1000 its 3.74 first gear ratio was higher than the Allison's first gear ratio was 3.10.
What this means is that the Aisin was very good at getting your truck and trailer going from a stand still. Then if you look at the 6th gear, this is where the fuel mileage is calculated, the lower the gear ratio the better the fuel mileage.
The Aisin was close but not better than the Allison in this category with its .63 to Allison’s .61. Then the larger torque converter may help the fuel economy because it makes sure the shifting is smooth.
Large torque converters are also stronger and more durable. The Aisin torque converter is 12.2 inches. Also, this transmission is very reliable and as reported earlier, the 658RFE has more repair issues than this one does.
Many truck owners go for the 68 RFE because they do not need the power or torque the Aisin supplies. They do not avoid it because it is a bad transmission.
The numbers will tell this story and once you see them you will notice that this transmission is very strong. It is known to last a very long time when aided by regular maintenance and fluid changes.
The power that the high output 6.7 Cummins motor puts out reaches 400 HP and 1000 lb-ft of torque. That is a lot of power and lets you know how strong this transmission is. But that is not the only clue to its strength.
This transmission is rated to help tow 31,000 pounds. That is a lot of strength especially when this transmission helps you get that heavy of a trailer over those steep mountain passes.
When compared to other brands’ transmissions, this is said to be one of the most problematic automatic transmissions around. But the 68RFE is said to break down more often than this transmission.
Most of those mechanical issues will be the result of the driving habits of the owner, how well they take care of their transmission, and other factors. Rough roads and the constant climbing over steep inclines will also take their toll. As would the weight you are towing.
In some ways yes it is because the Aisin is built with different tolerances and made to be more heavy-duty than the 68RFE. If you put the 68RFE with the same engine as the Aisin and have it try to tow the same weights etc., then you would see the difference between the two.
As it stands, while the 68RFE is a good transmission it is just built for a different purpose. It is for the standard output 6.7L Cummins diesel engine and is not heavy-duty enough to handle the power of the high output 6.7L Cummins diesel engine.
In some applications, the Aisin will be better than the 68RFE and in some cases, it may be too much power for the purpose. When it comes to fuel efficiency, the difference between the two is hardly noticeable.
The 68RFE will have the edge here and get better fuel mileage than the Aisin. In referring back to the problematic engine review, another owner has stated that the Aisin is practically bulletproof. That is one reason many owners buy their trucks with that transmission.
There are very few forum threads that talk about the Aisin troubles. That is because it does do better than some reviewers give it credit. It is a very heavy-duty transmission built for the heavy loads and hard work.
There seems to be more discussion on the mileage but the Asin is put into a 1-ton truck and mileage will be mileage and there is not much you can do about it.
Then the word is that when you buy a truck with the Aisin transmission included, you have more than enough truck to handle your driving duties. If you are not needing heavy-duty action, then go for the 68RFE. It is a good second choice.
There are many reasons for this problem. One is that the transmission will fail if it overheats. If you are familiar with transmission temperatures, going above 220 degrees F is starting to push the limits.
At about 240 you should change the fluid and the filter. Then another reason would be if you really soak the transmission. They are not built to handle water very well.
Once water gets inside, it seems that liquid delaminates the discs. When that happens you will have transmission trouble. But these are not the only two reasons why this transmission fails.
This transmission is a good model and many previous weak points have been upgraded over the years. However, there still are some problems upgrades cannot fix. One of those is user error.
If the owner does not take care of the transmission and provide it with good and regular maintenance over the years they own it, then the parts will wear down and the transmission will break down.
You need to watch that maintenance schedule and make sure to service the transmission on a regular basis. Then if the owner tows or hauls too much weight, this extra strain can harm the transmission, shortening its lifespan significantly.
One more example of user error, one owner has stated that one reason this transmission fails is that too many owners delete the tune or add a tune to the system. If you remain stock all the way around and do not touch the tune, then you should have no problem.
Finally, it is possible to fry the overdrive gears and clutches. The reason for that is that many owners do not break in their transmissions very well. Some owners are saying to lock out the 6th gear when towing loads uphill. That will protect you from this damage.
This transmission brand is built by Aisin Seiki and Aisin AW and Toyota Motor Corporation and Aisin Seiki are shareholders of Aisin VW. The last company is said to be the largest transmission builder and supplier in the world. They make transmissions for over 55 automakers.
Aisin AW makes transmissions for light-duty vehicles, while Aisin Seiki makes transmissions for heavy-duty vehicles. What follows are just 3 of the best transmissions these companies make:
Chrysler put this transmission in its 3500, 4500, & 5500 vehicles and started using it in 2007. It has three driving clutches, two brake clutches, a one-way sprag clutch, and three planetary gear assemblies.
When not installed in the 2007 to 2013 models of Dodge, etc., trucks, it is known as the A465. This transmission is very close in design and capability to the AS66RC transmission. The numbers and letters in this transmissions name are listed below
6: 6 forward gears
8: Torque capacity on a scale of 0-9
R: Rear-wheel drive
This was the upgraded version of the AS68RC. It also was put into the 3500, 4500, & 5500 truck chassis by Dodge, etc., in 2013. The upgraded parts include a larger input shaft, a new torque converter design, and a deleted F1 sprag clutch for first and reverse gears.
What made it stand out from other transmission models was its tow/haul mode. This was a push button feature that when activated it locked out the overdrive gears. Its name refers to the following specifics:
AS: Aisin Seiki
6: 6 forward gears
9: Torque capacity
R: Rear-wheel drive
This model of transmission was put into the same 3500, 4500, & 5500 truck chassis that the previous two models were placed. This was a very quick replacement for the AS69RC as it was used in 2014.
What made this model better was the compact gear train with three clutches, two brakes, and a new shift control algorithm, as well as the enhanced tow/haul mode.
This transmission also had the ability to turn off the exhaust brake while shifting. To do that you had to go through the transmission control module. Its label refers to:
AS: Aisin Seiki
6: 6 forward gears
6: Torque capacity
R: Rear-wheel drive
There was an article in 2020 that spread the rumor that Dodge may drop using the Aisin transmission in favor of other brand transmission models. The word was the company was thinking about using the ZF 8-speed automatic or a new 9-speed Allison automatic.
While this change did not seem to take place as you can still get the Aisin transmission in the heavy-duty Dodge trucks, there has been a slight modification.
It seems that Dodge or some aftermarket company is offering a kit that allows you to put the Allison 6-speed transmission behind the 5.9 and 6.7 L engines. This news comes from last year.
This rumor seems to have started in 2018 and does not seem to have any meat to it so far.
When you want a standard output truck and a diesel 6.7 engine, then it is best you go with the 68RFE transmission. That is what this model is built for. If you are going to do a lot of heavy towing and other work, then you should go for the Dodge truck that comes with the Aisin transmission. It is built for heavy-duty applications.