Cummins ATS 319904A326 4R100 Transmission Conversion KitConvert the Dodge 68RFE transmission over to the stronger more reliable 4R100 found in the Powerstroke. You can build the 4r100 to be as strong and reliable as you want to competition or general truck hauling duties. This full conversion kit from ATS is the only of it's kind and you can have a more durable transmission for the for the life of your truck.
An ATS performance built 68-RFE transmission with the Co-Pilot installed is great at power levels up to about 600 RWHP, although several out there are in the 900+ HP range, the 68-RFE is not the favored choice for that power level. Here are a few conditions that the 68-RFE suffers from: the 68 clutch apply and release is 100% computer controlled. That means every time a clutch pack is applied or released the computer must control the exact clutch apply rate and the exact clutch release rate during the shift with exact precision or one of the two clutch packs being applied and released will be damaged. This is the real issue with the 68 transmission.
There are 5 clutch packs in the 68 transmission that are responsible for all forward and reverse gears. If two clutch packs are applied you get one of 6 forward gear ratios, if one is applied you get no movement and if three are applied you get a bind-up or clutch drag! It is just short of a miracle that the Dodge TCM can adapt to such changing conditions that effect clutch to clutch application rates as well as it does. Here are a few of these changing conditions, fluid temperature, engine load, power level, throttle position, clutch coefficient, line pressure, internal hydraulic leaks, internal clutch clearance, solenoid resistance, wiring fatigue, corrosion, battery voltage, humidity, vibration, and the list goes on.
This is all wrapped around the envelope that the engineers calculated to be the environment that the 68 transmission would live in. This is why the 68 is relatively reliable in a bone stock truck using factory stock calibration. As soon as you increase power to the engine by installing a tuner you go beyond the ability for the TCM to accurately calculate the clutch volume index (CVI) of each clutch pack. CVIs are used by the TCM so it knows the clutch pack clearance of each clutch pack. The TCM must know the clutch pack clearance so it will know what CVI number to plug into its algorithm to accurately apply and release the on and off going clutch pack. The TCM must do this correctly every time under all power levels to ensure a consistent shift takes place. Where the 68 gets into trouble, this is dealt with by placing the Co-Pilot between the TCM and the transmission and apply another level of input (True engine load) to the TCM and take control of the transmission.
This allows the ATS Built 68-RFE to reliable and consistently handle up to 650 RWHP without the negative effects as long as the rest of the factory electronics are in good condition. As you can see 68 transmission is a slave to the outside environment and is very vulnerable to so many possible problems that can often cause total transmission failure in a very short time!
The 4R transmission is a synchronous type transmission which means there is no "clutch to clutch" timing issues that need to be dealt with by the computer! This in it self lay the foundation for a brutally reliable transmission package! Shift quality is much better controlled by the 4R trans, all shifts are actuated by an on/off shift solenoid that passes clutch application through a clutch fill valve that also has an accumulator to better control clutch fill time allowing for precise clutch application. This provides a near perfect shift at all power levels. The gear ratios of the 4R Transmission are evenly spaced providing a consistent RPM drop between all shifts.
This consistent RPM drop gives a smooth power transfer while reducing the air disturbance through the turbocharger maintaining even boost levels. The Torque converter clutch (TCC) application is a modern day type Pulse Width Modulation (PWM) signal that provides smooth controllable TCC application. All this combined adds up to a transmission that shifts through all the gears and applies the TC with smooth accurate operation.
The specialty built torque converter is custom manufactured to perfectly match the exact stall speed of the Cummins torque curve to provide the optimal RPM flash stall allowing the turbocharger to start making boost pressure while at the lowest RPM range possible. This is all because of the properly designed Turbine, Impeller and stator design. The billet stator directs fluid from the impeller back into the turbine to most efficiently harness the lost energy in the fluid that is not absorbed by the turbine.
All this means the torque multiplication is maximized providing a very smooth power transfer and maximum torque transfer from the engine to the transmission at a RPM that is well within the beginning of the torque curve of the engine. The lock up section of the converter is our patented Viskus Clutch pack design that allows for a smooth transition from fluid coupling to a 100% mechanical engagement providing over 3000 foot pounds of torque transfer without slip! The overly built Viskus clutch pack allows for a pulsed in TCC application at any power level without the concern of damage to the clutch pack.
What this means is the PWM application of the 4R Performance trans can be utilized in the programing to slowly apply the TCC providing a soft application while not damaging the TCC. All this translates to an even RPM drop any time the TCC clutch is applied. You will never again have to live with a hard TCC shift.
The 4R-Trans has a superb gear ratio set that really favors the Diesel engine. The gear ratio provides an even RPM drop between all shifts from 1st all that way to 4th gear. This coupled with the ability to release and apply the TCC between shifts gives the feeling of the smoothest power transfer at speeds up to 100 MPH! Here are the Ratios of the 4R-Trans, 1st=2.71:1 2nd=1.54:1 3rd=1.00:1 4th=0.71:1 R=2.88:1
Full Synchronous Shift
The synchronous shift application of the transmission mean there are no "clutch to clutch" timing concerns to deal with while making the transition between gear shifts. The 68-RFE transmissions require a managed application rate to apply a clutch while also having to manage the release of a clutch to achieve a desired shift. All this overhead presents a real problem when adapting to large power swings like a turbo charged diesel presents. This is the main reason the 68 transmission has a serious issue coping with the power fluctuation levels of the turbo charged Cummins. The 4R transmission clutch application only requires a single feed to apply all four gear applications. The simplicity of the hydraulic circuits and the synchronous operation provide a perfect performance transmission platform.
The 4R has electronic line pressure control, electronic accumulator control and PWM TCC control = All this allows the precision turning capability so the user can not only control when each shift occurs and the converter clutch occurs but the shift quality can be altered by changing line pressure along with tailoring the accumulator rate to optimize shift quality throughout the entire power curve. Not only can we taylor the shift quality but we can also tie the clutch application, TCC apply and accumulator rate directly to engine load instead of only throttle percentage! This equated to the best shifting transmission you have ever driven!
In general the ATS 4R Performance transmission package is the perfect transmission choice for just about any application. We offer a variety of mounting options so the transmission can be placed behind just about any 5.9 or 6.7L Cummins Engine. We have transmission internal build options from stock power to extreme 1500 HP+ applications. The transmission controller package is easy to install and comes complete with all plug-n-play wiring harness, software and instructions. We also have a full tech support team to answer any questions you have before, during or after the 4R Transmission package is installed.