Allpar Forums banner
1 - 1 of 1 Posts

Premium Member
2,290 Posts
The 45RFE, 545RFE, 65RFE, and 66RFE automatic transmission for Jeeps and Rams

by Michael Dickens

The 545RFE made its way into Chrysler's entire fleet of rear-wheel drive trucks, save for sedans and coupes: the Jeep Liberty, Dodge Ram, Dodge Dakota, Dodge Durango, and Jeep Commander. It was based on a similar automatic - the 45RFE.

In June 1998, Chrysler introduced the innovative 45RFE in its 1999 WJ Jeep Grand Cherokee. Produced at Chrysler's Indiana Transmission plant in Kokomo, it was paired with the 4.7 L PowerTech V8 engine. The 45 number refers to the torque rating (5) and number of forward gears (4); RFE refers to rear wheel drive application and full electronic controls.

Auto part Engine Vehicle

The 45RFE automatic transmission had three planetary gear sets instead of the two usually used in a four-speed automatic; that would, in time, allow it to become a six-speed. It included three multiple disc input clutches, three multiple disc holding clutches, and a dual internal filter system - one for the transmission sump, the other for the fluid cooler return system.

The transmission used four forward gears in normal acceleration, with a different second gear used for "kickdown" acceleration. Despite using five forward ratios, Chrysler played it safe and called it a "4-speed automatic."

Vehicle Engine Fictional character

In 2001, with programming changes and an extra, taller overdrive ratio, the 545RFE was born. With the change to overdrive, cruising at 70 miles per hour (110 km/h) with a standard axle ratio would yield 2000 rpm at the engine, about 200 rpm less than the 45RFE, cutting fuel use and noise. Now, it had six forward speeds - again, one reserved for kickdowns.

The 545RFE's engineering reached back to the rock-solid Torqueflites, but it brought the design up to date. Chrysler boasted of its tall 3.00:1 first gear for initial acceleration. Reverse was equal to the first gear to accommodate heavy loads. At the time it was launched, it had the widest range of gear ratios in its class; and its factory was brand new at launch.

The 545RFE has two overdrive gears that are fairly close to each other; engineer Bob Sheaves explained that this was because of the size available - the top 0.67:1 ratio gear was likely chosen because that was the largest one that could fit without making the transmission too large for the company's vehicles.

Some models had a "Tow/Haul" mode made faster shifts to cut wear on the transmission, and reduced gear searching by holding lower gears longer, also choosing lower gears when going downhill to increase engine braking.

In 2006, Chrysler claimed that the transmission had been "refined for higher-quality shifts;" it was strong enough to give the Jeep Commander and Grand Cherokee class-leading towing capacity of 7,200 lbs. The changes included a redesigned solenoid for quieter shifting (ending "solenoid clatter"), and a turbine damper to cut noise and vibration from the torque converter.

The computer controlled 545RFE was kept in a shiny, one-piece die-cast aluminum casing, ribbed for increased torsional rigidity. It took 6.2 liters (6.6 quarters) of ATF+4 fluid; early units could take ATF+3.

Gear ratios were aimed at providing reserve torque. The transmission was well suited for the large torque band of the Hemi V8, 3.7 V6, 4.7 V8, and VM 2.8 diesel.

In 2009, the computer was programmed to let drivers select the highest gear the transmission would shift to, for easier towing, hill climbing, and hill descent.

Six speeds: 68RFE and 65RFE automatics

In 2012, Chrysler launched three new six-speeds, all based on the 545RFE. The first out of the gate was the 68RFE, a heavier-duty automatic created essentially by using a similar clutch and hydraulic control system, with different planetary gears. Numerous parts, including the various shafts and clutches, gears, and the torque converter, were redesigned to handle the high torque of the Cummins 6.7 liter diesel. Pump capacity was increased to deal with heat more effectively.

Designed to work with the Cummins engine, the 68RFE has a lower first gear than the 545 for better launches, giving it a wider spread of ratios. The torque converter clutch is engaged in every forward gear but first, based on factors such as temperature, gear, tow/haul mode, exhaust brake activation, etc. The transmission was designed to include electronic range selection, and weighs 263 pounds.

The next six speed derived from the 545RFE was the 65RFE, used with V8 versions of the Ram 1500, Durango, and Grand Cherokee. The 65RFE only has six forward gears in ERS/AutoStick mode or kickdown mode; it is essentially a software and name change, which allows people to reach the "prime" gear via ERS as well as than kickdown. An internal Chrysler communiqué to dealers summarized the change in a similar fashion.

The 66RFE is a new transmission based on the same basic core as the 545RFE. It is similar to the 68RFE in basic construction, but differs in duty rating; for some of the possible differences, see the 68RFE page. Gearing is identical to the 68RFE.

1 3.593.003.23
6 .0670.625

You can draw a straight line from the original three-speed TorqueFlite to the current six-speed pickup automatics, but there are many differences in capability, control, and gearing, which have kept them up-to-date. While they are being pushed into niches by new generations of automatic transmissions, including the ZF eight-speed (which took over its Jeep uses), they still have a place in Ram trucks.

* On 545RFE, 3rd is only accessible via kickdown in some situations, and is referred to as "2 prime."
On 65RFE, 3rd is only accessible via kickdown in some situations and use of manual override.
** Chrysler specified a 2.21:1 reverse gear in some applications, including the Jeep Liberty diesel.


Chrysler 1904-2018

Spread the word via <!--Tweet or--> Facebook!

We make no guarantees regarding validity or accuracy of information, predictions, or advice - .
Copyright © VerticalScope Inc. All rights reserved. Dodge, Jeep, Chrysler, Ram, and Mopar are trademarks of Fiat Chrysler Automobiles.

1 - 1 of 1 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.