66RFE Shift Kit 1999-18, new and ready to install. Fits the 66RFE. Ships fast from the USA.
The 66RFE sits behind the gas Hemi in heavy-duty Rams: the 2012-2018 Ram 2500 and Power Wagon with the 5.7L, the 3500 chassis cab with the 5.7L, and from 2014 the Ram 2500 with the 6.4L. Those trucks tow and plow, and the complaints that lead owners to this kit are a lockup that thumps in under load, converter clutch slip codes, and overdrive clutches that burn up a second time after a rebuild. This is the TransGo SK 45RFE-A. TransGo catalogs it for every 45RFE, 545RFE, 65RFE, 66RFE and 68RFE from 1999 to 2018, but on a 66RFE the real coverage is 2012-2018, because that is when the 66RFE was built.
The 66RFE is a hybrid. It uses a 545RFE-style case with the heavier internals and gearset of the diesel 68RFE, so it carries Cummins-sized clutch hardware with a gas engine in front of it. Shift timing and clutch pressure are commanded by the computer through the solenoid block, which means a kit cannot simply turn up pressure. What it does is restore the oil that leaks away inside a worn unit. The key piece is a new self-cleaning low/reverse solenoid switch valve with its end plug. That valve lets one solenoid run the low/reverse clutch in first gear and then hand the same solenoid to the converter clutch. A worn bore lets those two circuits cross-feed, which shows up as erratic lockup and switch valve codes. The rest of the kit backs that up: a heavy-duty accumulator cover, accumulator seals, a spacer washer and two spare springs for the overdrive accumulator, revised converter clutch accumulator springs, a drop-in converter limit valve system for the pump, and a stronger flat snap ring for the underdrive/overdrive pressure plate.
Start with a scan. If the codes point to switch valve or pressure switch faults and the solenoids measure good, the hydraulics in this kit are a reasonable target. Electrical faults belong to the solenoid block instead, which our RFE solenoid testing guide explains step by step. If the truck will not reach top gear or keeps falling back to a limp gear, read why an RFE won't shift into overdrive to separate strategy from real failure. Sonnax lists the switch valve and its bore plug among the first areas to check when an RFE overdrive clutch fails, which is why this kit replaces both.
Fits 2012 through 2018 66RFE transmissions. It is not for 2019 and later 66RFE trucks, which moved to a blue-connector solenoid pack with separate converter clutch and reverse solenoids. Transmission Digest also describes a gray connector generation that dropped the overdrive solenoid, so note your pass-through connector color. Then count the check balls in the valve body and measure the switch valve; TransGo offers RFE switch valves in .420 and .453 inch sizes. Not sure what is in your truck? Send us the year and VIN. More parts for this unit are on our 66RFE parts page.
| Fits | 66RFE 1999-18 |
| Part type | Shift Kit |
| Condition | New |
| Brand | TransGo |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
2012-2018 Ram 2500 and Power Wagon with the 5.7L Hemi, the 3500 chassis cab with the 5.7L, and the Ram 2500 with the 6.4L Hemi from 2014.
Yes, the SK 45RFE-A covers both the 66RFE and 68RFE. The 66RFE shares many internals with the 68RFE, but your truck's years run 2012-2018, not 2007-2018.
It reduces the pressure leaks that let the converter clutch and overdrive clutch slip under load. It will not fix clutches that are already burnt.
No. 2019 and later units use a blue-connector pack and a separate converter clutch solenoid, so they need a different kit.
A gasket and seal kit, new filters, ATF+4, and new frictions if any clutch pack is worn. A scan tool is needed for the quick learn.
